| 1. |
- Duda, N, et al.
(författare)
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Multiple maternity in black-headed gull Larus ridibundus clutches as revealed by protein fingerprinting
- 2008
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 39:1, s. 116-119
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Tidskriftsartikel (refereegranskat)abstract
- Social monogamy with biparental care is the norm in gulls Laridae, but egg colour variation suggests that some nests may contain mixed clutches laid by more than one female. Here we use protein fingerprinting of egg albumen to assess the occurrence of mixed maternity clutches in three colonies of black-headed gulls. Among 160 analysed clutches with >1 egg, 34% contained eggs from more than one female, and 15% of the eggs in clutches >1 came from other females than the major female (laying most eggs in nest). Among clutches with 2–3 eggs 28% were mixed, and among clutches with 4 or more eggs 89% contained eggs from two or more females. There were significantly fewer eggs from the major female in mixed nests (mean=2.06±0.63 SD) than in non-mixed nests (mean=2.82±0.43 SD). In nests without evidence of female conflict, hatching success of minority eggs was similar to that of eggs from the major female (12.5 and 8.4%, respectively). In 21% of mixed maternity nests, one or more minority eggs was buried or punctured, and 25% of eggs from major females were also found evicted, suggesting conflict between females and rejection of eggs. Intra-specific nest parasitism seems the most likely cause of mixed clutches, but there are also other possible causes.
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| 2. |
- Isaksson, Caroline, 1976, et al.
(författare)
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Carotenoid diet and nestling provisioning in urban and rural great tits Parus major
- 2007
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 38:5, s. 564-572
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Tidskriftsartikel (refereegranskat)abstract
- Considering the importance of dietary constraints for the widely held view of carotenoid pigmentation as an honest quality indicator, there is surprisingly little data on carotenoid availability in different natural diets or along environmental gradients. Here we investigate the carotenoid availability in the main diet of breeding great tits Parus major, living in urban and rural environments with known differences in carotenoid pigmentation. Carotenoid availability for nestling great tits was investigated in two respects: (1) quantity and quality of diet (i.e., caterpillar abundance and their carotenoid concentration), and (2) parental feeding frequency. First, caterpillars were generally more abundant in the urban environment and the four common Lepidoptera (i.e., caterpillars) genera studied were also heavier here. Second, as determined by HPLC analysis of the caterpillar genera, carotenoid concentration was significantly lower in the urban caterpillars. Furthermore, all except one of the caterpillar genera had higher lutein/zeaxanthin ratio in urban areas, which is in accordance with earlier studies of carotenoid composition in great tit yolk. Third, parental feeding frequency was about twice as high to urban broods compared to rural broods. This result may simply reflect the higher caterpillar abundance (shorter search time) in the urban environment. Poor food quality (low carotenoid concentration) seems therefore to be compensated by quantity in the urban environment. As a consequence the carotenoid availability seems to be similar for nestlings in the two environments.
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| 3. |
- Round, P D, et al.
(författare)
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Lost and found: the enigmatic large-billed reed warbler Acrocephalus orinus rediscovered after 139 years
- 2007
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 38:2, s. 133-138
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Tidskriftsartikel (refereegranskat)abstract
- We present compelling evidence of the continued existence of the large-billed reed warbler Acrocephalus orinus, hitherto known only from the unique type specimen collected in NW India 139 years ago. Morphological and genetic analyses of an unusual Acrocephalus warbler mist-netted south-west of Bangkok, Thailand, on 27 March 2006, confirmed its identity as A. orinus, and revealed that it was heterozygous at four out of eight microsatellite markers, indicating the continued existence of a viable population whose breeding and wintering areas are still unknown.
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| 4. |
- Bensch, Staffan, et al.
(författare)
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Patterns of stable isotope signatures in willow warbler Phylloscopus trochilus feathers collected in Africa
- 2006
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 37:4, s. 323-330
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We conducted stable isotope analyses of nitrogen and carbon on feathers obtained from willow warblers in Africa to find an explanation for a previously observed pattern of different delta N-15 and delta C-13 values across a migratory divide in central Scandinavia. A new data set confirms that north Scandinavian birds of the subspecies P. t. acredula have higher delta N-15 values than south Scandinavian birds of the subspecies P. t. trochilus. In Africa, we found significant differences for both delta N-15 and delta C-13 values among feathers collected from major geographical regions as well as between countries within regions. Isotope signatures of delta N-15 and delta C-13 in Scandinavian acredula matched well with those of willow warblers sampled in southern parts of Africa, but differed from samples obtained in East and West Africa. Isotope signatures in Scandinavian trochilus did not agree with the pattern in any of the three African regions (West, East or South). However, a more detailed analysis of the isotopic data in feathers from countries within West Africa, which is the wintering region of Swedish trochilus based on ringing recoveries, revealed a correspondence with samples from Liberia, the Ivory Coast and Nigeria.
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| 5. |
- Eeva, T, et al.
(författare)
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Pollution related effects on immune function and stress in a free-living population of pied flycatcher Ficedula hypoleuca
- 2005
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 36:5, s. 405-412
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether exposure to heavy metal pollution affected the immune function of individuals in a free living population of a small insectivorous passerine bird, the pied flycatcher Ficedula hypoleuca. We measured humoral immune responses in two study areas: a polluted area in the vicinity of a copper smelter and a control area far from the smelter. Plasma corticosterone level and blood heterophil/lymphocyte ratio (H/L) were used as more general physiological measures of stress. The immune response of F hypoleuca was not suppressed by pollution stress. In contrast, we found that F hypoleuca males showed stronger Immoral immune responses to a novel antigen (tetanus toxoid) in the polluted environment than in the unpolluted one. After the immunization of males, numbers of lymphocytes rose significantly more in the polluted area, leading to a smaller H/L ratio than in males from the control area. Females showed no pollution related effects on their immune responses. Corticosterone levels of males and nestlings were not related to pollution levels. Nestlings showed somewhat higher H/L ratios and lower fledging success in the polluted area, both factors indicating increased stress levels in a polluted area. Our results suggest that Immoral immune response of male F hypoleuca may be enhanced under moderate levels of heavy metal Pollution. Enhanced immune function may, however, also be costly for birds and the higher humoral immune responses in polluted areas may thus have negative effects on the birds' breeding performance and survival.
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| 6. |
- Green, Martin, et al.
(författare)
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Do Arctic waders use adaptive wind drift?
- 2004
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 35:4, s. 305-315
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Tidskriftsartikel (refereegranskat)abstract
- We analysed five data sets of night directions of migrating arctic waders ill relation to,winds, recorded by tracking radar and optical range finder, in order to find out if these birds compensate for wind drift, or allow themselves to be drifted by winds. Our purpose was to investigate whether arctic waders use adaptive wind drift strategies or not. The data sets were collected in Siberia (two sets) and Canada during post-breeding (autumn) migration, and in Mauritania and South Sweden during pre-breeding (spring) migration. Both significant drift and compensation effects were found in three of the data sets, Canada, Mauritania and South Sweden. Almost no compensation was found in birds departing in easterly directions from the Siberian tundra (complete drift), while no drift effect was found in birds departing in westerly directions (complete compensation). There were indications that at least some populations of waders may use an adaptive drift strategy consisting of drift at high altitude and/or in high wind speed combined with compensation at low altitude and/or in lower wind speeds, but support for this idea was rather weak and not consistent. Our results were instead more in accordance with the adaptive drift theory that predicts initial drift during the migratory journey, followed by compensation during later stages as the birds are approaching their destinations. Such a strategy implies that arctic waders, at least adult birds, have the capacity of true navigation. A comparison with earlier studies of migrating arctic waders from different parts of the world show that all results so far may be interpreted in accordance with this general adaptive drift strategy An element of non-adaptive drift can, however, not be completely ruled out.
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| 7. |
- Hedenström, Anders
(författare)
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Flying with holey wings
- 2003
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 34:4, s. 324-327
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Neto, Julio, et al.
(författare)
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Using stable isotope analysis to determine the winter moult extent in migratory birds: the complex moult of Savi’s Warblers Locustella luscinioides.
- 2006
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 37:1, s. 117-124
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Tidskriftsartikel (refereegranskat)abstract
- Patterns of feather wear in birds captured in spring have traditionally been analysed to describe the extent of winter moult in long-distance migrants. However, the interpretation of feather wear may be rendered extremely difficult due to long moult periods, by the progress of the season, and by the existence of complex moult patterns. Here, stable isotope analysis is used to determine the origin of the wing feather generations present in Savi’s warblers Locustella luscinioides captured in Portugal. Carbon, nitrogen and hydrogen isotope ratios of feathers of known European origin differed significantly from those known to have grown in Africa. A discriminant analysis, in which 91.1% of the cross validated samples were correctly classified, was used to determine the origin of tail and wing feathers collected from birds caught when they returned to the breeding quarters. The interpretation of feather-wear generally agreed with the stable isotope analysis, but some inconsistencies were identified. The extent of winter moult in Savi’s warblers is described and its moult strategy discussed.
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| 9. |
- Nilsson, Jan-Åke, et al.
(författare)
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Does the strength of an immune response reflect its energetic cost?
- 2007
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 38:4, s. 488-494
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Tidskriftsartikel (refereegranskat)abstract
- The energetic cost of immune responses has been proposed to be an important basis for trade-offs between life-history traits, such as between survival and reproduction. A critical assumption of this hypothesis is that the magnitude of the energetic cost increases with the strength of an immune response, so that energy can be saved by partly suppressing a response. Here, we test this assumption experimentally. The immune system of great tits Parus major was experimentally activated by injecting different doses of phytohemagglutinin (PHA) in the wing web. We found the resting metabolic rate of immune challenged birds to increase by 5%. However, although great tits injected with a high dose had a stronger immune response, this was not paralleled by a higher metabolic rate. Thus, we found the energetic cost of the immune response to be relatively low and not dose-dependent. This suggests to us that the energetic cost of immune responses cannot form the basis for trade-offs between life-history traits.
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| 10. |
- Nilsson, Jan-Åke, et al.
(författare)
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Leafing phenology and timing of egg laying in great tits Parus major and blue tits P-caeruleus
- 2006
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 37:4, s. 357-363
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the importance of tree leafing for the start of laying and clutch size of birds, we compared the breeding phenology of great tits Parus major and blue tits P. caeruleus between one coastal and two inland sites in the same geographical region. Because of the cooling influence of the sea, trees at the coastal site were known to initiate budburst about a week later than at the inland sites. During 5 years, breeding by the tits and the leaf phenology of birch Betula pendula, and oak Quercus robur were monitored. The leaf phenology of birch and oak explained a significant part of the between-year variation in the start of egg laying in blue and great tits, respectively. The tits started laying earlier at the sites with an early budburst, i.e. normally inland. However, leaf phenology was not an absolute cue to the start of laying, since blue tits laid earlier relative to leafing at the inland site than at the coastal site, and both tit species laid eggs earlier relative to leafing during late springs. In neither species was clutch size affected by leafing phenology. However, great tit females at the coastal site consistently produced fewer eggs than did those at the inland site. No such difference was found in the blue tits. Although leafing phenology may predict the start of laying in tits, other factors also influence its timing. These factors might include other cues, or differing life-history trade-offs depending on site or general climatic factors during the spring.
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| 11. |
- Sandell, Maria, et al.
(författare)
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Pre-breeding diet affects the allocation of yolk hormones in zebra finches Taeniopygia guttata
- 2007
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 38:3, s. 284-290
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Tidskriftsartikel (refereegranskat)abstract
- The ability of mothers to modify offspring phenotype to match prevailing environmental conditions is an important component of reproductive success, especially in variable environments. Pre-breeding conditions, such as food abundance, may have significant consequences for both the number and quality of offspring a female produces as well as her ability to rear the offspring. In an experiment where pre-breeding diet was manipulated, we investigated if allocation of yolk androgens (testosterone and 5 alpha-dihydrotestosterone) was related to the quality of diet experienced prior to breeding. Female zebra finches Taeniopygia guttata produced larger clutches on high quality diet than on low quality diet but with no differences in egg mass. Yolk androgen levels were repeatable within subsequent clutches of the same female and females did not change mean androgen content in eggs in relation to diet quality. However, within-in Clutch pattern of yolk testosterone and DHT changed with diet treatment. Testosterone and DHT decreased with laying order on the low quality diet but remained constant on the high quality diet. Differential yolk androgen allocation within the clutch may alter the competitive differences between chicks and provide females the possibility to adjust reproductive investment and offspring phenotype already at the egg stage.
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| 12. |
- Stervander, Martin, et al.
(författare)
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Timing of spring migration in birds: long-term trends, North Atlantic Oscillation and the significance of different migration routes
- 2005
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 36:3, s. 210-221
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Tidskriftsartikel (refereegranskat)abstract
- We studied long-term trends and the yearly variation in mean spring passage time in 36 passerine bird species trapped at Ottenby Bird Observatory in south-eastern Sweden. Between the years 1952-2002, data were available for 22-45 years depending on species. Most long-distance migrant species passed progressively earlier over the study period (range: 2.5 days earlier to 0.7 days later per 10 years, with an average of 0.9 days earlier per 10 years). The annual variation in timing of migration in most species, regardless of migration distance, correlated negatively with the winter index of the North Atlantic Oscillation (NAO), a large-scale climate phenomenon influencing the climate in the North Atlantic region. Birds passed earlier after mild and humid winters., corresponding to the high phase of the NAO. This corroborates the pattern round at a nearby migration site with a comparable dataset (Helgoland, 600 km WSW of Ottenby). However, short/medium-distance migrant species at Otterby, in contrast to the situation at Helgoland, have shown no general trend of earlier passage in recent years. This was probably a consequence of the shorter study period at Ottenby, which included only the last 22-32 years (41 years at Helgoland), when the NAO showed no significant trend. At the species-specific level, the long-term trends in passage time were similar at the two sites, and there was some congruence to the extent that a given species was affected by NAO. Long-distance migrants wintering south and south-east of the breeding grounds showed some of the strongest changes in long-term trends (passing progressively earlier) at Ottenby, and for some of these species passage time varied negatively with NAO. Obviously, and contrary to previous suggestions, variations in NAO also influence birds migrating through eastern Europe, although the direct or indirect mechanisms through which this is achieved are unknown.
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| 13. |
- Sunde, Peter, et al.
(författare)
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Diurnal exposure as a risk sensitive behaviour in tawny owls Strix aluco?
- 2003
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 34:4, s. 409-418
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Tidskriftsartikel (refereegranskat)abstract
- Tawny owls Strix aluco generally roost in cryptic locations during the day. To test the hypothesis that this cryptic behaviour is an effort to avoid mobbers or avian predators, we measured diurnal behaviour and cause-specific mortality of radio-tagged birds. Non-breeding adults (assumed to be well fed individuals, optimising their own survival) roosted in less exposed locations than adults with young and newly independent juveniles. Parents roosted in the most exposed sites when their young were immature and vulnerable to depredation, probably to guard offspring. Newly independent juveniles apparently selected roosting sites in exposed places to get access to food, as this behaviour was associated with lower perching heights and higher prey abundance beneath their roosting sites. They also perched in more exposed sites, closer to the ground, in summers with low prey abundance compared to summers with high prey abundance. After previous encounters with goshawks Accipiter gentilis, dependent juveniles roosted in less exposed places compared to other young. The increased risk of being mobbed was highly significant with increasing roosting exposure. Once an owl was mobbed, the intensity of the mobbing correlated positively with the mass of the mobbers, but mobbing birds never killed any owls. In contrast, diurnal raptors caused 73% of natural owl deaths (n = 15) and the depredation rate by raptors was 3.8 times higher in population classes that generally roosted in more exposed locations than did non-breeding adults. We therefore suggest that depredation by diurnal raptors is the main factor shaping the diurnal behaviour of tawny owls.
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| 14. |
- Weimerskirch, H, et al.
(författare)
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Postnatal dispersal of wandering albatrosses Diomedea exulans: implications for the conservation of the species
- 2006
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 37:1, s. 23-28
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Tidskriftsartikel (refereegranskat)abstract
- Many large marine vertebrates are today threatened by human activities and it is therefore crucial to obtain information on their distribution and behaviour at sea. In particular little is known about the time necessary for juveniles to acquire the foraging skills of adults. We tracked 13 juvenile wandering albatrosses Diomedea exulans by satellite telemetry during their first year at sea. They covered an average distance of 184,000 km during the first year and restricted their dispersal to the unproductive waters of the subtropical Indian Ocean and Tasman Sea. This region of low wind velocities does not overlap with the foraging areas used by adults. After an innate phase of rapid dispersal with a fixed flight direction, young birds progressively increased their daily flight distances and attained adult flight efficiency within their first six months at sea. The complete overlap of the juveniles' foraging ranges with major long-line fisheries in the subtropical waters constitutes a major threat that could jeopardize the long term recovery ability of populations of the endangered wandering albatross in the Indian Ocean.
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| 15. |
- Zehnder, Susanna, et al.
(författare)
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Nocturnal autumn bird migration at Falsterbo, South Sweden
- 2001
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 32:3, s. 239-248
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the patterns of nocturnal bird migration in autumn 1998 at a coastal site on the Falsterbo peninsula in south-western Sweden, by means of a passive infrared device. In total 17 411 flight paths, including track direction and altitude, of migrating birds were recorded for 68 nights from August to October. Mean migratory traffic rate per night varied between 6 and 6618 birds km1 h1, with an average of 1319 birds km1 h1. Migration at Falsterbo showed a similar seasonal pattern to that reported for central Europe, with pronounced peaks of migration and intermittent periods with relatively low migratory intensities. Weather factors explained two thirds of the variance in the intensity of bird migration. During nights with intense migration, associated with weak winds, the mean track direction was close to that in central western Europe (225). Birds usually maintained a constant heading independent of wind directions and, in consequence, were drifted by the wind. The mean orientation clearly differed from that of the nearest coastline, suggesting that the birds did not use the topography below to compensate for wind drift.
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| 16. |
- Ådahl, Emma, et al.
(författare)
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Can intraspecific brood parasitism be detected using egg morphology only?
- 2004
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 35:4, s. 360-364
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Tidskriftsartikel (refereegranskat)abstract
- Intraspecific brood parasites lay their eggs in the nests of conspecifics. There are a number of methods for detecting intraspecific brood parasitism (IBP) in birds based on egg morphology. Here we test Eadie's (1989) method, which calculates the Euclidean distances between eggs in a given clutch in a three-dimensional space (weight, length and width). A parasitised clutch is predicted to contain an egg (or eggs) that is significantly different from the clutch's other eggs. Data from three species were analysed. Our captive zebra finch Taeniopygia guttata clutches did not include any instances of IBP, the wild jackdaw Corvus monedula data were unlikely to contain any, and for the goldeneye Bucephala clangula data set we had an observational estimate of IBP. We simulated IBP in the zebra finch, jackdaw and goldeneye data to test whether the method reliably detects an experimentally 'parasitised' clutch. We show that the distributions of the test statistics greatly overlap in 'parasitised' and unmodified clutches, and are dependent on the clutch size. We therefore conclude that the method can only be used with caution, after calibrating it for a given population.
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| 17. |
- Åkesson, Mikael, et al.
(författare)
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Genetic and phenotypic associations in morphological traits: a long term study of great reed warblers Acrocephalus arundinaceus
- 2007
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 38:1, s. 58-72
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Tidskriftsartikel (refereegranskat)abstract
- We present estimates of standardized selection (directional and quadratic) differentials via reproductive success on eight morphological traits in a newly founded long-term study population of great reed warblers Acrocephalus arundinaceus in Sweden. In order to predict the evolutionary response to selection in these traits we present estimates of heritabilities (h(2)), phenotypic (r(P)) and genetic (r(A)) correlations among the same traits. We also examined the extent of parental effects in the expression of the phenotypic traits. Overall, the population is subject to low levels of directional selection and higher levels of stabilizing selection. This makes us predict that the population is changing very little if anything, even though h(2) in many cases are considerable. Midparent-midoffspring h(2) ranged from 0.14 and 0.94 (mean 0.58) and were significant for seven of eight traits. We found indications of positive maternal effects in tarsus length. Phenotypic correlations between traits ranged from 0.02 to 0.43 (mean 0.15) and showed generally much lower values than the corresponding genetic correlations that ranged between 0.08 and 1.04 (mean 0.46). Overall, the correlation between r(P) and r(A) was significant, although moderate, but they tended to differ in magnitude, possibly due to overestimation of additive covariance between traits.
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| 18. |
- Ericson, Per G P, 1956-, et al.
(författare)
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Inter-generic relationships of the crows, jays, magpies and allied groups (Aves: Corvidae) based on nucleotide sequence data
- 2005
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 36:3, s. 222-234
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Tidskriftsartikel (refereegranskat)abstract
- Phylogenetic relationships were studied based on DNA sequences obtained from all recognized genera of the family Corvidae sensu stricto. The aligned data set consists 2589 bp obtained from one mitochondrial and two nuclear genes. Maximum parsimony, maximum-likelihood, and Bayesian inference analyses were used to estimate phylogenetic relationships. The analyses were done for each gene separately, as well as for all genes combined. An analysis of a taxonomically expanded data set of cytochrome b sequences was performed in order to infer the phylogenetic positions of six genera for which nuclear genes could not be obtained. Monophyly of the Corvidae is supported by all analyses, as well as by the occurrence of a deletion of 16 bp in the β-fibrinogen intron in all ingroup taxa. Temnurus and Pyrrhocorax are placed as the sister group to all other corvids, while Cissa and Urocissa appear as the next clade inside them. Further up in the tree, two larger and well-supported clades of genera were recovered by the analyses. One has an entirely New World distribution (the New World jays), while the other includes mostly Eurasian (and one African) taxa. Outside these two major clades are Cyanopica and Perisoreus whose phylogenetic positions could not be determined by the present data. A biogeographic analysis of our data suggests that the Corvidae underwent an initial radiation in Southeast Asia. This is consistent with the observation that almost all basal clades in the phylogenetic tree consist of species adapted to tropical and subtropical forest habitats.
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| 19. |
- Irestedt, Martin, et al.
(författare)
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Evolution of the ovenbird-woodcreeper assemblage(Aves: Furnariidae) - major shifts in nest architecture and adaptive radiation
- 2006
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 37:3, s. 260-272
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Tidskriftsartikel (refereegranskat)abstract
- The Neotropical ovenbirds (Furnariidae) form an extraordinary morphologically and ecologically diverse passerine radiation, which includes many examples of species that are superficially similar to other passerine birds as a resulting from their adaptations to similar lifestyles. The ovenbirds further exhibits a truly remarkable variation in nest types, arguably approaching that found in the entire passerine clade. Herein we present a genus-level phylogeny of ovenbirds based on both mitochondrial and nuclear DNA including a more complete taxon sampling than in previous molecular studies of the group. The phylogenetic results are in good agreement with earlier molecular studies of ovenbirds, and supports the suggestion that Geositta and Sclerurus form the sister clade to both core-ovenbirds and woodcreepers. Within the core-ovenbirds several relationships that are incongruent with traditional classifications are suggested. Among other things, the philydorine ovenbirds are found to be non-monophyletic. The mapping of principal nesting strategies onto the molecular phylogeny suggests cavity nesting to be plesiomorphic within the ovenbird–woodcreeper radiation. It is also suggested that the shift from cavity nesting to building vegetative nests is likely to have happened at least three times during the evolution of the group. We suggest that the shifts in nest architecture within the furnariine and synallaxine ovenbirds have served as an ecological release that has facilitated diversification into new habitats and new morphological specializations.
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| 20. |
- Irestedt, Martin, et al.
(författare)
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Phylogenetic relationships of woodcreepers (Aves: Dendrocolaptinae) - incongruence between molecular and morphological data
- 2004
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Ingår i: Journal of Avian Biology. - : Blackwell. - 1600-048X .- 0908-8857. ; 35:3, s. 280-288
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Tidskriftsartikel (refereegranskat)abstract
- The woodcreepers is a highly specialized lineage within the New World suboscine radiation. Most systematic studies of higher level relationships of this group rely on morphological characters, and few studies utilizing molecular data exist. In this paper, we present a molecular phylogeny of the major lineages of woodcreepers (Aves: Dendrocolaptinae), based on nucleotide sequence data from a nuclear non-coding gene region (myoglobin intron II) and a protein-coding mitochondrial gene (cytochrome b). A good topological agreement between the individual gene trees suggests that the resulting phylogeny reflects the true evolutionary history of woodcreepers well. However, the DNA-based phylogeny conflicts with the results of a parsimony analysis of morphological characters. The topological differences mainly concern the basal branches of the trees. The morphological data places the genus Drymornis in a basal position (mainly supported by characters in the hindlimb), while our data suggests it to be derived among woodcreepers. Unlike most other woodcreepers, Drymornis is ground-adapted, as are the ovenbirds. The observed morphological similarities between Drymornis and the ovenbird outgroup may thus be explained with convergence or with reversal to an ancestral state. This observation raises the question of the use of characters associated with locomotion and feeding in phylogenetic reconstruction based on parsimony.
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| 21. |
- Cresswell, Will, et al.
(författare)
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Ringing or colour-banding does not increase predation mortality
- 2007
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 38:3, s. 309-316
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Tidskriftsartikel (refereegranskat)abstract
- The use of metal and colour-rings or bands as a means of measuring survival, movements and behaviour in birds is universal and fundamental to testing ecological and evolutionary theories. The practice rests on the largely untested assumption that the rings do not affect survival. However this assumption may not hold for several reasons, for example because the ‘oddity effect’ predicts predators select prey that appear different to their neighbours in order to avoid the ‘confusion effect’. We compared the foraging behaviour and the death rates of redshanks Tringa totanus conspicuously marked with six colour rings and one metal ring each to unmarked birds in a study system, where routinely up to 50% of the total population are killed by avian predators during a winter. If avian predators selectively target and/or have a higher capture success of ringed birds then we would predict the proportion of colour-ringed birds in the population to decline through a winter. The proportion of colour-ringed birds in the population did not change over the course of three separate winters, and in one winter the ratio of marked:unmarked birds found killed by sparrowhawks Accipiter nisus was the same as the ratio of marked birds alive in the population. In the year with largest sample size, power was sufficient to detect a greater than 2.2% difference in predation rate between ringed and unringed groups. The average kill rate difference between ringed and unringed birds across the three winters was less than 1% (0.73±2.2%) suggesting that even if there were differences in predation rate that were not detected because of low statistical power they were extremely small. There were no differences in any foraging measures comparing ringed and unringed birds, suggesting that the rings did not affect the ability of birds to meet their daily energy budgets. The results showed that colour-ringed birds were not preferentially targeted or killed by avian predators, and suggest that the presence of a metal and even several large colour-rings is unlikely to affect behaviour and predation mortality even under extreme selection.
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| 22. |
- Ekman, Jan
(författare)
-
Family living among birds.
- 2006
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 37, s. 289-298
-
Tidskriftsartikel (refereegranskat)
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| 23. |
- Grønstøl, Gaute, 1968, et al.
(författare)
-
The importance of genetic evidence for identifying intra-specific brood parasitism
- 2006
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 37:2, s. 197-199
-
Tidskriftsartikel (refereegranskat)abstract
- Intra-specific brood parasitism is widespread among birds. When genetic evidence is not available, criteria like super-normal clutch size, high within-clutch variance in egg morphology, and shorter than normal laying intervals have been used to identify parasitized broods. Here we report genetically determined parentage of a clutch of super-normal size in a species with fixed clutch size, the northern lapwing Vanellus vanellus. Results from multi-locus DNA fingerprinting revealed no loss of parentage in this brood. Furthermore, no loss of parentage was found in another clutch with a high variance in egg size and colouration. These findings add to previous evidence that reliable classification of brood parasitism requires molecular analysis.
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| 24. |
- Post, P., et al.
(författare)
-
Predation by sparrowhawks Accipiter nisus on male and female pied flycatchers Ficedula hypoleuca in relation to their breeding behaviour and foraging
- 2006
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 37:2, s. 158-168
-
Tidskriftsartikel (refereegranskat)abstract
- Bright plumage, song display, and aggressive resource defence in males may cause higher predation on males than on females during the breeding season. However, in birds, higher predation on females is sometimes observed. Parental investment may be high in females (egg-laying, incubation and feeding of offspring), which might lead to a high risk of predation. We studied predation by sparrowhawks Accipiter nisus in relation to behaviour in pied flycatchers Ficedula hypoleuca where breeding males are more conspicuous than females in plumage and behaviour. Male pied flycatchers generally occupied more exposed perches than females. Females were more mobile and foraged more than males, especially prior to and during incubation. During the incubation and nestling stages, when predation on the sexes could be directly compared, sparrowhawks took about the same number of male and female pied flycatchers. During incubation, however, females spent about 77% of the day in the nest and were 4.7 times more vulnerable than males per unit of time available (i.e. outside the nest). A comparison with the chaffinch Fringilla coelebs, where hawks took more females than males, indicates that timing of breeding, foraging behaviour and parental roles of males and females affect predation risk.
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| 25. |
- Hasselquist, Dennis, et al.
(författare)
-
Daily energy expenditure of singing great reed warblers Acrocephalus arundinaceus
- 2008
-
Ingår i: Journal of Avian Biology. - 0908-8857. ; 39:4, s. 384-388
-
Tidskriftsartikel (refereegranskat)abstract
- According to honest signalling theory, signals must be costly to produce to retain information about the signaller's quality. The song produced by male birds during breeding is a vocal "ornament" used for intra- and inter-sexual purposes. The energetic cost of this vocal signal remains a contentious issue. We used the doubly labelled water method to measure field metabolic rate by estimating CO2 production and then convert this to daily energy expenditure (DEE) in great reed warbler males singing under natural conditions (10 at low to moderate intensity and 7 at very high intensity from dawn to dusk). There was a significant positive relationship between singing intensity and DEE. From this relationship we extrapolated the average DEE for intensely singing males (i.e., males producing song sounds 50% of the time and hence sitting at their elevated song post in the top of a reed stem more or less continuously throughout the similar to 20 h of daylight) to 3.3xBMR (basal metabolic rate) and for non-singing males to 2.2xBMR. The mean DEE measured for the seven males singing with very high intensity was 3.1xBMR. The maximum measured DEE for a single male was 3.9xBMR, i.e. close to the maximum sustainable DEE (4xBMR), and the minimum DEE was 2.1xBMR for a male singing at very low intensity. These results imply that producing intensive advertising song in birds may incur a substantial cost in terms of increased energy expenditure.
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| 26. |
- Nilsson, Johan, et al.
(författare)
-
Experimental reduction of incubation temperature affects both nestling and adult blue tits Cyanistes caeruleus
- 2008
-
Ingår i: Journal of Avian Biology. - 0908-8857. ; 39:5, s. 553-559
-
Tidskriftsartikel (refereegranskat)abstract
- Incubation was for a long time considered to be a period of decreased activity and low cost for parents. It was therefore ignored as a potential factor affecting life-history trade-offs in birds. Lately this view has started to change, and studies now show that there might be considerable costs connected to incubation. We experimentally reduced the nest temperature during incubation in blue tits Cyanistes caeruleus, thus increasing the energetic cost of incubation, to test the importance of incubation as a component of reproductive costs and for nestling quality. While most other studies use brood size manipulation to manipulate reproductive costs, we were able to separate treatment effects acting during the incubation period from those acting on later reproductive performance by applying a cross-foster design. We were also able to isolate the effects of decreased incubation temperature on the nestlings from treatment effects acting on incubating females. We found no experimental effect on the length of the incubation period or on hatching success. The lower temperature during incubation, however, caused lower growth rates in nestlings and reduced chick rearing capacity in adults. We conclude that incubation is a costly period, with the potential to affect both the trade-off between current and future reproduction and the one between parental effort and offspring quality within the current breeding attempt.
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| 27. |
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| 28. |
- Adler, Sven
(författare)
-
Body mass change and diet switch tracked by stable isotopes indicate time spent at a stopover site during autumn migration in dunlins Calidris alpina alpina
- 2016
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 47, s. 806-814
-
Tidskriftsartikel (refereegranskat)abstract
- Birds may change their diet and foraging habitat during or after migration. Dunlins Calidris alpina alpina breed in the tundra of northern Europe and Russia where they feed exclusively on terrestrial prey. However, up to 80% of the flyway population uses the Wadden Sea as their first important staging site on the way to wintering grounds, feeding exclusively on marine prey. Adult birds migrate earlier than immatures and tend to fly non-stop, whereas immatures may stage for at least a few days en route, mainly in the Baltic region. There they mostly feed on brackish water prey showing similar isotopic values compared to terrestrial prey. When they arrive in the Wadden Sea, dunlin body reserves are depleted and lower than those of individuals that have already staged for several days. We hypothesized that lighter individuals should retain a strong terrestrial isotopic blood signature, while heavier ones should show a stronger marine signature. We found a significant positive correlation between scaled mass index and carbon (delta C-13) and nitrogen (delta N-15) stable isotopes, reflecting the switch from terrestrial to marine prey during migration. A mixing model revealed differences in isotopic values between heavy and light adults and immatures, respectively, in relation to the isotopic prey signatures. Adults showed stronger marine signals compared with immatures, emphasizing the different modes of migration (i.e. a later departure in immatures) as well as the known spatial segregation of age classes in the Wadden Sea, i.e. adults use tidal flats distant from the shore while immatures use coastal areas influenced by terrestrial carbon sources. The results of this study demonstrate the value of scaled mass index in migratory birds as an indicator of time elapsed after diet switching following migration. Furthermore, this study extents the existing knowledge on the timing of dunlin migration by using an isotopic approach.
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| 29. |
- Aguilar, J. Rivero De, et al.
(författare)
-
MHC-I provides both quantitative resistance and susceptibility to blood parasites in blue tits in the wild
- 2016
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 47:5, s. 669-677
-
Tidskriftsartikel (refereegranskat)abstract
- Major histocompatibility complex (MHC) genes are central for the adaptive immune response against parasites. Here, we investigated potential associations among MHC-I alleles and blood parasite infections in a natural breeding population of a passerine bird, the blue tit Cyanistes caeruleus, in central Spain. We screened both infection status (presence/absence of infection) and infection intensity to the pathogenic blood parasites Haemoproteus and Leucocytozoon. Three MHC-I alleles (UA104, UA108 and UA117) were associated with higher or lower infection intensities by Leucocytozoon. Interestingly, these associations were dependent on age and were found both among young and adult birds. No MHC alleles were associated with infection intensity by Haemoproteus parasites. In addition, no significant relationships were detected between infection status by Haemoproteus and Leucocytozoon infections and MHC alleles. The very high prevalence of these two parasites in our study population (79-100%) poses challenges to identify associations with infection status and also suggests that clearance of infections may be rare. In conclusion, associations between specific MHC-I alleles and Leucocytozoon parasites were related to either high or low infection intensities, and hence increased susceptibility or resistance to infection.
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| 30. |
- Allander, Klas, et al.
(författare)
-
Temporal variation and reliability of blood parasite levels in captive Yellowhammer males Emberiza citrinella
- 1997
-
Ingår i: Journal of Avian Biology. - : JSTOR. - 0908-8857 .- 1600-048X. ; 28:4, s. 325-330
-
Tidskriftsartikel (refereegranskat)abstract
- The temporal variation of blood parasites in captive Yellowhammer males was studied in order to investigate possible costs of parasites. Birds were caught in the wild in early April and kept in aviaries during the study period. Blood samples were taken, body mass measured, and moult was scored twelve times for the same individuals from April to October. Blood parasites were detectable in smears during the whole study period with an intensity peak coinciding with breeding in the wild. Young birds had more parasites and a consistently higher body mass than older birds. There was no relationship between parasite intensity and mass in older birds but possibly one in young birds. Parasites did not seem to affect moult in either age class. Repeatability of parasite counts of smears from the same individual was very high and smears are therefore a reliable method for estimating parasite intensity. We conclude that blood parasites are probably most severe during, but occur in their hosts long after, the breeding season. Possible costs of parasites outside the breeding season require further study.
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| 31. |
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| 32. |
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| 33. |
- Andreasson, Fredrik, et al.
(författare)
-
Experimentally increased nest temperature affects body temperature, growth and apparent survival in blue tit nestlings
- 2018
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 49:2
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal environment experienced by birds during early postembryonic development may be an important factor shaping growth and survival. However, few studies have directly manipulated nest temperature (T n) during the nestling phase, and none have measured the consequences of experimental heat stress on nestlings’ body temperature (T b). It is therefore not known to what extent any fitness consequences of development in a thermally challenging environment arise as a direct, or indirect, effect of heat stress. We, therefore, studied how experimentally increased T n affected T b in 8–12 d old blue tit Cyanistes caeruleus nestlings, to investigate if increased thermoregulatory demands to maintain normothermic T b influenced nestling growth and apparent long-term survival. Nestlings in heated nest-boxes had significantly higher T b compared to unheated nestlings during most of the experimental period. Yet, despite facing T n 50°C (as measured in the bottom of the nest cup below the nestlings), the highest nestling T b recorded was 43.8°C with nestlings showing evidence of controlled facultative hyperthermia without any increased nestling mortality in heated nests. However, body mass gain was lower in these nestlings compared to nestlings from control nest-boxes. Contrary to our prediction, a larger proportion of nestlings from heated nest-boxes were recaptured during their first winter, or subsequently recruited into the breeding population as first- or second-year breeders. This result should, however, be treated with caution because of low recapture rates. This study highlights the importance of the thermal environment during nestling development, and its role in shaping both growth patterns and possibly also apparent survival.
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| 34. |
- Arnold, KE, et al.
(författare)
-
Sex-biased hatching sequences in the cooperatively breeding Noisy Miner
- 2001
-
Ingår i: JOURNAL OF AVIAN BIOLOGY. - : MUNKSGAARD INT PUBL LTD. - 0908-8857. ; 32:3, s. 219-223
-
Tidskriftsartikel (refereegranskat)abstract
- The Noisy Miner Manorina melanocephala (Meliphagidae) is a cooperatively breeding bird species in which sons often remain on their natal home ranges and help one or both of their parents. In a population of Noisy Miners in SE Queensland, Australia, a mole
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| 35. |
- Barani-Beiranvand, Hossein, et al.
(författare)
-
Phylogeny of penduline tits inferred from mitochondrial and microsatellite genotyping
- 2017
-
Ingår i: Journal of Avian Biology. - : WILEY. - 0908-8857 .- 1600-048X. ; 48:7, s. 932-940
-
Tidskriftsartikel (refereegranskat)abstract
- Penduline tits (Remiz spp.) are renowned for their diverse mating and parenting strategies, and are a well-studied system by behavioural ecologists. However, the phylogenetic relationships and species delimitations within this genus are poorly understood. Here, we investigate phylogenetic relationships within the genus Remiz by examining the genetic variation in the mitochondrial cytochrome-b gene of 64 individuals and in ten autosomal microsatellite markers from 44 individuals. The taxon sampling includes individuals from all currently recognized species (R. pendulinus, R. macronyx, R. coronatus, and R. consobrinus) and most subspecies in the Palearctic region. We showed that R. coronatus and R. consobrinus are genetically well differentiated and constitute independent evolutionary lineages, separated from each other and from R. pendulinus/macronyx. However, we found no evidence for significant differentiation among R. pendulinus/macronyx individuals in mtDNA haplotypes and only marginal differences between R. pendulinus and R. macronyx in microsatellite markers. Hence, based on present data our recommendation is to treat R. pendulinus and R. macronyx as conspecific and R. coronatus and R. consobrinus as separate species.
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| 36. |
- Bensch, Staffan
(författare)
-
The cost of polygyny - definitions and applications
- 1997
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 28:4, s. 345-352
-
Tidskriftsartikel (refereegranskat)abstract
- The polygyny threshold model was introduced in the 1960s in order to explain why females in some species choose to mate vith already mated males. Since then, a number of complementary or alternative hypotheses have been suggested. By using a hierarchical testing approach Searcy and Yasukawa (1989) organised the models that proposed to explain the maintenance of territorial polygyny. Here, I point out that there is no true way to organise the models, and that the organisation itself may influence which explanation the observations mill support. In particular, I discuss Searcy and Yasukawa's distinction between cost and no-cost models. As an alternative to the hierarchical approach I suggest careful comparisons of those variables that inflict costs of sharing with those that provide compensation. While the hierarchical approach may put very similar systems in different model families, a cost and benefit evaluation might instead show that the difference is quantitative rather than qualitative. Also, an identical cost of polygyny can arise from several different combinations of costs of sharing and benefits of sharing. Hence, the hierarchical approach may put systems with different mechanisms behind polygyny into the same model family.
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| 37. |
- Berglund, Åsa M. M., et al.
(författare)
-
Antioxidant status in relation to age, condition, reproductive performance and pollution in three passerine species
- 2014
-
Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 45:3, s. 235-246
-
Tidskriftsartikel (refereegranskat)abstract
- Oxidative stress has been suggested as a mediator in life-history trade-off. By spending more resources on for example reproduction an organism might sacrifice its antioxidant defence. So far, most conclusions on trade-offs between life-history traits and oxidative stress have been drawn from laboratory studies using a few model species and there is a need for studies conducted in natural settings. We investigated associations between markers for antioxidant status (antioxidant enzyme activities and antioxidant levels), body condition, age and reproduction in three species of wild-living passerines. The impact from an anthropogenic stressor (metal pollution) was also assessed. The three bird species showed interspecific variation in their SOD and CAT activities, indicating different pathways to eliminate radicals. The age of females affected both antioxidant status and the breeding performance, indicating the importance of age as a factor in life-history studies. Old birds had lower levels of antioxidants/antioxidant enzyme activities and they produced larger broods/more successful broods, though the latter might be confounded by surviving females having increased fitness. Metal exposure had a negative impact on breeding, and improved breeding outcome was also associated with increased antioxidant defence, but metal exposure was not directly related to the oxidative status of birds, emphasizing that additional stressors might independently affect the same traits. Our results highlight that caution has to be taken when generalizing and extrapolating results to even closely related species. The results support the idea that there is a cost of reproduction, in terms of increased resources spent on antioxidant defence, though this should be confirmed with experimental studies.
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| 38. |
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| 39. |
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| 40. |
- Bonaldi, Carlotta, et al.
(författare)
-
Recurrence, fidelity and proximity to previously visited sites throughout the annual cycle in a trans-Saharan migrant, the common cuckoo
-
Ingår i: Journal of Avian Biology. - 0908-8857.
-
Tidskriftsartikel (refereegranskat)abstract
- Most migratory birds return every year to the same breeding sites and some species show a similarly high fidelity to wintering grounds as well. Fidelity to stopover sites during migration has been much less studied and is usually found to be lower. Here, we investigate site fidelity and distance to previously visited sites throughout the annual cycle in the common cuckoo, a nocturnal trans-Saharan migrant, based on satellite-tracking data from repeated annual migrations of thirteen adult males. All birds (100%) returned to the same breeding grounds, with a median shortest distance of only 1 km from the locations in previous year. This was in strong contrast to a much lower and much less precise site fidelity at non-breeding sites during the annual cycle: In only 18% of the possible cases in all non-breeding regions combined, did the cuckoos return to within 50 km of a previously visited non-breeding site, with no significant differences among the main staging regions (Europe in autumn, Sahel in autumn, wintering in Central Africa, West Africa in spring, Europe in spring). The shortest distance to a previously visited non-breeding site differed among the staging regions with median shortest distances for the longest stopovers of 131 km [2;1223] (median [min;max]) in Europe, 207 km [1;2222] in Sahel in autumn and 110 km [0;628] in Central Africa. The distance to a previously visited staging site decreased with the time spent at the stopover in a previous year. Understanding the drivers of recurrence and site selection in migratory birds are important for guiding conservation efforts in this group but further studies are needed to establish whether the patterns observed in cuckoos are general among terrestrial migrants with continuous distribution of habitat.
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| 41. |
- Briedis, Martins, et al.
(författare)
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Breeding latitude leads to different temporal but not spatial organization of the annual cycle in a long-distance migrant
- 2016
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 47:6, s. 743-748
-
Tidskriftsartikel (refereegranskat)abstract
- The temporal and spatial organization of the annual cycle according to local conditions is of crucial importance for individuals' fitness. Moreover, which sites and when particular sites are used can have profound consequences especially for migratory animals, because the two factors shape interactions within and between populations, as well as between animal and the environment. Here, we compare spatial and temporal patterns of two latitudinally separated breeding populations of a trans-Equatorial passerine migrant, the collared flycatcher Ficedula albicollis, throughout the annual cycle. We found that migration routes and non-breeding residency areas of the two populations largely overlapped. Due to climatic constraints, however, the onset of breeding in the northern population was approximately two weeks later than that of the southern population. We demonstrate that this temporal offset between the populations carries-over from breeding to the entire annual cycle. The northern population was consistently later in timing of all subsequent annual events - autumn migration, non-breeding residence period, spring migration and the following breeding. Such year-round spatiotemporal patterns suggest that annual schedules are endogenously controlled with breeding latitude as the decisive element pre-determining the timing of annual events in our study populations.
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| 42. |
- Brodin, Anders, et al.
(författare)
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Gene-flow across the European crow hybrid zone - a spatial simulation
- 2013
-
Ingår i: Journal of Avian Biology. - 0908-8857. ; 44:3, s. 281-287
-
Tidskriftsartikel (refereegranskat)abstract
- In hybrid zones populations that are otherwise allopatric meet and produce hybrids. One of the most well-known hybrid zones occurs throughout much of Europe between the hooded and carrion crows. Even though these species (or subspecies) of crows look very different, genetic differentiation is weak, and introgression seems to be common. In a spatial simulation that was based on empirically estimated values, we investigated how introgressing alleles that would confer some fitness advantage would flow across the zone. The advantage was assumed to be some unknown factor that enhanced survival for carriers relative to non-carriers. We varied the yearly survival advantage between 0 to 10% and recorded how this would affect zone shape and position. In the simulation we cycled yearly' events such as reproduction, mortality and juvenile dispersal. We started the simulation by equipping all individuals of one crow type outside the zone with a homozygotic set of the beneficial allele. At all levels of advantage the allele first rapidly became fixed in the donator crow type, then transgressed into the receiving type more slowly and finally became fixed in all individuals. The time until fixation varied from around 176 yr for a 10% advantage to around 20 000 yr for 0% advantage. An exciting discovery was that the position of the zone would move during the introgression but then stop. The reason is that the beneficial allele would be common in the donating type but not in the receiving type during the introgression event. At large the crow hybrid zone appears to have been stable for a long time but there have been small recent northward movements of carrion crows in both Scotland and Denmark. We suggest that introgression by itself is a factor that should be considered as an explanation for why hybrid zones move temporarily.
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| 43. |
- Broggi, Juli, et al.
(författare)
-
Carry-over effects on reproduction in food-supplemented wintering great tits
- 2022
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 2022:8
-
Tidskriftsartikel (refereegranskat)abstract
- Bird winter-feeding has become a popular backyard activity around the world, particularly in northern regions of Europe and America with cold winters. However, the short- and long-term ecological consequences of such artificial feeding remain inconclusive. In seasonal environments, timing of breeding is a crucial aspect that can strongly influence reproductive output and ultimately fitness. Individual condition at the start of the breeding season is especially important in determining breeding success, by influencing the onset of and investment in breeding. However, empirical evidence on the effects of winter feeding on avian breeding performance remain equivocal. We studied onset of reproduction (laying date) and breeding investment (clutch size) over seven consecutive seasons in a population of wild great tits Parus major in southern Sweden. During the first three years of study, no experimental manipulation was undertaken, while over the last four years the study area was exposed to either supplemented or unmanipulated winter feeding conditions. Breeding was positively affected by supplementary feeding during winter, as birds breeding in the supplemented area increased their clutch size compared to birds from the control area, although laying date remained unaffected by winter feeding. Since differences in clutch size were absent during the three years prior to the experimental manipulation, the results suggest that winter supplementary feeding, and not inherent differences between the two areas, was the reason for the observed effect. Both breeding parameters varied over the years of study, although the effects of the experimental manipulation on clutch size remained consistent, which suggests a carry-over effect of winter feeding on subsequent breeding performance.
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| 44. |
- Bäckman, Johan, et al.
(författare)
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Activity and migratory flights of individual free-flying songbirds throughout the annual cycle : Method and first case study
- 2017
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 48:2, s. 309-319
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a method and device (< 1.2 g) for recording, processing and storing data about activity and location of individuals of free-living songbirds throughout the annual cycle. Activity level was determined every five minutes from five 100 ms samples of accelerometer data with 5 s between the sampling events. Activity levels were stored on an hourly basis throughout the annual cycle, allowing periods of resting/sleep, continuous flight and intermediate activity (foraging, breeding) to be distinguished. Measurements from a light sensor were stored from preprogrammed key stationary periods during the year to provide control information about geographic location. Successful results, including annual actogram, were obtained for a red-backed shrike Lanius collurio carrying out its annual loop migration between northern Europe and southern Africa. The shrike completed its annual migration by performing > 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4-11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals.
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| 45. |
- Cauchard, Laure, et al.
(författare)
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The relationship between plumage colouration, problem-solving and learning performance in great tits Parus major
- 2017
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 48:9, s. 1246-1253
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies suggest that individuals with better problem-solving and/or learning performance have greater reproductive success, and that individuals may thus benefit from choosing mates based on these performances. However, directly assessing these performances in candidate mates could be difficult. Instead, the use of indirect cues related to problem-solving and/or learning performance, such as condition-dependent phenotypic traits, might be favored. We investigated whether problem-solving and learning performance on a novel non-foraging task correlated with sexually selected plumage colouration in a natural population of great tits Parus major. We found that males successful in solving the task had darker blue-black crowns than non-solvers, and that males solving the task more rapidly over multiple attempts (i.e. learners) exhibited blue-black crowns with higher UV chroma and shorter-wavelength hues than non-learners. In contrast, we found no link between behavioural performance on the task and the yellow breast colouration in either sex. Our findings suggest that blue-black crown colouration could serve as a signal of problem-solving and learning performance in wild great tit males. Further research remains necessary to determine whether different sexually selected traits are used to signal cognitive performance for mate choice, either directly (i.e. cognitive performance influencing individual's health and ornamentation through diet for example) or indirectly (i.e. due to a correlation with a third factor such as individual quality or condition).
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| 46. |
- de la Hera, Ivan, et al.
(författare)
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Variation in the mechanical properties of flight feathers of the blackcap Sylvia atricapilla in relation to migration
- 2010
-
Ingår i: Journal of Avian Biology. - 0908-8857. ; 41:3, s. 342-347
-
Tidskriftsartikel (refereegranskat)abstract
- Migration causes temporal and energetic constraints during plumage development, which can compromise feather structure and function. In turn, given the importance of a good quality of flight feathers in migratory movements, selection may have favoured the synthesis of feathers with better mechanical properties than expected from a feather production constrained by migration necessities. However, no study has assessed whether migratory behaviour affects the relationship between the mechanical properties of feathers and their structural characteristics. We analysed bending stiffness (a feather mechanical property which is relevant to birds' flight), rachis width and mass (two main determinants of variation in bending stiffness) of wing and tail feathers in migratory and sedentary blackcaps Sylvia atricapilla. Migratory blackcaps produced feathers with a narrower rachis in both wing and tail, but their feathers were not significantly lighter; in addition, bending stiffness was higher in migratory blackcaps than in sedentary blackcaps. Such unexpected result for bending stiffness remained when we statistically controlled for individual variation in rachis width and feather mass, which suggests the existence of specific mechanisms that help migratory blackcaps to improve the mechanical behaviour of their feathers under migration constraints.
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| 47. |
- Deutschlander, Mark E., et al.
(författare)
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Fuel reserves affect migratory orientation of thrushes and sparrows both before and after crossing an ecological barrier near their breeding grounds
- 2009
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 40:1, s. 85-89
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Tidskriftsartikel (refereegranskat)abstract
- Fat reserves influence the orientation of migrating songbirds at ecological barriers, such as expansive water crossings. Upon encountering a body of water, fat migrants usually cross the barrier exhibiting 'forward' migration in a seasonally appropriate direction. In contrast, lean birds often exhibit temporary 'reverse' orientation away from the water, possibly to lead them to suitable habitats for refueling. Most examples of reverse orientation are restricted to autumn migration and, in North America, are largely limited to transcontinental migrants prior to crossing the Gulf of Mexico. Little is known about the orientation of lean birds after crossing an ecological barrier or on the way to their breeding grounds. We examined the effect of fat stores on migratory orientation of both long- and short-distance migrants before and after a water crossing near their breeding grounds; Catharus thrushes (Swainson's and gray-cheeked thrushes, C. ustulatus and C. minimus) and white-throated sparrows Zonotrichia albicollis were tested for orientation at the south shore of Lake Ontario during spring and autumn. During both spring and autumn, fat birds oriented in a seasonally appropriate, forward direction. Lean thrushes showed a tendency for reverse orientation upon encountering water in the spring and axial, shoreline orientation after crossing water in the autumn. Lean sparrows were not consistently oriented in any direction during either season. The responses of lean birds may be attributable to their stopover ecology and seasonally-dependent habitat quality.
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| 48. |
- Drobniak, Szymon M., et al.
(författare)
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Habitat shapes diversity of gut microbiomes in a wild population of blue tits Cyanistes caeruleus
- 2022
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Ingår i: Journal of Avian Biology. - : John Wiley & Sons. - 0908-8857 .- 1600-048X. ; 2022:2
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Tidskriftsartikel (refereegranskat)abstract
- Microbiome constitutes an important axis of individual variation that, together with genes and the environment, influences an individual's physiology and fitness. Microbiomes are dependent not only on an individual's body condition but also on external factors, such as diet or stress levels, and as such can be involved into feedbacks between the external ecological factors and internal physiology. In our study, we used a wild population of blue tits Cyanistes caeruleus to investigate the impact of external habitat composition on the microbiome of adult birds. We hypothesized that - through differences in plant composition, potentially affecting diet complexity - habitat type may impact the diversity and structure of the gut microbiome. Blue tits breeding in dense deciduous forests tended to have more diverse microbiomes and be significantly different in terms of microbiome composition from birds breeding in open, sparsely forested hay meadows. Distinct study plots also tended to differ in a number of parameters describing microbiome diversity. We observed no microbiome differentiation according to individual characteristics such as sex or age. The study emphasizes that external environment is one of the important modulators of microbiome diversity and calls for more such studies in wild animal populations.
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| 49. |
- Dufva, R
(författare)
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Blood parasites, health, reproductive success, and egg volume in female Great Tits Parus major
- 1996
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Ingår i: JOURNAL OF AVIAN BIOLOGY. - : MUNKSGAARD INT PUBL LTD. - 0908-8857. ; 27:1, s. 83-87
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The effect of different genera of blood parasites on female Great Tits Parus major was studied in central Sweden. Haemoproteus, Leucocytozoon, Hepatozoon, Plasmodium and Trypanosoma were found, but only the last mentioned had any measurable effect on the
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| 50. |
- Edelaar, Pim
(författare)
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Assortative mating also indicates that common crossbill Loxia curvirostra vocal types are species
- 2008
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Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 39
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Tidskriftsartikel (refereegranskat)abstract
- Compared to most other birds, the taxonomy of crossbills (Loxia) is still highly unsettled. However, much progress seemsto be achievable when data on vocalisations is included. In a recent paper, Summers et al. (2007) argued that strongassortative mating indicated that parrot crossbill Loxia pytyopsittacus, Scottish crossbill Loxia scotica and common crossbill Loxia curvirostra behave as good species when breeding in sympatry. Here I argue that their data, when placed in thecontext of other studies, also indicate that three vocally differentiated European populations within the common crossbillare species (following the biological species concept of Mayr (1963): species are groups of interbreeding naturalpopulations that are reproductively isolated from other such groups). If this tentative conclusion remains to be upheld, itmight have large repercussions for our understanding of the speciation process as well as for a number of more appliedissues such as the discovery and description of biodiversity and the conversation of mobile, cryptic species.
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