| 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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