| 61. |
- Stach, Robert, 1971-, et al.
(författare)
-
Geolocators reveal three consecutive wintering areas in the thrush nightingale
- 2012
-
Ingår i: Animal Migration. - : Walter de Gruyter GmbH. - 2084-8838. ; 1, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- The winter distribution of many migratory birds wintering in tropical Africa is poorly known. After the crossing of the Sahara Desert, some long-distance migrants typically stay in the Sahel zone for an extended period before continuing migration to their main wintering areas south of the equator. Here we show how two thrush nightingales (Luscinia luscinia) fitted with light-level geolocators, after a six to seven week long stay in the Sahel zone of Sudan, moved to an intermediate area in northern Kenya for a month-long stay before continuing to their final wintering areas in southern Africa. These data indicate that thrush nightingales may use three consecutive wintering sites during their stay in Africa. The migratory movements in Africa between wintering sites are well-coordinated with high precipitation in these areas, suggesting that thrush nightingales track peaks of insect abundance occurring after rains. This three-stage wintering strategy has, to our knowledge, previously not been described, and shows that long-distance migrants can have complex wintering behaviour.
|
|
| 62. |
- Stach, Robert, 1971-, et al.
(författare)
-
Migration routes and timing in a bird wintering in South Asia, the Common Rosefinch Carpodacus erythrinus
- 2016
-
Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 157, s. 671-679
-
Tidskriftsartikel (refereegranskat)abstract
- Only few bird species from Western Europe migrate eastward to wintering areas in South Asia, and little is known about this migratory flyway. The Common Rosefinch has in the past century expanded its breeding range westward to include Western Europe and migrate along this flyway to wintering sites in South Asia. This is the first study describing the migration routes of Common Rosefinches between Europe and Asia in detail, revealed by light level geolocators. The rosefinches showed loop-migration with more northerly routes in autumn than in spring, possibly in order to shorten the flight over the Central Asian deserts, which are very inhospitable at this time of the year. In spring the deserts are less dry and richer in vegetation, which may have supported the more southerly routes. During autumn migration the birds used several staging sites in Central Asia for prolonged periods. Although the birds passed over mountain regions at this time, which potentially act as barriers to them, the length of the stops seem unrealistically long for only fuel deposition. Instead, this suggests that the birds temporarily suspended migration to take advantage of abundant and predictable food sources in this region. During spring migration the birds made a few longer stops while still in north India or Central Asia, before migrating at fast speeds towards the breeding grounds. The birds covered 4–5000 km with only very short stopovers and thus most of the fuel used on spring migration must have been accumulated in Asia. Our results thus indicate that Central Asia, and north India, are important staging areas for this species in both autumn and spring. During winter, birds used two sites located several hundred kilometres apart, and relocation was probably a response to local food availability.
|
|
| 63. |
- Stach, Robert, 1971-
(författare)
-
Migratory routes and stopover behaviour in avian migration
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Migratory birds, some small and light weight as matchboxes, engage in seasonal inter-continental journeys in order to take advantage of the long summer days and abundance of food at northern latitudes to breed and raise their young, and then escape the harsh winters by migrating to lower latitudes. This thesis deals with two important aspects of migration, the routes taken during migration and the birds’ behaviour at stopovers. The migratory routes are for many species unknown, whole or in part, and this is especially true for species that migrate nocturnally. At stopovers birds replenish fuel reserves that powers migratory flight, and studying how birds utilise stopovers is important in order to understand how migration is organised. In this thesis I have used modern tracking technology to study both continental wide movements of thrush nightingales (Luscinia luscinia) and common rosefinches (Carpodacus erythrinus) using small light-level geolocators, and smaller scale movements at a single stopover site of garden warblers (Sylvia borin) using miniature radio-transmitters. I have also studied the fuelling behaviour of garden warblers during autumn migration in the field and in the lab, and great reed warblers (Acrocephalus arundinaceus) at a stopover site on Crete during spring migration after the Sahara crossing. The thesis discusses the significance of several aspects of migration shown by the birds that would have been very difficult to detect without the aid of modern tracking technology, such as loop migration, prolonged stops during migration, multiple wintering sites, and nocturnal relocations at stopover sites. Studies carried out at stopover sites also show that garden warblers and great reed warblers can attain large fuel loads even at sites where they have no barrier to cross and this might be a result of good foraging conditions. The thesis also highlights the importance of combining different techniques when studying stopover behaviour to get reliable estimates on stopover durations and fuel deposition rates as well as the importance of choosing sites preferred by birds when planning stopover studies.
|
|
| 64. |
- Stach, Robert, 1971-, et al.
(författare)
-
No compensatory fuelling due to late autumn migration in the Garden Warbler Sylvia borin
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Birds migrating late in the migration season may need to compensate for the late departure by increasing migration speed. To increase migration speed late migrants should depart from stopovers along the route with larger fuel loads than early migrants. Both higher migration speeds and increasing fuel loads with the progress of the season have been reported in the literature. Here we test if Garden Warblers (Sylvia borin) show different fuelling strategies when captured on migration in the early or late part of autumn migration and given unlimited access to food. We also included a group of birds that were captured early in the season but held under a light regime with shorter day lengths to simulate thirty days advancement in time. We found no difference in maximum body mass between the groups and all groups reached fairly large fuel loads (mean: 39.2 % of lean body mass). Maximum fuel load was also strongly correlated with fuel deposition rate and this may suggest that Garden Warblers migrate at high speed during the entire season, which leaves little room for increasing speed later in the season.
|
|
| 65. |
- Stach, Robert, 1971-, et al.
(författare)
-
Wide ranging stopover movements and substantial fuelling in first year garden warblers at a northern stopover site
- 2015
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 46:3, s. 315-322
-
Tidskriftsartikel (refereegranskat)abstract
- Migratory birds use stopovers to replenish their fuel reserves and they generally spend more time at stopover sites than theydo in actual fl ight. When arriving at a new stopover site birds may need to search extensively to fi nd a suitable feeding areaand this search and settling period may aff ect the duration of stopover. Stopover behaviour can thus have profound eff ectson the migratory programme and studies on stopover behaviour are important to understand migratory strategies. Wefollowed 51 fi rst-year garden warblers Sylvia borin with radio-transmitters at an autumn stopover site on the island ofGotland in southern Sweden. Our aim was to determine the distance birds relocated from the coastal capture site whensearching for an area to settle in, and also to establish the duration of stopover and put it in relation to refuelling rate byrecapturing a subset of the radio-tracked individuals. Sixteen birds made an extended stopover ( 2 d), relocated inlandfrom the capture site and settled on average 5.6 km from the capture site, with the longest recorded relocation being fourteenkilometres. Birds that relocated nocturnally settled in areas further away than birds that relocated diurnally. Th irteenbirds that continued migration after a short stop carried larger fuel stores than birds that stopped over longer and theyremained close to the capture site until departure. Th ree birds were re-trapped and showed high fuelling rates, between0.3 and 1.1 g d 1 . Th ey left the stopover site with fuel loads between 40 – 56 percent of lean body mass, which possiblywould have allowed them to reach the Mediterranean area without additional refuelling stops.
|
|
| 66. |
- Stratelis, Georgios, et al.
(författare)
-
High prevalence of emphysema and its association with BMI : A study of smokers with normal spirometry
- 2008
-
Ingår i: Scandinavian Journal of Primary Health Care. - : Informa UK Limited. - 0281-3432 .- 1502-7724. ; 26:4, s. 241-247
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To evaluate to what extent emphysema was evident, as identified by High Resolution Computed Tomography (HRCT), in smokers with normal lung function and to relate age, gender, smoking history, and body mass index (BMI) to the HRCT results. A secondary aim was to study to what extent emphysema was present in smokers with lower normal values of lung function defined as FEV1/FVC ratio percentage of predicted value (89-93% of predicted value for males and 90-93% for females) or FEF50 60% of predicted compared with smokers without this definition.Methods: Fifty-nine smokers, with a mean age of 53 years and with normal lung function, were examined with HRCT.Results: Emphysema evidenced visually by HRCT was present in 43% of the subjects. Using a 0-5 grade scale (0=normal finding; 5=emphysema in most slices), the degree of emphysema was almost exclusively 3-4. The type of emphysema was distributed as centrilobular emphysema predominant in 43.5%, paraseptal emphysema predominant in 43.5%, and as an equal mixture of these types in 13%. The presence of emphysema did not differ between the group of smokers with lower normal values of lung function and the rest of the smokers. Smokers with emphysema had significantly lower BMI than those devoid of emphysema, 24 and 27 respectively (p0.0011).Conclusion: There was a high occurrence of visual emphysema in middle-aged smokers with normal lung function. The densitometric quantitative analysis method is inadequate for detecting mild emphysema. High prevalence of emphysema was associated with low BMI.
|
|
| 67. |
- Vallin, Adrian, et al.
(författare)
-
An eye for an eye – on the generality of the intimidating quality of eyespots in a butterfly and a hawkmoth
- 2007
-
Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 61:9, s. 1419-1424
-
Tidskriftsartikel (refereegranskat)abstract
- Large eyespots on the wings of butterflies and moths have been ascribed generally intimidating qualities by creating a frightening image of a bird or mammal much larger than the insect bearing the eyespots. However, evidence for this anti-predator adaptation has been largely anecdotal and only recently were peacock butterflies, Inachis io, shown to effectively thwart attacks from blue tits, Parus caeruleus. Here we test whether large eyespots on lepidopterans are generally effective in preventing attacks from small passerines, and whether the size of insect or bird can influence the outcome of interactions. We staged experiments between the larger eyed hawkmoths, Smerinthus ocellatus, and the smaller peacock butterflies, I. io, and the larger great tits, Parus major, and the smaller blue tits, P. caeruleus. Survival differed substantially between the insect species with 21 of 24 peacocks, but only 6 of 27 eyed hawkmoths, surviving attacks from the birds. Thus, surprisingly, the smaller prey survived to a higher extent, suggesting that other factors than insect size may be important. However, great tits were less easily intimidated by the insects’ eyespots and deimatic behaviour and consumed 16 of 26, but the blue tits only 8 of 25 of the butterflies and hawkmoths. Our results demonstrate that eyespots per se do not guarantee survival, and that these two insects bearing equally large eyespots are not equally well protected against predation.
|
|
| 68. |
- Vallin, Adrian, et al.
(författare)
-
Constant eyespot display as a primary defense – survival of male and female emperor moths when attacked by blue tits
- 2010
-
Ingår i: The Journal of Research on the Lepidoptera. - : ISSN 0022-4324 (prINt) tHe lepIDopterA reSeArCH FoUNDAtIoN. - 0022-4324 .- 2156-5457. ; 43, s. 9-17
-
Tidskriftsartikel (refereegranskat)abstract
- Large conspicuous eyespots, commonly found on the wings of butterflies and moths, have been shown to thwart attacks from predators. Previous experiments have focused on lepidopteran species that expose eyespots only when harassed by a predator. In contrast, we investigate the potential efficiency of the constantly exposed eyespots of emperor moths thus constituting a primary defense. We staged experiments between blue tits and moths having either intact or painted over eyespots. Moths with eyespots were killed as often as moths without eyespots and were, additionally, approached earlier by the birds suggesting that birds were not intimidated by their eyespots. Female moths weighed three times more than males and were less often eaten, suggesting that their large size intimidated the birds. We suggest that the constant eyespot display of the emperor moth may be associated with a cost, because potential predators seem to be attracted rather than intimidated by the display.
|
|
| 69. |
|
|
| 70. |
- Vallin, Adrian, 1974-
(författare)
-
On the protective value of conspicuous eyespots in Lepidoptera
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Eyespots, circular patterns which resemble the general appearance of the vertebrate eye, are widespread throughout the animal kingdom and are for example, commonly found on the wings of butterflies where they have been proposed to confer protection against predation. However, empirical evidence of the adaptive value of eyespots, as well as knowledge of butterfly behaviour under the threat of predation, is scarce. In Paper I, we subjected three butterfly species to attacks by insect eating birds. Results show that, although being closely related, these three species have developed fundamentally different kinds of anti-predation adaptations. Paper II demonstrates that the conspicuous eyespots, in combination with the wing-flicking of peacock butterflies, Inachis io, provide efficient defence against blue tits, Parus caeruleus. Peacocks appear to be edible to blue tits, thus, this is an example of effective animal defence by bluffing. During winter hibernation however, Paper III suggests that adult peacock butterflies do not survive predation better compared with its close relative the small tortoiseshell, Aglais urticae, a species lacking eyespots. In Paper IV we argue that two edible insect species carrying equally large eyespots are not necessarily equally well protected against bird predation. In this study, a higher frequency of the larger prey, the eyed hawkmoth, Smerinthus ocellatus, were killed compared with the smaller prey, the peacock butterfly. Finally, Paper V shows that birds approach emperor moths, Saturnia pavonia, a species always exposing their eyespots, earlier after the onset of a trial, compared with eyed hawkmoths, a species hiding their eyespots until harassed by a bird. This suggests that large eyespots may catch the attention of a nearby predator and in situations where predators are not intimidated by the display, eyespots may switch from being potentially beneficial to being a costly trait.
|
|
