| 1. |
- Buchadas, Ana R. C., et al.
(författare)
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Future breeding and foraging sites of a southern edge population of the locally endangered Black Guillemot Cepphus grylle
- 2017
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Ingår i: Bird Study. - : Taylor & Francis. - 0006-3657 .- 1944-6705. ; 64:3, s. 306-316
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Tidskriftsartikel (refereegranskat)abstract
- Capsule: One of the southernmost populations of the Black Guillemot Cepphus grylle is currently endangered, and the risk may be exacerbated by climate change. Aims: We evaluated the future vulnerability of the Black Guillemot by predicting the impact of climate change on the geographic distribution of its breeding and foraging range in the Baltic Sea. Methods: We used MaxEnt, a species distribution modelling technique, to predict the current and future breeding grounds and foraging sites. Results: We found that although the foraging range is expected to increase in the southern Baltic Sea in future, these areas will no longer be suitable as breeding grounds due to a changing climate, creating a spatial mismatch. Conclusion: Our predictions indicate where threats to the species may be most severe and can be used to guide conservation planning. We advocate conservation measures which integrate potential future threats and focus on breeding sites across the current and future potential geographic range of the Black Guillemot.
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| 2. |
- Campos, Ana R., et al.
(författare)
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How do Robins Erithacus rubecula resident in Iberia respond to seasonal flooding by conspecific migrants?
- 2011
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 58:4, s. 435-442
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Tidskriftsartikel (refereegranskat)abstract
- Capsule The majority of Robins in Iberia are sedentary and stay in their nesting areas despite the pre- sumed increased competition that results from the seasonal flooding of the area by conspecific migrants. Aims To evaluate if Robins in Iberia are displaced from their nesting areas by the presence of large num- bers of competitors originating from higher latitudes. Methods Data from constant effort ringing sites were used to estimate the proportion of Robins that are strictly sedentary and the seasonal variation in Robin numbers. Hydrogen stable isotope ratios (d2H) in feathers, and sex ratios determined through molecular techniques, allowed an insight into the numerical importance of invading Robins from higher latitudes. Results Robins were more numerous outside the breeding season, with clear influxes in autumn. Around half of the locally nesting Robins were captured during winter, indicating they are truly sedentary. d2H in feathers suggests that a wide mixture of Robins from all European latitudes were present in winter, and these data, together with sex ratios, suggest that there may be similar numbers of local and foreign individ- uals in winter at the main study site. Conclusion Despite the occupation of their range by migrants, local birds are largely sedentary.
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| 3. |
- Champagnon, Jocelyn, et al.
(författare)
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Changes in Mallard Anas platyrhynchos bill morphology after 30 years of supplemental stocking
- 2010
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Ingår i: Bird Study. - 0006-3657 .- 1944-6705. ; 57:3, s. 344-351
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Massive releases of captive-reared Mallard for hunting purposes have been practiced for 30 years. During this period the number of lamellae per centimetre of bill length in wild Mallard populations has decreased. Aims Every year since the 1970s, several million captive Mallard have been released in Europe. This may lead to a spread of unnatural phenotypes into the wild. Nevertheless, the consequences of such introductions have not been examined. Methods Two widespread and common migratory ducks were studied: Mallard Anas platyrhynchos and Teal A. crecca. Mallard is the only duck species for which stocking programmes occur, and Teal served as a control. In a 'before-after' design, we compared duck bill lamellar density over the last 30 years. Results Lamellar density in Mallard, but not Teal, decreased. The observed 10% decrease occurred in the first (proximate) centimetre of the bill, the most crucial in terms of food filtration. Conclusions We hypothesize that the change in bill morphology was because of the propagation of captive Mallard into the wild: captive Mallard eat mainly large items, relaxing the natural selection pressure maintaining high lamellar density for sieving small prey in wild ducks.
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| 4. |
- Champagnon, Jocelyn, et al.
(författare)
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Changes in Mallard Anas platyrhynchos bill morphology after 30 years of supplemental stocking
- 2010
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Ingår i: Bird Study. - : Taylor and Francis Ltd.. - 0006-3657 .- 1944-6705. ; 57:3, s. 344-351
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Massive releases of captive-reared Mallard for hunting purposes have been practiced for 30 years. During this period the number of lamellae per centimetre of bill length in wild Mallard populations has decreased. Aims Every year since the 1970s, several million captive Mallard have been released in Europe. This may lead to a spread of unnatural phenotypes into the wild. Nevertheless, the consequences of such introductions have not been examined. Methods Two widespread and common migratory ducks were studied: Mallard Anas platyrhynchos and Teal A. crecca. Mallard is the only duck species for which stocking programmes occur, and Teal served as a control. In a 'before-after' design, we compared duck bill lamellar density over the last 30 years. Results Lamellar density in Mallard, but not Teal, decreased. The observed 10% decrease occurred in the first (proximate) centimetre of the bill, the most crucial in terms of food filtration. Conclusions We hypothesize that the change in bill morphology was because of the propagation of captive Mallard into the wild: captive Mallard eat mainly large items, relaxing the natural selection pressure maintaining high lamellar density for sieving small prey in wild ducks.
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| 5. |
- Dobson, Andrew D. M., et al.
(författare)
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The size and migratory origins of the population of Hen Harriers Circus cyaneus wintering in England
- 2012
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 59:2, s. 218-227
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Tidskriftsartikel (refereegranskat)abstract
- Capsule The majority of Hen Harriers Circus cyaneus that spend the winter in England are derived from the British breeding population. Aims To investigate the popular hypothesis that Hen Harriers which over-winter in England are derived principally from breeding populations in mainland Europe. Methods Demographic data were used to estimate numbers of Hen Harriers in Britain at the end of the breeding season. This figure was used, together with data from winter (October-March inclusive) recoveries of Hen Harriers ringed in Britain during the breeding season, to estimate the number of birds from the British breeding population wintering in England and in other parts of Europe. Results It was estimated that Hen Harriers wintering in England are derived primarily from British breeding populations. Published winter population figures for British Hen Harriers may be significant underestimates. Conclusion The link between breeding and wintering populations of Hen Harriers in Britain is closer than previously thought. Conservation action should be spread more equally between the environmental factors which limit populations in different seasons. The winter population in Britain, as monitored by the Hen Harrier Winter Roost Survey, may provide a good indication of the status of the breeding population.
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| 6. |
- Guillemain, Guillemain, et al.
(författare)
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Multiple tests of the effect of nasal saddles on dabbling ducks : combining field and aviary approaches
- 2007
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Ingår i: Bird Study. - 0006-3657 .- 1944-6705. - 0006-3657 ; 54:1, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Nasal saddles have no negative consequences apart from, under some circumstances, a potential bias in social relationships. Aims To test the effect of nasal saddles on Teal Anas crecca, Wigeon A. penelope, Mallard A. platyrhynchos and Pintail A. acuta. Methods The following features were compared between saddled and unsaddled individuals: body mass change of wild Teal between ringing and first live recovery, pairing probability of wild Teal through the winter, wild Teal and Wigeon time-budgets, captive Mallard and Pintail body mass fluctuations, testosterone levels and dominance in the aviary. Results We generally found no significant difference between values for birds with nasal saddles and control birds. Exceptions were for pairing probability, which was lower for marked Teal during one of the winters, and the proportion of aggressive interactions won by Pintail, which decreased after they were fitted with saddles, while this did not happen in Mallard. Conclusions Nasal saddles are an appropriate general method for marking dabbling ducks. However, saddles may not be appropriate for the study of social relationships in some conditions.
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| 7. |
- Guillemain, Guillemain, et al.
(författare)
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Multiple tests of the effect of nasal saddles on dabbling ducks : combining field and aviary approaches
- 2007
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Ingår i: Bird Study. - : Taylor and Francis Ltd.. - 0006-3657 .- 1944-6705. ; 54:1, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Nasal saddles have no negative consequences apart from, under some circumstances, a potential bias in social relationships. Aims To test the effect of nasal saddles on Teal Anas crecca, Wigeon A. penelope, Mallard A. platyrhynchos and Pintail A. acuta. Methods The following features were compared between saddled and unsaddled individuals: body mass change of wild Teal between ringing and first live recovery, pairing probability of wild Teal through the winter, wild Teal and Wigeon time-budgets, captive Mallard and Pintail body mass fluctuations, testosterone levels and dominance in the aviary. Results We generally found no significant difference between values for birds with nasal saddles and control birds. Exceptions were for pairing probability, which was lower for marked Teal during one of the winters, and the proportion of aggressive interactions won by Pintail, which decreased after they were fitted with saddles, while this did not happen in Mallard. Conclusions Nasal saddles are an appropriate general method for marking dabbling ducks. However, saddles may not be appropriate for the study of social relationships in some conditions.
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| 8. |
- Hedenström, Anders, et al.
(författare)
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Migration of the Little Ringed Plover Charadrius dubius breeding in South Sweden tracked by geolocators
- 2013
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 60:4, s. 466-474
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Little Ringed Plovers breeding in South Sweden migrate towards the southeast in the autumn, via the Middle East, to winter in Saharan and sub-Saharan locations or in India, while the spring migration is more directly towards the north.Aims To study the migration routes and wintering area of Little Ringed Plovers (Charadrius dubius) breeding in South Sweden, and to investigate the migration strategy and speed for this little studied shorebird.Methods We use light-level geolocators to track the year-round movements of Little Ringed Plovers breeding in South Sweden.Results Autumn migration proceeded towards the southeast, in three birds via lengthy stopovers in the Middle East, followed by movements towards the west and southwest to final winter destinations in Africa, while one male made a long stopover in northwestern Iran before migrating to India. The birds wintering in Africa probably stayed at freshwater locations in the Sahara or just south or north of the Sahara. Spring migration was more directly back to the breeding area. Overall migration speeds were similar during autumn and spring migration at about 189 and 209km/day, respectively. The migration was carried out mainly as many short flights between stopovers. In particular, autumn migration was longer than the direct distance between breeding and wintering sites.Conclusions This study shows that the geolocator method can successfully be used with relatively small (40g) shorebirds. We found that a local population of Little Ringed Plover may have widely differing wintering sites (low connectivity), from sub-Saharan Africa to the Indian subcontinent. The migration strategy of the Little Ringed Plover, with multiple short flights, deviates from that of many other long-distance migrating shorebirds that, instead, make one or a few long flights.
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| 9. |
- Hipkiss, Tim, et al.
(författare)
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Habitat use and ranging behaviour of juvenile Golden Eagles Aquila chrysaetos within natal home ranges in boreal Sweden
- 2014
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 61, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Fledgling Golden Eagles in northern Sweden preferred clearcuts and other open forest habitats, as well as steep slopes.Aims To study the post-fledging habitat use and ranging behaviour of juvenile Golden Eagles on their natal territories.Methods Fourteen juvenile Golden Eagles in northern Sweden were marked with GPS transmitters and tracked until they left their natal territory.Results Eagles fledged at the end of July-beginning of August and remained on their natal territories until October-early November. Fledged eagles' home range size before flying south was on average 41km(2). Juvenile eagles showed a preference for clearcuts, coniferous forest on lichen-covered bedrock and edges between clearcuts and forest, whilst all other habitat types were used less than expected. The eagles showed a preference for steep slopes, in particular south-facing ones, whilst north-facing slopes were used less than expected.Conclusion Golden Eagles' preference for clearcuts and steep slopes can be used in the planning and management of eagle friendly' wind farms.
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| 10. |
- Hipkiss, Tim, et al.
(författare)
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Variation in quality of Golden Eagle territories and a management strategy for wind farm projects in northern Sweden
- 2014
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 61, s. 444-446
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Breeding productivity of 86 occupied Golden Eagle territories in northern Sweden varied greatly, with the upper quartile of the most productive territories being responsible for 44% of the total productivity of the studied territories. This information is used in a regional strategy for managing wind farm project proposals in areas inhabited by Golden Eagles, whereby the more productive territories are provided with a greater degree of protection than their less productive counterparts.
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