| 1. |
- Arlt, Debora
(författare)
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RESEARCH NEEDS AND RECOMMENDATIONS FOR THE USE OF CONSPECIFIC-ATTRACTION METHODS IN THE CONSERVATION OF MIGRATORY SONGBIRDS
- 2010
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Ingår i: Condor. - : Oxford University Press (OUP). - 0010-5422. ; 112, s. 252-264
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have confirmed that when selecting habitat birds can use social information acquired from observing other individuals, and many aspects of this social information can be capitalized upon to manage bird populations. The conservation implications of attraction to conspecifics are especially promising for management, and as research progresses it is important to consider how this behavior can be applied to conservation practice. The biological underpinnings of conspecific attraction and the repercussions of manipulating species' distributions with attraction methods are not well understood, but conservation decisions often cannot wait for scientific research. Here we synthesize the current research on manipulation of songbirds by conspecific-attraction methods and review our knowledge gaps critically. We reviewed the published literature on conspecific-attraction experiments in songbirds and found that of 24 studies in which they were attempted, 20 were successful in attracting birds. Although many experiments have been successful in attracting conspecifics with various cues, we outline issues to be considered before songbirds are manipulated by attraction methods, and we highlight areas of research necessary to enhance the understanding of conspecific attraction and its use in conservation.
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| 2. |
- De Ruyck, Chris, et al.
(författare)
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n Appraisal of the use of Hydrogen-Isotope Methods to Delineate Origins of Migratory Saw-Whet Owls in North America
- 2013
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Ingår i: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422 .- 1938-5129. ; 115:2, s. 366-374
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Tidskriftsartikel (refereegranskat)abstract
- Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (delta H-2) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high infra-feather isotopic variance and mean delta H-2 values higher than predicted from delta H-2 isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of delta H-2 analysis of saw-whet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006-2007. Values of delta H-2 in saw-whet owl feathers were higher than predicted from a delta H-2 isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of delta H-2 in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in delta H-2 values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater H-2 enrichment in adult feathers. These results indicate that current delta H-2 isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of H-2 enrichment in owl feathers is required.
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| 3. |
- Lindström, Åke, et al.
(författare)
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A Puzzling Migratory Detour: Are Fueling Conditions In Alaska Driving The Movement Of Juvenile Sharp-Tailed Sandpipers?
- 2011
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Ingår i: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422. ; 113:1, s. 129-139
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Tidskriftsartikel (refereegranskat)abstract
- Making a detour can be advantageous to a migrating bird if fuel-deposition rates at stopover sites along the detour are considerably higher than at stopover sites along a more direct route. One example of an extensive migratory detour is that of the Sharp-tailed Sandpiper (Calidris acuminata), of which large numbers of juveniles are found during fall migration in western Alaska. These birds take a detour of 1500-3400 km from the most direct route between their natal range in northeastern Siberia and nonbreeding areas in Australia. We studied the autumnal fueling rates and fuel loads of 357 Sharp-tailed Sandpipers captured in western Alaska. In early September the birds increased in mass at a rate of only 0.5% of lean body mass day(-1). Later in September, the rate of mass increase was about 6% of lean body mass day(-1), among the highest values found among similar-sized shorebirds around the world. Some individuals more than doubled their body mass because of fuel deposition, allowing non-stop flight of between 7100 and 9800 km, presumably including a trans-oceanic flight to the southern hemisphere. Our observations indicated that predator attacks were rare in our study area, adding another potential benefit of the detour. We conclude that the most likely reason for the Alaskan detour is that it allows juvenile Sharp-tailed Sand-pipers to put on large fuel stores at exceptionally high rates.
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