Interaction of bodymass, fat, foraging and stopover period in trans-Sahara migrating passerine birds

Biebach, Herbert; Friedrich, Wolfgang; Heine, Georg

doi:10.1007/bf00377059

Cited by 264 publications

(211 citation statements)

References 27 publications

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“…At the individual level, it has been suggested that subcutaneous fat deposits are the main physiological determinant of stopover duration (e.g. Bairlein 1985;Biebach 1985;Biebach et al 1986;Cherry 1982;Gannes 2002;Moore & Kerlinger 1987, but see Kuenzi et al 1991;Lyons & Haig 1995).…”

Section: Introductionmentioning

confidence: 99%

Body fat influences departure from stopover sites in migratory birds: evidence from whole-island telemetry

et al. 2010

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).Migration remains one of the great mysteries of animal life. Small migratory birds rely on refuelling stopovers after crossing ecological barriers such as deserts or seas. Previous studies have suggested that fuel reserves may determine stopover duration but this hypothesis could not be tested because of methodological limitations. Here, we provide evidence that subcutaneous fat stores determine stopover duration by measuring the permanence of migratory garden warblers (Sylvia borin) on a small Mediterranean island during spring migration with telemetry methods. Garden warblers with large amounts of fat stores departed the island significantly sooner than lean birds. All except one fat bird left the island on the same evening after capture, with a mean total stopover estimate of 8.8 hours. In contrast, the mean estimated total stopover duration of lean birds was 41.3 hours. To our knowledge, this is the first study that measures the true minimum stopover duration of a songbird during migration.

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Section: Introductionmentioning

confidence: 99%

Body fat influences departure from stopover sites in migratory birds: evidence from whole-island telemetry

et al. 2010

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“…Furthermore, numbers of birds found in the desert during daytime were regarded as being comparatively low compared to the total number of migrants estimated by Moreau (Wood 1989). This non-stop hypothesis was challenged by Bairlein (1985Bairlein ( , 1992 and Biebach et al (1986Biebach et al ( , 1991 who proposed an alternative intermittent strategy that involves regular stopovers in the desert and in oases. The main argument for an intermittent migration strategy was that an unexpectedly high proportion of passerines grounded in oases were in good physical condition with sufficient fuel stores to continue migration (Bairlein et al 1983;Bairlein 1992;Biebach 1995).…”

Section: Introductionmentioning

confidence: 99%

Spring passerine migrants stopping over in the Sahara are not fall-outs

2009

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The strategy of migrants crossing the Sahara desert has been the subject of debate, but recent evidence from radar studies has confirmed that most passerines use an intermittent migration strategy. The latter has also been suggested from previous studies in oases during autumn migration. It was found that migrants with relatively high fuel loads rest in the desert during daytime and continue migration during the following night, whereas lean migrants stopover in oases for several days to refuel. However, data from the Sahara are scarce for spring migration. We captured passerine migrants near Bîr Amrâne (22°47 0 N, 8°43 0 W) in the plain desert of Mauritania for 3 weeks during spring migration in 2004. We estimated flight ranges of 85 passerines stopping over in the desert to test whether they carried sufficient fuel loads to accomplish migration across the Sahara successfully. High fat loads of the majority of birds indicated that they were neither ''fallouts'' nor too weak to accomplish migration successfully. The flight range estimates, based on mean flight speeds derived from radar measurements (59 km/h), revealed that 85% of all birds were able to reach the northern fringe of the desert with an intermittent migration strategy. Furthermore, birds stopping over in an oasis (Ouadâne, 370 km to the southwest of Bîr Amrâne) did not carry consistently lower fuel loads compared to the migrants captured in the desert.

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“…Therefore, birds are predicted to arrive relatively lean to a next stopover site, which may cause the birds to stay longer there and, in case of depletable resources, deplete these further. Some studies indeed have shown that lean arriving migrants generally stayed longer than fat ones (Cherry 1982;Bairlein 1985;Biebach et al 1986;Moore and Kerlinger 1987;Goymann et al 2010), or that stopover duration was longer when in a given year body condition at arrival at the stopover site was low (Russell et al 1994). However, some other studies have found no consistent relationship between arrival condition and stopover duration (Safriel and Lavee 1988;Butler et al 1997;Skagen and Knopf 1994;Lyons and Haig 1995;Holmgren et al 1993), possibly because departure was triggered more by time schedules or flight conditions (e.g.…”

Section: Discussionmentioning

confidence: 99%

Underuse of stopover site by migratory swans

Nolet

Gyimesi

2013

J Ornithol

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Many migratory birds use a chain of stopover sites to fuel their migration. Under time-minimizing migration, fuelling time and giving-up density at stopovers are predicted to depend on fuelling conditions. Fluctuations in food accessibility likely lead to changes in fuelling conditions, which should in turn be reflected in fuelling time and giving-up density. During their migration, Bewick's Swans Cygnus columbianus bewickii refuel on belowground tubers of Fennel Pondweed Potamogeton pectinatus in shallow lakes. We studied giving-up density and stopover use (expressed in bird-days) of Bewick's Swans at an autumn stopover site (Lauwersmeer, The Netherlands) during 1995-2008, as dependent on local environmental conditions. High water levels were hypothesized to restrict access to tuber stocks. High water levels at the stopover site were predicted to lead to higher giving-up densities and less bird-days spent at the stopover. Annual variation in givingup densities and number of bird-days was strongly associated with year-to-year differences in initial tuber biomass density and number of days with high water levels. As predicted, giving-up density increased and bird-days decreased with the number of days with high water level. We conclude that, in line with time-minimizing migration, changes in fuelling conditions may lead to underuse of a stopover site. Underuse of stopovers by migratory birds has been reported before but only in the sense that more food was left at stopover sites than at wintering sites. In contrast, in our case, dealing with a given stopover site, more food is left behind in some years than in other years.

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Interaction of bodymass, fat, foraging and stopover period in trans-Sahara migrating passerine birds

Cited by 264 publications

References 27 publications

Body fat influences departure from stopover sites in migratory birds: evidence from whole-island telemetry

Body fat influences departure from stopover sites in migratory birds: evidence from whole-island telemetry

Spring passerine migrants stopping over in the Sahara are not fall-outs

Underuse of stopover site by migratory swans

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