16
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

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

      Biology letters
      Animal Migration, physiology, Animals, Body Composition, Feeding Behavior, Geography, Italy, Likelihood Functions, Songbirds, Statistics, Nonparametric, Telemetry, Time Factors

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          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.

          Related collections

          Most cited references2

          • Record: found
          • Abstract: found
          • Article: not found

          Songbird migration across the Sahara: the non-stop hypothesis rejected!

          Billions of songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, twice a year. While crossing Europe, the vast majority use an intermittent flight strategy, i.e. fly at night and rest or feed during the day. However, it was long assumed that they overcome the Sahara in a 40 h non-stop flight. In this study, we observed bird migration with radar in the plain sand desert of the Western Sahara (Mauritania) during autumn and spring migration and revealed a clear prevalence of intermittent migration. Massive departures of songbirds just after sunset independent of site and season suggests strongly that songbirds spent the day in the plain desert. Thus, most songbirds cross the Sahara predominantely by the intermittent flight strategy. Autumn migration took place mainly at low altitudes with high temperatures, its density decreased abruptly before sunrise, followed by very little daytime migration. Migration was highly restricted to night-time and matched perfectly the intermittent flight strategy. However, in spring, when migratory flights occurred at much higher altitudes than in autumn, in cool air, about 17% of the songbird migration occurred during the day. This suggests that flying in high temperatures and turbulent air, as is the case in autumn, may lead to an increase in water and/or energy loss and may prevent songbirds from prolonged flights into the day.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Stopover decision during migration: physiological conditions predict nocturnal restlessness in wild passerines.

            During migration, a number of bird species rely on stopover sites for resting and feeding before and after crossing ecological barriers such as deserts or seas. The duration of a stopover depends on the combined effects of environmental factors, endogenous programmes and physiological conditions. Previous studies indicated that lean birds prolong their refuelling stopover compared with fat birds; however, the quantitative relationship between physiological conditions and stopover behaviour has not been studied yet. Here, we tested in a large sample of free-living birds of three European passerines (whinchats, Saxicola rubetra, garden warblers, Sylvia borin and whitethroats, Sylvia communis) whether the amount of migratory restlessness (Zugunruhe) shown at a stopover site depends on physiological conditions. An integrated measure of condition based on body mass, amount of subcutaneous fat and thickness of pectoral muscles strongly predicted the intensity of Zugunruhe shown in recording cages in the night following capture. These results provide novel and robust quantitative evidence in support of the hypothesis that the amount of energy reserves plays a major role in determining the stopover duration in migratory birds.
              Bookmark

              Author and article information

              Journal
              20164077
              2936206
              10.1098/rsbl.2009.1028

              Chemistry
              Animal Migration,physiology,Animals,Body Composition,Feeding Behavior,Geography,Italy,Likelihood Functions,Songbirds,Statistics, Nonparametric,Telemetry,Time Factors

              Comments

              Comment on this article