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- van Toor, Mariëlle L., et al.
(author)
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Flexibility of Continental Navigation and Migration in European Mallards
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8
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Journal article (peer-reviewed)abstract
- The ontogeny of continent-wide navigation mechanisms of the individual organism, despite being crucial for the understanding of animal movement and migration, is still poorly understood. Several previous studies, mainly conducted on passerines, indicate that inexperienced, juvenile birds may not generally correct for displacement during fall migration. Waterbirds such as the mallard (Anas platyrhynchos, Linnaeus 1758) are more flexible in their migration behavior than most migratory songbirds, but previous experiments with waterbirds have not yet allowed clear conclusions about their navigation abilities. Here we tested whether immature mallard ducks correct for latitudinal displacement during fall migration within Europe. During two consecutive fall migration periods, we caught immature females on a stopover site in southeast Sweden, and translocated a group of them ca. 1,000 km to southern Germany. We followed the movements of the ducks via satellite GPS-tracking and observed their migration decisions during the fall and consecutive spring migration. The control animals released in Ottenby behaved as expected from banding recoveries: they continued migration during the winter and in spring returned to the population's breeding grounds in the Baltics and Northwest Russia. Contrary to the control animals, the translocated mallards did not continue migration and stayed at Lake Constance. In spring, three types of movement tactics could be observed: 61.5% of the ducks (16 of 26) stayed around Lake Constance, 27% (7 of 26) migrated in a northerly direction towards Sweden and 11.5% of the individuals (3 of 26) headed east for ca. 1,000 km and then north. We suggest that young female mallards flexibly adjust their migration tactics and develop a navigational map that allows them to return to their natal breeding area.
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| 2. |
- van Toor, Mariëlle L., et al.
(author)
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Integrating sex‐specific habitat use for conservation using habitat suitability models
- 2011
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In: Animal Conservation. - : John Wiley & Sons. - 1367-9430 .- 1469-1795. ; 14:5, s. 512-520
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Journal article (peer-reviewed)abstract
- Divergent habitat utilization and niche partitioning can cause high degrees of ecological specialization even in generalist species. For example, sex‐specific specialization results in differential habitat use, which, if neglected in monitoring studies, can lead to biased estimates of population sizes. However, many widely used methods of population monitoring such as bioacoustical surveys of echolocating bats cannot take such demographic differences into account, due to methodological limitations. Here, we use ecological niche factor analysis (ENFA) to derive habitat suitability maps (HSMs) of male and female parti‐coloured bat Vespertilio murinus using previously published radio‐tracking data. The ENFA revealed that males and females were highly specialized and ecologically segregated. Accordingly, we found that significantly more high‐quality habitats were available for males than for females, with no spatial overlap between sexes. The HSMs allowed us to estimate the skew in the distribution of the sexes in space. Our approach provides a way to estimate intra‐species spatial segregation and consequently generate a more accurate prediction of effective population size and niche requirements of vulnerable species. This study also highlights the importance of making geographic and environmental data, as well as animal occurrence and movement data publicly available for the benefit of conservation efforts.
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