PhD projects

  • Migratory connectivity of Arctic long-distance migratory seabirds [Rob van Bemmelen]

Conservation goals for migratory birds can only be achieved if the full migration cycle between breeding and non-breeding is understood. In this project we aim to elucidate the migration of an elusive (and therefore poorly studied) group of bird species: long-distance migratory Arctic-breeding seabirds, some of which even undertake the epic journey between the Arctic and seas around Antarctica. Combining the recently developed technical tracking devices and isotope signatures analysis of feathers, opens the possibility to map resource use along individual migratory routes. Such information can be used to identify productive areas and areas of high conservation value. Capitalising on international collaboration we have the unique possibility to carry out simultaneous field studies at five Arctic sites on four different seabird species: Arctic Skua Stercorarius parasiticus, Long-tailed Skua S. longicaudus, Arctic Tern Sterna paradisaea and Red-necked Phalarope Phalaropus lobatus. These species cover different trophic levels (phalaropes low, terns and skuas high) and functions in both the marine and tundra ecosystems, but all share the same breeding areas. Especially in the light of expected developments in the Arctic (climate change, increase in shipping, oil and gas extraction, increase in fishing pressure), a thorough understanding of the connectivity of the Arctic with the oceans further south is paramount in conservation planning.

This project is funded by NWO and will cover the period 2014-2019.

  • A Golden life: Ecology of breeding waders in low Lapland [Paula Machín]

Three main threats of climate change for migrant waders have been identified (Meltofte et al. 2007b, Sutherland et al. 2016): (1) habitat loss, for example through sea-level rise (Purkey & Johnson 2010) and latitudinal and altitudinal treeline migration (Soja et al. 2007, Sjögersten & Wookey 2009), (2) food web changes, in particular an increase in predators (and thus predation rates), related to the increase in rodent numbers (Krebs et al. 2002), and (3) trophic mismatches, in particular the mismatch between timing of breeding and peak food availability (McKinnon et al. 2012). In this context, detailed ecological knowledge of the species life cycles is required, but such data are unavailable for most species of conservation concern.

We recognized that especially waders breeding in the Subarctic remain understudied, thus the general goal of our study was to improve our knowledge on the ecology of waders breeding in the Subarctic. We focussed on two key life-history phases, incubation and chick rearing, as these are the two main drivers of reproductive output in waders (Roodbergen et al. 2012). The first aim was to describe the nesting success of waders in relation to environmental conditions like abundance of predators, abundance of alternative prey (lemmings and rodents), and weather conditions (e.g. snow cover). The second aim was to describe the ecology of the chicks, i.e. what they eat, their habitat use, and their growth, again in relation to environmental conditions (food abundance in different habitats, weather). Subsequently, we aimed to put these results in an annual cycle perspective, by describing the annual cycle, i.e. when the species moult and migrate. Finally, we aimed to make a comparison between waders breeding in the Arctic and Subarctic, highlighting differences and similarities.

To learn more about the ecology of waders breeding in the Subarctic, we studied waders in the Vindelfjällen Nature Reserve, Ammarnäs, Swedish Lapland, a typical subarctic breeding site, from 2009-2013. For the study on nesting success we made a general annual survey of the study area, locating as many wader nests as possible, and recording the fate of these nests at regular intervals. For this particular study, also data from 2008 collected in the area was used. At the same time abundance of predators, lemmings and rodents, and weather variables including snow cover were recorded. For the studies on the ecology of chicks, we focussed on one wader species, the Eurasian Golden Plover (Pluvialis apricaria) .

This study focused on Golden Plover because (1) it is representative for subarctic waders and does not occur in the Arctic, (2) it is a common species in the study area and thus a sufficient number of chicks could be studied, (3) it is a relatively large species, with chicks large enough to carry radiotransmitters, which was essential to be able to follow individual chicks during their development, (4) it is a species that is relatively easy to observe on the relatively open tundra habitats, and (5) the species has been studied rather intensively during the non-breeding period at stopover and wintering sites (Jukema 1982, Kirby and Lack 1993, Kirby 1997, Byrkjedal and Thompson 1998, Gillins et al. 2007, Jukema et al. 2001, Piersma et al. 2003, Lindström et al. 2010). This gave me the opportunity to study moult and migration of the Golden Plover. When studying moult, we included information from other breeding areas, Iceland and Russia, as this helped us to understand the timing of moult in the annual cycle of the Scandinavian plovers. For the comparison between arctic and subarctic waders, we reviewed the literature, extracting information about nesting success, chick growth, and moult.

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