Phenology of migration and use of wintering sites by the increasing population of dark‐bellied brent geese Branta bernicla bernicla

Abstract

With 5 figures in the text)During the recovery of the population of dark-bellied brent geese Branru herniclu bernicla, traditional wintering sites in Britain have experienced increases in numbers and new sites have been colonized. Goose counts were used to describe the migration phenology and winter use of Scolt Head, north Norfolk (a traditional site) and the Burry Inlet, South Wales (a relatively new site) over the period of re-colonization and colonization, respectively. During the 1950s, only a few hundred birds wintered at Scolt Head, and most stayed for only a short period. By the late 1980s/early 199Os, numbers had reached several thousands, their period of stay was longer and there was little variation between years in median arrival (28 October) and departure (1 1 March) dates. A similar process was observed during the entire colonization phase at the Burry Inlet; initially birds arrived late and departed early, but arrived progressively earlier and departed later as wintering numbers increased. The autumn arrival rates at both sites were slower than the spring departure rates. During years of good breeding productivity, those adults with young arrived slightly later in Norfolk than failed breeders and non-breeders, and a higher proportion of young birds remained in spring after the main departure. However, the overall pattern of arrival and departure did not vary according to whether there had been a good or poor breeding season. Some adults of breeding age also remained until May. The effects of food depletion and use of novel feeding habitats in relation to migration phenology and winter use of sites are discussed.

Multi-colony tracking reveals spatio-temporal variation in carry-over effects between breeding success and winter movements in a pelagic seabird

“…Thus, unsuccessful individuals departed the colony earlier and, for some colonies, reached their winter destination sooner and spent longer at those destinations, in line with previous findings (Summers et al 1996, Phillips et al 2005, Bogdanova et al 2011). However, our study contrasted with previous work on 1 study population (on the Isle of May), which found a relationship between breeding success and subsequent winter destination, with unsuccessful individuals typically migrating to the NW Atlantic and successful individuals to the northeast Atlantic or North Sea (Bogdanova et al 2011).…”

“…First, we hypothesised that, across colonies, there would be an overall relationship between breeding success and scheduling and location of migration, such that unsuccessful individuals depart the colony earlier, migrate farther, reach their winter destinations sooner and spend longer at those destinations, in line with previous findings in this and other species (Summers et al 1996, Phillips et al 2005, Bogdanova et al 2011. Second, we hypothesised that there would be spatial variation in the strength of carry-over effects among colonies, since variation in environmental conditions among colonies is likely, and more favourable conditions are predicted to dampen carry-over effects (Legagneux et al 2012, Harrison et al 2013).…”

Spatially explicit, individual‐based, behavioural models of the annual cycle of two migratory goose populations

“…Thus, the simulated within‐site movements between habitats are consistent with the behaviour of brent geese. At the larger spatial scale of movements throughout Europe, it is well established that the first birds to arrive in western Europe in autumn are generally failed or non‐breeders, with families containing birds of the year arriving sometime later (Summers et al . 1996; Ganter 1998).…”

Seasonal interactions in the black-legged kittiwake, Rissa tridactyla : links between breeding performance and winter distribution

“…Previous studies have shown that unsuccessful breeders leave the breeding grounds earlier than successful breeders (e.g. [14,16,17]). Although these differences in the timing of departure were associated with wintering periods that were extended for up to several months, there were no apparent differences in winter distribution.…”