Satellite tracking of the migratory pathways of first-year Lesser Black-backed Gulls Larus fuscus departing from the breeding grounds of different subspecies (original) (raw)
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On the species level, the non-breeding distribution and the migration patterns of most European birds are well known. In contrast, the knowledge of the contribution of different breeding populations to particular non-breeding sites (migratory connectivity) is far more limited. We studied the non-breeding distribution of individually colour-ringed Lesser Black-backed Gulls (Larus fuscus graellsii) from Iceland and sought information on their migration pattern in respect to other populations (leap-frog, chain migration, random mix). Most winter resightings (94%) were from the southern part of the known winter range (Iberian Peninsula and northwest Africa). No statistical difference was found according to age on the latitudinal winter distribution, although 1st winter birds were on average 2° further south. Both 2nd and 3rd calendar year (cy) birds performed a northward spring migration,but spent the summer at lower latitudes than adults. The autumn migration for adults was earlier compared with 1st cy birds. A comparison of resightings of birds ringed in Iceland and in two projects from the Netherlands showed that these populations are not likely to contribute much to the wintering population in the UK. The proportion of winter resightings from Icelandic and Dutch populations showed that 44–65% were from the Iberian Peninsula. However, Dutch birds were much more likely to be seen in France (18–48 vs. 0.4%), but Icelandic birds were more likely to be seen in Africa (29 vs. 6–16%). These results indicate that Icelandic birds to some extent leap-frog more southerly populations.
Global Ecology and Conservation
In contrast to many other gull species, nominate lesser black-backed gulls (Larus fuscus fuscus, nLBBG) have shown generally decreasing population trends throughout their breeding area in northern and eastern Fennoscandia over the past decades and are now red-listed. Interspecific competition, predation, increased disturbance, organochlorine poisoning and food shortages were suggested as main reasons for the overall decrease. Here we contribute to a better understanding of population declines by comparing foraging movements of satellite tracked adult gulls in three geographical areas of Finland (West, South, and East) that differ in their population trends. Our analysis examines potential differences and preferences in the feeding site behaviour of adult gulls. Our comparison of the three geographical areas showed that nLBBGs preferred feeding at fur farms in West Finland, waste dumps in South Finland, and lakes and fields in East Finland. We found individual gulls of this purportedly generalist species to be highly specialised in their foraging behaviour, particularly those that might be associated with their survival probabilities. We ms 23-Mar-2017
Flyways and migratory behaviour of the Vega gull (Larus vegae), a little-known Arctic endemic
PLOS ONE, 2023
Large gulls are generalist predators that play an important role in Arctic food webs. Describing the migratory patterns and phenology of these predators is essential to understanding how Arctic ecosystems function. However, from all six large Arctic gull taxa, including three long-distance migrants, to date seasonal movements have been studied only in three and with small sample sizes. To document the flyways and migratory behaviour of the Vega gull, a widespread but little-studied Siberian migrant, we monitored 28 individuals with GPS loggers over a mean period of 383 days. Birds used similar routes in spring and autumn, preferring coastal to inland or offshore routes, and travelled 4000-5500 km between their breeding (Siberia) and wintering grounds (mainly the Republic of Korea and Japan). Spring migration mainly occurred in May, and was twice as fast and more synchronized among individuals than autumn migration. Migration bouts mainly occurred during the day and twilight, but rates of travel were always higher during the few night flights. Flight altitudes were nearly always higher during migration bouts than during other bouts, and lower during twilight than during night or day. Altitudes above 2000m were recorded during migrations, when birds made nonstop inland flights over mountain ranges and vast stretches of the boreal forest. Individuals showed high inter-annual consistency in their movements in winter and summer, indicating strong site fidelity to their breeding and wintering sites. Within-individual variation was similar in spring and autumn, but between individual variation was higher in autumn than in spring. Compared to previous studies, our results suggest that the timing of spring migration in large Arctic gulls is likely constrained by snowmelt at breeding grounds, while the duration of migration windows could be related to the proportion of inland versus coastal habitats found along their flyways ('fly-and-forage' strategy). Ongoing environmental changes are hence likely in short term to alter the timing of their migration, and in long term possibly affect the duration if e.g. the resource availability along the route changes in the future.
2015
legged Gulls Larus [cachinnans] michahellis from two small western Mediterranean colonies. Atlantic Seabirds 4(3): 101-108. In this study we analyse recoveries and resightings of ringed Yellow-legged Gulls Larus [cachinnans] michahellis from two small colonies located along the E and SE Mediterranean Iberian coast. Results show that birds follow the same migratory routes as birds of other colonies of the western Mediterranean. Gulls move to the Atlantic coast of France and Iberia after fledging, where they summer and winter, although equally important numbers probably remain close to their natal colonies. Immature gulls (1y + 2y) seem to return and stay in the vicinity of their natal colonies during spring. Long-range movements target Atlantic areas with a high primary production during periods of food scarcity in the western Mediterranean. Adult gulls probably do shorter-term long-range dispersal movements than juveniles and immatures, owing to their larger experience on where to f...
Scientific Reports, 2018
Sex-, size- or age-dependent variation in migration strategies in birds is generally expected to reflect differences in competitive abilities. Theoretical and empirical studies thereby focus on differences in wintering areas, by which individuals may benefit from avoiding food competition during winter or ensuring an early return and access to prime nesting sites in spring. Here, we use GPS tracking to assess sex- and size-related variation in the spatial behaviour of adult Lesser Black-backed Gulls (Larus fuscus) throughout their annual cycle. We did not find sex- or size-dependent differences in wintering area or the timing of spring migration. Instead, sexual differences occurred prior to, and during, autumn migration, when females strongly focussed on agricultural areas. Females exhibited a more protracted autumn migration strategy, hence spent more time on stopover sites and arrived 15 days later at their wintering areas, than males. This shift in habitat use and protracted aut...
2002
2002. Movements of Yellowlegged Gulls Larus [cachinnans] michahellis from two small western Mediterranean colonies. Atlantic Seabirds 4(3): 101-108. In this study we analyse recoveries and resightings of ringed Yellow-legged Gulls Larus [cachinnans] michahellis from two small colonies located along the E and SE Mediterranean Iberian coast. Results show that birds follow the same migratory routes as birds of other colonies of the western Mediterranean. Gulls move to the Atlantic coast of France and Iberia after fledging, where they summer and winter, although equally important numbers probably remain close to their natal colonies. Immature gulls (1y + 2y) seem to return and stay in the vicinity of their natal colonies during spring. Long-range movements target Atlantic areas with a high primary production during periods of food scarcity in the western Mediterranean. Adult gulls probably do shorter-term long-range dispersal movements than juveniles and immatures, owing to their larger experience on where to find alternative food sources.