Understanding
the processes involved in the establishment and persistence of new seabird
colonies is important for improving conservation and management strategies.
Over the past few decades, kelp gull Larus
dominicanusnumbers have increased in Patagonia,
Argentina, and
new colonies have been reported. We studied a recently established colony to
analyse aspects of its population dynamics and breeding biology. The number of
breeding pairs at Punta Loma increased from 13 to 233 in the seven years after
the colony was established (2004-2011) and the number of chicks fledged per
nest was low (< 1 chick per nest) compared to that of other long-established
kelp gull colonies in the region. Modelled estimates of abundance assuming
closed population dynamics for the Punta Loma colony were lower than observed
(70% lower or more), suggesting that the observed growth cannot be explained by
local productivity alone. Immigration from other colonies was likely to be the
main factor responsible for the observed growth, being considerably higher than
local recruitment. This study constitutes the first characterisation of
demographic processes occurring during the initial years following colony
establishment in kelp gulls. The main findings include rapid population growth
driven by immigration and poor breeding performance potentially linked to a
high proportion of young breeders. Our results highlight the key role of
source-sink dynamics on the growth and persistence of new seabird colonies.
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