Vagrancy and Colonization by Birds: Escape from Climate Extinction?

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Wild birds often turn up in unexpected places, far away from where they breed or usually migrate. These presumably lost individuals are called “vagrants”. Historically, they have viewed as sad events – an unfortunate consequence of something gone wrong. This project will explore an alternative perspective – that vagrancy is a normal event, caused by young birds from rapidly growing populations exploring the world for new, less-crowded places to live. This idea will be tested by placing trackers on 50 Lesser Black-backed Gulls captured in New York and Massachusetts, then recording their positions by satellite for roughly 2 years. The species is not known to breed nearby. The closest major breeding colonies are in Greenland and those colonies have been growing quickly. Therefore, researchers expect the tracked gulls to be from Greenland and for some to return there. In addition to tracking data, genetic testing will be used to link individuals captured in New England to populations in Greenland or perhaps Iceland. Data from this project will be useful in understanding birds’ abilities to respond to a changing climate. In particular, this work will reveal the extent to which some seabirds actively explore and adapt to a changing world.This project will use ICARUS GPS units to track movements of 50 Lesser Black-backed Gulls trapped by cannon net at Fire Island, New York and Nantucket Island, Massachusetts. Based on position data from the GPS units, three predictions will be tested: (1) Wintering birds trapped in North America will return to Greenland. This prediction is based on the observation that the greatest population growth of Black-backed Gulls anywhere during the period of largest increase of wintering birds in North America (1990-present) was in Greenland. (2) Non-adult birds (4 years old, determined by plumage) will engage in more exploratory behavior, as measured by First Passage Time Analysis, than adult birds. (3) Birds trapped in North America will be derived from Greenland populations. This will be tested by population genetics, based on genetic analysis of feathers from birds captured in New England with those from birds in Greenland, Iceland and western Europe.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.