Methods The study took place on 92 islands suitable for bird nesting. Surveys were timed to take place during each species’ breeding periods. Surveys were separately conducted across 4 breeding periods: winter (December to March); spring (April to May); summer (July); and Autumn (early September). To assess bird populations, we estimated the number of breeding pairs by counting nests. Two different counting methods were used depending on the species. For strictly colonial species, the perimeter of the colony was marked with GPS and the number of eggs, chicks and scrapes found in each colony were counted. For loosely colonial and single nest species, every nest was photographed and linked to its location, and the content recorded. Example distribution of nests and colonies is shown below for Quman Island, based on surveys conducted in 2021. Observations at the islands and nest contents were used to determine the seasonality of the breeding cycle for each species.
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