The Breeding Biology of the Endemic Azores Woodpigeon Columba palumbus azorica

Abstract

The Azores Woodpigeon Columba palumbus azorica is considered an endemic subspecies and is currently listed in the Annex I of the EU Birds Directive. However, despite its status, the bird has rarely been studied and is classified as ‘Data Deficient’ in the Portuguese Red Data Book. Herewith, we present the first results on the breeding biology of this subspecies, based on data collected from November 2012 to October 2014 on Terceira Island. Data were obtained by monitoring nests, and additional information on breeding phenology was provided during regular counts from 100 points distributed over the island. Fifty-four nests were found mainly in exotic trees, suggesting that the species does not depend on the highly degraded native laurel forest for nesting. Egg-laying occurred from late-February to late-September, reaching its peak in May; the main laying period lasted 140 days from 1 April to 19 August. Mean clutch size (±SE) was 1.77 ± 0.06 eggs (range 1–2 eggs) and did not vary with time. Overall breeding success, calculated using the Mayfield method, was amongst the lowest ever detected for this species across its breeding range: 0.091 ± 0.048 (SE). Extreme weather events and predation by introduced mammals are likely to explain high nest failure. The population is likely to have undergone a period of growth since 1992, following a period in the 1960's when the bird was very scarce in the Archipelago due to hunting pressure. In recent years, farmers have increasingly complained to the Regional Government about damage to crops, including vineyards, caused by the Azores Woodpigeon on some of the Azorean islands.