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Site description (2008 baseline)
The proposed IBA is 273 km2 in size and is important for the population of Roseate Tern that breeds here, as well as for a population of Common Tern of around 315 pairs. This IBA includes the marine areas adjacent to terrestrial IBAs PT066, PT081 and PT067 and it is estimated that a population of over 8,200 Cory's Shearwaters use it. The Cabras and Contendas islets, near the IBA, are classified as SPA. Cabras islet has a significant breeding potential for seabirds as it is large and difficult to access, although it has problems with rats and is used as a grazing ground for sheep. This island supports colonies of gulls; a breeding population of over 700 pairs has been estimated here (Neves et al. 2006a). The Contendas islet are extensively used as a leisure area and line-fishing area, which limits its potential for breeding of seabirds.

Key biodiversity
Cory's Shearwater Calonectris diomedea: The breeding population of this species is spread throughout the whole of Terceira island. A raft count has yielded an estimate of around 8,260 breeding pairs within the proposed IBA, which represents almost 40% of the total population of the island. Roseate Tern Sterna dougallii: The maximum population estimated on the Terceira IBA was 59 breeding pairs, distributed across two colonies: Contendas and Quatro Ribeiras. Historically, yearly monitoring survey data indicate that the Contendas colony is one of the most important for breeding of this species. However, since 2002, there has been a drastic decrease in the number of breeding pairs in this area, possible due to the colonization of the island by rats. Common Tern Sterna hirundo: the total population in the area of the proposed IBA is estimated at 315 breeding pairs approximately, with Contendas and Quatro Ribeiras being the most important colonies for Terceira island (Neves 2007). Other species observed in this IBA: Great Shearwater, Yellow-legged Gull.

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Terceira (Portugal). Downloaded from https://datazone.birdlife.org/site/factsheet/terceira-iba-portugal on 27/12/2024.