Past and present status and conservation of the seabirds breeding in the Azores Archipelago

The breeding seabirds of the Azores comprise five species of Procellariiformes, four Charadriiformes and one Pelecaniform. This paper reviews their past and present status, ecology and conservation. Historical population trends inferred from 16th and 17th century chronicles indicate dramatic declines for most species. While the main islands were important breeding places in the past, most seabird populations are now restricted to small islets. Intra- and inter-specific competition for nest sites is noteworthy among burrowing Procellariiformes and shortage of optimal breeding habitat seems important in limiting their populations. The chick-rearing periods of Procellariiformes with similar ecological niche do not overlap, suggesting that segregation related to partitioning of food resources or breeding habitat may be operating. Current threats to the Azores seabirds are diverse and may differentially affect the various species. They range from predation by introduced mammals, human disturbance and exploitation, habitat loss due to invasive alien plants and overgrazing by rabbits, and, potentially, competition with fisheries. Although the importance of the Azores seabird fauna was recognised in recent inventories, accurate population estimates are lacking and many potential breeding areas need surveying. For effective conservation much direct action is needed, including management plans for virtually all sites and wardening at the most important sites.