Thursday, 22 May 2014

Cahow (Bermuda Petrel) recorded in Irish waters

One of the world’s rarest species of bird, the Cahow (also known as Bermuda Petrel) was seen off the West coast of Ireland from the Marine Institute’s R.V. Celtic Voyager on Monday 19th May 2014 over the Porcupine Bank, approximately 170 nautical miles West-Northwest of Slea Head, Co. Kerry.

The endangered seabird was recorded during a survey for cetaceans (whales & dolphins) and seabirds in the area being conducted by staff from BirdWatch Ireland, Irish Whale & Dolphin Group and Ecologists Ireland.

The Cahow was first observed at 17:56pm, travelling alongside the survey vessel at c.250m range, over a water depth of 1,030m whilst approaching the head of a canyon on the Western slope/shelf edge of the Porcupine Bank. It was on view for a maximum of 1 minute before heading off in a South East direction.

Cahow seen from the R.V. Celtic Voyager © Ryan Wilson-Parr

This is the first ever sighting of this species in Irish waters and in the North East Atlantic as a whole.

Originally thought to have numbered over half a million birds, its population suffered a catastrophic decline after the colonisation of Bermuda by humans in the early 1600's. Extensively hunted for food by the settlers and preyed upon by introduced rats, cats, dogs and pigs, the Cahow was believed to have become extinct as quickly as 1620. After 350 years it was rediscovered in 1951 surviving on tiny offshore islets where as few as 17 or 18 breeding pairs clung on. Thanks to an intensive conservation program which began in the 1960's, there are now 108 breeding pairs of Cahow in existence yet it still remains an incredibly rare bird.

Studies on their migration and foraging movements using geolocators have shown that they range widely across the North Atlantic, including a small number of birds that reach as far East as Irish waters in Spring (these are thought to be failed breeders or non-breeding immature birds). Sightings of this species at sea are very rare however. Small numbers are sighted annually off the East coast of USA and the first sighting from Canadian waters was made in April of this year. A single bird has also been recorded visiting a site in the Azores between 2002 and 2006.

Cahow seen from the R.V. Celtic Voyager © Ryan Wilson-Parr

Niall Keogh (BirdWatch Ireland Seabird Fieldworker) who was lucky enough to see this particular bird, elaborates: “With no more than 350 individuals in existence, the chances of encountering one bird from the small proportion that visit Irish waters was very slim. As such we were absolutely thrilled to have recorded this Cahow, not only because it was a privilege to see one of the world’s rarest seabirds, but also as it confirms the presence of yet another example of threatened wildlife utilising the dynamic and ecologically important marine habitats that exist in the Irish Exclusive Economic Zone (EEZ). The seabird team at BirdWatch Ireland is committed to mapping the diversity of marine avifauna in Irish waters so as to better understand their ecological requirements in this area and help inform conservation practices accordingly.

Jeremy Madeiros of the Cahow Recovery Program who is working tirelessly to conserve the species on the breeding grounds in Bermuda also had this to say: “This is a great confirmation of the information and tracks we were getting from geolocaters attached to adult breeding Cahows several years ago, which clearly showed that some Cahows at least during the period April to early June were approaching rather closely (to within 100-200 miles) of both western Ireland and northwestern Spain/Portugal.

Cahow seen from the R.V. Celtic Voyager © Ryan Wilson-Parr

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