The Cahow or Bermuda Petrel (Pterodroma cahow)
The Cahow is an endangered species of seabird and endemic to Bermuda. It breeds nowhere else in the world, although it is occasionally seen on pelagic birdwatching trips in the Gulf Stream off the Carolinas.
Formerly abundant, hundreds of thousands of birds were slaughtered or eaten by the first human settlers in the 16th and 17th centuries. Introduced hogs, cats, dogs and rats also preyed on nesting birds. By 1620 the Cahow was thought to be extinct.
The Cahow was re-discovered in 1951. In 1961, when a recovery programme started, only 18 pairs existed on isolated off-shore islands. In 2006 there were 75 pairs, thanks to conservation measures. It is Bermuda’s official national bird.
Characteristics
- A tube-nose gadfly petrel. Length 15 inches. Wingspan 36 inches
- Plumage: blackish-grey cap extends to nape and hindneck; rest of head, including forehead, white; remaining upperparts grey; underparts mostly white
- A fast flier with scimitar shaped wings
- This pelagic seabird returns to breeding grounds in October/November
- Only enters and exits the nesting burrows at night
- Nesting takes place from January to June
- Pairs only lay one egg
- Breeding pairs have an approximate 50% success rate in fledging young
- Similar species: Black-capped Petrel (Pterodroma hasitata)
Threats
- Global warming and the associated rising sea-level flooding nesting burrows
- Increasing frequency of hurricanes destroying nesting burrows
- Competition for nest sites from White-tailed Tropicbirds (Phaethon lepturus)
- Predation by rats
- Cane Toads (Bufo marinus) occupying burrows
Conservation Measures
- A recovery programme has been in existence for over 45 years
- Artificial burrows have been provided on the nesting islands
- Inspection lids allow regular monitoring of birds
- Wooden ‘baffle’ at the entrance of the burrow allows Cahows to enter, but keeps out Tropicbirds
- Nesting grounds are regularly monitored for rats and removed if found
- Removal of toads from the nesting islands
- Young Cahows are being translocated to Nonsuch Island
Cahow Translocation Project
- Scores of artificial burrows have been constructed on the higher, larger and more suitable Nonsuch Island. Since 2004, a total of 55 Cahow chicks have been placed in these artificial burrows before they leave their burrows on the small nesting islets. When the birds finally exit the burrows and eventually depart, it is hoped that Nonsuch Island will be imprinted on the birds, and they will return there to breed. This method has already been used with great success on the similar Gould’s Petrel in Australia.
Cahow Bird of the Month contributed by Andrew Dobson
Bird of the Month - June 2006 - West Indian Whistling-Duck
