The 2018 Cahow Nesting Season is off to a great start with a record 125 nesting pairs having been identified thus far.
Watch the Video Update with Senior Terrestrial Conservation Officer Jeremy Madeiros as he conducts a health check with our CahowCam Star then read his Cahow Nesting Season Update below.
Cahow Nesting Season Update | Nov 15th 2017
Although we will not know for certain until the birds lay their eggs around the beginning of January, 2018, best indications so far are that there are123 to 125 breeding pairs of Cahows this year. A pair is considered a breeding pair only if it produces an egg, whether it hatches or not. Newly establishing pairs often "go through the motions", court, build a nest together and mate, but often do not produce an egg during their first year together, and so are not considered a breeding pair for that year.
In addition, a small number of established pairs may have produced successfully fledging chicks for several consecutive years, but then become exhausted (and many of us know how exhausting raising a child can be!). If their body condition and weight falls beyond a certain point, they may meet at the burrow, build a nest, but take a "sabbatical year" off and not produce an egg that year. This usually enables them to recover and resume egg laying/chick rearing the following year.
The most exciting developments this nesting season will be to follow the progress of the first Nonsuch-produced Cahows during their first nesting season. To explain, Cahows were eradicated from Nonsuch and all the larger islands of Bermuda as early as 1620, due to hunting by the early settlers and predation by introduced mammal predators, including rats, cats, dogs and pigs. Cahows were only re-introduced to Nonsuch during the period 2004-2008, when chicks were moved or translocated from nests on the 4 original tiny half-acre nesting islets (which are suffering increasing erosion from hurricane waves and sea-level rise). These chicks were moved into artificial concrete burrows on Nonsuch and hand-fed on squid and fish until they fledged to sea, imprinting on Nonsuch rather than their original natal island. After spending 3 to 5 years at sea, these birds then returned to Nonsuch as young adults, paired up and started nesting in the same artificial burrows. The first chick to hatch on Nonsuch since the 1620s fledged to sea in 2009, and this new colony has now grown to 16 breeding pairs, producing a total of 54 chicks in the last 8 years. The first two of these Nonsuch-born chicks returned to Nonsuch in the 2016-2017 nesting season, and should produce their first eggs in the 2017-2018 nesting season.
This first translocation has been so successful that a second translocation project was started in 2013, moving chicks to a second group of artificial burrows at a different location on Nonsuch. The first translocated birds from this "B" site returned to the new location in 2017, and 2 new pairs may produce their first eggs at this new site in the upcoming season.
More updates & developments will be provided as the nesting season progresses.
All the best, Jeremy
Jeremy Madeiros | Senior Conservation Officer (Terrestrial) | Dept. of Environment and Natural Resources | BERMUDA