First Two CahowCam Chicks Have Returned!

Both "Backson" from 2013 and "Lightning" from 2014 have returned after surviving the odds of their first few years alone at sea.

Even more incredibly Backson, now confirmed to be a female has laid her first egg with her mate in a nest that they have been prospecting in Translocation Colony B on Nonsuch Island.

Jeremey Madeiros | Returns of 2013 and 2014 “CahowCam” Cahow Chicks

The present 2017-2018 Cahow breeding season has already produced a number of surprises and developments in the Recovery Program for Bermuda’s critically endangered National Bird, the Cahow or Bermuda Petrel, one of the rarest seabirds on Earth.

Since 2013, the team has been video monitoring one of the deep Cahow nest burrows on the Nonsuch Island Nature Reserve, to help fulfill one of the primary objectives of the Cahow Recovery Program, that of public outreach and education.

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In 2013 an infrared video "CahowCam" (developed by LookBermuda as part of the Nonsuch Expeditions) was installed for the first time in the R832 Cahow burrow at the “A” Cahow colony on Nonsuch Island. This chick hatched on the 13th of March, 2013, and developed normally over the next 3 months, reaching a peak weight of 393 grams on the 6th of June. It then rapidly developed its adult feathers and carried out 6 nights of pre-departure exercising activity, coming out of the nest burrow at night to exercise and strengthen its flight muscles and imprint on the nest colony site. During this period, it “slimmed down” to a normal departure weight of 293 grams, fledging out to sea on the night of 16th June, 2013. The chick was then not seen for several years, living out on the open ocean and learning how to find and catch food, avoid predators, and learn how to survive on one of the harshest environments on Earth; the North Atlantic Ocean.

Over 4 years later, on the 5th December, 2017, I was carrying out a check of nest burrows at the “B” nesting colony on Nonsuch Island. This second site has had Cahow chicks translocated to it since 2013, in an effort to establish a second nesting colony on the island, following the success of the first, “A” colony. Earlier, on October 30th, one of the nests at this second site was prospected for the first time, with a male Cahow found in it that had been translocated to this site in 2013.

On this day, I could see a Cahow in the burrow that had already begun building a grass nest, and when captured and brought out of the nest for examination, I could see that it was one of the birds that I had previously banded as a chick. The band number, E0500, also seemed oddly familiar, so I checked my records and confirmed that this bird was indeed Backson, our first CahowCam video star! It was very satisfying to see that Backson had not only survived its risky adolescent period at sea, as typically only about one-third of fledging Cahow chicks survive this period to return as adults, but that it had already paired up with another Cahow.

Normally, new pairs of Cahows do not produce eggs during their first year together, but on the 22nd January, 2018, I found Backson incubating a newly laid, fertile egg in this nest burrow. I was also able to confirm for the first time that Backson was indeed a female. As of this time, we are just waiting to see if this egg hatches, which would happen in the next two weeks or so.

As if all this was not exciting enough, on the 20th January, 2018, I had discovered another newly returned Cahow, prospecting inside a nest burrow on one of the original small nesting islets. Upon examination of its band number, this bird turned out to be the second CahowCam chick, which was named “Lightning” by Sophie Rouja in the 2014 nesting season. This bird, from the R831 nest on Nonsuch Island, hatched on March 2nd, 2014, reached a peak weight of 422 grams on May 6th, and fledged to sea on May 27th, 2014. (This bird’s name was prophetic, as the CahowCam was knocked out twice by lightning strikes on Nonsuch Island while the chick was developing, which has led to a fair weather naming policy). So far, this bird has not attracted a mate to its new nest site, but we will continue to monitor for new developments in this regard as the season progresses.

Jeremy Madeiros, Senior Terrestrial Conservation Officer, Dept. of Environment and Natural Resources

Critically Endangered Bermuda Skink visits CahowCam Burrow

A Bermuda Skink was recently filmed visiting the CahowCam burrow as we wait for the female to return to lay her egg. Historically, they have a long-standing, important relationship with the Cahows as they help keep the nests clean.

Jeremy Madeiros | " The management and protection of the small nesting islands where the endangered Cahow nests also has an added bonus, in that this also protects a number of other native and endemic plant and animal species. One of the most significant of these is the critically endangered Bermuda Skink, which used to be common across most of Bermuda, but is now found only on isolated offshore islands and in a few small, fragmented populations in coastal locations such as Spittal Pond. It is now one of the rarest lizard species on Earth, and is found on at least 4 of the small islands where the Cahow nests. 

For many years, I have observed Skinks in Cahow nest burrows on these islands, often when the Cahows themselves are in residence. They seem to tolerate each other's presence, and there is evidence that the both species benefit from the association, with the Skinks using the burrows for shelter, eating insects, spilled food, infertile eggs etc., keeping the burrows clean and disease-free for the Cahows. It was known that a small colony of Skinks lived in the Cahow colony on Nonsuch, with surveys indicating that this population may have increased in the last couple of years; this was the first time that we had been able to record a skink visiting the CahowCam nest."

Mark Outerbridge | MSc, PhD, Wildlife Ecologist, Government of Bermuda

History

·        The skink is Bermuda's only endemic, four-legged, terrestrial vertebrate (in other words they are the only living land animal with a backbone to have reached Bermuda before humans, and they exist nowhere else in the world) 

·        Skinks are descended from a species that once inhabited the eastern U.S.A. and subsequently dispersed over oceanic waters to Bermuda (Brandley et al., 2010)

·        Fossil evidence indicates that skinks were living on Bermuda more than 400,000 years ago but paleontological and geological evidence suggest they may have been present here for 1-2 million years (Olsen et al., 2006)

·        Skinks were historically described as being very common, frequenting the old walls and stone heaps in the cedar groves of Bermuda (Jones, 1859). Now, most of the fragmented populations are only found within the rocky coastal environment.

Ecology

·        Adult skinks grow to 15-25 cm in length and weigh between 13-22 g. Hatchlings are 6 cm long, weigh about 1 g and have bright blue tails (which fades as they grow older).

·        Skinks are thought to live for 20+ years

·        Skinks are diurnal and are most active mid-morning and late afternoon

·        Active year-round (they don’t brumate – reptile equivalent of hibernation - during the winter months)

·        Ground dwelling species (don’t climbing trees)

·        Omnivorous diet; insects, arthropods, prickly pear fruit and carrion from burrow-nesting birds (e.g. cahows and longtails)

·        Oviparous species (i.e. egg laying). Nesting occurs in May and June (3-6 eggs typically laid on the soil under rocks). Females guard their eggs.

·        Hatching begins in July and August after a 5 week incubation period.

Threats

·        Bermuda’s skinks are now on the brink of extinction. They are listed as critically endangered and receive protection under the Protected Species Act.

·        Habitat alteration and predation from introduced species are considered to be the main causes of population fragmentation and decline

·        The total island-wide (hence global) population was estimated to be 2300-3500 individuals (Edgar et al., 2010)

·        Skinks have been reported from at least 24 separate locations across Bermuda (Edgar et al., 2010) but the greatest concentration is found within the Castle Islands Nature Reserve

·        Various population assessments have been undertaken over the past two decades. Some of the fragmented populations consist of only 50 individuals while others number in the hundreds. The largest population is currently found on Southampton Island (estimated 500 skinks).

Nonsuch skinks

·        Surveys conducted on Nonsuch over the past 50 years suggest the population is declining and those skinks that remain are only found in a few locations on the island.

·        In the early 1960s, the vegetation on Nonsuch was mostly grass and coastal shrubs – ideal habitat for skinks (dense ground cover for concealment from predatory birds and rich in insect prey)

·        The reforestation efforts that have occurred since the 1960s drastically changed the interior of the island, making it less favorable as suitable skink habitat (Wingate, 1998)

·        The creation of the two cahow nesting sites is expected to benefit the skinks; as the cahow colony grows on Nonsuch, so too should the skink colony.