2018 saw the first use of the “Candling” technique in the Cahow Recovery Program, thanks to Carla Marquardt, who has had extensive experience in the technique working with breeding various Parrot, Macaw and Cockatoo species in Florida. Incidentally, Carla spent part of many summers growing up on Nonsuch Island, as mentioned in the book “Nonsuch Summer” by Janet Wingate, as her father was a superintendent in the Bermuda Parks Department in the 1970s, and his family would stay for a month every summer in the Cottage on the island. (This Cottage is now used to house visiting scientists and researchers)
Candling is a method used to determine whether eggs are fertile or infertile, and to study the growth and development of an embryo inside an egg. The method uses a bright light source behind the egg to show internal details through the shell, and is so called because in the past, the original sources of light used were candles.
Using this method, Carla was able during several visits to both Nonsuch and the smaller nesting islets to determine which eggs were infertile, and whether the embryos were developing normally or not. For example, out of the 18 Cahow nesting pairs on Nonsuch this season, she was able to confirm that two of the eggs were infertile, and that the embryos had died in early development in another two eggs. We were also able to follow the development of embryos in the good eggs through follow-up checks.
Candling has proven to be a useful and worthwhile technique for the Cahow recovery Program and will continue to be incorporated in future management of the species.
Jeremy Madeiros, Senior Terrestrial Conservation Officer, Dept. of Environment and Natural resources