A photographic guide for determining egg incubation stage in the Superb Fairy-wren (Malurus cyaneus)

Elisa Resendez, Paulo Ditzel, Paul Kessler, Emma Buckley, Claire Huff, Colleen Poje, Joleah B Lamb, James Kennerley, Jonathan Coleman, Jordan Boersma, Michael Webster, William Edgar Feeney

When monitoring the nesting biology of wild birds, nests are often found after the eggs have been laid and incubation has commenced. Candling—the use of a bright light to illuminate egg contents—is a useful method for estimating embryo development and incubation stage. This information is used to estimate when incubation started and predict when eggs will hatch. As the focus of several long-term monitoring studies, a guide for assessing the stage of embryo development in the Superb Fairy-wren (Malurus cyaneus) will enable a standardized estimation of egg development for nests found after laying has been completed. Here, we present a photographic guide for determining embryo development using candling in the Superb Fairy-wren. In the process of developing this guide, we also address the need for a cost-effective and accessible method for candling eggs in the field with a portable candling device.