Data from: Measuring embryonic heart rate of wild birds: an opportunity to take the pulse on early development

Embryonic heart rate has the potential to provide great insight into physiological variation and ontogenic status in early development. The availability of a relatively inexpensive and portable piece of equipment – the Buddy egg monitor (Vetronic Services, UK), provides the opportunity to measure embryonic heart rate non-invasively in the field. Here we demonstrate the application of this equipment in the climatically harsh Australian outback. We characterize variation in embryonic heart rate in the zebra finch with respect to a range of abiotic and biotic variables. Heart rate increased throughout embryonic development and was positively correlated with ambient temperature. There was a strong effect of the nest of origin but no clear effect of laying order, or egg size, on embryonic heart rate. Our results demonstrate the sensitivity of embryonic heart rate to environmental conditions, and/or natal origin. We review studies that have used the digital egg monitor, and in discussing our own results identify areas of avian biology that could benefit from embryonic heart rate measurements in the future