The effect of telemetric devices on the flight and swimming performance of birds

Abstract

In studying animal behavior the use of telemetric devices is very common, as it is able to give detailed information about the animal’s activities (e.g. migration routes, population dynamics etc.) from a distance. Telemetric devices are also used to study physiological aspects, like heart rate and body temperature. However, equipping animals with devices could influence their behavior and ecology. Through literature research the effect of external devices on migratory and aquatic bird species have been determined. It turns out that external devices are causing an increase in drag which strongly affects the flight performance of migrating species and the swimming performance of aquatic species. For migrating species this means that there is an increase in energy expenditure, decrease in migration range and a decrease in return rates for equipped birds. Furthermore, it turned out that bird species migrating longer distances had a stronger decrease in return rates than birds with medium or short migration distance. For aquatic bird species equipped with devices, mostly penguins, the devices were causing an increase in energy expenditure and an increase in diving time. Also a negative correlation with the size of the device (i.e. cross-sectional area) and swimming speed and diving depth was determined for some penguin species. The results strongly point out the importance of being critical as it comes to using telemetric devices. It is suggested that researchers try to minimize the effects of the devices by first studying the effects of the device on the animal (literature of practical research) and stay critical as it comes to interpreting their data.