Externally attached biologgers cause compensatory body mass loss in birds

Animal-borne logging devices are now commonly used to record and monitor the movements, physiology behaviours of free-living animals. It is imperative that impacts these have on animals themselves minimised. One important consideration interaction between body mass animal device. Using captive homing pigeons, we demonstrate birds lose equivalent amount compared device attached. With our experiments, calculated compensatory loss because equates a total 1,140 kJ energy bird, over 25-day period. This 32% per day their daily budget. We suggest practitioners biologging give due possibility device-induced decrease in when making decisions regarding size, considering period time year at which appears, based results present study, attachment likely be most disruptive during periods regulated change, especially gain precede stored reserves extensively utilised. These findings significant consequences for anyone using technology both wild volant Further studies utilising needed fully understand how context- species-dependent physiological responses externally attached are.