LAUSR

Understanding changes in body temperature is central to several fields in biology, but doing so accurately without harming or restraining individuals can be challenging, particularly for small species. We tested firstly whether body temperature readings differed between injection of Passive Integrated Transponder (PIT) tags subcutaneous inter-scapulae (i.e. solely through the skin) and intra-peritoneal injection (through the skin and abdominal muscle wall) and, secondly, whether intra-peritoneal tag injuries differed among three weight classes of passerines. We found no significant difference in body temperature readings between subcutaneous intra-scapulae and intra-peritoneal PIT-tags, and observed that the intra-peritoneal injection of PIT-tags may cause adverse effects among smaller (< 25 g) birds. Our findings suggest a reduced gradient between core and peripheral Tb in small species, which to the best of our knowledge has not yet been quantified. We further show that risk of detrimental injury was greatest in small species, and thus recommend implanting PIT-tags subcutaneously between the scapulae for smaller birds. This article is protected by copyright. All rights reserved.