LAUSR

Blood sampling from the brachial vein and sub-cutaneous implantation of PIT-tags (‘passive integrated transponders’) are techniques widely practiced in ornithological research. Longer-term consequences of these procedures (across months or years) have been studied in detail. However, it remains largely unknown how blood sampling and PIT-tagging affect birds during and immediately following the procedure. Here, we test the impact of these procedures on respiration rate and on behavioural correlates of avian pain, stress, and discomfort in the Blue Tit Cyanistes caeruleus. Ten wild-caught Blue Tits were divided in two groups: five were measured, ringed, blood sampled and implanted with a PIT tag (‘treatment birds’); the other five were handled in the same way, but blood sampling and PIT-tagging were conducted as a sham-procedure (‘control birds’). Treatment and control birds did not differ in respiration rates during handling, but treatment birds showed behaviours indicative of an acute stress event associated with brief and moderate pain. Following release in an aviary, treatment and control birds did not differ in behaviour. Birds showed no indication of pain or stress. Instead, they foraged, preened and explored the aviary immediately after handling. Individuals spent much of their time pecking at their new rings. Our results suggest that blood sampling and implantation of PIT-tags have limited short-term effects on Blue Tits. However, the process of handling and ringing itself may have substantial behavioural consequences, which may be relevant for animal welfare and the quality of collected data.