Responses of captive common eiders to implanted satellite transmitters with percutaneous antennas

Abstract

Implanted transmitters have been used for over a decade to track the migrations and habitat use of many sea duck species, but their effects remain largely unstudied. To address this, I assessed the physiological and behavioral responses and characterized the clinical responses of six Common Eiders implanted with a transmitter with a percutaneous antenna. To maintain a semi-natural feeding regime, I fed birds benthicly in a 4.9 m deep dive column. I collected blood, feces, mass, and video data prior to surgery to establish baselines and at staggered intervals for 3.5 months post surgery to determine responses. All birds had some clinical complications, but most abated within 2 weeks of surgery. Mass increased in the first two weeks, but no trend was evident thereafter. Most biomarkers and dive performance metrics were altered at some point after surgery. While most biochemical values returned to baseline within weeks of surgery, a few remained deviated for longer. Additionally, dive speeds were slower for up to 3.5 months after implantation. Although it is uncertain how these changes would ultimately affect birds in the wild, effects on physiological condition and behavior seem likely in the first few weeks after surgery with longer-term effects also possible. Scientists should consider these responses and possible effects on the validity of PIT data when designing studies and analyzing information from implanted transmitters in sea ducks.