Using sutures to attach miniature tracking tags to small bats for multimonth movement and behavioral studies

Abstract

Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (<30 g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration, particularly in the context of emerging conservation issues such as fatalities at wind turbines and diseases. We tested a novel method of attaching lightweight global positioning system (GPS) tags and geolocating data loggers to small bats. We used monofilament, synthetic, absorbable sutures to secure GPS tags and data loggers to the skin of anesthetized big brown bats (Eptesicus fuscus) in Colorado and hoary bats (Lasiurus cinereus) in California. GPS tags and data loggers were sutured to 17 bats in this study. Three tagged bats were recaptured 7 months after initial deployment, with tags still attached; none of these bats showed ill effects from the tag. No severe injuries were apparent upon recapture of 6 additional bats that carried tags up to 26 days after attachment; however, one of the bats exhibited skin chafing. Use of absorbable sutures to affix small tracking devices seems to be a safe, effective method for studying movements of bats over multiple months, although additional testing is warranted. This new attachment method has the potential to quickly advance our understanding of small bats, particularly as more sophisticated miniature tracking devices (e.g., satellite tags) become available.

Evidence of region‐wide bat population decline from long‐term monitoring and Bayesian occupancy models with empirically informed priors

“…A second solution will be to close the information gap about bat migration and other bat natural history using novel methods such as transmitter suturing developed by Castle, Weller, Cryan, Hein, and Schirmacher (2015) that has revealed long-distance movements of hoary bats (Weller et al, 2016). A third solution will be to integrate geographically extensive coordinated acoustic surveys into a conservation information system that draws on multiple lines of evidence.…”

First Direct Evidence of Long-distance Seasonal Movements and Hibernation in a Migratory Bat

“…Bats were released at the capture site after allowing them 20 minutes to recover from anesthesia. Bats to which tags were attached did not exhibit unusual levels of mass loss, skin irritation, or mobility while entering roosts 53 .…”

“…We attached tags to adult male hoary bats, which comprise >95% of captures at this site, selecting individuals with the highest mass captured on a given night. We attached tags to the dorsum, caudal to the scapulae and cranial to the pelvis using sutures following the methods of Castle et al 53 . Bats were released at the capture site after allowing them 20 minutes to recover from anesthesia.…”

“…We attempted to recapture tagged individuals using mist net surveys along the Bull Creek waterway on 19 nights between Sep 26 and Oct 19 2014, 13 nights between Oct 27 2014 and Apr 02 2015, and 22 nights between Apr 12 and 28 May 28 2015. When bats carrying GPS tags were recaptured during autumn 2014 we downloaded data and recharged and reprogrammed tags while they were attached to bats 53 . In contrast, recovery of data from data loggers required removal of the tag.…”

High detectability with low impact: Optimizing large PIT tracking systems for cave‐dwelling bats

“…Another alternative is radio‐tracking; however, a comprehensive review has found that most radio‐tracking devices used to study bats are too heavy, are being used with minimal ethical justification, and remain attached for an average of just 9 days (O'Mara et al, ). A more recent innovation for the use on small bats has been miniaturized GPS tags; however, currently this has only been successfully attempted with the use of anesthesia and sutures to attach the loggers—and battery life, tag weight and recapture rates remain ongoing issues (Castle, Weller, Cryan, Hein, & Schirmacher, ; Weller et al, ).…”