Survival probability in a small shorebird decreases with the time an individual carries a tracking device

Effects of tracking devices on survival are generally considered to be small. However, most studies to date have been conducted over a time-period of only one year, neglecting the possible accumulation of negative effects and consequently stronger negative impacts on survival when the individuals have carried the tracking devices for longer periods. We studied the effects of geolocators in a closely monitored and colour-ringed southern dunlin (Calidris alpina schinzii) population breeding in Finland. Our capture-recapture data spans 2002-2018 and includes individual histories of 338 colour-ringed breeding adult dunlins (the term ‘recapture’ includes resightings of colour-ringed and individually recognizable birds). These data include 53 adults that were fitted with leg-flag mounted geolocators in 2013-2014. We followed their fates together with other colour-ringed birds not equipped with geolocators until 2018. Geolocators were removed within 1-2 years of attachment or were not removed ...