Factors influencing immediate post-release survival of spectacled eiders following surgical implantation of transmitters with percutaneous antennae

Abstract

Surgically implanted transmitters are a common method for tracking animal movements. Immediately following surgical implantation, animals pass through a critical recovery phase when behaviors may deviate from normal and the likelihood of individual survival may be reduced. Therefore, data collected during this period may be censored to minimize bias introduced by surgery‐related behaviors or mortality. However, immediate post‐release mortalities negate a sampling effort and reduce the amount of data potentially collected after the censoring period. Wildlife biologists should employ methods to support an animal's survival through this period, but factors contributing to immediate post‐release survival have not been formally assessed. We evaluated factors that potentially influenced the immediate post‐release survival of 56 spectacled eiders (Somateria fischeri) marked with coelomically implanted satellite transmitters with percutaneous antennae in northern Alaska in 2010 and 2011. We modeled survival through the first 14 days following release and assessed the relative importance and effect of 15 covariates hypothesized to influence survival during this immediate post‐release period. Estimated daily survival rate increased over the duration of the immediate post‐release period; the probability of mortality was greatest within the first 5 days following release. Our top‐ranking model included the effect of 2 blood analytes, pH and hematocrit, measured prior to surgical implantation of a transmitter. We found a positive response to pH; eiders exhibiting acidemia (low pH) prior to surgery were less likely to survive the immediate post‐release period. We found a curvilinear response to hematocrit; eiders exhibiting extremely low or high pre‐surgery hematocrit were also less likely to survive the immediate post‐release period. In the interest of maximizing the survival of marked birds following release, hematological data obtained prior to surgical implantation of telemetry equipment may be useful when screening for optimal surgical candidates or informing appropriate response to mitigate potentially deleterious disorders such as acidemia. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Reliable methods for identifying animal deaths in GPS‐ and satellite‐tracking data: Review, testing, and calibration

“…Satellite and GPS‐tags are increasingly used in conservation and management‐based projects to monitor the well‐being of individuals of threatened species (e.g., individuals released during reintroductions), to assess their mortality threats, to uncover illegal activities that may be hidden by perpetrators and thus pass under‐reported or to detect cryptic sources of mortality concentrated in remote areas of difficult access or under‐reported because politically conflictual (e.g., deaths of threatened species at wind energy facilities) (reviews in Cooke, ; Kays et al., ). In addition, these tagging devices are used to evaluate specific procedures of management or research (e.g., angling methods, hunter cooperation with legal prescriptions, predator removal, techniques of tag attachments: Bengsen, ; Donaldson, Arlinghaus, Hanson, & Cooke, ; Sexson, Mulcahy, Spriggs, & Yers, ; Wiskirchen, Jacobsen, Sullivan, & Ditchkoff, ). In all these contexts, improved precision in proper identification of remotely sensed casualties would yield marked advances in management planning, implementation, and efficiency.…”

Annual cycle of White-winged Scoters (Melanitta fusca) in eastern North America: migratory phenology, population delineation, and connectivity

“…More detailed and robust descriptions of intra-winter movements and home range size are described in Meattey (2018). To minimize potential bias in habitat use and D r a f t movement behavior associated with capture and surgery trauma, we excluded the first 14 days of data collected after release (Esler 2000;Sexson et al 2014). For the same reason, we only included birds that transmitted >60 days after release in our analyses.…”

Reduction in adverse effects of tracking devices on waterfowl requires better measuring and reporting

“…Post-surgery survival of Spectacled Eiders Somateria fischeri equipped with implants with external antennas was found to be impacted by pH and haematocrit values of the blood prior to surgery. Birds with low pH, or extremely low or high haematocrit had lower survival rates during the critical first five days after surgery [77]. Obtaining these values prior to surgery may help reduce the mortality rate.…”