Bio-logging, new technologies to study conservation physiology on the move: a case study on annual survival of Himalayan vultures

Sherub Sherub,Wolfgang Fiedler,Olivier Duriez,Martin Wikelski

doi:10.1007/s00359-017-1180-x

Abstract

Bio-logging, the on-animal deployment of miniaturised electronic data recorders, allows for the study of location, body position, and physiology of individuals throughout their ontogeny. For terrestrial animals, 1 Hz GPS-position, 3D-body acceleration, and ambient temperature provide standard data to link to the physiology of life histories. Environmental context is added at ever finer scales using remote sensing earth observation data. Here we showcase the use of such bio-logging approaches in a conservation physiology study on endangered Himalayan vultures (Gyps himalayensis). We determine environmental, behavioural, and physiological causes of survival in immature birds that roam from wintering sites in India, Bhutan, and Nepal towards summer areas in Tibet and Mongolia. Five of 18 immature griffons died during one year. Individuals that died had failed to migrate sufficiently far northward (>1500 km) in spring. Individuals likely died if they flew against headwinds from the north or were less able to find thermal updrafts. Surviving individuals migrated to cold and dry areas with low population density. We highlight flight experience, long distance movements, and remote places with low human population as factors critical for the survival of Himalayan vultures. High-resolution bio-logging studies can advance conservation management by pinpointing where and why migratory animals have problems and die.

Highlights

Physiological investigations of animals can increasingly ‘go wild’ with the rapid advancement of ever smaller electronic bio-logging units (Block 2005; Ropert-CoudertJ Comp Physiol A (2017) 203:531–542 and Wilson 2005; Wilson et al 2008, 2014, 2015; Bridge et al 2011)
The departure direction of Himalayan vultures was predominantly north-easterly (Fig. 1b), with a median departure direction of 52.5° during their winter-to-summer migration
Environmental factors that we considered to potentially affect survival, but that apparently did not influence the survival of Himalayan vultures were: flight altitude above the surface (p = 0.09), absolute flight height (p = 0.41), sunshine duration (p = 0.08), precipitation (p = 0.17), or the proportion of time flying via thermalling (p = 0.18) or via straight-line flight (p = 0.31)

Summary

Introduction

J Comp Physiol A (2017) 203:531–542 and Wilson 2005; Wilson et al 2008, 2014, 2015; Bridge et al 2011) Such investigations into the exact details and physiological mechanisms underlying life history or population processes are increasingly important today in light of widespread, global population declines of many animal species (Wikelski and Cooke 2006; Morales et al 2010; Cooke et al 2014; Lennox et al 2016). Used sensors report GPS position, 3D-accelerometry, lightlevel information, conductivity, salinity, external as well as body temperature, heart rate or neuro-state (Rattenborg et al 2008a; Nathan et al 2012). As these sensors have different power requirements, not all of them can be recorded at the same rate. GPS sensing is scheduled whenever the battery power is sufficiently high to allow for high-definition reporting, usually at 1 Hz intervals (Flack et al 2016), but reaching up to 10 Hz (Bouten et al 2013)

Methods

Results

Conclusion