DOI: 10.5061/dryad.31zcrjdjr
title: Data from: Drivers of site fidelity in ungulates

description: While the tendency to return to previously visited locations – termed
 ‘site fidelity’ – is common in animals, the cause of this behaviour is not
 well understood. One hypothesis is that site fidelity is shaped by an
 animal’s environment, such that animals living in landscapes with
 predictable resources have stronger site fidelity. Site fidelity may also
 be conditional on the success of animals’ recent visits to that location,
 and it may become stronger with age as the animal accumulates experience
 in their landscape. Finally, differences between species, such as the way
 memory shapes site attractiveness, may interact with environmental drivers
 to modulate the strength of site fidelity.  We compared
 inter-year site fidelity in 669 individuals across eight ungulate species
 fitted with GPS-collars and occupying a range of environmental conditions
 in North America and Africa. We used a distance-based index of site
 fidelity and tested hypothesized drivers of site fidelity using linear
 mixed effects models, while accounting for variation in annual range size.
 Mule deer Odocoileus hemionus and moose Alces alces exhibited relatively
 strong site fidelity, while wildebeest Connochaetes taurinus and
 barren-ground caribou Rangifer tarandus granti had relatively weak
 fidelity. Site fidelity was strongest in predictable landscapes where
 vegetative greening occurred at regular intervals (i.e. high temporal
 contingency). Species differed in their response to spatial heterogeneity
 in greenness (i.e. spatial constancy). Site fidelity varied seasonally in
 some species, but remained constant over time in others. Elk employed a
 ‘win-stay, lose-switch’ strategy, in which successful resource tracking in
 the springtime resulted in strong site fidelity the following spring. Site
 fidelity did not vary with age in any species tested. Our results provide
 support for the environmental hypothesis, particularly that regularity in
 vegetative phenology shapes the strength of site fidelity. Large
 unexplained differences in site fidelity suggests that other factors,
 possibly species-specific differences in attraction to known sites,
 contribute to variation in the expression of this behaviour. Understanding
 drivers of variation in site fidelity across groups of organisms living in
 different environments provides important behavioural context for
 predicting how animals will respond to environmental change.
description: Data were collected using GPS telelmetry by various projects and
 were compiled for this study. We calculated the minimum inter-year
 distance (IYD) as an inverse metric of the strength of site fidelity. This
 involved several processing steps: (1) subsample GPS datasets to daily fix
 rates, and (2) censor GPS data so that site fidelity was calculated up to
 a maximum of one year per individual, and (3) calculated
 "iyd_log" by taking the the natural log of the minimum
 inter-year distance (<i>IYD</i>) between the spatial location
 (<i>xy</i>) for individual <i>i </i>on Julian date
 <i>j </i>in year <i>t </i>and the set of spatial
 locations within a window of time (<i>w </i>days)<i>
 </i>surrounding that same Julian dates during the previous
 year<i><sub> </sub>t</i>-1. See equation in
 Morrison et al..