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Data from: Drivers of site fidelity in ungulates

Citation

Morrison, Thomas et al. (2021), Data from: Drivers of site fidelity in ungulates, Dryad, Dataset, https://doi.org/10.5061/dryad.31zcrjdjr

Abstract

  1. 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. 
  2. 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.
  3. 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.
  4. 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.
  5. 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.

Methods

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 (IYD) between the spatial location (xy) for individual i on Julian date j in year t and the set of spatial locations within a window of time (w days) surrounding that same Julian dates during the previous year t-1. See equation in Morrison et al.. 

Funding

Horizon 2020, Award: 641918

Horizon 2020, Award: 794760

National Science Foundation, Award: GRF 1252375

National Science Foundation, Award: DEB 0919383

Alaska Department of Fish and Game

U.S. Bureau of Land Management

Boone and Crockett Club

Bowhunters of Wyoming

Environment Yukon

Zoologische Gesellschaft Frankfurt

James E. Ellis Memorial Scholarship

Knobloch Family Foundation

Lord Kelvin Adam Smith Fellowship

Muley Fanatic Foundation

PacifiCorp

Parks Canada

Sierra Trading Post

University of Wyoming, Award: Berry Fellowship

U.S. Department of Agriculture

National Institute of Food and Agriculture, Award: 2014-01928

Wyoming Animal Damage Management Board

Wyoming Game and Fish Department

Wyoming Governor's Big Game License Coalition

Wyoming Outfitters and Guides Association

Wyoming Wild Sheep Foundation

Wyoming Wildlife and Natural Resource Trust

Boone and Crockett Club

Bowhunters of Wyoming

Environment Yukon

James E. Ellis Memorial Scholarship

Lord Kelvin Adam Smith Fellowship

PacifiCorp

Sierra Trading Post

Wyoming Animal Damage Management Board

Wyoming Game and Fish Department

Wyoming Governor's Big Game License Coalition

Wyoming Outfitters and Guides Association

Wyoming Wild Sheep Foundation