Functional responses in animal movement explain spatial heterogeneity in animal-habitat relationships
Authored by Daniel Fortin, Tom H E Mason
Date Published: 2017
DOI: 10.1111/1365-2656.12682
Sponsors:
No sponsors listed
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Model Code URLs:
Model code not found
Abstract
1. Understanding why heterogeneity exists in animal-habitat spatial
relationships is critical for identifying the drivers of animal
distributions. Functional responses in habitat selection - whereby
animals adjust their habitat selection depending on habitat availability
- are useful for describing animal-habitat spatial heterogeneity.
However, they could be yielded by different movement tactics, involving
contrasting interspecific interactions.
2. Identifying functional responses in animal movement, rather than in
emergent spatial patterns like habitat selection, could disentangle the
effects of different movement behaviours on spatial heterogeneity in
animal-habitat relationships. This would clarify how functional
responses in habitat selection emerge and provide a general tool for
understanding the mechanistic drivers of animal distributions.
3. We tested this approach using data from GPS-collared woodland caribou
(Rangifer tarandus), a prey species under top-down control. We tested
how caribou selected and moved with respect to a key resource
(lichen-conifer stands) as a function of the availability of surrounding
refuge land-cover (closed-conifer stands), using step selection
functions.
4. Caribou selected resource patches more strongly in areas richer in
refuge land-cover - a functional response in habitat selection. However,
adjustments in multiple movement behaviours could have generated this
pattern: stronger directed movement towards resource patches and/or
longer residency within resource patches, in areas richer in refuges.
Different contributions of these behaviours would produce contrasting
forager spatial dynamics.
5. We identified functional responses in both movement behaviours:
caribou were more likely to move towards resource patches in areas
richer in refuge land-cover, and to remain in these patches during
movement steps. This tactic enables caribou to forage for longer in
safer areas where they can rapidly seek refuge in dense cover when
predators are detected.
6. Our study shows that functional responses in movement can expose the
context-dependent movement decisions that generate heterogeneity in
animal-habitat spatial relationships. We used these functional responses
to characterise anti-predator movement tactics employed by a large
herbivore, but they could be applied in many different scenarios. The
movement rules from functional responses in movement are well-suited to
integration in spatial explicit individual-based models for forecasting
animal distributions in landscapes undergoing environmental change.
Tags
individual-based models
Spatial distribution
Marginal value theorem
Decision-Making
Foraging
Predation risk
Woodland caribou
Ungulate
Boreal forest
Taiga
Resource selection
Anti-predator behaviour
Predator-prey spatial
games
Ssf
Prey shell games
Spatiotemporal dynamics
Changing availability
Behavioral-response
Limiting factors