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Dryad

Data from: Scottish mountain hares do not respond behaviorally to camouflage mismatch

Cite this dataset

Zimova, Marketa et al. (2024). Data from: Scottish mountain hares do not respond behaviorally to camouflage mismatch [Dataset]. Dryad. https://doi.org/10.5061/dryad.hqbzkh1rc

Abstract

Climate change has resulted in myriad stressors to wild organisms. Phenotypic plasticity, including behavioral plasticity, is hypothesized to play a key role in allowing animals to cope with rapid climate change and mitigate its negative fitness consequences. Camouflage mismatch resulting from decreasing duration of snow cover presents a stressor to species that undergo coat color molts to maintain camouflage against seasonally changing backgrounds. Winter white animals appear highly conspicuous against dark, snowless background and experience increased predation-induced mortality. Here, we evaluate the potential of behavioral plasticity to buffer against camouflage mismatch in mountain hares (Lepus timidus) in Scotland. We carried out field surveys in three populations over two years and found no evidence that hares modify their behaviors in response to increasing camouflage mismatch. Hares did not prefer to rest closer to light-colored rocks or farther from conspecifics with increasing color contrast. Furthermore, whiter hares did not seek to rest closer to snowy backgrounds; rather, hares preferred to sit farther from snow. These results suggest that behavioral plasticity might not be a universal, rapid mechanism facilitating adaptation to climate change.

README: Scottish mountain hares do not respond behaviorally to increased camouflage mismatch

https://doi.org/10.5061/dryad.hqbzkh1rc

Abstract

Climate change has resulted in myriad stressors to wild organisms. Phenotypic plasticity, including behavioral plasticity, is hypothesized to play a key role in allowing animals to cope with rapid climate change and mitigate its negative fitness consequences. Camouflage mismatch resulting from decreasing duration of snow cover presents a stressor to species that undergo coat color molts to maintain camouflage against seasonally changing backgrounds. Winter white animals appear highly conspicuous against dark, snowless background and experience increased predation-induced mortality. Here, we evaluate the potential of behavioral plasticity to buffer against camouflage mismatch in mountain hares (Lepus timidus) in Scotland. We carried out field surveys in three populations over two years and found no evidence that hares modify their behaviors in response to increasing camouflage mismatch. Hares did not prefer to rest closer to light-colored rocks or farther from conspecifics with increasing color contrast. Furthermore, whiter hares did not seek to rest closer to snowy backgrounds; rather, hares preferred to sit farther from snow. These results suggest that behavioral plasticity might not be a universal, rapid mechanism facilitating adaptation to climate change.

Description of the data and file structure

This dataset contains the following variables:

  • Date: Date of stationary hare observation.
  • Area: Area where the observation was taken.
  • Dist_Rock: The distance a stationary hare was to the closest light-colored rock in meters. Measurements are in 1 m increments between 0 and 20 m. >20 marks occasions when a hare was farther than 20 m from the closest rock. 0 indicates occasions when a resting hare was immediately adjacent to a rock. 'n/a's signify that data was not collected. 
  • Dist_Snow: The distance a stationary hare was to the closest snow field/patch in meters. Measurements are in 1 m increments between 0 and 20 m. >20 marks occasions when a hare was farther than 20 m from the closest snow field/patch. 0 indicates occasions when a hare was resting on snow field/patch. 'n/a's signify that data was not collected. 
  • Dist_Hare: The distance a stationary hare was to the closest conspecific. Measurements are in 1 m increments between 1 and 20 m. >20 marks occasions when a hare was farther than 20 m from another hare. 'n/a's signify that data was not collected. 
  • Snow_5m: The percent snow cover within 5-m radius circle centered at the hare's resting site. Estimated in 25% increments. 'n/a's signify that data was not collected. 
  • Snow_10m: The percent snow cover within 10-m radius circle centered at the hare's resting site. Estimated in 25% increments. 'n/a's signify that data was not collected. 
  • Hare_White: Hare's coat color measured in percent white in four categories ; 0% (completely dark), 25% (mostly dark), 50% (half-dark and half-white), 75% (mostly white) or 100% white (completely white). For detailed description of categories see Zimova et al. 2020 ProcB. 'n/a's signify that data was not collected. 

Methods

Study Sites

Field surveys were carried out at three sites (Lecht [57.193 ̊ N, −3.240 ̊ W], Findhorn High [57.235 ̊ N, −4.136 ̊ W], Findhorn Low [57.206 ̊ N, −4.102 ̊ W]) in the northeast and central highlands of Scotland, UK. All sites were located between 430-730 m a.s.l. and dominated by dwarf heath and subalpine plant communities. The Lecht site included areas of eroded peat, and both sites were scatted with occasional white/pale, sometimes lichen covered, hare-sized rocks.

Field Surveys

We surveyed mountain hares twice a month in fall (October–January) and spring (March–June) seasons during 2015 and 2016 for a total of 5–11 surveys per season (Zimova et al. 2020b). During each survey, one surveyor walked along a predetermined route (ca 3–6 km long) and observed hares as they were either flushed (moved from their resting site in response to disturbance), or less frequently, detected by the surveyor during the frequent and thorough binoculars scans of the landscape. Hares are largely inactive during the day when they sit at a resting site above ground. We only used observations during which the observer had a clear view that allowed coat color to be assessed and was confident of the hare’s original resting location.

For all hares detected within 200 m of the observer, we photographed the hare and recorded coat color following (Watson 1963). Coat color was ranked into four categories ; 0% (completely dark), 25% (mostly dark), 50% (half-dark and half-white), 75% (mostly white) or 100% white (completely white) (for detailed description of categories see Zimova et al. 2020b). For observations accompanied by photographs (> 80% of all observations) field estimates of molt were later verified by one of us (MZ).

Finally, for each hare’s original resting site, we visually estimated the minimum distance a hare was to 1) any light-colored rocks of equal or larger size than the size of a resting hare, 2) another hare, and 3) snow. All distances between 0 and 20 m were estimated in 1 m increments; all other distances were recorded as ‘>20 m’ as we were not able to accurately estimate distances beyond 20 m.

Funding

Southeast Climate Adaptation Science Center

The Explorers Club

National Science Foundation, EPSCoR

Rural and Environment Science and Analytical Services

Norwegian Environment Agency