|
temporal
|
time of day
|
hour of the day
|
diel variation in environmental conditions, associated with predation risk levels
|
continuous
|
hourly
| |
| |
Julian day
|
day of the year
|
proxy for fine-scale seasonal variation in environmental conditions and diet quality
|
continuous
|
daily
| |
|
year
|
season-year (e.g. winter season 2013/2014, summer season 2014)
|
interannual variation in environmental conditions
|
categorical
|
annual
| |
|
light
|
light conditions (daylight or darkness) at time of observation
|
light, visibility, associated with predation risk levels
|
categorical
|
hourly
|
determined using ‘streamMetabolism’ package in R
|
|
static
|
landcover type
|
NDVI-derived landcover classification (NDVI ≥0.35 = ‘dense vegetation’, 0.1–0.35 = ‘sparse vegetation’, < 0.1 = ‘bare ground’ (including non-vegetated areas such as glaciers, perennial snow and lakes))
|
associated with plant productivity, forage abundance
|
categorical
|
30 m
|
vegetation classes classified based on NDVI, using Landsat 4-5TM satellite image, dated 17 July 2009; non-vegetated derived from 1:100.000 topographic maps, field measurements from study area [23, 33]
|
| |
elevation (m.a.s.l.)
|
elevation above sea level
|
associated with plant productivity and snow accumulation
|
continuous
|
30 m
|
ASTER Global Digital Elevation Model (DEM) Version 2 (https://asterweb.jpl.nasa.gov/gdem.asp)
|
|
terrain ruggedness (index)
|
mean of the absolute differences between the value of a cell and the value of its 8 surrounding cells, i.e. measure of terrain heterogeneity
|
associated with vegetation heterogeneity and variation in snow conditions
|
continuous
|
30 m
|
calculated from DEM using ‘terrain’ function in ‘raster’ package in R
|
|
distance to coast (m)
|
Euclidian distance to coastline
|
proxy for coast-inland gradients in e.g. precipitation, temperature
|
continuous
|
30 m
|
calculated from DEM using ‘raster’ package in R
|
|
hillshade (unitless)
|
amount of incoming radiation, combining slope and aspect
|
associated with local temperature, plant productivity and snow melt dynamics
|
continuous
|
30 m
|
calculated from DEM using ‘hillShade’ function in ‘raster’ package in R
|
|
dynamic
|
snow depth (m)
|
snow depth
|
associated with forage accessibility and costs of foraging/movement
|
continuous, modelled
|
300 m, 3 h
|
MicroMet high-resolution meteorological model coupled with SnowModel snow-evolution modelling tool [17, 18, 34]
|
| |
ambient temperature (°C)
|
ambient air temperature (2 m above ground surface)
|
thermal conditions, associated with insect harassment
| | | |
|
wind speed (m/s)
|
wind speed (2 m above ground surface)
|
associated with thermal conditions (windchill effect) and insect harassment
| | | |
|
wind direction (degrees from north)
|
wind direction (2 m above ground surface)
|
associated with thermal conditions (windchill effect)
| | | |
|
precipitation (mm)
|
precipitation (rainfall or snow) at time t
|
precipitation, associated with thermal conditions
| | | |
|
NDVI (index)
|
Normalized Difference Vegetation Index (NDVI)
|
measure of vegetation greenness, related to vegetation growth and aboveground biomass [35]
|
continuous, observed
|
300 m, daily
|
Moderate Resolution Imaging Spectroradiometer (MODIS) Daily Surface Reflectance [34]
|
