Table 1:
The biological, anthropogenic and habitat-related covariates considered to explain body condition of grizzly bears in Alberta, Canada
| Covariate | Rationale | References | Data source |
|---|---|---|---|
| Reproductive class | Based on gender, age and presence of cub(s)-of-year, which influence habitat selection patterns and energetic demands, individuals were classified as adult males or females (>5 years old), juvenile males or females (2–5 years old) or adult females with cub(s)-of-year | Boulanger et al. (2013) Nielsen et al. (2013a) | Grizzly bear capture data |
| Number of previous captures | Multiple handlings may adversely influence body condition | Cattet et al. (2008) | |
| Capture date (Julian date) | Seasonal changes in food availability and habitat selection during the non-denning period may influence body condition | McLellan (2011) | |
| Index of habitat net-energy demand | Factors related to anthropogenic disturbance and habitat characteristics influence predicted hair cortisol concentrations in grizzly bears. Predicted hair cortisol concentration values are interpreted as a sex-specific indicator of net-energy demand | Macbeth et al. (2010) Bourbonnais et al. (2013) Bryan et al. (2013) | Bourbonnais et al. (2013) |
| Roads (distance decay) | Provide human access to grizzly bear habitat; contribute to landscape fragmentation; herbaceous foods are present in areas adjacent to roads | Munro et al. (2006) Berland et al. (2008) Roever et al. (2008) Graham et al. (2010) | AESRD; FRIGBP; Landsat 5 TM; Landsat 7 ETM + |
| Oil and gas well sites (distance decay) | Localized areas of human activity; create forest edges and contribute to landscape fragmentation | Laberee et al. (2014) | |
| Density of secondary linear features (km/km2) | Seismic lines, power lines and pipelines create forest edges and contribute to landscape fragmentation and provide access to grizzly bear habitat | Linke et al. (2005) Stewart et al. (2013) | |
| Density of forest harvest blocks (km/km2) | Disturbance features associated with presence and abundance of herbaceous foods | Nielsen et al. (2004a, c) Munro et al. (2006) Berland et al. (2008) | |
| Percentage of parks and protected areas | Considered core refugia and represent a marked contrast in land use compared with the surrounding industrialized landscape | Gibeau et al. (2002) | |
| Elevation (variation) | Influences vegetation composition, human access and potential habitat net-energy demand | Nielsen et al. (2004b, c) Bourbonnais et al. (2013) | Landsat 5 TM; Landsat 7 ETM+; DEM |
| Crown closure (variation) | Influences understory vegetation abundance and growth of herbaceous foods | Franklin et al. (2002, 2003) Nielsen et al. (2013a) | |
| Percentage of conifer tree cover | Characterization of forest species distribution and correlated with berry abundance | Franklin et al. (2002, 2003) | |
| Percentage of mixed and broadleaf tree cover | Influences distribution of herbaceous foods and correlated with presence of ungulates | Nielsen et al. (2010) Stewart et al. (2013) | |
| Percentage of regenerating forest | Regenerating forests have greater availability of herbaceous foods | Nielsen et al. (2004c, 2010) | |
| Percentage of shrub and herbaceous landcover | Correlated with availability of herbaceous foods and berries | Franklin et al. (2002, 2003) | |
| Forest age | Younger seral forests have a greater abundance of herbaceous foods | Nielsen et al. (2004c, 2010) | |
| Vegetation productivity | Total vegetation productivity (cumulative greenness) influences availability of herbaceous foods | Coops et al. (2008) Fontana et al. (2012) | AVHRR DHI |
| Vegetation seasonality | Seasonal variability (coefficient of variation) in vegetation productivity influences timing and availability of herbaceous foods | Coops et al. (2008) Fontana et al. (2012) |
Abbreviations: AESRD, Alberta Environment and Sustainable Resource Development; AVHRR, Advanced Very High Resolution Radiometer; DEM, digital elevation model; DHI, Dynamic Habitat Index; ETM+, Enhance Thematic Mapper Plus; FRIGBP, Foothills Research Institute Grizzly Bear Project; TM, Thematic Mapper.