Aspects Of Warming Research Articles

Rocky Mountain bighorn sheep (Ovis canadensis canadensis) winter habitat selection and seasonal movements in an area of active coal mining

Winter is an important period for most mountain ungulates due to limited availability of preferred forage and costs associated with travel through deep snow. We examined winter habitat selection by Rocky Mountain bighorn sheep (Ovis canadensis canadensis Shaw, 1804) where four large, open-pit coal mines are in operation. Sheep in this area generally winter at high elevation on windswept, south-facing native grasslands. We used GPS collars and Resource Selection Function analysis to examine movements and habitat selection. A majority (79%) of the sheep were migratory and fidelity to winter ranges was high (88%). Sheep showed low use (∼10%–20%) of mine areas between November and April, followed by increased use peaking at 60%–65% in September–October. Wintering sheep were positively associated with high elevations, closeness to escape terrain, and warmer aspects. High-elevation, native grasslands were the highest ranked cover class. Most sheep that used mine areas during winter used reclaimed habitats, primarily reclaimed spoils and pits. Primary winter ranges comprised 4.3% of merged sheep range, emphasizing the limited amount of occupied winter ranges within the landscape. Disturbance to native winter range resulting from development should be minimized or be conducted in a manner that effectively manages and (or) mitigates the impacts.

Spatial factors related to mortality and population decline of endangered mountain caribou

ABSTRACTMountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that historically occurred throughout the high snowfall regions of southeast British Columbia and the northwestern United States. The decline in caribou is thought to be due to apparent competition where increases in early‐seral conditions stimulate a numerical response in primary ungulate prey and their predators and these incidentally kill an unsustainable number of caribou. Based on the known location of death of 207 radio collared animals, we tested hypotheses pertaining to relationships between landscape composition and predator‐specific mortality of mountain caribou at 2 ecologically based spatial scales. Relative to landscape conditions within subpopulation boundaries (level 1) or within home ranges (level 2), caribou were at greater risk of predation at low elevations particularly within otherwise complex terrain (i.e., valleys) with more variation in overstory canopy closure and greater road densities. Caribou vulnerability to bears was also positively related to the variation in overstory age. Cougar predation was not related to roads or terrain complexity but occurred more often in landscapes with warmer aspects and greater proportions of stands of <120 years. Wolf predation occurred primarily at low elevations at the broader scale and in association with roads at the finer scale. Our results indicate that caribou vulnerability to predation was a function of both static (e.g., terrain) and dynamic (e.g., overstory conditions) factors, but we did not find evidence that localized habitat fragmentation due to forest harvest influenced predation on caribou. This result is not inconsistent with the apparent competition hypothesis but suggests that habitat change largely functions at broader spatial scales involving landscapes that can be beyond those occupied by caribou, including the winter ranges of primary ungulate prey. These changes and the season‐dependent dispersion of other ungulates and their predators may largely influence mortality risk to mountain caribou. Although roads and forest fragmentation are interrelated, roads may further contribute to caribou predation by increasing the efficiency of movement of some predators and thereby increasing encounter rates with caribou. © 2013 The Wildlife Society.

Assessing the utility of lidar remote sensing technology to identify mule deer winter habitat

Winter habitat for mule deer (Odocoileus hemionus) is a critical concern throughout interior British Columbia, Canada. In winter, mule deer require a food source of twigs and woody browse and face significant winter snow cover. A range of studies have established that good winter range for mule deer reduces the impact of a negative energy balance by providing adequate food, good vegetative cover, and shallow snow. Generally, sites with old Douglas-fir and moderate to high canopy cover on warmer aspects and moderately steep slopes are preferred, resulting in a suite of structural stand conditions, which can be used to map mule deer winter range habitat within the interior Douglas-fir range. The increased availability of light detection and ranging (lidar) data to management agencies and the recent adoption of lidar technology by forestry agencies allow us to assess the capacity of this technology to map some variables important to winter mule deer habitat suitability, using criteria similar to those defined using conventional aerial photography. Results indicate that lidar-derived solar radiation regime, elevation, and overstorey cover are all useful attributes in decision-tree models relating lidar to conventionally derived descriptors of mule deer winter habitat. These lidar-derived models describe up to 75% of the variance in overall stand structure and confirm that this technology is a viable tool which can be used to assess habitat throughout this region.

Wintering strategies by mountain goats in interior mountains

As with many ungulates inhabiting areas with potentially deep snow, winter is an important season for mountain goats ( Oreamnos americanus (de Blainville, 1816)) and is characterized by restricted movements and high juvenile mortality. We examined winter habitat selection and wintering strategies by mountain goats in two adjacent areas of southeastern British Columbia characterized by deep, moist snow and by shallow, dry snow. Fifteen GPS collars were placed on mountain goats in each area over two winters. Winter-range size did not differ between areas and comprised, on average, 2.2%–7.4% of male home range and 8.0%–14.1% of female home range. Topographic variables dominated habitat model selection. At the broad scale, mountain goats in both areas selected winter ranges closer to escape terrain on warmer aspects that contained lesser amounts of mature dense forest. At the fine scale, mountain goats in both areas selected rugged habitat at upper mid-elevations and on warmer aspects. Alpine areas were avoided in the deep snow area and selected in the shallow snow area. No selection for mature forests was observed in either area. Mountain goats, therefore, appeared to utilize open, high-elevation habitats in shallow snow zones, but they did not seek reduced snow levels in mature forest stands in deep snow areas.

Classification of the eastern alpine vegetation of Lesotho

Abstract Five vegetation communities in the alpine catchments of Lesotho were identified by hierarchical classification of the botanical composition data. Discriminant analysis indicated that these communities occupy particular topographic positions. The community‐environment relationships identified in this study were similar to those reported from other alpine areas of Lesotho. Grasslands at high altitudes are temperate in nature, with a high proportion of C3 grass species. Below 2 950 m on the warmer aspects and below 2 750 m on south‐facing slopes, subtropical grass species (C4) dominate the sward. Within the temperate and subtropical vegetation belts, slope orientation dictates the proportion of C3 species present in the sward. It is proposed that topography acts to modify the factors that directly influence plant growth by modifying solar radiation patterns.

Stream temperatures in an Alpine area

The phase angles and amplitudes of sine curves fitted to the annual cycle of stream temperatures are used as quantitative indices of the thermal characteristics of catchments and their associated stream waters. Higher altitudes result in lower temperatures but for streams with similar altitudinal ranges those with warmer aspects have higher temperatures. The extent of a forest cover influences temperatures by decreasing seasonal variations.