Dispersion of introduced arctic hares (Lepus arcticus) on islands off Newfoundland's south coast

1991 ◽  
Vol 69 (10) ◽  
pp. 2618-2623
Author(s):  
Robert J. Small ◽  
Lloyd B. Keith ◽  
Robert M. Barta
Keyword(s):  
Environmental Factors ◽  
Home Range ◽  
Social Dominance ◽  
Snow Depth ◽  
Nearest Neighbor ◽  
South Coast ◽  
Food Sources ◽  
Snow Conditions

We describe dispersion of radio-collared arctic hares (Lepus arcticus) introduced to three islands off Newfoundland's south coast. Nearest-neighbor analyses indicated that home-range activity centers were aggregated during both summer and winter. Mean distances between activity centers were significantly less during winter than during summer, with the greatest aggregation observed when rates of fox predation were least and snow depth and persistence were greatest. Arctic hares apparently lack a rigid social-dominance system; hence, environmental factors such as availability of food sources, snow conditions, and presence of predators may primarily influence dispersion.

Critical snow density threshold for Dall’s sheep (Ovis dalli dalli)

2018 ◽  
Vol 96 (10) ◽  
pp. 1170-1177 ◽  
Author(s):  
Kelly J. Sivy ◽  
Anne W. Nolin ◽  
Christopher L. Cosgrove ◽  
Laura R. Prugh
Keyword(s):  
Snow Depth ◽  
Animal Movement ◽  
Population Declines ◽  
Snow Density ◽  
Energetic Costs ◽  
Snow Properties ◽  
Ovis Dalli ◽  
Snow Conditions ◽  
Dall’S Sheep ◽  
Density Threshold

Snow cover can significantly impact animal movement and energetics, yet few studies have investigated the link between physical properties of snow and energetic costs. Quantification of thresholds in snow properties that influence animal movement are needed to help address this knowledge gap. Recent population declines of Dall’s sheep (Ovis dalli dalli Nelson, 1884) could be due in part to changing snow conditions. We examined the effect of snow density, snow depth, and snow hardness on sinking depths of Dall’s sheep tracks encountered in Wrangell–St. Elias National Park and Preserve, Alaska. Snow depth was a poor predictor of sinking depths of sheep tracks (R2 = 0.02, p = 0.38), as was mean weighted hardness (R2 = 0.09, p = 0.07). Across competing models, top layer snow density (0–10 cm) and sheep age class were the best predictors of track sink depths (R2 = 0.58). Track sink depth decreased with increasing snow density, and the snowpack supported the mass of a sheep above a density threshold of 329 ± 18 kg/m3 (mean ± SE). This threshold could aid interpretation of winter movement and energetic costs by animals, thus improving our ability to predict consequences of changing snowpack conditions on wildlife.

scholarly journals Seasonal influence of snow conditions on Dall’s sheep productivity in Wrangell-St Elias National Park and Preserve

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0244787
Author(s):  
Christopher L. Cosgrove ◽  
Jeff Wells ◽  
Anne W. Nolin ◽  
Judy Putera ◽  
Laura R. Prugh
Keyword(s):  
Snow Depth ◽  
National Park ◽  
Meteorological Data ◽  
Multiple Regression Model ◽  
Snow Accumulation ◽  
Population Declines ◽  
Climate Conditions ◽  
Remote Cameras ◽  
Snow Conditions ◽  
Dall’S Sheep

Dall’s sheep (Ovis dalli dalli) are endemic to alpine areas of sub-Arctic and Arctic northwest America and are an ungulate species of high economic and cultural importance. Populations have historically experienced large fluctuations in size, and studies have linked population declines to decreased productivity as a consequence of late-spring snow cover. However, it is not known how the seasonality of snow accumulation and characteristics such as depth and density may affect Dall’s sheep productivity. We examined relationships between snow and climate conditions and summer lamb production in Wrangell-St Elias National Park and Preserve, Alaska over a 37-year study period. To produce covariates pertaining to the quality of the snowpack, a spatially-explicit snow evolution model was forced with meteorological data from a gridded climate re-analysis from 1980 to 2017 and calibrated with ground-based snow surveys and validated by snow depth data from remote cameras. The best calibrated model produced an RMSE of 0.08 m (bias 0.06 m) for snow depth compared to the remote camera data. Observed lamb-to-ewe ratios from 19 summers of survey data were regressed against seasonally aggregated modelled snow and climate properties from the preceding snow season. We found that a multiple regression model of fall snow depth and fall air temperature explained 41% of the variance in lamb-to-ewe ratios (R2 = .41, F(2,38) = 14.89, p<0.001), with decreased lamb production following deep snow conditions and colder fall temperatures. Our results suggest the early establishment and persistence of challenging snow conditions is more important than snow conditions immediately prior to and during lambing. These findings may help wildlife managers to better anticipate Dall’s sheep recruitment dynamics.

DENSITY AND LINKAGE ESTIMATORS OF HOME RANGE: NEAREST-NEIGHBOR CLUSTERING DEFINES MULTINUCLEAR CORES

Ecology ◽  
2001 ◽  
Vol 82 (7) ◽  
pp. 1905-1920 ◽  
Author(s):  
Robert E. Kenward ◽  
Ralph T. Clarke ◽  
Kathy H. Hodder ◽  
Sean S. Walls
Keyword(s):  
Home Range ◽  
Nearest Neighbor

scholarly journals Sex Differences in Space Use of Breeding Common Ravens in Western Marin County, California

The Condor ◽  
2004 ◽  
Vol 106 (3) ◽  
pp. 529-539 ◽  
Author(s):  
Jennifer E. Roth ◽  
John P. Kelly ◽  
William J. Sydeman ◽  
Mark A. Colwell
Keyword(s):  
Sex Differences ◽  
Home Range ◽  
Space Use ◽  
Home Range Size ◽  
Range Size ◽  
Food Sources ◽  
Small Scale ◽  
Corvus Corax ◽  
Marin County ◽  
Core Areas

Abstract We estimated core areas and home-range sizes and evaluated sex differences in home-range size, seasonal variation in movements, and space use for breeding Common Ravens (Corvus corax) in western Marin County, California. There were no significant interannual differences in average core area or average home-range size for either sex, although there were small-scale shifts in home-range use for 67% of females and 63% of males. There was no significant difference in home-range size between the sexes. Home-range size was positively correlated with distance to food source. Ravens traveled shorter distances from the nest during the incubation + nestling stage compared to other stages of the breeding season. Core areas were centered around nest sites and food sources, with significantly aggregated locations for 83% and 100% of females in 2000 and 2001, respectively. Males were more variable in their use of space, with significantly aggregated locations for 38% and 44% of males in 2000 and 2001, respectively. Individual variation in home-range size, movements, and space use was likely due to differences in the distribution of important food sources in the area. Diferencias Sexuales en la Utilización del Espacio en Corvus corax en el Oeste del Condado Marin, California Resumen. Estimamos los tamaños del área núcleo y rango de hogar y evaluamos las diferencias entre sexos en el tamaño del rango de hogar, variaciones estacionales de los movimientos y utilización del espacio en Corvus corax en el oeste del condado Marin, California. No hubo diferencias interanuales significativas en el área núcleo promedio ni en el rango de hogar promedio para ninguno de los sexos, aunque para el 67% de las hembras y el 63% de los machos hubo cambios de pequeña escala en el uso del rango de hogar. No hubo diferencias significativas en el tamaño de los rangos de hogar entre sexos. El tamaño del rango de hogar estuvo positivamente correlacionado con la distancia a la fuente de alimento. Los cuervos viajaron distancias más cortas desde el nido durante los períodos de incubación y de cría de polluelos en comparación con otros períodos durante la época reproductiva. Las áreas núcleo se centraron en los sitios de nidificación y las fuentes de alimento, con posiciones significativamente agregadas para el 83% y 100% de las hembras en 2000 y 2001, respectivamente. Los machos presentaron mayor variabilidad en la utilización del espacio, con posiciones significativamente agregadas para un 38% y 44% de los machos en el 2000 y 2001, respectivamente. Las variaciones individuales en el tamaño de los ámbitos de hogar, movimientos y uso del espacio fueron probablemente dadas por las diferencias en la distribución de los recursos alimenticios importantes en el área.

Habitat selection and home-range dynamics of the Gaspé caribou: a hierarchical analysis

2003 ◽  
Vol 81 (7) ◽  
pp. 1174-1184 ◽  
Author(s):  
Arnaud Mosnier ◽  
Jean-Pierre Ouellet ◽  
Luc Sirois ◽  
Nelson Fournier
Keyword(s):  
Home Range ◽  
Habitat Use ◽  
Rangifer Tarandus ◽  
Large Diameter ◽  
Habitat Type ◽  
Spatial And Temporal Scales ◽  
Management Plans ◽  
Forested Areas ◽  
Range Dynamics ◽  
Snow Conditions

We used several spatial and temporal scales to determine space and habitat use of the caribou (Rangifer tarandus caribou) of the Gaspé Peninsula. Thirty-five radio-collared caribou were followed from November 1998 to April 2001. Habitat use was studied by superimposing radiolocations on ecoforestry maps using five predefined habitat types (deciduous, immature, mature spruce, mature fir, and barren). At a finer scale, we tracked caribou in forested areas during winter 2000 and 2001 in order to describe physical and biological characteristics of foraging tracks and used stands. Our results indicated that the distribution of caribou extended beyond the limits of Gaspé Conservation Park. Patterns of space use showed the existence of three groups, which formed a metapopulation. These groups consisted of spatially distinct units that used space and habitat differently. At the home-range level, caribou preferred barren areas found in alpine and subalpine zones at all times of the year. The most frequently used forested habitat type was the mature fir. At the finer scale of foraging tracks, caribou selected fir stands characterized by dense snow conditions and large diameter trees bearing greater quantities of lichen. Our results demonstrated the importance of protecting areas outside the park that are likely to become used or reused by caribou, and of managing these areas to increase settlement by caribou. Lastly, management plans must be adapted to each of the three groups forming this metapopulation.

scholarly journals How Are Spring Snow Conditions in Central Canada Related to Early Warm-Season Precipitation?

2013 ◽  
Vol 14 (3) ◽  
pp. 787-807 ◽  
Author(s):  
Hua Su ◽  
Robert E. Dickinson ◽  
Kirsten L. Findell ◽  
Benjamin R. Lintner
Keyword(s):  
Soil Moisture ◽  
Snow Depth ◽  
Large Scale ◽  
Spatial Scales ◽  
Warm Season ◽  
Surface Model ◽  
Central Canada ◽  
Snow Conditions ◽  
Snow Precipitation ◽  
Soil Moisture Anomaly

Abstract The response of the warm-season atmosphere to antecedent snow anomalies has long been an area of study. This paper explores how the spring snow depth relates to subsequent precipitation in central Canada using ground observations, reanalysis datasets, and offline land surface model estimates. After removal of low-frequency ocean influences, April snow depth is found to correlate negatively with early warm-season (May–June) precipitation across a large portion of the study area. A chain of mechanisms is hypothesized to account for this observed negative relation: 1) a snow depth anomaly leads to a soil moisture anomaly, 2) the subsequent soil moisture anomaly affects ground turbulent fluxes, and 3) the atmospheric vertical structure allows dry soil to promote local convection. A detailed analysis supports this chain of mechanisms for those portions of the domain manifesting a statistically significant negative snow–precipitation correlation. For a portion of the study area, large-scale atmospheric circulation patterns also affect the early warm-season rainfall, indicating that the snow–precipitation feedback may depend on large-scale atmospheric dynamical features. This analysis suggests that spring snow conditions can contribute to warm-season precipitation predictability on a subseasonal to seasonal scale, but that the strength of such predictability varies geographically as it depends on the interplay of hydroclimatological conditions across multiple spatial scales.

Factors influencing permafrost temperatures across tree line in the uplands east of the Mackenzie Delta, 2004–20101This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Contribution 03611.

2012 ◽  
Vol 49 (8) ◽  
pp. 877-894 ◽  
Author(s):  
M.J. Palmer ◽  
C.R. Burn ◽  
S.V. Kokelj
Keyword(s):  
Snow Depth ◽  
Applied Research ◽  
Abrupt Change ◽  
Late Winter ◽  
Mackenzie Delta ◽  
Near Surface ◽  
Ground Temperatures ◽  
Winter Snow ◽  
Shrub Tundra ◽  
Snow Conditions

Air and near-surface ground temperatures, late-winter snow conditions, and characteristics of the vegetation cover and soil were measured across the forest–tundra transition in the uplands east of the Mackenzie Delta, Northwest Territories, in 2004–2010. Mean late-winter snow depth decreased northward from 73 cm in the subarctic boreal forest near Inuvik to 22 cm in low-shrub tundra. Annual near-surface ground temperatures decreased northward by 0.1–0.3 °C/km near the northern limit of trees, in association with an abrupt change in snow depth. The rate decreased to 0.01–0.06 °C/km in the tundra. The freezing season is twice as long as the thawing season in the region, so measured differences in the regional ground thermal regime were dominated by the contrast in winter surface conditions between forest and tundra.

scholarly journals Pastures, calf production and carcass weights of reindeer calves in the Oraniemi co-operative, Finnish Lapland

Rangifer ◽  
1992 ◽  
Vol 12 (3) ◽  
pp. 93 ◽  
Author(s):  
Jouko Kumpula ◽  
Mauri Nieminen
Keyword(s):  
Nutritional Status ◽  
Home Range ◽  
Milk Production ◽  
Detrimental Effect ◽  
Annual Variations ◽  
Finnish Lapland ◽  
Blood Sucking ◽  
Green Vegetation ◽  
The Mean ◽  
Snow Conditions

The effects of climatic and density-dependent factors on calf production and carcass weights of reindeer calves were studied between the years 1965-87 in the Oraniemi co-operative, Finnish Lapland (67&deg;50&acute;N). The Oraniemi area is divided into five pasture regions, in which the annual home range of the reindeer varied from 300 to 600 km2. The more than trebled reindeer density over the period 1965-87 in Oraniemi had no detrimental effect on calf production (range 15-74 calves/100 females), nor on the mean carcass weight of the calves in 1974-87 (range 16.8-23.2 kg). The annual variations in calf% were explained best by snow conditions during the previous winter and spring and their effects on the nutritional status of the females. The carcass weights of the calves were greater following a warm, rainy May and lower following a warm, rainy June and July. The weather in spring affects the emergence of green vegetation, which is reflected in the condition of females and their milk production, while the weather in early and mid-supper probably affects the quantities of blood-sucking insects and their activity. Carcass weights upon slaughtering rose from September to the beginning of December but then fell quickly. The differences in reindeer densities between the five pasture regions was not reflected in the calf% over the period 1984-87, but the carcass weights of calves were lower following high densities in the pasture regions, especially in the winter pastures.

scholarly journals Subgrid parameterization of snow distribution at a Mediterranean site using terrestrial photography

2016 ◽  
Author(s):  
Rafael Pimentel ◽  
Javier Herrero ◽  
María José Polo
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Scale Effects ◽  
Control Area ◽  
Sigmoid Function ◽  
Snow Cover Fraction ◽  
Snow Distribution ◽  
Snow Model ◽  
Snow Conditions ◽  
High Level

Abstract. Subgrid variability introduces non-negligible scale effects on the GIS-based representation of snow. This heterogeneity is even more evident in semiarid regions, where the high variability of the climate produces various accumulation melting cycles throughout the year and a large spatial heterogeneity of the snow cover. This variability in a watershed can often be represented by snow depletion curves (DCs). In this study, terrestrial photography (TP) of a cell-sized area (30 x 30 m) was used to define local snow DCs at a Mediterranean site. Snow cover fraction (SCF) and snow depth (h) values obtained with this technique constituted the two datasets used to define DCs. A flexible sigmoid function was selected to parameterize snow behaviour on this subgrid scale. It was then fitted to meet five different snow patterns in the control area: one for the accumulation phase and four for the melting phase in a cycle within the snow season. Each pattern was successfully associated with the snow conditions and previous evolution. The resulting DCs were able to capture certain physical features of the snow, which were used in a decision-tree and included in the point snow model formulated by Herrero et al. (2009). The final performance of this model was tested against field observations recorded over four hydrological years (2009–2013). The calibration and validation of this DC-snow model was found to have a high level of accuracy with global RMSE values of 84.2 mm for the average snow depth and 0.18 m2 m-2 for the snow cover fraction in the control area. The use of DCs on the cell scale proposed in this research provided a sound basis for the extension of point snow models to larger areas by means of a gridded distributed calculation.

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