scholarly journals Estimation of snowshoe hare population density from turd transects

1987 ◽  
Vol 65 (3) ◽  
pp. 565-567 ◽  
Author(s):  
Charles J. Krebs ◽  
B. Scott Gilbert ◽  
S. Boutin ◽  
R. Boonstra
Keyword(s):  
Population Density ◽  
Fecal Pellet ◽  
Accurate Method ◽  
Yukon Territory ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Model Average ◽  
Pellet Counts ◽  
Hare Population ◽  
Kluane Lake

We counted the number of snowshoe hare (Lepus americanus) fecal pellets on 50 quadrats of 0.155 m2 on each of six areas near Kluane Lake, Yukon Territory, once a year from 1977 to 1983. On four of these areas we livetrapped hares once a month and estimated population density from the Jolly–Seber model. Average hare density for the year was linearly related to fecal pellet counts (r = 0.94) over the range 0–10 hares/ha. Mean turd counts also are related to the variance of these counts by Taylor's power law with exponent 1.30, indicating a clumped pattern in turd deposition. Fecal pellet counts provide a quick and accurate method for snowshoe hare censuses on an extensive scale.

scholarly journals Estimating snowshoe hare population density from pellet plots: a further evaluation

2001 ◽  
Vol 79 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Charles J Krebs ◽  
Rudy Boonstra ◽  
Vilis Nams ◽  
Mark O'Donoghue ◽  
Karen E Hodges ◽  
...  
Keyword(s):  
Population Density ◽  
Strong Relationship ◽  
Geographic Range ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Fecal Pellets ◽  
Density Estimates ◽  
Snowshoe Hares ◽  
Pellet Counts ◽  
Hare Population

We counted fecal pellets of snowshoe hares (Lepus americanus) once a year in 10 areas in the southwestern Yukon from 1987 to 1996. Pellets in eighty 0.155-m2 quadrats were counted and cleared each June on all areas, and we correlated these counts with estimates of absolute hare density obtained by intensive mark–recapture methods in the same areas. There is a strong relationship between pellet counts and population density (r = 0.76), and we present a predictive log–log regression to quantify this relationship, which improves on our previously published 1987 regression, particularly at low hare densities. The precision of density estimates can be improved most easily by increasing the number of sets of quadrats in an area (one set = 80 plots), rather than increasing the number of plots counted within one set. The most important question remaining concerns the generality of this relationship for snowshoe hares living in other habitats in the eastern and southern portions of their geographic range.

Proximate causes of losses in a snowshoe hare population

1986 ◽  
Vol 64 (3) ◽  
pp. 606-610 ◽  
Author(s):  
Stan Boutin ◽  
C. J. Krebs ◽  
A. R. E. Sinclair ◽  
J. N. M. Smith
Keyword(s):  
Population Density ◽  
Population Increase ◽  
Snowshoe Hare ◽  
Snowshoe Hares ◽  
Causes Of Mortality ◽  
Proximate Causes ◽  
Hare Population ◽  
Kluane Lake ◽  
Predation Rates

We used radiotelemetry to monitor proximate causes of mortality of snowshoe hares during a population increase, peak, and decline at Kluane Lake, Yukon. Predation and starvation rates increased 1.6- and 9-fold, respectively, in the winter of peak population density. Predation accounted for 58% of the losses during the winter of peak densities while losses were equally divided between predation and starvation in the winter following the peak. Starvation and predation rates were lower on a food-supplemented grid than on control grids in the peak winter. In the following spring and winter, starvation rates remained low on the food grid while predation rates increased to equal those on control areas. We conclude that both starvation and predation were the proximate causes of mortality during the hare decline at Kluane Lake.

Effects of precommercial thinning on snowshoe hare habitat use during winter in low-elevation montane forests

2005 ◽  
Vol 35 (1) ◽  
pp. 206-210 ◽  
Author(s):  
David E Ausband ◽  
G Ross Baty
Keyword(s):  
Habitat Use ◽  
Fecal Pellet ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Precommercial Thinning ◽  
Treatment Type ◽  
Northwestern Montana ◽  
Before And After ◽  
Pellet Counts ◽  
Mature Stands

We assessed snowshoe hare (Lepus americanus L.) habitat use during winter on two precommercial thinning treatments in sapling stands in northwestern Montana, USA. One treatment type retained 0.2-ha patches of unthinned saplings, representing 8% of the total stand area, and the second retained 0.8-ha patches of unthinned saplings, representing 35% of the stand area. Snowshoe hare habitat use was also estimated within a nearby control sapling stand and mature conifer stands. We used snow tracking and fecal pellet counts to estimate use before and after thinning treatments were applied. Although we did not find a conclusive trend in hare use of sapling stands after thinning, use within the control stand and adjacent mature stands suggested there was considerable movement of hares to nearby untreated stands after thinning. Hares used retention patches regardless of size, even though large retention patches were four times larger than small retention patches. Because hares demonstrated an affinity for dense patches of residual forest, any retention of untreated saplings may be beneficial for hares during winter when applying precommercial thinning treatments in areas where stand sizes are relatively small (10–14 ha), and the resulting thinned matrix is less harsh than in larger thinned stands. Use within thinned portions of the stand and unthinned remnant blocks suggests that over the winter hares may also benefit from a connectivity of dense cover.

Estimating low-density snowshoe hare populations using fecal pellet counts

2002 ◽  
Vol 80 (4) ◽  
pp. 771-781 ◽  
Author(s):  
Dennis L Murray ◽  
James D Roth ◽  
Ethan Ellsworth ◽  
Aaron J Wirsing ◽  
Todd D Steury
Keyword(s):  
Fecal Pellet ◽  
Nonlinear Models ◽  
Robust Estimator ◽  
Snowshoe Hare ◽  
Low Density ◽  
Intensive Study ◽  
Pellet Counts ◽  
Pellet Density ◽  
Study Sites ◽  
Northern Idaho

Snowshoe hare (Lepus americanus) populations found at high densities can be estimated using fecal pellet densities on rectangular plots, but this method has yet to be evaluated for low-density populations. We further tested the use of fecal pellet plots for estimating hare populations by correlating pellet densities with estimated hare numbers on 12 intensive study areas in Idaho; pellet counts from extensive transects (n = 615) across northern Idaho enabled rectangular plots (0.155 m2) to be compared with paired small (0.155 m2) and large (1 m2) circular plots (metre-circle plots). Metre-circle plots had higher pellet prevalence, lower sample variance, and lower estimates of pellet density than the other plot types. Transects comprising circular plots required less establishment time, and observer training reduced the pellet-count bias attributable to plot shape. The number of hares occupying intensive study sites was correlated with pellet density on all plot types, but rectangular plots provided a slightly closer linear fit to hare numbers than did metre-circle plots. The relationship between pellet density and hare number may have been curvilinear rather than linear, but linear and nonlinear models provided similar numerical estimates over much of the range of pellet densities. These results indicate that pellet counts are a robust estimator of hare numbers in low-density populations, and that metre-circle plots represent an improvement over standard rectangular plots in terms of unbiased pellet counts, sacrificing little predictive power. We recommend using pellet counts in metre-circle plots for estimating populations of snowshoe hares in their southern distribution.

Experimental analyses of dispersal in snowshoe hare populations

1976 ◽  
Vol 54 (12) ◽  
pp. 2061-2081 ◽  
Author(s):  
Lamar A. Windberg ◽  
Lloyd B. Keith
Keyword(s):  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Lower Body ◽  
Population Densities ◽  
Population Response ◽  
Partial Removal ◽  
Resident Population ◽  
Body Weights ◽  
Sex Ratio Imbalance ◽  
Hare Population

Dispersal was investigated in snowshoe hare (Lepus americanus) populations near Rochester, Alberta, from May 1970 to May 1974. Ingressing hares (dispersers) were removed every 3 to 4 weeks after removal of the initial resident population from an 11.3-ha study area. Dispersal into this vacant habitat occurred during all seasons of each year. The highest rates of ingress were recorded during the winter of peak population densities (1970–1971). There was a higher proportion of short-yearlings among ingressing hares than among residents. During two winters of known food shortage (1970–1971 and 1971–1972) dispersing hares had lower body weights than residents. Lighter adrenals and a higher incidence of scarring were also found among ingressing hares during winter 1970–1971.During winter 1971–1972 the resident hare population was removed from another area. Comparable recapture rates between marked immigrants on this area and hares on unmanipulated study areas indicated that ingressing individuals had settled in the vacant habitat.Hare population response to sex-ratio imbalance, created by partial removal of each sex on different areas, was studied during 1970 and 1971. Pregnancy rates declined significantly only on the male-removal area. Movements by adults during the breeding season and by predominantly juveniles over winter tended toward rebalancing population sex ratios.

scholarly journals California encephalitis virus endemicity in the Yukon Territory, 1972

1973 ◽  
Vol 71 (2) ◽  
pp. 391-402 ◽  
Author(s):  
D. M. McLean ◽  
Alison M. Clarke ◽  
E. J. Goddard ◽  
A. S. Manes ◽  
C. A. Montalbetti ◽  
...  
Keyword(s):  
Yukon Territory ◽  
Ground Squirrels ◽  
Lepus Americanus ◽  
Encephalitis Virus ◽  
Tamiasciurus Hudsonicus ◽  
Snowshoe Hare ◽  
Snowshoe Hares ◽  
Tree Squirrels ◽  
Culiseta Inornata ◽  
Aedes Communis

SUMMARYSera from 218 of 1574 (14%) small mammals collected in the Yukon Territory between 14 May and 13 August 1972 neutralized a Yukon strain of California encephalitis virus (snowshoe-hare subtype). These included 133 of 319 (42%) snowshoe hares (Lepus americanus), 84 of 1243 (7%) ground squirrels (Citellus undulatus) and 1 of 12 (8%) tree squirrels (Tamiasciurus hudsonicus). California encephalitis virus (snow-shoe hare subtype) was isolated from four pools of unengorged Aedes communis mosquitoes collected near Whitehorse (61° N., 135° W.) and on one occasion each from pools of the same species collected at Hunker Creek (64° N., 138° W.) and at mile 125, Dempster Highway (66° N., 138° W.) during July 1972. Replication of a Yukon strain of California encephalitis virus was observed in wild-caught Culiseta inornata and Aedes canadensis mosquitoes after intrathoracic injection and holding at temperatures of 80°, 50° and 40° F.

Comparaison de quatre méthodes statistiques pour estimer les niveaux de population du lièvre d'Amérique, Lepus americanus

1975 ◽  
Vol 53 (5) ◽  
pp. 657-660
Author(s):  
Jean-Clet Gendron ◽  
Jean-Marie Bergeron
Keyword(s):  
Linear Regression ◽  
Population Density ◽  
Lepus Americanus ◽  
Snowshoe Hare

Our FORTRAN IV program allowed us to estimate (P > 99%) the population density of the snowshoe hare following the method of linear regression and those of Schnabel and Hayne. This latter method represents the first attempt to estimate the population levels of this rodent. The Lincoln index is the least reliable of the four tests.

scholarly journals Estimating abundance, temporary emigration and the pattern of density dependence in a cyclic snowshoe hare population in Yukon, Canada

2021 ◽  
Author(s):  
Madan K. Oli ◽  
Alice J. Kenney ◽  
Rudy Boonstra ◽  
Stan Boutin ◽  
Vratika Chaudhary ◽  
...  
Keyword(s):  
Population Density ◽  
Large Scale ◽  
Seasonal Pattern ◽  
Survival Rates ◽  
Population Cycles ◽  
Sampling Period ◽  
Snowshoe Hare ◽  
Temporary Emigration ◽  
Cyclical Fluctuation ◽  
Hare Population

Estimates of demographic parameters based on capture-mark-recapture (CMR) methods may be biased when some individuals in the population are temporarily unavailable for capture (temporary emigration). We estimated snowshoe hare abundance, apparent survival, and probability of temporary emigration in a population of snowshoe hares (Lepus americanus Erxleben 1777) in the Yukon using Pollock’s robust design CMR model, and population density using spatially-explicit CMR models. Survival rates strongly varied among cyclic phases, seasons, and across five population cycles. We found strong evidence that temporary emigration was Markovian (i.e., non-random), suggesting that it varied among individuals that were temporary emigrant in the previous sampling period and those that were present in the sampled area. The probability of temporary emigration for individuals that were in the study area during the previous sampling occasion (γ´´) varied among cycles. Probability that individuals that were temporarily absent from the sampled area would remain temporary emigrants (γ´) showed strongly seasonal pattern, low in winter and high during summers. Snowshoe hare population density ranged from 0.017 (0.015–0.05) hares/ha to 4.43 (3.90–5.00) hares/ha and large-scale cyclical fluctuation. Autocorrelation functions and autoregressive analyses revealed that our study population exhibited statistically significant cyclic fluctuations, with a periodicity of 9-10 years.

How do population density and food supply influence social behaviour in the snowshoe hare (Lepus americanus)?

1993 ◽  
Vol 71 (6) ◽  
pp. 1084-1089 ◽  
Author(s):  
Jean Ferron
Keyword(s):  
Population Density ◽  
Breeding Season ◽  
Group Size ◽  
Food Availability ◽  
Social Behaviour ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Agonistic Behaviour ◽  
Nonbreeding Season ◽  
The Impact

The influence of population density and food on the social behaviour of the snowshoe hare (Lepus americanus) was studied in an outdoor enclosure. The year was divided into two periods: the nonbreeding season (October to March) and the breeding season (April to August). During each period, data on social interactions were recorded for groups of 4, 6, 8, and 10 animals, with three different sets of animals for each group size. Agonistic behaviour characterized social encounters between hares year-round. During the nonbreeding season, there was a significant correlation between agonistic behaviour and group size for females only. During the breeding season, the rate of interaction was lower and agonistic behaviour was significantly and negatively correlated with group size for males only. Two-way ANOVA of total agonistic behaviour revealed that group size and sex interacted significantly only during the nonbreeding season. The different categories of agonistic behaviour (aggression, threat, and taking the place of another animal) were also analysed separately. The distribution of aggression within each of the experimental groups indicated that the two top-ranking animals were generally males and that they initiated most of the aggressive encounters. Another experiment with restricted food availability was conducted to study the impact of limited resources on agonistic behaviour. Hares were significantly more aggressive when food was restricted than when food was available ad libitum. It thus appears that food availability has a stronger influence on social behaviour than does hare density.

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