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.

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.

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.

Dynamics of a snow shoe hare population in fragmented habitat

1993 ◽  
Vol 71 (7) ◽  
pp. 1385-1392 ◽  
Author(s):  
Lloyd B. Keith ◽  
Sara E. M. Bloomer ◽  
Tomas Willebrand
Keyword(s):  
Patch Size ◽  
Canis Latrans ◽  
Lepus Americanus ◽  
Fragmented Habitat ◽  
Proximate Cause ◽  
Lower Survival ◽  
The Third ◽  
Snowshoe Hares ◽  
Poorly Drained Soils ◽  
Hare Population

During November 1988 – December 1991 we livetrapped, radio-collared, and monitored the survival, reproduction, and movements of snowshoe hares (Lepus americanus) in highly fragmented habitat near the species' geographic limit in central Wisconsin. Our 7 study areas centered on 5- to 28-ha patches of prime habitat: dense stands of willow (Salix), alder (Alnus), and regenerating aspen (Populus) on poorly drained soils. Maximum hare densities averaged 1.6 – 0.8/ha, and were unrelated to patch size. Rapid declines to extinction occurred on 3 of the 5 smallest study areas; on another, where extinction seemed imminent, juvenile ingress restored the population. On the 2 largest areas (23 – 28 ha of prime habitat) hare populations were stationary during the first 2 years, but declined by 50 – 70% in the third as mean annual (September – August) survival of radio-collared hares fell from 0.27 (1988 – 1990) to 0.07 (1990 – 1991). Annual survival on the 3 extinction sites averaged just 0.015 compared with 0.179 elsewhere. Reproduction did not differ between small (5 – 7 ha) vs. larger (23 – 28 ha) patches nor between years. Estimated dispersal of adult and juvenile hares from the 5 small study areas was twice as high as from the 2 larger, viz. 16 vs. 35% annually. Dispersers appeared to have markedly lower survival. Predation, chiefly by coyotes (Canis latrans), was the proximate cause of 96% (117 of 122) of natural deaths among radio-collared hares, and was therefore the overwhelming determinant of survival and thus population trend. Results of this study suggest that probabilities of extinction in such fragmented habitat depend importantly on patch size and attendant hare numbers; i.e., fall populations of < 10 hares frequenting patches of prime habitat ≤ 5 ha are not likely to persist long without ingress.

Impact of helminth parasitism on a snowshoe hare population in central Wisconsin: a field experiment

1995 ◽  
Vol 73 (10) ◽  
pp. 1891-1898 ◽  
Author(s):  
Sara E. M. Bloomer ◽  
Thomas Willebrand ◽  
Ingegerd M. Keith ◽  
Lloyd B. Keith
Keyword(s):  
Survival Rates ◽  
Snowshoe Hare ◽  
Marrow Fat ◽  
Proximate Cause ◽  
Risk Of Death ◽  
Snowshoe Hares ◽  
Condition Indices ◽  
Time Specific ◽  
And Control ◽  
Hare Population

We tested the hypothesis that helminth parasitism is demographically significant to a noncyclic population of snowshoe hares (Lepus americanus) near the species' geographic boundary in central Wisconsin (U.S.A.). During November 1988 to December 1991, we injected 93 individuals (≥760 g, aged ≥2 months) with anthelmintics: Ivermectin for nematode and Droncit for cestode infections. We injected 98 control hares with propylene glycol, the common vehicle for both drugs. All treated and control hares were radio-collared with mortality-sensing transmitters and monitored daily to weekly from the ground or air. Prevalence and intensity of lungworms (Protostrongylus boughtoni), intestinal worms (Nematodirus triangularis), and stomach worms (Obeliscoides cuniculi) were markedly reduced by Ivermectin treatment. No other nematodes were found to be present. Treatment with Droncit to remove intestinal cestodes was apparently unnecessary, as prevalence among necropsied untreated hares and controls was just 10%. We compared body-condition indices (mass changes, response to trap stress, and bone-marrow fat), reproduction (pregnancy rate and litter size), home-range sizes, and time-specific survival rates of anthelmintic-treated versus control hares. None of these demographic variables differed significantly between treated and control cohorts, nor was there any evidence that parasitism increased the risk of death from predation, which was the proximate cause of 96% of all natural mortalities. We conclude that helminth parasitism played no detectable role in the dynamics of this Wisconsin snowshoe hare population.

Reproductive change in the 10-year cycle of snowshoe hares

1979 ◽  
Vol 57 (2) ◽  
pp. 375-390 ◽  
Author(s):  
John R. Cary ◽  
Lloyd B. Keith
Keyword(s):  
Pregnancy Rate ◽  
Litter Size ◽  
Weight Change ◽  
Ovulation Rate ◽  
Population Cycle ◽  
Snowshoe Hare ◽  
Cyclic Variation ◽  
Reproductive Parameters ◽  
Snowshoe Hares ◽  
Hare Population

Reproduction was monitored during a 16-year study of snowshoe hare (Lepus americanus) populations near Rochester, Alberta. Pregnancy rate, ovulation rate, and litter size changed markedly between successive litters within the breeding season; these parameters were thus further categorized by litter in our analyses. Most reproductive components varied significantly between years; a significant '10-year' periodicity was the dominant source of this variation. The cyclic fluctuations of reproductive parameters were broadly synchronous and tended to precede the population cycle by about 3 years, thereby producing a range in potential natality annually of 7.5 to 17.9 young per female. The year-to-year variability of pregnancy rate, ovulation rate, and litter size was markedly larger in the later litters than in the early ones. Paunched weight, mean age, incidence of endoparasites, liver and spleen weights, and midwinter-to-spring weight change also possessed significant 10-year cycles; paunched weight cycled directly with the hare population, but the others cycled either directly with or counter to reproduction. We believe that the correspondence between midwinter-to-spring weight change and reproduction implicates winter nutrition as the primary cause of the cyclic variation. Onset of spring accounted for a significant amount of variability in onset of breeding, adding to that due to the periodic change.

scholarly journals Patterns and potential drivers of intraspecific variability in the body elemental composition of a terrestrial consumer, the snowshoe hare (Lepus americanus)

2019 ◽  
Author(s):  
Matteo Rizzuto ◽  
Shawn J. Leroux ◽  
Eric Vander Wal ◽  
Yolanda F. Wiersma ◽  
Travis R. Heckford ◽  
...  
Keyword(s):  
Body Size ◽  
Chemical Composition ◽  
Intraspecific Variability ◽  
Lepus Americanus ◽  
The Body ◽  
Whole Body ◽  
Snowshoe Hare ◽  
Weak Relationship ◽  
Snowshoe Hares ◽  
P Content

AbstractIntraspecific variability in ecological traits is widespread in nature. Recent evidence, mostly from aquatic ecosystems, shows individuals differing at the most fundamental level, that of their chemical composition. Age, sex, or body size may be key drivers of intraspecific variability in the body concentrations of carbon (C), nitrogen (N), and phosphorus (P). However, we still have a rudimentary understanding of the patterns and drivers of intraspecific variability in chemical composition of terrestrial consumers, particularly vertebrates.Here, we investigate the whole-body chemical composition of snowshoe hare Lepus americanus, providing one of the few studies of patterns of stoichiometric variability and its potential drivers for a terrestrial vertebrate. Based on snowshoe hare ecology, we expected higher P and N concentrations in females, as well as in larger and older individuals.We obtained whole-body C, N, and P concentrations and C:N, C:P, N:P ratios from a sample of 50 snowshoe hares. We then used general linear models to test for evidence of a relationship between age, sex, or body size and stoichiometric variability in hares.We found considerable variation in the C, N, and P concentrations and elemental ratios within our sample. Contrary to our predictions, we found evidence of N content decreasing with age. As expected, we found evidence of P content increasing with body size. As well, we found no support for a relationship between sex and N or P content, nor for variability in C content and any of our predictor variables.Despite finding considerable stoichiometric variability in our sample, we found no substantial support for age, sex, or body size to relate to this variation. The weak relationship between body N concentration and age may suggest varying nutritional requirements of individuals at different ages. Conversely, P’s weak relationship to body size appears in line with recent evidence of the potential importance of P in terrestrial systems. Snowshoe hares are a keystone herbivore in the boreal forest of North America. The substantial stoichiometric variability we find in our sample could have important implications for nutrient dynamics in both boreal and adjacent ecosystems.

REGIONAL DIFFERENCES IN REPRODUCTIVE TRAITS OF THE SNOWSHOE HARE

1966 ◽  
Vol 44 (5) ◽  
pp. 953-961 ◽  
Author(s):  
Lloyd B. Keith ◽  
Orrin J. Rongstad ◽  
E. Charles Meslow
Keyword(s):  
Litter Size ◽  
Adult Female ◽  
Regional Differences ◽  
Reproductive Traits ◽  
Geographic Range ◽  
Lepus Americanus ◽  
Species Range ◽  
Snowshoe Hare ◽  
Breeding Female ◽  
Genetically Determined

Reproductive characteristics of the snowshoe hare (Lepus americanus) over its principal geographic range were summarised. The onset of breeding each spring was chronologically similar throughout a major portion of the species' range, although Alaska hares tended to be about 2 weeks later than those elsewhere. Mean litter size increased significantly from south to north, and studies with captive snowshoes demonstrated that such regional differences are genetically determined. Both the average number of litters, and the average number of young, per adult female per year were greatest at intermediate latitudes. It is suggested that regional differences in mean litter size reflect the general "fitness" of the breeding female and (or) her young relative to their particular environment, as governed by the physiological consequences of species adaptation and of reproduction.

What factors determine cyclic amplitude in the snowshoe hare (Lepus americanus) cycle?

2014 ◽  
Vol 92 (12) ◽  
pp. 1039-1048 ◽  
Author(s):  
Charles J. Krebs ◽  
John Bryant ◽  
Knut Kielland ◽  
Mark O’Donoghue ◽  
Frank Doyle ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Forest Succession ◽  
Monitoring Program ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Amplitude Variation ◽  
Regional Monitoring ◽  
Snowshoe Hares ◽  
Existing Data

Snowshoe hares (Lepus americanus Erxleben, 1777) fluctuate in 9–10 year cycles throughout much of their North American range. These cycles show large variations in cyclic amplitude and we ask what factors could cause amplitude variation. We gathered data from 1976 to 2012 on hare numbers in the boreal forest of Alaska, Yukon, Northwest Territories, and northern British Columbia to describe the amplitude of hare fluctuations and to evaluate four possible causes. First, weather could cause variation in amplitude via hare reproduction or survival, but this mechanism does not fit our data. Second, bottom-up processes involving forest succession could explain amplitude variation through changes in winter forage availability, but succession is too slow a variable in our study areas. Third, plant defenses entrained by hare over-browsing in one cycle can produce variation in plant quality and quantity in subsequent cycles. A mathematical model suggests this is a possible explanation. Fourth, predator recovery following the cyclic low is inversely related to hare cyclic amplitude, and the existing data are consistent with this mechanism. A standardized regional monitoring program is needed to improve our understanding of cyclic amplitude variation in hares and the possible role of predators and winter foods in affecting amplitude.

scholarly journals Serologic Survey of Snowshoe Hares (Lepus americanus) in the Greater Yellowstone Area for Brucellosis, Tularemia, and Snowshoe Hare Virus

2015 ◽  
Vol 51 (3) ◽  
pp. 769-773 ◽  
Author(s):  
Jack Rhyan ◽  
Dan Tyers ◽  
Jeremy Zimmer ◽  
Kristen Lewandowski ◽  
Steve Hennager ◽  
...  
Keyword(s):  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Greater Yellowstone Area ◽  
Snowshoe Hares ◽  
Greater Yellowstone ◽  
Serologic Survey

Antibodies to Francisella tularensis in the snowshoe hare (Lepus americanus struthopus) populations of Nova Scotia and Prince Edward Island and in the moose (Alces alces americana Clinton) population of Nova Scotia

1982 ◽  
Vol 28 (4) ◽  
pp. 403-405 ◽  
Author(s):  
M. B. Akerman ◽  
J. A. Embil
Keyword(s):  
Nova Scotia ◽  
Francisella Tularensis ◽  
Prince Edward Island ◽  
Alces Alces ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Serological Survey ◽  
First Report ◽  
Snowshoe Hares

A serological survey showed antibodies to Francisella tularensis present in 1.55% of snowshoe hares (Lepus americanus struthopus) and 1.06% of moose (Alces alces americana Clinton) sampled in Nova Scotia. No antibody-positive hares were found in Prince Edward Island, however. We believe this to be the first report of antibodies to F. tularensis in the moose.

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