An assessment of overwinter food limitation in a snowshoe hare population at a cyclic low

Oecologia ◽  
1999 ◽  
Vol 120 (1) ◽  
pp. 50-58 ◽  
Author(s):  
Dennis L. Murray
Keyword(s):  
Food Limitation ◽  
Snowshoe Hare ◽  
Hare Population

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.

Influence of forest herbicide on snowshoe hare population dynamics: reproduction, growth, and survival

1996 ◽  
Vol 26 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Thomas P. Sullivan
Keyword(s):  
Body Mass ◽  
Demographic Parameters ◽  
Snowshoe Hare ◽  
Growth And Survival ◽  
Physiological Processes ◽  
Adult Females ◽  
Breeding Condition ◽  
Glyphosate Herbicide ◽  
Hare Population ◽  
Treatment Population

This study was designed to assess the influence of forest applications of glyphosate herbicide on reproduction, growth, and survival in snowshoe hare (Lepusamericanus Erxleben) populations in control (reference) and treatment habitats near Prince George, B.C. Proportion of adult hares in breeding condition and number of successful pregnancies showed no consistent differences between control and treatment populations. Recruitment of hares was generally similar except for significantly more juvenile females entering the control than treatment population at one study area. At a second study area, total recruitment was significantly higher in the treatment than control population for both sexes in 1990 and for adult females in 1991, the 2 post-treatment years. There was little difference in survival of hares between control and treatment populations. Lack of significant differences in mean body mass and growth rates suggested that this herbicide treatment had little or no effect on metabolic or general physiological processes in the development of young hares. Similar profiles of body mass distribution between control and treatment populations indicated that comparable levels of biomass of hares were available as prey for predators. Use of this forest herbicide did not measurably affect demographic parameters of snowshoe hare populations.

Demographic Parameters of a Snowshoe Hare Population

1968 ◽  
Vol 32 (4) ◽  
pp. 812 ◽  
Author(s):  
E. Charles Meslow ◽  
Lloyd B. Keith
Keyword(s):  
Demographic Parameters ◽  
Snowshoe Hare ◽  
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.

Lynx Recruitment during a Snowshoe Hare Population Peak and Decline in Southwest Yukon

1996 ◽  
Vol 60 (2) ◽  
pp. 441 ◽  
Author(s):  
Garth Mowat ◽  
Brian G. Slough ◽  
Stan Boutin
Keyword(s):  
Snowshoe Hare ◽  
Population Peak ◽  
Hare Population

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.

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