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

scholarly journals Biases in the estimation of the demographic parameters of a snowshoe hare population

1999 ◽  
Vol 68 (3) ◽  
pp. 501-512 ◽  
Author(s):  
Daniel. T. Haydon ◽  
Elizabeth. A. Gillis ◽  
Carol. I. Stefan ◽  
Charles. J. Krebs
Keyword(s):  
Demographic Parameters ◽  
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.

The ecophysiology of survival in juvenile red kangaroos Macropus rufus: greater demands and higher costs.

2004 ◽  
Vol 26 (2) ◽  
pp. 161 ◽  
Author(s):  
AJ Munn ◽  
TJ Dawson
Keyword(s):  
Body Mass ◽  
Arid Regions ◽  
Resting Metabolic Rate ◽  
High Quality ◽  
Energy Turnover ◽  
Growth And Survival ◽  
Risk Of Predation ◽  
Macropus Rufus ◽  
High Fibre ◽  
Lactating Females

Red kangaroos (Macropus rufus) are large (> 20 kg) herbivorous marsupials common to the arid and semi-arid regions of inland Australia. The population dynamics of M. rufus is tightly linked to environmental factors, which operate partly through the survival of juveniles. A crucial period is the young-at-foot (YAF) stage when juveniles have permanently left the mother?s pouch. YAF and weaned kangaroos have the highest drought-related mortalities of any cohort and show notable differences from adults in their basic physiology. YAF and weaned M. rufus, for example, had a resting metabolic rate (kJ kg-1 d-1) twice that of mature females and 1.5 times that expected for an adult marsupial of equivalent body mass (i.e., kJ kg-0.75 d-1). This greater energy turnover was largely explained by their metabolic demands for growth; juveniles required 70 - 95% of the digestible energy intake (kJ d-1) of mature, non-lactating females. Meeting these costs may not be a problem for juveniles when high-quality, low-fibre forage is available, but they were constrained when only hard-to-digest, high-fibre forage was available. YAF and weaned kangaroos, for example, were unable to sustain growth on forages of more than 40 ? 50% fibre, fibre levels characteristic of forages in arid regions during drought. Yet mature, non-lactating females were capable of maintaining body mass on similar forage. Additionally, juvenile M. rufus required relatively more water than adults for thermoregulation (by up to 2.5-fold), especially under hot conditions, and may need to drink more frequently than adults. Thus, juveniles appear constrained to remain close to water points, increasing their risk of predation and limiting their ability to find the high-quality forage needed for their growth and survival.

Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) on Svalbard

1990 ◽  
Vol 68 (3) ◽  
pp. 470-475 ◽  
Author(s):  
Morten Ryg ◽  
Thomas G. Smith ◽  
Nils Are Øritsland
Keyword(s):  
Body Composition ◽  
Body Mass ◽  
Seasonal Changes ◽  
Adult Males ◽  
Phoca Hispida ◽  
Core Mass ◽  
Adult Females ◽  
Ringed Seals ◽  
Body Fat Content ◽  
Body Mass Changes

Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) from the Svalbard Islands are described. The blubber content of adult females decreased from a high of about 50% at the beginning of the pupping season in March–April to a low of 31% during moulting in June. In adult males, the blubber content decreased from 41% in March to 29% in June. By estimating an individual seal's body mass by 1 April from its standard body length, we calculated an average daily loss of body mass of 160 g/day in adult females and 100 g/day in adult males from the start of lactation to the middle of moulting. The blubber content of sexually immature seals was less in June and July than in April, but the seasonal changes were smaller than in adult seals. We found no evidence of significant changes in core mass in adult seals, and suggest that the seasonal body mass changes are mostly due to changes in body fat content.

Severe Obesity: Effects on Foot Mechanics During Walking

1994 ◽  
Vol 15 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Stephen P. Messier ◽  
Angela B. Davies ◽  
Dominic T. Moore ◽  
Shala E. Davis ◽  
Robert J. Pack ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Weight Control ◽  
Severe Obesity ◽  
Normal Weight ◽  
Control Group ◽  
Posterior Aspect ◽  
Adult Females ◽  
Q Angle ◽  
Severely Obese

The purpose of our study was to determine the effects of severe obesity on the foot mechanics of adult females. Twenty-nine adult females between the ages of 20 and 48 years volunteered as subjects for this investigation. The subjects were separated into a severely obese (O) group (body mass index = 41.14 ± 2.61; N = 16) and a normal weight control group (body mass index = 20.84 ± 0.47; N = 13). A Locam camera (100 Hz) positioned perpendicular to the subjects’ posterior aspect was used to film the rearfoot movement of the subjects during the final 15 sec of a 10 min treadmill walk. The O group had a significantly greater touchdown angle ( P = .05), more total eversion range of motion ( P = .001), and a faster maximum eversion velocity ( P < .001). Moreover, analysis of dynamic foot angles indicated that the O group had significantly ( P = .003) more forefoot abduction. Finally, anthropometric data revealed statistically different ( P < .001) Q angle measurements between the O and control groups. The results of this study suggest that severely obese females have significantly greater rearfoot motion, foot angle, and Q angle values than normal weight females.

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