Snowshoe Hare Mortality Monitored by Telemetry

Brand, Chris; Vowles, Richard H.; Keith, Lloyd B.

doi:10.2307/3800236

Cited by 25 publications

(23 citation statements)

References 13 publications

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“…We reject a reviewer's suggestion that coyotes were simply scavenging animals that had starved to death during November and December for the following reasons: (i) coyotes have never scavenged hare carcasses set out by us, e.g . , 10 during the winter of 1972-1973 in Alberta (Brand et al 1975), nor 25 set out during the winter of 1991 -1992 in Manitoba (D. Murray, personal communication), although coyotes were abundant in both areas; (ii) femur-marrow fat levels were 24 and 50% in the two cottontails whose carcass remains permitted such analyses. Snowshoe and arctic (Lepus arcticus) hares that starved to death in the wild have had marrow-fat levels averaging 16 % (range 13 -19 % , n = 7) and 10 % (range 6 -16 % , n = 8), respectively (Keith et al 1984;Barta et al 1989).…”

Section: Proximate Causes Of Deathmentioning

confidence: 96%

Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin

Keith¹,

Bloomer²

1993

Can. J. Zool.

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1993. Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin. Can. J. Zool. 71: 1694 -1697 . During 1990 and 1991 we livetrapped and radio-collared cottontail rabbits (Sylvilagus floridanus) and snowshoe hares (Lepus americanus) on five sites (three in lowland deciduous cover, two in conifer bogs) in central Wisconsin. The survival rates of these sympatric cottontails and snowshoes were equally high during snow-free periods from mid-March through October. With the onset of persistent snow cover (mean depth 20 cm) and low temperatures (mean daily minimum -14°C) in November 1991, the 60-day survival rate of cottontails plummeted from 0.89 to 0.18 (P < 0.01) whereas snowshoe survival declined only moderately from 0.84 to 0.63 (P = 0.19). This interspecific difference reflected continued high survival of snowshoes (0.80), but not of cottontails (0.15), in the conifer bogs. Predation, primarily by coyotes, was the proximate cause of 37 of 39 rabbit and hare deaths, and was thus the overwhelming determinant of survival. We speculate that where persistent snow and low temperatures characterize winter, the cottontail's greater foot loading, brown coloration, and escape behavior markedly increase its vulnerability to predators. This probably explains the absence of cottontails from the forests of northern Wisconsin. KEITH, L.B., et BLOOMER, S.E.M. 1993. Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin. Can. J. Zool. 71 : 1694-1697. Au cours de 1990 et 1991, nous avons capture vivants et munis d'un collier emetteur des Lapins h queue blanche (Sylvilagus floridanus) et des Likvres d'Am6rique (Lepus americanus) en cinq endroits (trois dans une forst dkcidue en terre basse, deux dans des tourbikres h conifkres) dans le centre du Wisconsin. Les taux de survie de ces likvres et lapins sympatriques ktaient kgalement 6levks au cours des pkriodes sans neige, de la mi-mars h la fin d'octobre. Avec l'arrivee d'une couverture de neige persistante (profondeur moyenne de 20 cm) et des temperatures basses (minimum quotidien moyen de -14°C) en novembre 1991, le taux de survie pendant 60 jours a subi une chute magistrale, de 0,89 h 0,18 (P < 0,01), chez les lapins, alors que la survie des likvres a diminuk beaucoup moins, soit de 0,84 h 0,63 (P = 0,19). La diffkrence se reflktait aussi bien dans les tourbikres, oh le taux de survie restait eleve chez les likvres (0,80), mais pas chez les lapins (0,15). La predation, principalement par les coyotes, s'est averee la cause immediate de 37 des 39 mortalitks enregistrkes chez les lapins et les likvres et il s'agit donc lh, et de loin, du principal facteur determinant de la survie. Nous croyons que, 18 oh la neige persistante et les temperatures froides caractkrisent l'hiver, les lapins, h cause de la charge plus importante sur leurs pattes, et h cause de leur coloration brune et de leur comportement de fuite, sont beaucoup plus vuln6rables aux predateurs. Ce phknomkne explique probablement l'absence de Lapin...

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Section: Proximate Causes Of Deathmentioning

confidence: 96%

Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin

Keith¹,

Bloomer²

1993

Can. J. Zool.

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“…These results suggest that lower survival is, at best, only weakly involved in determining regional population dynamics. Moreover, I summarized the small sample of studies that evaluated, via radiotelemetry, proximate cause of mortality and survival in hares; I found that for cyclic populations (n = 4) in Alberta, Yukon, and Manitoba (Brand et al 1975;Keith et al 1984;Boutin et al 1986;Murray et al 1997 Note: Data from most studies were obtained from mark-recapture studies and compiled by Keith (1990). Estimates for adults refer to yearly survival, whereas those for juveniles represent summer to spring values.…”

Section: Snowshoe Hare Distribution and Population Trendsmentioning

confidence: 99%

A geographic analysis of snowshoe hare population demography

Murray¹

2000

Can. J. Zool.

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Snowshoe hare (Lepus americanus) populations across northern Canada and Alaska undergo 8-to 11-year cycles in numbers, but population trends in southern Canada and the contiguous United States are apparently either weakly cyclic, irruptive, or largely stable. Although the demographic attributes (population density, reproductive rates, and survival rates) of northern and southern hare populations should differ considerably to account for such differential trends, to date limited rangewide analyses of hare demography have been undertaken. I reviewed hunter harvest estimates and basic demographic attributes for hare populations across North America, and assessed the effect of latitude, longitude, and latitude × longitude interaction on the magnitude and variation of such attributes. Harvest estimates tended to be synchronous across the Great Lakes area and along the St. Lawrence River, whereas they varied more dramatically along a westward gradient and in hare populations suspected of being cyclic. Hare densities tended to be higher among apparently noncyclic than cyclic populations at numerical lows, as well as among studies where hare numbers were apparently increasing. Populations from northern latitudes tended to breed later than those in the south, and females from western areas produced larger, but fewer litters, than those from eastern populations; total productivity was similar across geographic areas. Survival rates for both adult and juvenile hares were higher in increasing populations than in decreasing populations. Survival of adults also decreased along a northwest gradient, whereas that of juveniles decreased across a western gradient and with longitude, was lower in apparently noncyclic populations, and was also lower in populations in areas of high lynx (Lynx canadensis) densities. I conclude that, although disparity clearly exists in the trends of various hare populations, the absence of strong latitudinal gradients in demographic attributes fails to support the hypothesis that differential survival/predation is responsible for the regional differences in numerical trends.Résumé : Les populations de lièvres (Lepus americanus) du nord du Canada et de l'Alaska ont un cycle de densité de 8-11 ans, mais les tendances démographiques des populations du sud du Canada et des états américains adjacents semblent être moins cycliques, explosives ou assez stables. Bien que l'on s'attende à ce que les variables démographiques (densité de la population, taux de reproduction, taux de survie) diffèrent suffisamment chez les populations du nord et du sud pour causer ces tendances opposées, il existe à ce jour peu d'analyses de la démographie des lièvres à l'échelle de toute leur répartition. J'ai examiné les rapports des chasseurs et les caractéristiques démographiques de base des populations de lièvres dans toute l'Amérique du Nord, et tenté d'évaluer les effets de la latitude, de la longitude et de l'interaction latitude × longitude sur l'amplitude et la variation des caractéristiques démographiques. Les captures ...

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“…With regard to predation, the available evidence suggests that it is the most important proximate source of hare mortality during the period of population decline (Brand et al 1975, Boutin et al 1986, Trostel et al 1987). What is less certain is the role of predation in arresting hare population growth during the cycle's increase phase.…”

Section: Introductionmentioning

confidence: 99%

The Geometry of a Population Cycle: A Mechanistic Model of Snowshoe Hare Demography

King

Schaffer

2001

Ecology

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The phenomenology and causes of snowshoe hare cycles are addressed via construction of a three‐trophic‐level population dynamics model in which hare populations are limited by the availability of winter browse from below and by predation from above. In the absence of predators, the model predicts annual oscillations, the magnitude of which depends on habitat quality. With predators in the system, a wide range of additional dynamics are possible: multi‐annual cycles of various periods, quasiperiodicity, and chaos. Parameterizing the model from the literature leads to the conclusion that the model is compatible with the principal features of the cycle in nature: its regularity, mean period, and the observed range of peak‐to‐trough amplitudes. The model also points to circumstances that can result in the cycle's abolition as observed, for example, at the southern edge of the hare's range. The model predicts that the increase phase of the cycle is brought to a halt by food limitation, while the decline from peak numbers is a consequence of predation. This is consistent with factorial field experiments in which hare populations were given supplemental food and partial surcease from predators. The results of the experiments themselves are also reproducible by the model. Analysis of the model was carried out using a recently developed method in which the original dynamical system is reformulated as a perturbation of a Hamiltonian limit wherein exist infinite numbers of periodic, quasiperiodic, and chaotic motions. The periodic orbits are continued numerically into non‐Hamiltonian regions of parameter space corresponding to the situation in nature. This procedure allows one to obtain an overall understanding of the geometry of parametric dependencies. The present study represents the first formulation of a full three‐trophic‐level snowshoe hare model and the first time any model of the cycle has been parameterized entirely using independently measured quantities.

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Snowshoe Hare Mortality Monitored by Telemetry

Cited by 25 publications

References 13 publications

Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin

Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin

A geographic analysis of snowshoe hare population demography

The Geometry of a Population Cycle: A Mechanistic Model of Snowshoe Hare Demography

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