An experimental study of red fox predation on arctic and snowshoe hares

Abstract

SMALL, R. J., and KEITH, L. B. 1992. An experimental study of red fox predation on arctic and snowshoe hares. Can. J. Zool. 70: 1614-1621. We tested the relative vulnerability of arctic (Lepus arcticus) and snowshoe (Lepus americanus) hares to predation by red foxes (Vulpes vulpes) in experimental trials on three islands off Newfoundland's southwest coast. Arctic hares were significantly more vulnerable than snowshoe hares to fox predation: they were killed at a higher rate, and though the probability of death increased slightly for arctic hares over a trial period, it decreased for snowshoe hares. Rates of fox predation on arctic hares were inversely related to home-range size and nutritional status, whereas predation on snowshoe hares was inversely related to the percentage of home-range core areas with dense understory cover. We believe the arctic hare's greater vulnerability to fox predation, found in this study, coupled with its apparent inability to utilize food resources in forested areas that support snowshoe hares, which we found in an earlier study, largely accounts for the current restriction of arctic hares in Newfoundland to certain mountain and coastal barrens. The status of arctic hare populations before the introduction of snowshoe hares is unclear. However, distribution and abundance likely decreased as red foxes and lynx (Lynx canadensis) increased and began to cycle with snowshoe hares. Dispersal of foxes, and perhaps of lynx, from forested areas following snowshoe hare declines would have periodically intensified predation on the barrens. SMALL, R. J., et KEITH, L. B. 1992. An experimental study of red fox predation on arctic and snowshoe hares. Can. J. Zool.70 : 1614-1621. Nous avons CprouvC la vulnCrabilitC relative de Likvres arctiques (Lepus arcticus) et de Likvres d'AmCrique (Lepus americanus) B la prCdation par des Renards roux (Vulpes vulpes) au cours d'expkriences sur trois iles au large de la c8te sud-ouest de Terre-neuve. Les Likvres arctiques Ctaient significativement plus vulnCrables que les Likvres d'AmCrique B la prCdation : les taux de mortalit6 des Likvres arctiques par prCdation Ctaient plus ClevCs et, alors que leur probabilitk de mourir par prCdation augmentait 1Cgkrement au cours d'une expkrience, celle des Likvres d'AmCrique diminuait. Les taux de prCdation des Likvres arctiques Ctaient fonctions inverses de la taille du domaine et du statut alimentaire, alors que la prkdation des Likvres d'AmCrique Ctait fonction inverse de la proportion en pourcent des flots B forte couverture au sol dans le domaine. Nous croyons que la vulnCrabilitC plus grande des Likvres arctiques B la prCdation par les Renards roux (constatCe ici) combinCe B l'apparente incapacitk de ces likvres d'utiliser les ressources alimentaires des forets qui abritent les Likvres d'AmCrique (Ctude antkrieure des mCmes auteurs), explique en grande partie la restriction des Likvres arctiques de TerreNeuve B certaines zones sans arbres des montagnes et de la c8te. La dkmographie des Likvres arctiques avant l'intr...

Vegetative Characteristics and Size of Home Ranges Used by Pygmy Rabbits (Brachylagus idahoensis) during Winter

“…Pygmy rabbits consume all three subspecies of big sagebrush (A. t. tridentata, A. t. wyomingensis, and A. t. vaseyana). We suggest that amount of vege- -Ferron and Ouellet, 1992; and may provide protection from predators (Small and Keith, 1992). As cover of shrubs decreases, vegetative corridors connecting clumps of tall plants are eliminated.…”

“…The percentage cover and height of sagebrush in habitats used by rabbits at Fossil Butte were similar to cover and height of shrubs used during summer on a similar scale (Green and Flinders, 1980a). The consistency between habitats used by pygmy rabbits in Idaho and Wyoming implies that amount and structure of cover are as critical to pygmy rabbits as they are to rabbits in other ecosystems (Gibb, 1993;Kolb, 1994;MacCracken et aI., 1988;Small and Keith, 1992;Swihart and Yanher, 1984;Trent and Rongstad, 1974).…”

Experimental manipulation of predation and food supply of arctic ground squirrels in the boreal forest

“…Impacts of predators on density and survival of alternative prey species as a result of a cyclic decline in another herbivore are often reported (e.g., Angelstam et al 1984;Sutherland 1988;Marcström et al 1989;Keith and Cary 1991;Korpimäki and Norrdahl 1991;Small and Keith 1992;Patterson et al 1998;Angerbjorn et al 1999). Keith and Cary (1991) inferred that increased predation may have occurred on populations of alternative prey (including Franklin's ground squirrels, Spermophilus franklinii) during a snowshoe hare population decline in Alberta.…”

Ecology and conservation of lynx in the United States

“…Hares may have smaller home ranges at higher densities (Boutin 1984c;, but hares on sites with supplemental food do not appear to have smaller home ranges than hares on unsupplemented sites, despite higher densities (Boutin 1984b; and contrary to the typical pattern for other small mammals (Boutin 1990). Hares in predator exclosures may have smaller home ranges than unprotected hares ), but Small and Keith (1992) found no differences in hares' home range sizes before and after red foxes were introduced to islands.…”