Snowshoe hare demography during a cyclic population low

Abstract

Summary 0[ Snowshoe hare "Lepus americanus Erxleben# populations were studied in south! west Yukon during the low phase of the 09!year population cycle[ Food availability and predator abundance were manipulated in a factorial design to determine the importance of each factor in hare dynamics during this phase[ 1[ Food was abundant during the low phase\ and snowshoe hares were not food limited[ 2[ Survival of hares was higher than at any other phase of the cycle\ and predators were scarce\ but ×64) of hare deaths resulted from predation[ 3[ Food addition resulted in higher hare densities and better body condition than on control sites[ There were no observable e}ects of food addition on population rate of increase\ recruitment\ survival or age structure[ 4[ Mammalian predator reduction resulted in higher hare densities\ higher survival\ better body condition and an older age structure[ Relative to control populations\ recruitment was lower and population rates of increase similar[ 5[ The joint manipulation of food addition ¦ predator reduction had greater positive e}ects on hare density and body condition than either single factor manipulation[ Survival was better than on control sites\ and the age structure was older than on control sites[ Population rates of increase were similar\ but recruitment was higher on the control areas[ 6[ We conclude that snowshoe hare dynamics at the low of the cycle are dominated by the interaction of food and predation[ Risk of predation also had indirect e}ects on snowshoe hare age structure and body condition[ Key!words] body condition\ food addition\ population density\ predator reduction\ survival[ Journal of Animal Ecology "0888# 57\ 470Ð483

Stand-level Attributes of Snowshoe Hare (<em>Lepus americanus</em>) Habitat in a Post-Fire Trembling Aspen (<em>Populus tremuloides</em>) Chronosequence in Central Yukon

“…Deadfall above the forest floor likely serves as hiding cover (Hodges 1998;Andruskiw 2003;Berg et al 2012), possibly as thermal cover in winter (Conroy et al 1979;Roy et al 1995), and likely facilitates safer movement by Snowshoe Hares through the local vegetation. Not all young forest stands contained deadfall, possibly due to the pre-fire characteristics of a stand or the intensity of local burning, nor were older stands devoid of the material.…”

“…Most precipitation (177 of 279 mm) occurs in summer, but ~72 cm of snow falls on average during November-March. Wildfires have been a common disturbance agent in the study area, with extensive burns in 1958, and 1998(Englefield 2003. The location and distribution of sampled sites as well as the extent of more recent wildfires in the study area were reported by Strong (2009).…”

Modelling the Canada lynx and snowshoe hare population cycle: the role of specialist predators

“…Since the minimum hare densities observed in the boreal forest are much lower than existing models predict, we have yet to understand what drives the hare density to such low values during the cycle troughs Hodges et al 1999). Predation by lynx is apparently not sufficient.…”

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

“…Squirrels were studied on eight 9-ha experimental grids containing 100 grid points spaced 30 m apart and located in a 10 × 10 array: (i) four unmanipulated control grids (controls A, B, C, and D; controls A and B were trapped from 1990 to 1995, control C from 1993 to 1995, and control D from 1992 to 1995); (ii) two food-supplemented grids (food 1 and food 2) nested within snowshoe hare trapping grids and provisioned ad libitum with pelleted rabbit chow (minimum 16% crude protein) distributed with a fertilizer spreader along four 600-m lines cut through the forest; (iii) one predator-exclosure grid nested within a 1-km 2 area surrounded by a 8600-V electric fence to exclude large terrestrial mammalian predators and partially covered by monofilament fishing lines spaced 20 cm apart to deter avian predators; and (iv) one predatorexclosure + food-supplemented grid nested within a 1-km 2 area surrounded by an electric fence, as above, and provisioned with pelleted rabbit chow, as above, but with no monofilament lines to deter avian predators. The predator-exclosure, food, and predator-exclosure + food-supplemented grids were all located within experimental treatments established to manipulate snowshoe hare populations, as described in Boutin et al (1995), Krebs et al (1995), Hubbs and Boonstra (1997), and Hodges et al (1999). Squirrels were able to move freely in and out of the experimental plots at all times.…”