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Ecological theory predicts that the intensity of antipredator responses is dependent upon the spatiotemporal context of predation risk (the risk allocation hypothesis). However, most studies to date have been conducted over small spatial extents, and did not fully take into account gradual responses to predator proximity. We simultaneously collected spatially explicit data on predator and prey to investigate acute responses of a threatened forest ungulate, the boreal caribou (Rangifer tarandus), to the spatiotemporal dynamics of wolf (Canis lupus) distribution during spring. Movement analysis of GPS-collared individuals from both species revealed high plasticity in habitat-selection decisions of caribou. Female caribou avoided open areas and deciduous forests and moved relatively fast and toward foraging areas when wolves were closer than 2.5 km. Caribou also avoided food-rich areas only when wolves were within 1 km. Our results bridge the gap between long-term perceived risk and immediate flight responses by revealing dynamic antipredator tactics in response to predator proximity. [ABSTRACT FROM AUTHOR]

Logging negatively affects the threatened forest-dwelling caribou ( Rangifer tarandus caribou) through its positive effects on large predator populations. As recruitment is a key component of caribou population growth rate, we assessed calving rates of females and calf survival rates during the most critical period for calf survival, the calving period. We also identified causes of calf mortality and investigated the influence of predation risk, food availability, and human disturbance on habitat selection of females during the calving period at both the home-range and forest stand scales. We hypothesized that caribou should display habitat selection patterns to reduce predation risk at both scales. Using telemetry, we followed 22 females and their calves from 2004 to 2007 in a highly managed study area in Québec, Canada. Most females (78.5 ± 0.05 [SE]) gave birth each year, but only 46.3 ± 8.0% of the calves survived during the first 50 days following birth, and 57.3 ± 14.9% of them died from black bear ( Ursus americanus) predation. At the home-range scale, caribou selected calving areas located at upper slope positions and avoided high road density areas. Surprisingly, they also selected the forested habitat type having the lowest lateral cover (mixed and deciduous stands) while avoiding the highest cover (regenerating conifer stands). At the forest stand scale, caribou selected areas located at relatively high elevations and with a lower basal area of black spruce trees. The selection of upper slope positions likely favored spatial segregation between calving females and wolves ( Canis lupus) but not black bear. Our results suggest that calving females used areas from which they could visually detect approaching predators. While wolf avoidance appeared to be effective in a highly managed landscape, caribou did not appear to have adjusted their predator avoidance strategy to the recent increase in black bear abundance, who have benefited from increased food abundance. This situation requires focused attention from wildlife managers as logging activities are progressing towards the north within the core of forest-dwelling caribou range. © 2011 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Reduced to small isolated groups by anthropogenic habitat losses or habitat modifications, populations of many endangered species are sensitive to additive sources of mortality, such as predation. Predator control is often one of the first measures considered when predators threaten survival of a population. Unfortunately, predator ecology is often overlooked because relevant data are difficult to obtain. For example, the endangered Gaspésie caribou (Rangifer tarandus caribou) has benefited from 2 periods of predator control that targeted black bears (Ursus americanus) and coyotes (Canis latrans) in an attempt to reduce predation on caribou calves. Despite a high trapping effort, the number of predators removed has remained stable over time. To assess impact of predator movements on efficacy of a control program, we studied space use of 24 black bears and 16 coyotes over 3 years in and around the Gaspésie Conservation Park, Quebec, Canada, using Global Positioning System radiocollars. Annual home ranges of black bears averaged 260 km² and 10 individuals frequented area used by caribou. Annual home ranges of resident coyotes averaged 121 km², whereas dispersing coyotes covered >2,600 km². Coyotes were generally located at lower altitudes than caribou. However, because coyotes undertook long-distance excursions, they overlapped areas used by caribou. Simulations based on observed patterns showed that 314 bears and 102 coyotes potentially shared part of their home range with areas used by female caribou during the calving period. Despite low densities of both predator species, extensive movement and use of nonexclusive territories seem to allow predators to rapidly occupy removal areas, demonstrating the need for recurrent predator removals. Our results underscore the necessity of considering complementary and alternative solutions to predator control to assure long-term protection of endangered species. [ABSTRACT FROM AUTHOR]

Accurate and precise population estimates for the forest-dwelling ecotype of Woodland Caribou (Rangifer tarandus caribou) are very difficult to obtain because these Caribou are found at very low densities and in small herds dispersed over large areas. In order to suggest a standardized method, data from aerial surveys conducted in 1991 and 1993 (12 000 Km2 blocks) were used to simulate various survey scenarios. Simulations showed that all the major groups of Caribou would have to be found and counted to obtain a confidence interval of ± 20% (α = 0.10). We tested this technique in a survey carried out in winter 1999 in a 42 539 Km2 study site, opting for a total coverage carried out in two phases. In phase one, we used an airplane, flying north-south transects spaced 2.1 km apart so as to detect most Caribou track networks. In phase two, a helicopter was used to count and determine the sex and age classes (calves/adults) of Caribou found in phase one. Using 20 radio-collared Caribou, the visibility rate of Caribou groups (phase one) and that of Caribou within the groups (phase two) were estimated at 0.90 and 0.94 respectively for an overall rate of 0.85 (SE = 0.08; α = 0.10). The corrected density was estimated at 1.6 Caribou per 100 Km2 with a 15% confidence interval (α = 0.10). The survey cost approximately $4/Km2, which is lower than that of two previous surveys ($7/Km2). Two main factors contributed to diminish costs: (1) the use of long-range airplanes (5-7 hours flying range) in phase one to minimize travel between the airports and the study site, and (2) the use of helicopters only in phase two for counting and determining the age and sex of the Caribou. [ABSTRACT FROM AUTHOR]