Michel Crête

Moose-wolf dynamics and the natural regulation of moose populations

SummaryIn southwestern Québec, non-harvested moose populations stabilize at a density of ≃0.40 animal·km-2. In an attempt to test whether or not moose were regulated by predators, we investigated wolf predation near this equilibrium density (0.37) and at 2 lower densities (≃0.23, 0.17). Scat analysis in summer and feeding observations in winter indicated a greater use of alternative food resources by wolves at lower moose densities. Each wolf pack killed on average 5.3, 1.8, 1.1 moose·100 days in the area of 0.37, 0.23, and 0.17 moose·km-2, respectively. Consumption of moose per wolf was 2.8, 1.7, and 1.6 kg/day, respectively. January wolf densities were estimated at 1.38, 0.82, and 0.36 animals·100 km-2, respectively. Year-long predation rates proved to be density-dependent, increasing with moose density from 6.1 to 19.3% of the postnatal populations. We conclude that moose populations in southwestern Québec are regulated largely by predators (wolves and maybe black bears) at a density where competition for forage produces no detrimental effect. We support the concept that wolf predation can have an important regulatory effect at low moose densities but also a depensatory (inversely density-dependent) effect at higher densities.

Food choice by white-tailed deer in relation to protein and energy content of the diet: a field experiment

Abstract Optimality models of food selection by herbivores assume that individuals are capable of assessing forage value, either directly through the currency used in the model or indirectly through other variables correlated with the currency. Although energy and protein are the two currencies most often used, controversy exists regarding their respective influence on food choice. Part of the debate is due to the difficulty of teasing apart these two nutrients, which are closely correlated in most natural forages. Here we offer a test of the assumption that energy and protein contents of the forage are both currencies that large mammalian herbivores can use when selecting their food. We observed feeding behavior of 47 wild white-tailed deer (Odocoileusvirginianus) during winter while individuals were presented with four experimental foods representing two levels of energy and protein (dry matter digestibility: 40–50%; crude protein: 12–16%). Using experimental foods allowed us to separate the influences of energy and protein and clearly distinguish between the roles of these two nutrients. Deer discriminated between foods through partial selection, and selected diets higher in energy but lower in protein. The observed choices appeared consistent with physiological needs of deer wintering at the study site, where digestible energy was in short supply in the natural environment while protein was probably not. Results are in good agreement with recent findings on domesticated ruminants. They support a basic assumption of optimality models of food selection that use energy and/or protein as a currency, although the physiological mechanisms behind the food selection process remain unclear. We urge students of food selection by herbivores to replicate our experiment with other foods and/or in other circumstances before more general conclusions are drawn.

Evidence for a trade-off between growth and body reserves in northern white-tailed deer

We contrasted patterns of growth and accumulation of body reserves in autumn between two high-density (HD) white-tailed deer populations facing winters of different severity and length. Both populations occurred in the absence of effective predators and suffered from some forage competition based on reduced body masses. A third population living at low density (LD) and confronting long and severe winters (SW) served to distinguish the influence of food competition and winter severity on growth and body reserves. We estimated body components (water, protein, fat and ash) of deer during the first half of November and compared growth patterns between sexes and regions. HD-SW males continuted growth to an older age than HD males facing short and mild winters (MW) but females of both regions reached adult body mass at the same age. LD-SW deer exhibited a growth pattern similar to that of HD-SW animals but were the heaviest and the largest, suggesting that growth patterns are related to winter harshness (or length of the growing season) and that final body size is related to forage competition in summer. Sexual dimorphism became evident at an older age in the HD-SW population than in the HD-MW population, demonstrating that winter harshness does not affect immature males and females in the same manner. Fawns from the HD-SW population had proportionally longer legs and a higher percentage of body fat. Adaptations of immature deer to long and severe winters suggest that survival during the first winter represents the most critical step in the life span of northern white-tailed deer.

Pattern of cadmium contamination in the liver and kidneys of moose and white-tailed deer in Québec

Samples of moose (N = 431) and white-tailed deer (N = 225) liver and kidneys were collected during the 1985 hunting season from 14 zones south of the 50 degree latitude in Québec. Regional differences in cadmium level in the liver were detected and three homogeneous areas were delineated for each species. Uptake was greater for moose than for deer: in the liver, mean concentrations were 2.9-15.9 mg kg-1 (dry weight) for moose and 0.8-2.6 for deer, depending on the area and sex; in kidneys, means ranged between 31.8-100.5 and 20.9-39.0 mg kg-1, respectively. Female moose had lower levels than bulls. Less affected moose, in eastern Québec, contained cadmium concentrations comparable to the highest values measured in Scandinavia. Cadmium uptake in deer was on the same level or higher than in the United States. Our results indicate a widespread presence of this heavy metal in the environment that may be linked to acid precipitation. We do not recommend consuming wild cervid liver or kidneys in Québec for the moment. Further research is needed on the overall mechanisms involved in the cadmium contamination of the environment and on the actual intake of this metal in the human diet.

The low performance of forest versus rural coyotes in northeastern North America: Inequality between presence and availability of prey

Abstract Coyotes, which originate from central and southwestern North America, recently extended their range into forests of the Northeast. Forest coyotes occur in lower densities, have lower body reserves, and consume more fruits during summer than their counterparts occupying adjacent rural landscapes. We hypothesised that the forest landscape offered less animal prey to coyotes during summer than did the rural landscape. Coyote densities were higher in the rural landscape (2.7 animals 10 km-2) than in the forest landscape (0.5 animals 10 km-2) during the summer of 1997. During the summers of 1996 and 1997, coyotes in both landscapes fed mainly on wildberries (< 45% of dry matter intake), small mammals (< 10%), and snowshoe hare (< 10%). The biomass of the most abundant animal prey, snowshoe hares, was greater in the forest landscape (1.24 and 1.53 kg ha-1 in 1996 and 1997, respectively) than in the rural landscape (0.46 and 0.40 kg ha-1 in corresponding years). The biomass of the other major animal prey (small mammals), was comparable in both landscapes but irrupted during the second summer (0.09 and 0.50 kg ha-1 in 1996 and 1997, respectively). The biomass of fruits remained relatively constant in the rural landscape during the summers of 1996 and 1997 (ª 6 kg ha-1), but it tripled in the forest landscape during the second year (1.69 kg ha-1 in 1996 versus 5.30 kg ha-1 in 1997). Contrary to our prediction, the availability of animal prey in the forest landscape exceeded that in the rural landscape. Our results illustrate that the presence of prey does not correspond to its availability to predators. Coyotes appear poorly adapted for hunting in dense forest vegetation during summer and compensate for shortage of animal prey by consuming more berries.

Caribou pregnancy diagnosis from immunoreactive progestins and estrogens excreted in feces

Using radioimmunoassay, we measured immunoreactive progestins and estrogens in 116 fecal samples of caribou (Rangifer tarandus) as potential indicators of pregnancy. Progestins provided a reliable diagnosis by Day 50 of pregnancy and for the remainder of the gestation period. Estrogen levels of pregnant females were distinctly high during the last trimester of pregnancy. Males had levels of progestins and estrogens comparable to nonpregnant females. Measuring reproductive hormones in the feces of free-ranging caribou is a noninvasive method to assess pregnancy with a high level of confidence. J. WILDL. MANAGE. 54(2):279-283 Pregnancy in wild ungulates can be detected by rectal palpation (Greer and Hawkins 1967), ultrasound (Barrett 1981), and serum assays (Wood et al. 1986). Often, the stress of capturing an animal for blood sampling and physical examination precludes use of these methods. Capture can increase mortality (Valkenburg et al. 1983), can reduce reproductive success (Ballard and Tobey 1981, Larsen and Gauthier 1989), and can be stressful in most situations. Furthermore, physical restraint might alter the normal endocrine profile of an animal, thus generating spurious results for serum assays (Welsh and Johnson 1981). The measurement of reproductive steroids and their metabolites excreted in urine (Kirkpatrick et al. 1988) or feces (Desaulniers et al. 1989) provides a new technique for detecting pregnancy among free-ranging mammals. During pregnancy of most mammals, estrogens and progesterone are produced by the placenta. These steroids and their metabolites circulate in the peripheral plasma of the mother (Robertson and King 1979) and may be excreted via urine, feces, and milk (Desaulniers 1989). Recent studies of captive animals revealed that measurements of estrogens and progestins (i.e., progesterone and its metabolites) in feces were indicative of pregnancy status (Bamberg et al. 1984, Safar-Herman et al. 1987, Desaulniers et al. 1989). We tested the use of steroid levels in feces as a pregnancy diagnosis for free-ranging caribou. The confirmation of pregnancy from field-collected feces would constitute an easy, noninvasive procedure with no mortality risk or stress to the animals. We thank D. Le Henaff and B. Picard for their field assistance. B. R. Neal, M. A. Ramsay, This content downloaded from 157.55.39.92 on Wed, 22 Jun 2016 06:49:51 UTC All use subject to http://about.jstor.org/terms 280 PREGNANCY IN CARIBOU * Messier et al. J. Wildl. Manage. 54(2):1990 and 2 anonymous reviewers provided critical comments on the manuscript.

Variation in cadmium content of caribou tissues from northern Québec

Samples of kidney, liver, skeletal muscle, heart, mesentery and rumen wall were collected during 1985-1986 in northern Québec from 121 caribou belonging to the Rivière George herd. Significant seasonal variations were found for cadmium concentration in kidneys, liver and skeletal muscles, the level being higher in winter than in autumn. The concentration in liver and kidneys increased with age, while the effect of this factor was complex in skeletal muscles. Sex-related differences were found in muscle and liver levels of cadmium. According to season, sex and age, mean dry-weight concentrations varied between 5.6 and 51.3 micrograms g-1 in kidneys, 1.7 and 4.0 micrograms g-1 in liver and 0 and 0.27 microgram g-1 in skeletal muscles. Season and sex-related differences could be explained by seasonal variation in cadmium intake and by the annual weight cycle exhibited by caribou kidneys and liver. Because of the relatively high cadmium content, it was recommended not to consume liver and kidneys of free-ranging caribou in Québec; this restriction did not apply to meat, heart, mesentery or rumen wall that contained limited concentrations of this heavy metal.

Contrasting the summer ecology of white-tailed deer inhabiting a forested and an agricultural landscape

Abstract: We compared habitat use, home range size, movements, and activity during summer between rural (12 animals km-2) and forest (<; 1 animal km-2) white-tailed deer populations, hypothesizing that competition for natural forage at high density would influence deer behaviour. Biomass of preferred forage at forester sites was 6 times greater in the forest than in the rural landscape. Forest deer avoided conifer and mixed stands, whereas rural deer tended to avoid stands of shade-tolerant hardwoods. Rural deer intensified their use of cultivated fields at night and ate a greater variety of native plants than forest conspecifics, including species rarely consumed by forest deer (e.g., ferns). Rural deer used smaller home ranges but moved at a greater rate than forest counterparts. Activity pattern of deer did not differ between the two landscapes, with peaks at dawn and dusk. Our results suggest that rural deer adapted to the rarity of natural forage by exploiting agricultural crops.

Suitability of the forest landscape for coyotes in northeastern North America and its implications for coexistence with other carnivores

Abstract We compared rural and forest coyotes in northeastern North America under the hypothesis that the forest landscape represents a marginal habitat for this species. We predicted that forest coyotes would have larger home ranges and higher rates of mortality and/or emigration than rural coyotes. We also predicted that coyotes would select for open habitats in both landscapes throughout the year, and would not follow white-tailed deer in their migration to wintering areas. Forest (n = 14) and rural (n = 10) coyotes foraged over 89 and 27 km2, respectively, during the trapping season (18 October - 1 March), and over 111 and 48 km2 during the rest of the year. Annual survival rate did not vary significantly (P = 0.34) between adult forest and rural coyotes, averaging 74% and 60%, respectively; pups died at a higher rate in both landscapes (P < 0.01). All monitored coyotes died from anthropogenic factors, mostly from trapping. Forest coyotes exhibited a tendency to disperse and to make forays in the rural landscape where some died. We detected no selection for open habitats, irrespective of season or landscape, nor did coyotes show a strong preference for deer wintering areas. However, coyotes with deer wintering areas in their home ranges intensified their use of these areas when deer concentrated in them between December and April. We conclude that the forest landscape of northeastern North America possesses a low carrying capacity for coyotes even in the absence of wolves. We also conclude that eastern coyotes cannot replace gray wolves in this biome, and we speculate on the consequences of the arrival of this new predator for the conservation of other mesocarnivores.

Status and conservation of the gray wolf (Canis lupus) in wildlife reserves of Québec

Wolf populations have been relatively stable during the last 15 years in seven of nine wildlife reserves located in southern Quebec, despite harvest by legal trapping. Wolf densities, estimated via hunter surveys and an equation linking questionnaire data and radio-tracking data, varied between 0.7 and 2.2 animals/100 km2. In some reserves, wolf populations persisted at ca. 1 individual/100 km2 with low prey densities (i.e. 35%. Although the viability of wolf populations in southern Quebec seems not to be threatened by trapping, some wildlife reserves act as population sinks, instead of sources, for wolves. The long-term conservation of wolves requires reduction of harvests in some reserves, and simultaneous monitoring of wolf populations outside wildlife reserves.