White-tailed deer (Odocoileus virginianus) declined in the Superior National Forest of Minnesota between 1968 and 1974. In a 3,000 sq km area of the poorest habitat, deer were decimated. Contributing factors were severe winters, deteriorating habitat, and wolves. Wolves killed older deer, but insufficient fawns were available to replace them.

Research Paper↗

USGS1977

Status, distribution, and movements of martens in northeastern Minnesota

The decline of martens in Minnesota is reviewed and a recent increase documented. Adjacent and partially overlapping home ranges of 4.3 to 19.9 sq km were determined by telemetry for a female and three males. Habitat use is described. If current trapping and timber management practices persist, martens should continue to increase.

Research Paper↗

USGS1976

Reproductive activity in nine- and ten-month-old wolves

No abstract available.

Journal of Mammalogy↗

USGS1976

White-tailed deer migration and its role in wolf predation

Seventeen white-tailed deer ( Odocoileus virginianus ) were radio-tagged in winter yards and tracked for up to 17 months each (881 locations) from January 1973 through August 1974 in the central Superior National Forest of NE Minnesota following a drastic decline in deer numbers. Ten vyolves ( Canis lupus ) from 7 packs in the same area were radiotracked before and/or during the same period (703 locations). Deer had winter ranges averaging 26.4 ha. Spring migration took place from 26 March to 23 April and was related to loss of snow cover. Deer generally migrated ENE in straight-line distances of 10.0 to 38.0 km to summer ranges. Two fawns did not migrate. Arrival on summer ranges was between 19 April and 18 May, and summer ranges varied from 48.1 to 410.4 ha. Migration back to the same winter yards took place in early December, coincident with snow accumulation and low temperatures. Social grouping appeared strongest during migration and winter yarding. Survival of the radio-tagged deer was studied through 1 May 1975. Four deer were killed by wolves, one was poached, and one drowned. Mean age of the captured deer was 5.4 years and estimated minimum survival after capture was 2.6 years, giving an estimated total minimum survival of 8.0 years. This unusually high survival rate appeared to be related to the fact that both winter and summer ranges of these deer were situated along wolf-pack territory edges rather than in centers. In addition, most summer ranges of the radio-tagged deer were along major waterways where the deer could escape wolves.

Journal of Wildlife Management↗

USGS1976

Behavioral and intellectual adaptations of selected mammalian predators to the problem of hunting large animals

Explore the source record for details and available documents.

Book chapter↗

USGS1975

Weights, growth, and survival of timber wolf pups in Minnesota

Weights, growth rates, canine tooth lengths, and survival data were obtained from 73 wild wolf ( Canis lupus ) pups that were 8 to 28 weeks old when live-trapped in three areas of northern Minnesota from 1969 to 1972. Relative weights of wild pups are expressed as percentages of a standard weight curve based on data from captive pups of similar age. These relative weights varied greatly within litters, between litters, and between years; extremes of 31 to 144 percent of the standard were observed. Growth rates ranging from 0.05 to 0.23 kilograms per day were observed, and similar variations in general development and in replacement and growth of canine teeth were noted. Survival data based on radio-tracking and tag returns indicated that pups with relative weights less than 65 percent of standard have a poor chance of survival, whereas pups of at least 80 percent of standard weight have a high survivability. Pups born in 1972 were especially underweight, probably a result of declining white-tailed deer ( Odocoileus virginianus ) densities in the interior of the Superior National Forest study area.

Minnesota↗

USGS1975

Blood analyses of wolf pups and their ecological and metabolic interpretation

Blood samples were obtained from 32 wolf ( Canis lupus ) pups live-trapped over a three-year period in northern Minnesota. The results of 21 laboratory analyses of hematology and blood chemistry are tabulated and analyzed in terms of study area, age, sex, and year of collection. Mean values are compared to those reported for dogs in the same age group. The numerous differences between dog and wolf pups are interpreted in terms of nutritional levels and dietary composition with the suggestion that the wolves are not achieving their full growth potential. Individual abnormal test results are tabulated and possible interpretations are suggested. Abnormal results were observed in 13 animals including 10 of 11 animals sampled in 1972. The results in the 1972 animals indicated a poorer nutrition. This preponderance of abnormal test results in pups from 1972 is correlated with ecological studies on this wolf population indicating decreased survival. The potential value of such long-term integrated field and laboratory studies for providing a more complete understanding of changes in the dynamics of natural populations in terms of the responses of individual animals is demonstrated.

Minnesota↗

USGS1975

Disproportionate sex ratios of wolf pups

Males comprised 66 percent of wild wolf ( Canis lupus ) pups from a saturated, high-density wolf range in northeastern Minnesota, possibly reflecting disproportionate conception of males. Packs from areas of lower wolf density in other areas of Minnesota had equal sex ratios of pups or a disproportionate number of female pups. Captive wolves showed a slight preponderance of male pups.

Minnesota↗

USGS1975