Ecological Studies of the Timber Wolf in Northeastern Minnesota

Part 1

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USDA FOREST SERVICE RESEARCH PAPER NC-52 1971

Ecological Studies of the TIMBER WOLF in Northeastern Minnesota

NORTH CENTRAL FOREST EXPERIMENT STATION FOREST SERVICE U. S. DEPARTMENT OF AGRICULTURE

FOREWORD

The largest population of timber wolves remaining in the United States (excluding Alaska) lives in northern Minnesota. Many of these wolves inhabit the Superior National Forest, so protecting the habitat of this endangered species is largely a Forest Service responsibility.

As the "Age of Ecology" broadens into the 1970's, wolves and wolf habitat will become a subject of concerted research. Forest land managers will have to know more about how the timber wolf fits into a forest system. Building on nearly 50 years of research in northern forests, we at the North Central Station intend to expand our studies of wildlife habitat. We are happy to publish the enclosed papers as one step in this direction.

D. B. King, Director

North Central Forest Experiment Station D. B. King, Director Forest Service--U.S. Department of Agriculture Folwell Avenue St. Paul, Minnesota 55101

ECOLOGICAL STUDIES OF THE TIMBER WOLF IN NORTHEASTERN MINNESOTA

L. David Mech and L. D. Frenzel, Jr. (Editors)

CONTENTS

Movements, Behavior, and Ecology of Timber Wolves in Northeastern Minnesota L. David Mech, L. D. Frenzel, Jr., Robert R. Ream, and John W. Winship 1

An Analysis of the Age, Sex, and Condition of Deer Killed by Wolves in Northeastern Minnesota L. David Mech and L. D. Frenzel, Jr. 35

The Effect of Snow Conditions on the Vulnerability of White-Tailed Deer to Wolf Predation L. David Mech, L. D. Frenzel, Jr., and P. D. Karns 51

The Possible Occurrence of the Great Plains Wolf in Northeastern Minnesota L. David Mech and L. D. Frenzel, Jr. 60

THE AUTHORS

Dr. Mech, formerly with the Department of Biology, Macalester College, St. Paul, Minnesota, is now employed by the U.S. Bureau of Sport Fisheries and Wildlife, Twin Cities, Minnesota.

Dr. Frenzel, formerly with the Department of Biology, Macalester College, St. Paul, Minnesota, is now employed by the Department of Entomology, Fisheries, and Wildlife, University of Minnesota, St. Paul, Minnesota.

Dr. Ream, formerly with the North Central Forest Experiment Station (maintained in cooperation with the University of Minnesota), Forest Service, U.S. Department of Agriculture, is now employed by the School of Forestry, University of Montana, Missoula, Montana.

Mr. Winship is with the U.S. Bureau of Sport Fisheries and Wildlife, Twin Cities, Minnesota.

Mr. Karns is with the Minnesota Department of Conservation, Forest Lake, Minnesota.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

MOVEMENTS, BEHAVIOR, AND ECOLOGY OF TIMBER WOLVES IN NORTHEASTERN MINNESOTA

L. David Mech, L. D. Frenzel, Jr., Robert R. Ream, and John W. Winship

The largest population of wolves (Canis lupus) remaining today in the continental United States outside of Alaska is in northern Minnesota. As of mid-1970 this population was not legally protected, and the species, which once ranged over almost all of North America, is now considered by the U.S. Department of the Interior to be in danger of extinction in the contiguous 48 States. Until the present research, the only field studies of Minnesota wolves were those of Olson (1938 a, b) and Stenlund (1955). Those investigations provided much useful general information about Minnesota wolves and gave the present authors an excellent background with which to begin more detailed investigations.

This paper reports on the basic aspects of a series of studies that began in 1964, and concentrates primarily on wolf movements and activity, social behavior, hunting behavior, and population organization. Most of the data were collected during January, February, and March 1967; February, November, and December 1968; and January through August 1969. A total of 192 days was spent in the field.

According to a distribution map of wolf subspecies (Goldman 1944), the race of wolves in our study area is Canis lupus lycaon. However, evidence presented by Mech and Frenzel (see page 60) suggests that there may be strong influence by C. l. nubilus, a more western race of wolf formerly thought to be extinct (Goldman 1944).

Part 2

Between 1965 and the present, wolves in the study area were neither protected nor bountied, and the influence of trapping and hunting is thought to have been negligible.

THE STUDY AREA

This study was conducted in the Superior National Forest (fig. 1) in northern St. Louis, Lake, and Cook Counties of northeastern Minnesota (92 deg. west longitude, 48 deg. north latitude), an area well described by Stenlund (1955). Most of the data were collected from within and immediately south of the Boundary Waters Canoe Area, a special wilderness region in which travel by motorized vehicles is restricted. The total study area encompasses approximately 1.5 million acres, and numerous lakes and rivers comprise about 15 percent of this area (fig. 2). The topography varies from large stretches of swamps to rocky ridges, with altitudes ranging from 1,000 to 2,300 feet above sea level (fig. 3). Winter temperatures lower than -30 deg. F. are not unusual, and snow depths generally range from 20 to 30 inches on the level. However, an important exception occurred in early 1969 when depths of 45 inches and more accumulated in much of the area. Further details on snow conditions in the study area during the period of this investigation are given by Mech et al. (see page 51). Conifers predominate in the forest overstory, with the following species present: jack pine (Pinus banksiana Lamb.), white pine (P. strobus L.), red pine (P. resinosa Ait.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (P. glauca (Moench) Voss), balsam fir (Abies balsamea (L.) Mill.), white cedar (Thuja occidentalis L.), and tamarack (Larix laricina (DuRoi) K. Koch). However, as a result of extensive cutting and fires much of the conifer cover is interspersed with large stands of white birch (Betula papyrifera Marsh.) and aspen (Populus tremuloides Michx.). Detailed descriptions of the forest vegetation were presented by Ohmann and Ream (1969).

METHODS

The observations discussed in this paper were all made from aircraft, the method of flying being that reported by Burkholder (1959) and Mech (1966a). The following aircraft were used (in order of size): Aeronca Champ, Supercub, Cessna 172, Cessna 180, and Cessna 206. The smaller aircraft were excellent for holding in tight circles during observations but had the disadvantage of being slow and cold; the larger planes could cover the study area much more quickly and were more comfortable, but were not as maneuverable during observations. For radiotracking, to be discussed below, the best compromise seemed to be a Cessna 172.

To make observations of wolves, we flew over frozen waterways until tracks were found, and then followed the tracks until we lost them or saw the wolves (fig. 4). Several times we located wolves directly just by scanning the lakes. However, because there seemed to be a number of packs in the area, and because most wolves were the same color (with the exception of a few black or white individuals) (see Mech and Frenzel, page 60), it usually was not possible to follow packs from one day to the next and be certain of identification. Moreover, it was impossible to locate any pack at will because most wolves also spent much time inland.

Therefore, to facilitate our observations and to obtain data on wolf movements and extent of range, we began a radiotracking program in 1968-69. A professional trapper, Robert Himes, was employed to capture the wolves. Using Newhouse No. 4 and 14 steel traps at scent-post sets, he caught two wolves, and captured another with a live-snare similar to that used by Nellis (1968); the senior author trapped two additional wolves (fig. 5).

The four wolves held in steel traps were restrained by a choker (fig. 6), and then anesthetized by intramuscular injections (fig. 7A, B) of a combination of 30 mg. of phencyclidine hydrochloride (Sernylan, Parke-Davis Co.) and 25 mg. promazine hydrochloride (Sparine, Wyeth Laboratories) as prescribed by Seal and Erickson (1969); these drugs proved most satisfactory.

The fifth wolf (a female), which was captured around the chest by the live-snare, was handled without drugs. A forked stick was used to hold down her head (Kolenosky and Johnston 1967), and she offered no resistance (fig. 8). Evidently she went into shock or some other psychophysiological state of unconsciousness, for after her release she remained on her side and did not move for 1.5 hours, despite our prodding during the first few minutes (fig. 9). Then suddenly she leaped up and ran off.

Each wolf was examined, outfitted with a radio transmitter collar 15 inches inside circumference (fig. 10) and tagged with identification numbers in both ears (fig. 11). Each transmitter was of a different frequency in the 150 MHz range, emitted a pulsed signal ranging from 75 to 350 pulses per minute, and had a calculated life of at least 300 days (fig. 12). Two types of 12-inch whip antennas were used on the transmitters: one type extended up the side of the collar and then stuck out above for 6 inches; the other was fully attached inside the collar and extended up one side, around the top, and partly down the other side. The transmitter, batteries, and antenna were molded into a collar of acrylic weighing 11 ounces (Mech et al._ 1965). All radio equipment functioned flawlessly for at least 5 months, and one transmitter continued operating for at least 9 months.

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