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Coyote Population Fluctuations and Spatial Distribution in Relation to Wolf Territories in Riding Mountain National Park, Manitoba

LUDWIG N. Carbyn

Canadian Wildlife Service, 9942-108 Street, Edmonton, Alberta T5K 2J5

Carbyn, Ludwig N. 1982. Coyote population fluctuations and spatial distribution in relation to Wolf territories in Riding Mountain National Park, Manitoba. Canadian Field-Naturalist 96(2): 176-183.

Observations of competition between Wolves (Canis lupus) and Coyotes (C. latrans) were recorded in Riding Mountain National Park, Manitoba, from July 1974 to March 1979. Twenty-two Wolves and 34 Coyotes were radio-collared and radio tracked. Home range overlap of four Coyotes and three Wolves were studied. Abundance indices obtained from howling surveys indicated that as wolf densities declined Coyotes increased. Seven known or suspected wolf-killed Coyotes were examined. Two of four radio-collared Coyotes in one Wolf pack territory were killed by Wolves, and two Coyotes may have been killed by Wolves. Average survival from time of capture for the four radio-collared Coyotes was 145 days (range 71 to 265 days). Wolves did not consume Coyotes. Coyote survival along Wolf territory edges was greatest at moderate Wolf densities.

Key Words: Coyote, Canis latrans. Wolf, C lupus, population fluctuations, spatial distribution, Manitoba

Competition between Wolves and Coyotes was given as a reason for the extirpation of Coyotes on Isle Royale(Mech 1966; Krefting 1969; Allen 1979). Mech ( 1 966: p. 1 60) stated that "since coyotes and wolves are closely related, and since wolves are strongly territorial, it is not unlikely that on a limited range such as Isle Royale, wolves would chase and probably kill every coyote encountered." Killing of Coyotes by Wolves has been reported (Seton 1929; Young and Goldmann 1944; Munro 1947; Stenlund 1955; Berg and Chessness 1978). The co-existence of Wolves and Coyotes in Riding Mountain National Park is therefore of interest, and this paper describes the relationship between the two species. Hoskinson and Mech (1976) and Mech (1977) observed that Wolf territoriality may result in buffer zones between pack territories where prey is less likely to be killed. They reasoned that Wolf territory boundaries served as sanctuaries to prey if neighboring packs avoided these areas in order to reduce fatal intraspecific strife.

Fuller and Keith (1981) indicated that the home range of one radio-collared Coyote and capture site of four others were along edges of Wolf pack territories. Higher survival of Coyotes at the periphery of Wolf territories could be attributed to either (1) resident Coyotes avoiding Wolves, and this was easiest at the edge of Wolf territories or, (2) Wolf packs being less

likely to frequent peripheral areas (Mech 1977). This relationship can best be studied by monitoring radiocollared animals of both species occupying the same ranges. Information reported in this paper is preliminary, as data were collected secondarily to Wolf studies. However, results obtained did provide insights into the relationship between the two species. To investigate Wolf/ Coyote relationships further,

movements of four Coyotes within the territory of the BL-78 Wolf pack were studied.

Study Area

The BL-78 Wolf pack ranged in the central portion of RMNP (Figure 1). The 2944 km^ park is located in southwestern Manitoba. A unique feature of the park is its isolation as a wilderness area completely surrounded by agricultural land. The park falls within the general aspen parkland region which is a transition zone between grasslands (prairie) to the south and boreal forests to the north.

Water bodies are important features in RNMP. The western southcentral and central portions of the park contain slow flowing, sluggish streams and poorly drained areas. The eastern portion of the park is deeply incised with gullies formed by fast running, often seasonal streams that run down the Manitoba

escarpment.

Relief, drainage and fire history are important factors that determine the plant cover in the park. Vegetation is predominantly aspen-forest, interspersed with upland fescue prairie, wetlands (sedge-willow plant cover), upland grassland and coniferous forest.

The climate of southwestern Manitoba is characteristic of the dry interior continental climate of the prairie provinces. Summers are warm, and on the plateau in the eastern portion of the park, the climate is affected by local turbulence because of updrafts from the lowlands.

Methods

Coyotes and Wolves were trapped in #4 and #14 steel traps along park trails (Mech 1974). During the study 22 Wolves and 76 Coyotes were captured but

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Carbyn: Coyote Population Fluctuations

177

Baldy Lake^

Audy Lake

Study Area

Riding Mountain National Park

• BL Wolf Pack -D G19 Coyote -^ B14 Coyote

o G18 Coyote ^ B23 Coyote

Figure 1 . Distribution of 4 radio-collared Coyotes within the BL Wolf pack territory in Riding Mountain National Park,

Manitoba.

only 21 Wolves and 34 Coyotes were collared. This paper discusses only home range overlaps of Coyotes (n= 4) and Wolves (n= 3) whose home ranges were sympatric. Animals were immobilized with Sernylan (phencyclidine hydrochloride) and Sparine (promazine hydrochloride). Dosages used were similar (1 mg of each drug per kg of Coyote weight) to those used for Wolves (Carbyn 1981 unpublished CWS report). Radio-collared animals were monitored from the air with a Maul (M5) fixed-wing aircraft.

Locations of instrumented animals were plotted on topographic maps (scale 1:50 000). Detailed movements, predation rates, prey consumption, and hunting sequences of the BL pack were monitored from 23 October 1978 to 13 March 1979. Because monitoring flights were usually less than 1.5 hours long, fixes were obtained in order of proximity of animals to one another. An H.P. 9830 desk computer was used to plot radio locations, to calculate distances between them and to delineate territories. Radio signals that


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came from a stationary source were evidence that animals were dead. Carcasses were examined as soon as possible. Dead animals were located on the ground using a receiver and a hand-held loop antenna.

Indices of canid abundance were obtained from nocturnal howling surveys along major trails in the park at 1.6 km intervals (Pimlott 1960). Responses from Coyotes and Wolves were elicited through human imitations of Wolf howls. Attempts were made to cover portions of all trails in a two-week cycle during July and August, 1974-78. Locations of all canid responses were mapped, and Coyote responses and sightings were superimposed on Wolf territory delineations from the previous winter.

Results

1. Coyote I Wolf spatial relationship in BL pack

territory

Three members from a pack of eight Wolves (BL pack) were captured 1, 24 October and 21 November 1978. Movements of this pack were recorded to 31

March 1979. When territory size was plotted against the number of radio locations an asymptote occurred for the BL Wolf pack at the first 19 fixes. Total radio fixes was 64, so that the BL Wolf pack territory boundaries were well delineated. Within the BL Wolf pack territory four radio-collared Coyotes had home ranges (Figure 1). Details about the radio-collared Coyotes were as follows:

Coyote G-19, a yearling male, was captured 28 March 1978. Its movements were monitored to 18 December 1978. Signal was stationary thereafter and the carcass recovered on 24 January 1979. Cause of death was unknown as the carcass was found largely consumed by scavengers. The Coyote ranged for at least 265 days within a portion of the BL-78 pack territory (Figure 1 ). Of the 265 days, 79 days covered a period of time (fall and winter) when there is a possible increase in vulnerability (Carbyn 1981 unpublished CWS report) of Coyote mortality to Wolves. The home range of G-19 overlapped with B-14.

Coyote B-14, an adult female, was captured 16 September 1978. During 165 days of monitoring (148 days of which were during the period when vulnerability was possibly increased) its movements were entirely within the BL-78 pack territory (Figure 1). A Coyote (presumably B-14 or another member of a pair) was heard to howl near an American Elk {Cervus cana-

densis) carcass on 25 February 1979. A ground check on 26 February revealed that B-14 and a second Coyote had scavenged there and that four Wolves had converged on the bedded Coyote. Chest and neck regions were severely mangled. Postmortem examination revealed that the posterior region and uterus were partially destroyed. The Coyote was in fair physical

condition and weighed 15.5 kg at death; kidney fat at its widest point measured 14 mm.

Coyote G-18, an adult male, was captured 14 October 1978. His movements, during the period when Wolf movements were monitored, were entirely within the central portion of BL-78 pack territory (Figure 1). Movements of G-18 overlapped home ranges of B-14, G-19, and B-23. G-18 survived in the territory of BL-78 Wolf pack for at least 80 days from the date of capture. He died between 11 and 18 January of unknown causes.

Coyote B-23, an adult female was captured on 14 October 1978. Movements of this Coyote were entirely within the BL-78 pack territory. The animal was found dead on 23 January 1979, after the signal was recorded as stationary on 23 December 1978. The Coyote lived for 71 days after capture within the BL78 pack territory. Postmortem of the animal indicated

that it almost certainly was killed by Wolves. Rib-cage muscles exhibited bite wounds similar to those of B-14, but genitalia were not affected.

The average survival, after capture, of Coyotes trapped in fall was 105 days. When the one spring capture was included, average survival time was 145 days. Two of the four radio-collared Coyotes found dead in BL Wolf pack territory were known or suspected Wolf kills and two may have been. During the study three other, non-collared Coyotes in the park were also found killed by Wolves in mid to late winter.

2. Coyote family group responses in relation to Wolf

territories

Location of summer Coyote sightings and howling responses (Table 1) during 1974 to 1978 have been plotted for each year (Figures 2 and 6). Delineation of Wolf territories began in 1975/76 and these are shown also. During the 3.5 years of study a total of 21 Wolves were radio-collared and their movements studied. Wolf densities were highest in winter 1975/76 (1 wolf/25 km2) and decreased in 1976/77 (1 wolf/40 km2) and 1977/78 (1 wolf/ 57 km2) with slight increases recorded for 1978/79 (1 wolf/47 km^ — Carbyn 1980 unpublished CWS report). Coyote responses were high in the year before intensive Wolf

studies (Figure 2). No data on Wolf abundance is available for that year. Howling response indices suggested that as Wolf numbers decreased Coyote numbers increased. The number of responses, and sightings of Coyotes, was low to moderate in 1975, the year of increasing Wolf numbers (Figure 3) and lowest (Figure 4) in 1976 the winter after the highest recorded Wolf densities. In fact, the only known denning Coyotes that year were recorded in a fenced Bison {Bison bison) pasture (Figure 4). Wolves sometimes crawled under the fence, but packs were seldom in the


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area. Other Coyote sightings and responses, with one exception in 1976, came from Wolf territory edges or outside known territories (Figure 5). In 1977 and 1978 the Wolf population was low and Coyote numbers increased appreciably.

The Audy Lake Wolf pack in 1 978 consisted of only

three animals that ranged widely, and Coyote responses and sightings were made throughout the pack territory. However, Coyote family groups were recorded only along the territory edge (Figure 6).

Discussion

Wolves often kill Coyotes, but in RMNP, unlike the Isle Royale situation (Mech 1966; Krefting 1969), the interaction has not resulted in extirpation of Coyotes. The fact that Wolves kill, but rarely consume Coyotes is an interesting phenomenon, an explanation of which requires further study.

An analysis of distances between Wolves and Coyotes in this study did not result in convincing evidence that Coyotes consistently avoided Wolves,

Table I — Results of Coyote howling responses during howling surveys conducted during July and August periods from 1974 to 1978 in Riding Mountain National Park, Manitoba

'Figure does not include Coyote groups and single responses within Bison enclosure separately.

an artificial situation and dealt with

Gunn

Bald^

Whitewater^

I Audy

Pup sighting

Adult sighting

Single response

Group response

Highway

Trail

Park boundary

Figure 2. Coyote responses and sightings in Riding Mountain National Park in the year prior to increase in Wolf numbers (summer, 1974).


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Baldy^/

Pup sighting

Adult sighting

Single response

Group response

Highway

Trail

Park boundary

Figure 3. Coyote responses and sightings in Riding Mountain National Parkduring the year of increase in Wolf numbers (summer, 1975).

I I Wolf territory (symbols vary )

v"> Bison enclosure

• Adult sighting

o Single response

Group response

Highway

Trail

Park boundary

FiGU RE 4. Coyote responses and sightings in the summer of 1 976, a year after Wolf populations had increased. Territories of radio-collared Wolf packs during the previous winter are shown in Riding Mountain National Park, Manitoba.


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Wolf territory

Adult sighting

Single response

Group response

Highway

Trail

Park boundary

Figures. Coyote responses and sightings in Riding Mountain National Park during a year of population decline (summer, 1977). Territories of radio-collared Wolf packs during the previous winter are shown.

Wolf territory Group sighting Pup sighting Adult sighting Single response Group response Highway Trail Park boundary

Figure 6. Coyote responses and sightings during summer 1978 (a year of low Wolf numbers) in Riding Mountain National

Park, Manitoba. Territories of radio-collared packs during the previous winter are indicated.


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but it did suggest that Coyotes more often avoided Wolves in mid to late winter than was the case in early winter. Two factors could contribute to this process: 1) snow conditions in mid to late winter may differentially affect the species, and 2) avoidance may partly be a learned process. The results of a preliminary analysis are presented here in the hope that it might stimulate further research along these Hues.

In thick, soft snow, Coyotes were more restricted in their movements than were Wolves (personal observations in RMNP and in Jasper National Park). R. Leonard (personal communication) also noted that in RMNP during severe snow conditions (1978/79) Coyotes were reluctant to leave snowmobile tracks when approached on foot. Two of three Coyotes that I found killed by Wolves in previous studies (in Banff

and Jasper National Parks) were killed on snowmobile trails. Follow-up work is required to examine the effects of snow thicknesses on canid mobility in greater detail. In both RMNP and in Jasper National Park, Coyotes often trailed Wolves through thick snow. Similar observations were made by John Kansas (personal communication) in various Canadian Rocky Mountain National Park locations. The reason may be either convenience of travel or anticipation of scavenging on Wolf kills. Thus, it appears that even though Coyotes may avoid Wolves, after a "refractory period", they may actually trail them at a safe distance in search of food. Evidence, therefore, is not clear as to when Coyotes trail Wolves or when they avoid them and it is conceivable that it is a learned response.

Different behavior and activity patterns of Wolves and Coyotes probably are important and should be further studied. Wolf packs often rest in mid-day and there are suggestions (Carbyn 1981 unpublished CWS report, as per G. Bergeson personal communication) that Wolves avoid areas close to humans during daylight hours. Coyotes may then also adjust their movements in relation to Wolf activities. The ability to do so, however, could be related to snow thickness, so animals less capable of avoiding Wolves would perish first. According to Mech's 1977 hypothesis one

would expect Wolves more often to kill Coyotes in core areas of Wolf territories than at the periphery. Furthermore, observations of Hoskinson and Mech (1976) that buffer zones between Wolf packs provide greater prey survival than core areas would be particularly applicable to present circumstances if Coyote movements are more restricted in mid to late winter. A factor not discussed before, however, is whether differential vulnerability of prey in core areas varies with Wolf densities. Presumably, at high Wolf densities Wolves would use peripheral areas more often than during low densities.

Mortality of radio-collared Coyotes within the BL pack territory showed that they could not always avoid being killed by Wolves through occupation of buffer zones. However, even though some Coyotes did get killed in buffer zones, overall Coyote survival appeared to be greater there, particularly in years of moderate Wolf densities.

Wolf pack territories in RMNP are more flexible from year to year than is the case for unexploited, stable Wolf populations. However, prey biomass and prey availability is high (Carbyn 1981 unpublished CWS report). Contrasting with the general situation was the Whitewater Lake pack whose southern boundary was stable. Accordingly, Coyote responses from year to year were higher in that area, supporting the

buffer zone concept.

Wolf-related Coyote mortality in RMNP was highest when Wolf densities were high, and indicators are that regardless of their location in the Wolf territory, Coyotes can be affected under such conditions. However, when the Wolf population is at a moderate level, chances of survival of at least a few Coyotes appear greatest at the Wolf pack territory edges. At peak Wolf populations. Coyote survival was very low, especially in summer of 1976. Summer responses to howling along roads show that the number of Coyote family groups in such areas probably provide a good indication of the distribution of the overwinter survival of Coyotes. The summer after the Wolf population was highest (summer 1976), the only Coyote family recorded along roads was within a "protected" area (Bison enclosure). In this study Coyote howling response surveys were limited to available roads and may have biased the results. Sightings and responses of single Coyotes were common within a large territory of the small (3-member) AL Wolf pack, probably because winter mobility of this small pack was more restricted.

Acknowledgments

The study was funded by Parks Canada, and I am

grateful for their involvement in all phases of the work. Park wardens C. Allen, T. Hoggins, G. Pylypuik, and technician D. Patriquin assisted in field work. Student assistants A. Kennedy, H. Samoil, T. Trottier, J. Tutt (deceased), and K. Whaley conducted the howling surveys and assisted in winter field work. Personnel from Dauphin Air provided us with the necessary fixed-wing aircraft support. F. Anderka assembled radio-collars. R. Leonard, L. D. Mech and E. Telfer provided critical review of the paper.

References

Allen,D. L. 1979. Wolves of Minong — their vital role in a wild community. Houghton Mifflin Company Boston. 499 pp.


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Berg, W. E. andR. A. Chessness. 1978. Ecology of coyotes in northern Minnesota. In Coyotes: biology, behaviour,

and management. Edited by M. Bekoff, Academic Press, New York. 384 pp.

Fuller, T. and L. B. Keith. 1981. Non-overlapping ranges of coyotes and wolves in northeastern Alberta. Journal of Mammalogy 62: 403-405.

Hoskinson, R. L. and L. D. Mech. 1976. White-tailed deer migration and its role in wolf predation. Journal of Wildlife Management 40: 429-441.

Krefting, L. W. 1969. The rise and fall of the coyote on Isle Royale. Naturahst 20(4): 24-31.

Mech, L. D. 1966. The wolves of Isle Royale. USDI National Parks Service, Fauna Series 7. 210 pp.

Mech, L. D. 1974. Current techniques in the study of elusive wilderness carnivores. Proceedings of the International Congress of Game Biologists 11: 315-322.

Mech, L. D. 1977. Wolf-pack buffer zones as prey reservoirs. Science 198: 320-21.

Munro, J. A. 1947. Observations of birds and mammals in central British Columbia. Occasional Papers of the British Columbia Provincial Museum No. 6. 165 pp.

Pimlott, D. 1960. The use of tape-recorded wolf howls to

locate timber wolves. Midwest Fish and Wildlife Conference 22. 15 pp. Mimeo.

Seton, E. T. 1929. Lives of game animals. Doubleday, Doran and Company, New York.

Stenlund, M. H. 1955. A field study of the Timber Wolf (Canis lupus) on the Superior National Forest, Minnesota. Minnesota Department of Conservation Technical Bulletin 4. 55 pp.

Young, S. P. and E. A. Goldman. 1944. The wolves of North America. Dover Publications, Inc. New York. 632 pp.

Received 10 September 1981 Accepted 19 June 1982