Notes on the captive wolf (Canis lupus) colony, Barrow, Alaska

JACK W. LENTFER~ Alaska Department of Fish and Game, Barrow, Alaska

AND

DON K . SANDERS Naval Arctic Research Laboratory, Barrow, Alaska

Received November 27, 1972

LENTFER, J. W., and D. K. SANDERS. 1973. Notes on the captive wolf (Canis lupus) colony, Barrow, Alaska. Can. J. Zool. 51: 623-627.

The Naval Arctic Research Laboratory wolf colony at Barrow, Alaska, originated from 15 pups taken shortly after birth from dens near Anaktuvuk Pass, Alaska. Controlled breeding has resulted in , ..- 17 litters. Minimum breeding age for both sexes is 22 months. Maximum observed but not established breeding age for a Barrow colony female is 7 years and for a male is 9 years. An Anchorage, Alaska, zoo female wolf had young at 9 years. Birth dates extend from 19 May to 7 June. Rivalries, especially among females, increase just before the breeding season. Original breeding stock have passed their predominantly dark coloration to offspring.

LENTFER, J. W., et D. K. SANDERS. 1973. Notes on the captive wolf (Canis lupus) colony, Barrow, Alaska. Can. J. Zool. 51: 623-627.

La colonie de loups du Naval Arctic Research Laboratory & Barrow, en Alaska, provient de 15 petits prPl&. peu ap* Icur aaissance, dans dw repaires situks prks d'Anaktuvuk Pass, Alaska. Un Bevage contr618 a donnk 17 port&. L'Age minimal de la reproduction est de 22 mois pour les deux sexes. L'Lge maximal de reproduction observk, mais non ktabli, dans cette colonie, est de 7 ans pour une femelle et dc 9 ans pour un mile. Dans un zoo d 'hchorap , en Alaska, une louve a eu des petits & 9 ans. Les naissances se produisent entre Ic 19 mai et le 7 jwn. On observe une augmentation des rivalitks, surtout entre les fernell-, justc avanl la saison de reproduction. La coloration foncke des individus de la souche d'origine se retrouve uhez Ics dmcendants. [Traduit par le journal]

Introduction hard-packed snow in winter. In winter, canvas over and along the sides of cages facing the prevailing wind breaks

The Arctic Research at the wind and limits snow accumulation. Doors between Barrow, Alaska, maintains a colony of captive adjacent cages, controlled from outside the enclosures, wolves as part of its mission to provide support allow animals to be grouped as desired for breeding, for scientific investigation in the in ti^. R ~ - raising young, studying behavior, isolating and examining

specific animals, and cleaning of cages. ported studies with physiolog~ and Most breeding has been controlled by caging two behavior (Ferguson and Folk 1969; Folk 1964; selected animals together before or during the breeding Folk et al. 1970; Fox 1971, 1972; Henshaw and season. Plywood houses 76 cm wide by 121 cm long with Folk 1968, 1969. 1971 : Henshaw et al. 1972). a door 51 cm in diameter in one end are provided for

This paper rePoits on several aspects of rep&- W~~$,"~8~,"2~~"1~~g;3 kg of raw meat or per duction and behavior, pelt coloration, facilities day. Enough food is given so that only a small mount

for holding wolves, and diet. remains at the next feeding. Most of the meat is reindeer

Materials and Methods From 1962 through 1967, Eskimos at Anaktuvuk Pass,

400 km southeast of Barrow in the Brooks Range, stocked the colony with 15 wolf pups taken from dens shortly after birth. Since 1967, 17 litters have been born in captivity. The colony has been maintained at about 50 animals since 1970.

Wolves are kept outside in 6.1 by 12.2m enclosures divided into four 3.0 X 6.1 m cages. Cage floors are metal matting about 30 cm above gravel pads. Floors are covered with hay or straw in summer and drifted,

1Present address: U.S. Fish and Wildlife Service, 813 D Street, Anchorage, Alaska 99501.

supplemented by butcher shop moose and caribou scraps in fall and early winter. Wolves receive meat and fish on alternate days. In the winter, meat is thawed before feeding. Wolves receive water only in the summer when snow is not available. Pregnant and lactating females and their young receive additional foods. A typical diet of a mother and four 6-week-old pups is 1.4-1.8 kg reindeer meat, 0.5 kg reindeer liver, 1.8 kg whitefish, 0.3 kg seal or whale blubber, 0.9 kg canned dog food, and 3 liters milk each day and two fresh rabbits each week.

Small groups of wolves have occasionally escaped when cage doors were left open, and have had to be recaptured. Free wolves were uncertain of themselves and never aggressive toward humans. Several times animals went back into their cage after people encircled

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624 CAN. J. ZOOL. VOL. 51, 1973

them and the cage entrance. One animal entered its cage activity. Also, unfrozen food in summer may be after other free animals had been captured, and efforts more palatable than meat after it freezes in to capture it were stopped. Animals that remained outside their cages could nearly always be approached winter. As with the Arctic fox (Underwood to within 15-25 m and then captured by injecting 0.75- 1971), winter fur probably provides exceedingly 1.00 mg of the immobilizing drug, phencyclidine hydro- effective insulation so wolves do not need to chloride (Sernylan, Bio-Ceutic Laboratories, St. Joseph, produce more energy in winter to maintain Missouri), intramuscularly with a syringe gun. body heat.

Barrow females first bred at 22 months Findings and Discussion (Table I), the minimum breeding age reported

The amount of food (1.4-2.3 kg daily) fed to by Murie (1944), Pulliainen (1965), and Rausch Barrow wolves is similar to that (1.6 kg) given (1967). All four pairings of 22-month-old each wolf at the New York Zoological Park females with mature males resulted in pups. (Crandall 1964, p. 271). Mech (1970, p. 183) Three males first bred at 22 months (Table I), states that 1.7 kg of raw meat can probably be the minimum breeding age reported by Rabb regarded as an accurate daily minimum main- et al. (1967). Not all 22-month-old males bred, tenance requirement for wolves in the wild. however. A 22-month-old male placed with a Barrow wolves prefer meat to fish. They consume 4-year-old estrus female did not engage in any most of the bones of reindeer and all of the fish. breeding activity. Littermates (five males and Wolves appear to eat more in summer than two females) together since birth did not engage winter, probably because they are more active in breeding activity until they were nearly 3 during the continuous daylight of summer. years of age. More people view the colony during summer and The oldest wolves to produce young were a thus contribute to the animals' increased 7-year-old female bred to a 9-year-old male in

TABLE 1 Reproduction of wolves at Naval Arctic Research Laboratory,

Barrow, Alaska, 1968-1972

Offspring Parents

No. by color Female Mate

Tan-black Year bred Age Color Age Color Black mix (dark)

1968 6 Gray 5 Tan-black mix (dark) 1 1 1968 3 Black 5 Tan-black mix (light) 1 1 1969 4 Black 6 Tan-black mix (light) 5 5 1969 2 Gray 2 Tan-black mix (dark) 2 -

or black 1969 2 Tan-black 2 Tan-black mix (dark) - 3*

mix (light) 1970 5 Black 7 Tan-black mix (light) 4 1 1970 3 Gray 3 Black 3 3 1970 3 Tan-black 3 Tan-black mix (dark) - 4

mix (dark) 1970 2 Tan-black 2 Black or tan-black 2 3

mix (dark) mix (dark) 1971 6 Black 8 Tan-black mix (light) 3 5 1971 4 Black 3 Black 4 -

1971 4 Tan-black 3 Black 3 1 mix (light)

1971 4 Tan-black 3 Tan-black mix (dark) - 4 mix (dark)

1971 2 Black 4 Tan-black mix (dark) 2 2 1972 7 Black 9 Tan-black mix (light) 5 - 1972 3 Tan-black 3 Black or tan-black 2 1

mix (dark) mix (dark) 1972 3 Black 3 Black 5 -

*Includes one tan-black mix (light).

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LENTFER AND SANDERS: CAPTIVE WOLF IN ALASKA 625

1972 (Table 1). They had pups the 5 preceding years, and their maximum breeding age is not yet known. A female 9-year-old wolf at the Children's Zoo in Anchorage, Alaska, had young in 1972 after having been bred to a 22- month-old male furnished to the zoo from the Barrow colony. The female had been raised since it was a pup by the Arctic Health Research Center of the Alaska U.S. Public Health Service. When 2 and 3 years old, she had litters sired by a German shepherd dog and when 4 years old, she had a litter sired by a sled dog. There was no attempt to have her bred again until she was 9 years old (R. L. Rausch, personal communication). The maximum breeding age for this female is not yet known.

Several wolves in the Barrow colony engaged in breeding activity, both with and without copulatory ties, but did not produce young. Woolpy (1968) states that a copulatory tie where animals cannot separate for a period following copulation is necessary for fertile mating but does not present substantiating data. A tie is not essential to successful breeding by domestic dogs and may not be essential for wolves, but certainly conception is more likely if a tie occurs. A female was paired with the same male when she was 5, 6, 7, and 8 and he was 4, 5, 6, and 7 years old. They produced litters the first 2 years. They bred with a copulatory tie the 3rd year and without an observed tie the 4th year. Both years the female did not appear to be pregnant and did not have pups. Advanced age may have caused one or both animals to be infertile. The same female, when 9 years old, was placed with a 4-year-old male who had fathered a litter the preceding year. They had a copulatory tie at least once, but did not produce

TABLE 2 Observed dates of breeding and parturition dates of wolves at Naval Arctic Research Laboratory, Barrow,

Alaska

Observed copulatory Parturition Interval, tie dates date days

13 Mar. 21 May 69 14 Mar. 24 May 71 18,20, 25, and 28 Mar. 19 May 52-62 25,26, 28,29, and 30 Mar. 1 June 63-68 30 Mar. 28 May 59 1 Apr. 6 June 66 1 and 2 Apr. 3 June 62-63

young. The same pair tied a year later, but again did not have a litter. A male, who sired a litter at age 5 and unsuccessfully mated with an old female when he was 6 and 7, was caged with a 4-year-old female when he was 8. She came into heat but he did not attempt to breed her.

Copulatory ties were observed for seven pairs of wolves that later had litters. The breeding dates in Table 2 are not necessarily the exact dates on which conception took place as unob- served breeding probably also occurred. All litters were born between 19 May and 7 June. An equal number were born before and after 1 June.

Breeding and birth date observations generally agree with a reported gestation period of 62 + 3 or 4 days (Brown 1936; Woolpy 1968). This gestation period establishes the period of con- ception between 13 March and 10 April. All observed breeding occurred during this period. Some animals were not placed together until after females had entered estrus. If all mates had been paired at the beginning of the breeding season, the established period of conception and the parturition period would probably have been a few days earlier. The breeding season for these Anaktuvuk Pass (68'18' N. latitude) and Barrow (71'20' N. latitude) wolves falls within the range reported by Rausch (1967) for 60' to 70' N. latitude in Alaska. It is later than breeding seasons for wolves at latitudes from southcentral Alaska to Illinois (summary of data, Mech 1970, p. 117).

Average size of the 17 Barrow litters was 4.5 (range 2-10). Average litter size of 2-year-old females was 3.3 (range 2-5) and of older females was 4.8 (range 2-10). Successive sizes for litters produced 5 consecutive years by one pair, beginning when the female was 3 and the male was 5 years old, were 2, 10, 7, 8, and 5. Litter sizes of Barrow wolves are smaller than the average number of fetuses Rausch (1967) reports in Arctic Alaska wolves (4.7 for 2-year- olds and 6.0 for adults). Litter sizes at Barrow support Rausch's statement that 2-year-old female wolves apparently have a lower potential productivity than animals that have bred pre- viously.

Dominance rivalries, especially among fe- males, increased in most cases during the breed- ing season. One of the three females in a litter

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626 CAN. J. ZOOL. VOL. 51. 1973

of five together since birth fought with and killed a sibling female at 22 months. The winning female was the only female of the two surviving to have a litter and had apparently prevented the other female from breeding. In another litter of two males and three females together since birth, only one female had young at 24 months. In another incident, on 18 February, a 4-year-old female, caged with her mate of the previous season and three of their 10-month-old pups, burrowed at considerable effort through hard-packed snow under a gate into an adjoining cage containing a 3-year-old female and her two 10-month-old pups. There the 4-year-old female killed the 3-year-old female.

In contrast, the two females of a litter of seven, together since birth, showed no rivalry, were both bred by several males at 22 months, and produced young. In another instance, a 3-year-old male was placed with two 4-year-old female littermates who had been together since birth and not allowed to breed. They both became pregnant, were separated, and had young. The females showed extreme hostility toward each other when placed together about 5 months later.

Antagonistic behavior is similar to behavior of a wolf pack at the Chicago Brookfield Zoo, where dominance rivalries increase greatly just before the breeding season, especially among the

TABLE 3 Pelt colors of 14 wolf litters and parents,

Naval Arctic Research Laboratory, Barrow, Alaska

Parent colors

Black X black Black X gray Black X tan-black

mix (dark) Black X tan-black

mix (light) Gray X tan-black

mix (dark)

No. by color of offspring

Tan- Tan- black black

No. mix mix litters Black (dark) (light)

an-black mix (dark) X tan- black mix (dark) 2

Tan-black mix (light) x tan- black mix (light) 1 2 1

Total 14 36 29 1

females, and the dominant female is the only one to mate (Rabb et al. 1967; Woolpy 1968).

Slightly less than half the Barrow colony are black, most others are a tan-black mix, and a very few are gray (Table 3). Underfur and guard hairs of black wolves are black. Tan-black mix animals have mostly tan underfur and varying amounts of black guard hairs. Most tan-black mix animals have a generally dark appearance; a few, however, are light. The few gray animals were originally black but gradually changed after about 4 years of age. Based on 14 matings producing 66 offspring, where colors of parents are known, black X tan-black crosses produced black and tan-black offspring, black parents produced black offspring, and tan-black parents produced tan-black offspring (Table 3).

The proportion of light-colored animals in the Barrow colony is much lower than reported for wild populations in northern Alaska. Pelt colors were 28% black, 3% brown, 64% gray, and 5y0 unrecorded for 417 wolves bountied during 1959-1967 from the Alaska Department of Fish and Game Koyukuk game management unit, which extends 250 km to the south and about 100 km to the east and west of Anaktuvuk Pass (Rausch 1968). Pelt colors for 513 wolves bountied from the crest of the Brooks Range north to the Arctic coast during the same period were 19% black, 4% brown, 72% gray, 1% white, and 4% unrecorded (Rausch 1968). Only 9y0 of 259 wolves tabulated north of the Brooks Range in 1952 were classified as dark (Kelly 1954). The high percentage of dark animals in the Barrow colony probably results from pre- dominantly dark breeding stock passing their coloration to offspring.

Detailed geneologies and reproductive his- tories for individual animals are on file at the Naval Arctic Research Laboratory, Barrow, Alaska.

Acknowledgments We gratefully acknowledge support and

records made available by present and former directors of the Naval Arctic Research Labora- tory, J. F. Schindler and M. C. Brewer; support furnished by Alaska Federal Aid in Wildlife Restoration Project W-17-4; and encouragement of G. E. Folk, Jr. Laboratory personnel who established and have maintained the wolf colony include M. C. Brewer, P. Sovalik, J. H. High,

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LENTFER AND SANDERS: CAPTIVE WOLF IN ALASKA 627

and R. G. Dickerson. Investigators who have assisted with the colony include G. E. Folk, Jr., M. Folk, and R. E. Henshaw; they were sup- ported by the Arctic Institute of ~ o r t h ~ m e r i c a under contractual arrangement with the Office of Naval Research.

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