ARCTIC
VOL. 48, NO. 4 (DECEMBER 1995) P. 329-332
© The Arctic Institute of North America
Reprinted with permission from the Arctic Institute of North America
and from L. David Mech.
L. DAVID MECH
U.S. National Biological Service, Patuxent Environmental Science
Center, Laurel, Maryland 20708, U.S.A.; mailing address: North
Central Forest Experiment Station, 1992 Folwell Ave., St. Paul,
Minnesota 55108, U.S.A.
(Received 22 December 1994; accepted in revised form 4 April
1995)
ABSTRACT. A pack of two to eight adult wolves (Canis
lupus arctos) and their pups was observed during ten summers
(1986-95) on Ellesmere Island, Northwest Territories, Canada.
The author habituated the wolf pack to his presence in the first
summer and reinforced the habituation each summer thereafter.
The first alpha female produced four to six pups each year between
1986 and 1989. However, her daughter, who succeeded her as the
alpha female, produced only one to three pups each year between
1990 and 1992 and in 1994, and apparently did not whelp in 1993
or in 1995. The tenure of the first alpha male was at least two
years, and his successor was alpha male for the remaining eight
years of the study. The wolf pack was characterized by highly
variable annual productivity. The second alpha male-and-female
breeding pair likely was an older brother and a younger sister.
Early survival of wolf pups was high and constant, with all pups
surviving through August of their first year. The pack's demography
was consistent with what is known for wolf packs in other regions
of North America, but its productivity was more typical of arctic
packs.
Key words: wolf, Canis lupus, productivity, demography,
breeding tenure, survival
Résumé. On a observé une bande comprenant
de deux à huit loups adultes (Canis lupus arctos)
et leurs louveteaux au cours de dix étés (1986-95),
dans l'île d'Ellesmere située dans les Territoires
du Nord-Ouest au Canada. L'auteur a accoutumé la bande
à sa présence durant le premier été
et a renforcé l'accoutumance durant chaque été
subséquent. La premiére femelle alpha a produit
de quatre à six louveteaux chaque année entre 1986
et 1989. Cependant, sa fille, qui lui a succédé
en tant que femelle alpha, a produit seulement de un à
trois louveteaux chaque année entre 1990 et 1992 et en
1994, et n'a apparemment pas mis bas en 1993 ni en 1995. Le premier
mâle alpha a conservé son statut au moins deux ans,
et son successeur a été le mâle alpha durant
les huit autres années de l'étude. La bande de loups
était caractérisée par une productivité
annuelle extrêmement variable. Le deuxième couple
reproducteur mâle et femelle alpha était probablement
constitué d'un frère et de sa soeur plus jeune. La
survie précoce des louveteaux était élevée
et constante, tous les louveteaux étant toujours en vie
à la fin du mois d'août de leur première année.
La démographie de la bande s'accordait avec ce que l'on
connaît des bandes de loups dans d'autres régions
de l'Amérique du Nord, mais sa productivité était
plus typique des bandes arctiques.
Mots clés: loup, Canis lupus, productivité,
démographie, statut de reproducteur, survie
Traduit pour la revue Arctic par Nésida Loyer.
INTRODUCTION
Wolves (Canis lupus) are long-lived animals (Mech, 1988a).
However, because they are difficult to study (Mech, 1974; in press),
there is little long-term demographic and productivity information
about individuals or their packs. An eight-year demographic description
of a pack of radio-tagged wolves in the Superior National Forest
of Minnesota seems to be the sole record available (Mech and Hertel,
1983) except for general information about certain packs or individuals
on Isle Royale, Michigan (Peterson, 1977; Peterson and Page, 1988).
The present study was conducted during the summers from 1986
to 1995 on Ellesmere Island, Northwest Territories, Canada (80ûN,
86ûW). There, wolves prey on arctic hares (Lepus arcticus),
muskoxen (Ovibos moschatus), and Peary caribou (Rangifer
tarandus pearyi) (Mech 1988b).
During 1986, I habituated a pack of wolves to my presence and
reinforced the habituation each summer (Mech, 1988b). The wolf
pack frequented the same area each year and generally used the
same den (Mech and Packard, 1990) or nearby dens (Mech, 1993)
each summer. The habituation allowed me to remain with the wolves
each day and observe them regularly from distances as close as
one metre. I usually began observing the pack each year between
14 and 28 June when the pups were about 10-25 days old, and ended
observations in early August.
Individual wolves were recognized on the basis of gender (from
urination posture), behavior toward me, presence or absence of
dark-tinged fur on the back, and such individual features as a
missing tooth, ear notch, and scars. Although not all of the individuals
in the study were recognizable by single definitive features,
combinations of characteristics appeared to be definitive.
None of the pups from a given year was individually recognizable
as a specific pup or as a specific yearling the following year,
but the assumption was made that all apparent yearlings were the
pack's pups from the previous year. This assumption was supported
by the fact that all such yearlings demonstrated the habituation
to me resulting from their habituation as pups the previous year.
In three observations involving 10 individual wolves not from
the habituated pack, the animals did not demonstrate habituation;
instead, they failed to let me approach closely and ran off.
The study pack consisted of 2-8 adults and yearlings each summer,
including an alpha pair (Table 1). Besides the alpha pair, five
adults ("auxiliaries") were present during 1986 and 1987 and were
assumed to be previous offspring of the alpha pair. No auxiliary
remained with the pack after 1987 except a male, "Left Shoulder,"
which became alpha male in 1988. In later years, no auxiliary
except each of two females remained with the alpha pair for more
than three summers after its birth year (Table 1). "Whitey," one
of the auxiliaries that remained, became the alpha female. "Mom,"
the other auxiliary, was the breeder from 1986 through 1989, and
when post-reproductive, was the only wolf that remained with the
pack as a mature non-alpha animal. This implies that the other
auxiliaries dispersed, similarly to wolves elsewhere (Fritts and
Mech, 1981; Van Ballenberghe, 1983; Peterson et al., 1984; Messier,
1985; Fuller, 1989; Gese and Mech, 1991).
In 1988, none of the 1986 or 1987 auxiliaries was present, but
two other individuals, Whitey and "Gray Back," accompanied the
alpha pair. They were assumed to be pups of the previous year
because they were habituated. Whitey and Gray Back were also present
in 1989, along with the alpha pair and the four 1988 pups.
When I arrived each year, the study pack was tending pups in
the same "traditional" den during five of the eight years they
had pups; in 1990, it moved its only pup there from a pit den
2.8 km away, and in 1991 it used dens within2.8 km of the traditional
den (Mech, 1993). During 1989, the pack denned 24 km from the
traditional den, but this was the first year after a photographer
had crawled into the traditional den and filmed the pups.
During the two summers when the pack was not tending pups when
I arrived, the appearance of the abdomen of the alpha female indicated
that she had not nursed pups. Furthermore, during 1993 there was
no fresh digging at the traditional den or at any of the alternate
or subsidiary dens nearby. Thus the pack probably had not produced
pups that year. In 1995, there was fresh digging but no pups.
Two females produced pups during the study: Mom and her daughter
Whitey. Mom produced four to six pups each year from 1986 through
1989 (Table 2). Of Mom's pups, only the 1988 litter of four could
be sexed (by urination posture), and the ratio was three males
to one female. All of Mom's pups observed each year in early summer
survived at least through early August. Her 1988 litter of four
survived at least through August 1989.
Mom remained with the pack but produced no more pups after 1989.
Assuming that in 1986 Mom was at least three years old (the age
at which Whitey began producing pups) and probably more like five
years old judging from her general appearance and behavior, she
must have been seven to nine years old when she stopped reproducing,
and she could have been much older. Reproductive ability in wild
wolves appears to extend through about 11 years of age (Mech,
1988a).
Whitey was born to Mom in 1987 and was first distinguishable
as a yearling because of her pure white coat which no adult female
in 1986 or 1987 possessed. After replacing Mom as the breeder
in 1990 at age three, she produced a single male pup during her
first year, two males the next year, two females and a male the
following year, none the fourth year, and a single male again
during her fifth year, and no pup during her sixth year (Table
2). All survived through early August of their first year, but
only the 1992 litter of three survived through its entire first
year (Table 2); the 1994 pup survived at least through October
1994.
Mom helped care for Whitey's pups during 1990 and 1991 but was
not seen after that. Whitey had dominated Mom during summer 1989
as evidenced by her dominant posture, her behavior towards Mom,
and her raised-leg urination. Whitey continued to dominate Mom
in summer 1990 and 1991 when Whitey produced the pups. In 1990,
when I arrived and Whitey's single pup was estimated to be 10
days old, Mom and Whitey both attended the den.
However, on the day I arrived in 1991, when Whitey's two pups
were estimated to be 10-14 days old, I did not see Mom. Nevertheless,
when the pups were about 17 days old on 19 June, Whitey and the
alpha male chased a third wolf that could have been Mom from around
the den for a distance of at least 2 km. The next day, Mom was
seen lying 50 m from Whitey and the pups. Although Whitey thoroughly
dominated and chased Mom several times during the next few days,
by 24 June, Mom had reintegrated into the pack. During the rest
of the summer, her behavior was similar to that of a regular pack
member: she attended the pups and accompanied the alpha pair on
hunting trips and when the pair moved the pups.
The pack had two consecutive alpha males during the ten-year
study period, "Alpha Male" in 1986 and 1987, and Left Shoulder
from 1988 through 1995. Left Shoulder was believed to be one of
the 1986 pack members judged to be two years old at that time.
This animal in 1986 had a wound behind his left shoulder blade
about 10 cm in diameter (Mech, 1988b). In 1987, the scar was still
apparent through the fur. In 1988, Alpha Male, who had a lower
incisor missing, was absent, and I and another worker who had
observed the wolves in 1986 and 1987 independently judged that
the alpha male in 1988 was Left Shoulder.
The origin of Left Shoulder is unknown, but if he was the offspring
of Mom and Alpha Male, Whitey would have been his younger sister.
Thus his mating from 1988 through 1994 with Whitey would have
constituted inbreeding. If Left Shoulder was at least 2 years
old in 1986, then he was at least 4 years old when assuming the
alpha male role in 1988 and at least 11 years old in 1995. Nevertheless,
in 1995 his canine teeth still appeared quite sharp.
DISCUSSION
Whitey's productivity was low compared to that of her mother and
to that of wolves in lower latitudes, which usually average litter
sizes of five to six (Mech, 1970). This could be related to inbreeding
depression (Laikre and Ryman, 1991) if Whitey and Left Shoulder
are siblings. However, at the high latitude where this pack resided,
average litter sizes appear to be about two to three (Marquard-Petersen,
1994), so Whitey's production may not be unusual.
The cause of Whitey's lack of reproduction in 1993 may be related
to the fact that all three of her 1992 pups survived into 1993.
Feeding three pups from birth through the breeding season may
have left Whitey with too few body reserves to ovulate, conceive,
or carry pups to term. During summer 1993, both Whitey and Left
Shoulder regularly delivered food to their three yearlings, and
the yearlings often remained at rendezvous sites as most pups
do through their first five months. Such an explanation would
not account for Whitey's barrenness in 1995, however, for 1994's
pup was not present then. Also notable is the fact that neither
Whitey's 1990 pup nor her two 1991 pups survived beyond autumn,
and probably her 1994 pup failed to survive.
The data obtained in this study are consistent with what is
known about wolf pack demography from other areas (Fritts and
Mech, 1981; Mech and Hertel, 1983; Peterson et al., 1984; Fuller,
1989; Gese and Mech, 1991; Meier et al., in press), except for
Whitey's low productivity. However, this study extends that information
in several ways, demonstrating the breeding tenures, productivity,
and intrapack relations of individual wolves, documenting the
high survival of young pups through the summer, and questioning
the cause of one female's relatively low productivity and survival
of pups.
ACKNOWLEDGEMENTS
This project was supported by the National Geographic Society,
the United States Fish and Wildlife Service, the United States
National Biological Service, and the United States Department
of Agriculture North Central Forest Experiment Station. Logistical
help of the Polar Continental Shelf Project, Natural Resources
Canada; Atmospheric Environment ServicEBes (AES), Environment
Canada; and High Arctic International are also greatly appreciated.
Permits were granted by the Department of Renewable Resources
and the Grise Fiord Hunter and Trapper Association of the Northwest
Territories. The observations of AES personnel during autumn and
the logistical help of one or two field assistants each year who
accompanied the author during the study are gratefully acknowledged.
REFERENCES
FRITTS, S.H., and MECH, L.D. 1981. Dynamics, movements and feeding
ecology of a newly protected wolf population in northwestern Minnesota.
Wildlife Monograph 80:1-79.
FULLER, T.K. 1989. Population dynamics of wolves in North-Central
Minnesota. Wildlife Monograph 105:1-41.
GESE, E.M., and MECH, L.D. 1991. Dispersal of wolves (Canis
lupus) in northeastern Minnesota, 1969-1989. Canadian Journal
of Zoology 69(12):2946-2955.
LAIKRE, L., and RYMAN, L. 1991. Inbreeding depression in a captive
wolf population. Conservation Biology 5(1):33-40.
MARQUARD-PETERSEN, U. 1994. Dens and summer pack size of Arctic
wolves in Hold with Hope, East Greenland. Polar Record 30(172):46-49.
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species. New York: Natural History Press, Doubleday Publishing
Company.
---. 1974. Current techniques in the study of elusive wilderness
carnivores. Proceedings of the Eleventh International Congress
of Game Biologists. 315-322.
---. 1988a. Longevity in wild wolves. Journal of Mammalogy 69(1):197-198.
---. 1988b. The arctic wolf: Living with the pack. Stillwater,
Minnesota: Voyageur Press.
---. 1993. Resistance of young wolf pups to inclement weather.
Journal of Mammalogy 74(2):485-486.
---. In press. What more do we need to know about wolves and how
do we learn it? In: Carbyn, L.D., Fritts, S.H., and Seip, D.R.,
eds. Ecology and conservation of wolves in a changing world. Edmonton:
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in a changing world. Edmonton: Canadian Circumpolar Institute.
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210 p.
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Isle Royale wolves. Journal of Mammalogy 69(1):89-99.
PETERSON, R.O., WOOLINGTON, J.D., and BAILEY, T.N. 1984. Wolves
of the Kenai Peninsula, Alaska. Wildlife Monographs 88. 52 p.
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of wolves in southcentral Alaska. Journal of Mammalogy 64(1):168-171.
| TABLE 1. Tenures of individual wolves of the
study pack on Ellesmere Island, N.W.T. during summer. |
| Pack Members |
Sex |
86 |
87 |
88 |
89 |
90 |
91 |
92 |
93 |
94 |
95 |
| Mom |
F |
X1 |
X |
X |
X |
X |
X |
- |
- |
- |
- |
|
| Alpha Male |
M |
X |
X |
- |
- |
- |
- |
- |
- |
- |
- |
| Left Shoulder |
M |
X |
X |
X |
X |
X |
X |
X |
X |
X |
X |
| Mid Back |
F |
X |
X |
- |
- |
- |
- |
- |
- |
- |
- |
| Lone Ranger |
M |
X |
X |
- |
- |
- |
- |
- |
- |
- |
- |
| Shaggy |
F |
X |
X |
- |
- |
- |
- |
- |
- |
- |
- |
| Scruffy |
? |
X |
X |
- |
- |
- |
- |
- |
- |
- |
- |
| Whitey |
F |
- |
-2 |
X |
X |
X |
X |
X |
X |
X |
X |
| Gray Back |
M |
- |
-2 |
X |
X |
- |
- |
- |
- |
- |
- |
| Scar Nose |
M |
- |
- |
-2 |
X |
- |
- |
- |
- |
- |
- |
| Little Girl |
F |
- |
- |
-2 |
X |
- |
- |
- |
- |
- |
- |
| No Name |
M |
- |
- |
-2 |
X |
- |
- |
- |
- |
- |
- |
| No Name |
M |
- |
- |
-2 |
X |
- |
- |
- |
- |
- |
- |
| Explorer |
F |
- |
- |
- |
- |
- |
- |
-2 |
X |
X |
- |
| White Face |
F |
- |
- |
- |
- |
- |
- |
-2 |
X |
- |
- |
| Gray Back II |
M |
- |
- |
- |
- |
- |
- |
-2 |
X |
X |
X |
| Total Adults |
| 7 |
7 |
4 |
8 |
3 |
3 |
2 |
5 |
4 |
3 |
- Indicates breeder for that year.
- Present as a pup but not yet individually recognizable.
TABLE 2. Wolf pup production and survival for wolf pack
studied on
Ellesmere Island, N.W.T.
|
|
Pups Produced1
|
| Year |
Males |
FemaleS |
? |
Survival Time2 |
| 1986 |
- |
- |
6 |
> 3 mo |
| 1987 |
- |
- |
5 |
1M > 2 mo; 1F > 8 yr |
| 1988 |
3 |
1 |
0 |
> 2 mo |
| 1989 |
- |
- |
4 |
> 10 mo |
| 1990 |
1 |
0 |
0 |
6 mo |
| 1991 |
2 |
0 |
0 |
> 2 mo |
| 1992 |
1 |
2 |
0 |
IF > 17 mo; 1F > 27 mo; 1M > 37 mo |
| 1993 |
0 |
0 |
0 |
- |
| 1994 |
1 |
0 |
0 |
> 5 mo |
| 1995 |
0 |
0 |
0 |
- |
- Produced by Mom during 1986-89 and by Whitey during 1990-95.
- Survival beyond August each year determined through observations
of government weather station personnel.
