Adult white-tailed Deer (Odocoileus virginianus) chased by Wolves (Canis lupus) in the dense forests of northeastern Minnesota escape most of the time when chased during winter (Nelson and Mech 1993), and adult does are rarely killed during summer when dispersed on individual summer home ranges (Nelson and Mech 1986). Because Wolf pack territories (Mech 1973) are orders of magnitude larger than an individual deer's home range (Nelson 1979), most deer may encounter Wolves infrequently.
However, deer chased by Wolves often stop running to view their backtrail and
only continue fleeing if the Wolves catch up to them (Mech 1970; Nelson and Mech
1993). Furthermore, nearby deer not being chased do not immediately leave the
area, and we have even observed fresh deer tracks at 1-day-old kill sites. These
observations suggest that deer might not vacate their home ranges when Wolves
headquarter near them even though one might expect them to do so to minimize
their exposure to Wolves. Nevertheless, it is unknown how deer respond in such
situations.
The opportunity to gain insight into this subject arose when a pack of 15
Wolves (three wearing radio-collars) in 1987 established a late summer homesite
adjacent to four radio-collared adult does, and another pack of five Wolves
(including the radio-collared breeding female) in 1996 denned near three other
radio-collared does in northeastern Minnesota, 48° N 92°W (Nelson and Mech
1981, 1987). We located the four does from the ground daily during fawning in
late May and early June and one to two times/week by small aircraft July -
September. We similarly located the three does weekly during April-May, daily
during 1-14 June, twice daily during 15 June - July, and once/week thereafter.
Ground and aerial observations of Wolves and aerial radio-tracking one to two
times/week provided the Wolf homesite data. Ground (hand-held antenna) and
aerial radio-tracking error was < 2 ha and 50 m respectively (Hoskinson 1976;
Nelson 1979).
Both groups of our radioed does in 1987 and 1996 remained in their summer
ranges after wolves established a den or rendezvous site within 0.8-1.8 km of
them (Table 1). We observed single fawns with three of the four 1987 deer
in August and September. On 25 August we found the chewed collar of one of the
deer, a 7-year-old doe, cached in the Wolf homesite. The doe had used an area
0.5 km south of the homesite, and it is uncertain how she died, whether she had
moved closer to the homesite, or if Wolves had carried her collar there. This
doe had increased her movements during July - August, nearly tripling her range
size, suggesting that she had lost her fawn(s) sometime in June (Nelson and Mech
1981). Our three radioed does in 1996 survived throughout the wolf denning
period, but we have no information about whether they had fawns during that
time.
These findings indicate that forest deer do not necessarily vacate their home
ranges when Wolves headquarter within 0.8-1.8 km of them. Our sample of seven
deer is too small to analyze survival probabilities, but their proximity to
Wolves would suggest some added risk of predation, and perhaps that was a factor
in the death of one of them. However, the noteworthy unequivocal observation is
that seven does remained on their traditional home ranges despite proximity to
Wolf homesites and did not attempt to minimize exposure to the Wolves by moving
away.
3
Fawns
11
May -