The necessary capture, captivity, translocation and contact of the
experimental wolves with humans had an unknown effect on the wolves.
They had been exposed to humans for over 2 months while in captivity. No
attempts were made to tame them, and they never passed the escape stage
of socialization as described by Woolpy and Ginsburg (1967). The
dominant wolves (No. 11 and No. 12) were more relaxed when approached
than were No. 10 and No. 13, however.
The failure of female No. 11 to bear young probably can be attributed to
her captivity and handling. The fact that two couplings were observed
over a 5-day period indicates normal estrus in the female, and a normal
response in the male. Conception would have been expected from such a
mating. In wild wolves, it is known that there is only a small loss
between number of ova shed, number of embryos implanting, and number of
fetuses being carried (Rausch 1967). Thus it seems unlikely that, if No.
11 conceived, she lost her fetuses _in utero_. Rather, she probably did
not conceive, or perhaps the embryos never implanted. This wolf lost
about 11% of her capture weight during captivity, despite an adequate
food supply. This fact, plus the results of her blood tests indicate a
high degree of stress, which probably explains why she never produced
pups.
The possible interference of the drugs used can be ruled out, for they
were chosen because of their known lack of effect on pregnancy (Seal et
al. 1970).
The radio collars placed on the wolves had no noticeable effect on the
animals. Radioed wolves are regularly accepted back into their packs in
Minnesota, where they also reproduce and function normally (Mech and
Frenzel 1971; Mech 1973, 1974).