From ANIMAL PEOPLE, November 1997:
HELENA, Montana––A little publicized aspect of
the Yellowstone region wolf reintroduction is that although
tranquilizer darts and net guns are also used in captures and
recaptures, the wolves involved may be repeatedly legholdtrapped,
with potentially tragic consequences.
Many of the initial breeding wolves were first
leghold-trapped in Alberta for outfitting with radio collars a
year or more before they were recaptured, sometimes again by
leghold trapping, for relocation to Yellowstone and central
Idaho. Then they may have been leghold-trapped on further
occasions, for maintenance of their radio collars, removal
from proximity to livestock, and checks of reproductive status.
Offspring are also routinely leghold-trapped to be fitted with
radio collars, if they can’t be caught by other means.