Suchergebnisse

A passive tracking index method that has been successfully applied to dingoes
(Canis lupus dingo) in Australia was shown to have more
general applicability to wild canids by monitoring coyote
(Canis latrans) populations in southern Texas. The index
was calculated simultaneously for multiple species of animals from
observations on the number of intrusions onto a series of tracking plots over
several days. We found that the index reflected changes in coyote activity
before and after a trapping program on each of 2 ranches. We also were able to
simultaneously monitor bobcat (Felis rufus) and
white-tailed deer (Odocoileus virginianus) populations,
producing some interesting (and unexpected) insights. In our study area, we
found it difficult to distinguish the number of rabbit and rodent intrusions
into the plots, but these animals might be indexed in other habitats. Analyses
of the data as binary responses (presence or absence of spoor on each tracking
plot), as has been done in scent-post surveys, reduced the sensitivity and
accuracy of inferences.

We evaluated a passive tracking index (PTI) when plots were placed on lightly
used dirt roads versus placement on naturally occurring bare ground in natural
habitat. PTIs were calculated before and after removal of coyotes and some
non-target species during another study that evaluated capture devices. Six
mammals were simultaneously monitored with the PTI: coyotes, raccoons,
white-tailed deer, feral swine, javelina, and rabbits. PTIs from road plots
were significantly higher than from off-road plots, except for deer and
javelina, for which no differences were detected. After removal of coyotes,
PTIs were significantly lower, both from on- and off-road plots. For coyotes
and raccoons, the decline in index values primarily reflected population
reductions. For animals hunted for sport (deer, swine, javelina), population
reductions were minor compared with coyotes, and their declines in index
values likely reflected conditioned responses to the activity and shooting
that accompanied evaluations of the capture devices. We conclude that the PTI
is sensitive to changes in population or changes in activity in response to an
event for a variety of species, and it is most useful when placed on lightly
used dirt roads.