Data from: Maximizing the detection probabilities of dusky grouse for population monitoring

Despite its status as a game species in the western United States,
rigorous monitoring of dusky grouse (Dendragapus obscurus) populations is
limited. Obtaining an adequate number of observations for effective
population monitoring of dusky grouse is challenging due to
difficult-to-reach montane habitats, cryptic behaviors, and limited
personnel, time, and funds at conservation agencies. While habitat
accessibility and survey effort constraints may be outside a manager’s
control, identifying the most effective protocols to better detect a
target species is possible and will improve monitoring programs. Our
objectives were to 1) evaluate field-based protocols for maximizing dusky
grouse detections and 2) identify survey conditions and timing that
maximize the probability of detecting dusky grouse in western Montana. We
conducted replicated point-count surveys with and without electronic
playback of grouse calls in spring and summer 2019, and spring surveys
solely with electronic playback in 2020–2021. We used N-mixture models to
compare the probability of detecting dusky grouse in spring versus summer
sampling and evaluate the effects of electronic playback of grouse calls,
route type (off-trail, trail, and road), weather, background noise, day,
and time on the probability of detection. Spring sampling yielded
substantially more dusky grouse detections than summer sampling. The use
of electronic playback of female sooty grouse calls in the spring
increased detection probability, but dusky grouse chick distress calls
during the summer did not improve detection rates. The probability of
detecting a dusky grouse was similar across the different route types
(off-trail, trail, and road), and maximized on clear days, with little
wind and background noise, with surveys occurring 9–162 minutes
post-sunrise during 3–23 May. By examining the effects of different
factors on dusky grouse probability of detection, our results provide
necessary information for the development of effective protocols for field
surveys for population monitoring of dusky grouse.