Aerial Surveys

The distribution and status of mule deer on the northern range is monitored through aerial classification surveys. Researchers use helicopters to conduct counts in winter and estimate recruitment (presence of fawns) during spring.

Winter Mule Deer Classification Survey: Researchers have conducted aerial winter surveys in the Gardiner basin (mostly outside Yellowstone) since 1990. The surveys are done in late December or early January, after the autumn hunting season ends and before antler shedding occurs. Portions of all major drainages are sampled, with the goal of observing at least 500–600 deer. The winter survey is not meant to be an inclusive population count.

Spring Mule Deer Count and Recruitment Survey: Since 1986 researchers have conducted a spring helicopter survey of mule deer on the Gardiner basin winter range. The goal of the spring survey is to obtain a total population count and to classify a large sample of deer to estimate recruitment. The distribution of mule deer across the landscape is also recorded.