Summary: | The enumeration of moose (Alces alces) population to obtain estimates of moose density, and bull:cow, and calf:cow ratios are important to successful management of moose populations. Aerial surveys using the Gasaway-DuBois-Reed-Harbo method, GDRH, (Gasaway et al. 1986) assume that sightability is identical for all strata. The GDRH method uses a stratified double sample design, and as a result, sightability must be calculated and applied within strata to be statistically valid. We also present data suggesting sightability is not identical for all strata. We present a modification to the GDRH method that allows sightability to vary between strata and offer software that includes these modifications.
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