During 1987-94 we used capture-mark-resight (CMR) methodology and
rates of observation (bears/hour and bears/100 km2) of unmarked brown bears
(Ursus arctos middendorffi) during intensive aerial surveys (IAS) to estimate
abundance of brown bears on Kodiak Island and to establish a baseline for
monitoring population trends. CMR estimates were obtained on 3 study areas;
density ranged from 216-234 bears/1,000 km2 for independent animals and 292-342
bears/1,000 km2 including dependent offspring. Rates of observation during IAS
ranged from 1.4-5.4 independent bears/hour and 2.9-18.0 independent bears/100
km2. Density estimates for independent bears on each IAS area were obtained by
dividing mean number of bears observed during replicate surveys by estimated
sightability (based on CMR-derived sightability in areas with similar habitat.
Brown bear abundance on 21 geographic units of Kodiak Island and 3 nearby
islands was estimated by extrapolation from CMR and IAS data using comparisons
of habitat characteristics and sport harvest information. Population estimates
for independent and total bears were 1,800 and 2,600. The CMR and IAS
procedures offer alternative means, depending on management objective and
available resources, of measuring population trend of brown bears on Kodiak
Island.
