An aerial moose survey conducted on Kanuti National Wildlife Refuge resulted in an estimated 588 moose on the Refuge, a significant decline from previous estimates.  The 2007 estimated moose density of 0.22 moose per square mile was the lowest density since the first survey was conducted on the refuge in 1989.  As in previous surveys, biologists found that moose tended to concentrate in 10 to 35 year old burns rather than in river corridors where moose are commonly found elsewhere.  Large fires in 2004 and 2005 burned almost 25 percent of the Refuge and will hopefully produce more good moose habitat in the future.  Most hunters access the Refuge by boat, but because much of the burned area is not adjacent to rivers, many of the moose are essentially unavailable to hunters. 

The aerial survey was conducted from November 8 to 14, 2007, in cooperation with the Alaska Department of Fish and Game and National Park Service.  To count moose in such a large area, the Refuge was divided into 508 rectangular survey units, each about 5.3 square miles in size.  During the first step of the survey, the stratification, each of the survey units was quickly over flown by a Cessna 206 aircraft and observers categorized each unit as having high or low moose density based on the number of moose and moose tracks seen.  For the Kanuti stratification, low density units were anticipated to contain three or fewer moose.  The stratification resulted in 69 high density and 439 low density units on the Refuge.  All of the high density units and a random selection of 81 low density units were then thoroughly surveyed using a two-person tandem-seat aircraft such as a Supercub, Husky, or Scout.  It took about 40 minutes to survey a unit, and each aircraft team could survey about 8 to 10 units per day during the short November days.  Four such teams were used during the Kanuti survey.

Observers counted 291 moose in the 150 units surveyed, classifying each moose as either a bull, cow, or calf.  Bulls were further classified according to antler size.  Yearlings have spike or forked antlers, large bulls have an antler spread over 50 inches, and medium bulls have intermediate-sized antlers.  The Refuge-wide population estimate was statistically calculated based on the observed number of moose and the distribution of high and low density sample units on the refuge.  

Population estimates on Kanuti have been plagued with high variability in the past, partly due to sample sizes (number of units surveyed) that were too small.  The 2007 estimate was more precise than previous ones- as shown by error bars in Figure 1- partly due to the larger sample size (150 units surveyed versus 82 in 2005 and 103 in 2004) and possibly due to a more accurate stratification.