These inventories, commonly called surveys, are used to measure the overall status of a big game herd and includes estimating animal abundance, sex and age composition, recruitment and geographical distribution.
Every year, wildlife managers must determine which populations are to be surveyed by aircraft. The decision to survey a specific area is based upon the following ranking factors:
Aerial surveys are typically flown in January and depend on snow cover in the survey area. A minimum snow base depth of 25 cm is required in the pre-selected area. An area is first stratified by fixed-wing aircraft to determine animal densities and then random sample units are intensively searched by helicopter.