There are two populations of sandhill cranes in the Flyway: the Mid-continent (MCP) and the Rocky Mountain (RMP) population. Population size is estimated at different times of the year for each.
During the winter months and at staging areas during migration, when birds are concentrated in a few places, some birds from the MCP occur in the same places as the RMP. This confounds any attempt to measure the size of the RMP during these times. However, these cranes form large and small flocks on pre-migration staging areas and this is currently where counts that permit their management occur. This survey occurs in parts of Utah, Colorado, Idaho, Wyoming and Montana. This combined aerial and ground survey takes nearly two weeks.
The sandhill cranes of the MCP are counted during their spring migration when a majority gather or stage in the central portion of the Platte River valley in Nebraska before continuing on to their breeding grounds. Cranes are also counted during the late-March survey period in the states of Kansas, Colorado, Oklahoma, New Mexico and Texas but greater than 90% of the total counted is typically found in Nebraska. The survey has been conducted since 1974 and photographs have been used to correct those counted by human observers since 1982. New techniques such as using infra-red video cameras after the birds have settled onto the sandbars in the river for the night are being tested to improve the current estimates of population size.
More information is available on this website about both populations of sandhill cranes.
Sandhill crane harvest is estimated in a somewhat different manner than for other migratory birds. All crane hunters need to have a crane hunting permit issued by states. The database of hunters has provided the important "sampling frame" from which a sample of crane hunters can be drawn and asked about their harvest and hunting activity - this system has been in place since 1975. The USFWS conducts the mail survey of hunters. In addition, several states operate "check" stations, where hunters bring their birds, so ancillary data about the harvest (e.g., crane size and weight) can be collected.