SANDHILL CRANE USE OF THE MID-PECOS VALLEY OF EASTERN NEW MEXICO

Sandhill cranes (Grus canadensis) were monitored during winters 1989-94 in the mid-Pecos River Valley of eastern New Mexico to detennine how many used this region following a population decline in the 1980\u27s. Numbers annually increased to a late October/early November peak (X = 7,017), fluctuated around 6,000 through December, declined in January (X = 3,531), and again peaked in February/early March (X = 5,737). Annual crane use-days (weekly counts X 7) varied from 500,545 to 1,007,673 (X = 760,606). Cranes foraged mainly in corn and sorghum stubble and alfalfa fields. Crop averages (ha) during 1990-92 were alfalfa 21,449, corn 2,462 (cut green for ensilage), sorghum 169 (down from 5,666 ha in 1970), and other crops 6,441. Starting in 1991, Biner Lake National Wildlife Refuge (NWR) provided 43-55 ha of sorghum and com. The amount of available food appeared to limit the number of wintering cranes. Hunting disturbances caused approximately 50% of the cranes to leave the valley on 1 occasion, but usually cranes responded by moving from off-refuge sites to protected roosts at Bitter Lake NWR