Winter Waterfowl Survey
Waterfowl surveys have been conducted on this refuge from at least the early 1950's. Both ground count and aerial survey methods have been utilized. Earlier surveys were conducted each week throughout the entire year with most counts occurring from the ground. In 1991, the refuge changed the waterfowl survey timing to bi-weekly counts from September 1 - April 15 and stated that the preferred survey method would be aerial surveys. In 1998 the surveys were further modified the timing to bi-weekly counts from mid-October through the first week of March.
Currently, the surveys are conducted twice a month beginning in mid-October and ending in early March. All surveys are now conducted using a fixed-wing aircraft with one observer in addition to the pilot. The twice monthly approach allows more time to accomplish the survey, which is needed since weather more often impacts when aerial surveys can be conducted. Attempts are made using the same observer to survey all the waterfowl habitats within the refuge following the same route during each survey period. The data is recorded by waterfowl species. In addition to waterfowl, bald eagles (by age class - adult/immature), golden eagles (by age class - adult/immature), sandhill cranes, white pelicans, and common loons are recorded when observed. Beginning in 2001 winter waterfowl counts could be accessed online.
Duck and goose populations typically fluctuate from year to year on the refuge, much of which is related to weather conditions. Other changes in waterfowl populations reflect large-scale changes in migration patterns. Refuge duck populations arrive two weeks later now as compared to what occurred in the 1970s. The delay in the goose peak on the refuge is even greater. This delay in migration and the lower goose populations has resulted in a significant reduction goose use on the refuge.