Birds at the Rawhide Energy Station - The 2004 Ryder Report

Since 1986 Dr. Ronald A. Ryder, Professor Emeritus, Department of Fishery and Wildlife Biology, Colorado State University, has conducted an ongoing study of migrating bird populations using the Rawhide Energy Station site. His objective is to document, by species and population numbers, birds frequenting Hamilton Reservoir at Rawhide and the adjacent wetland and surrounding short-grass prairies at key periods of the year. He also determines peaks of migration, routes, places of breeding, and wintering areas for the more abundant species.

The program involved capturing and banding various species of waterbirds. No birds were banded in 2004 due to few birds coming to the bait site (high water level). During 2004, 28 counts were conducted, biweekly in spring and fall, bimonthly most months. Counts indicated far fewer birds used Rawhide compared to the previous 18 years, probably because of drought, maintenance and construction activities, and the reduced abundance of aquatic plants (food) resulting from efficient feeding by three species of herbivorous carp. Counts showed a decline in many species the last 5 years, but the 2004 Christmas Bird Count (CBC) had above average total species (61) and total individuals (9,703). Canada Geese were again the most abundant species, over 6,000, but more than twice that were recorded in 1996 (see tables for details). In 2004, a new species of goose was recognized by the American Ornithologists’ Union, the Cackling Goose. In past years it was considered a subspecies. At least 37 of this Mallard-sized goose were tallied on the CBC in 2004. Most diving ducks (especially Canvasback, Redhead, Scaup and Mergansers) showed a steady decline the past 5 years. Exceptions were Common Goldeneye and Bufflehead which still were noted in fair numbers. Dabbling ducks (Mallard, Pintail, Green-winged Teal, Shoveler, Gadwall, and American Wigeon) also showed declines. The American Coot has shown an alarming decline - only 16 on the CBC and 65 individuals on 1 October. Some years over 1,000 have been noted in migration; 961 on the 1988 CBC. The usual raptors were seen in average numbers, but there was a high of 31 American Kestrels on the 2004 CBC.

A newcomer to Colorado, the Eurasian Collared-Dove, was noted the last 3 CBC’s to the southwest of the Rawhide Energy Station. They increased from 2 in ‘02 and 4 in ‘03 to 64 on the 2004 CBC.

Dr. Ryder has coordinated studies for U. S. Fish and Wildlife, the Colorado Division of Wildlife, and U. S. Public Health Service, documenting the presence of heavy metals, pesticides, Vibrio cholerae, equine encephalitis and West Nile Virus, if observed, in the migratory species. Dr. Ryder has presented findings to the Colorado Field Ornithologists, The Wildlife Society, the International Ornithological Congress in New Zealand, the Colorado-Wyoming Academy of Sciences, and the Cooper Ornithological Society. Dr. Ryder has hosted many ornithological organizations on field trips to Rawhide and conducts the National Audubon Society’s annual Christmas Bird Count (an international event) which includes the Rawhide Energy Station.

2000 Ryder Report
2001 Ryder Report
2002 Ryder Report
2003 Ryder Report
2005 Ryder Report
2006 Ryder Report
2007 Ryder Report

Statistics HTML pages:

Birds 1986-2011 (pdf) 8.5X14 (legal-sized)