Preface • Introduction • Study Objectives • Community Participation • Regional, Physical and Ecological Setting
Bird Use Days
A bird day is defined as one bird spending 24 hours within the study area during the study period. The GSL bird use day five-year mean was 86,752,258 (Table 8). Data from 1997 were only used in the five-year mean calculations of selected suites of species in Table 10. The 1997 data were omitted from the other tables to minimize variation in individual year means, because the survey season in 1997 had eight fewer survey periods than the other four years.
Bird use days are noticeably smaller in 1999. Bird use days by avocets and stilts were greatest in 2000 and 2001, and for dowitchers and waterfowl in 1998. The years 2000 and 2001 showed greater bird use days for gulls. Herons and egrets seemed to be more uniform in their use of the lake through 1998-2000, but diminished in 2001. The greatest year of peep sandpiper presence was 2000, while for phalaropes the highest use year was 2001 (Table 9).
An examination of the five-year mean bird use days by suite reflects the importance of the lake to avocets, phalaropes, waterfowl, and gulls--each present at GSL in the millions of bird days (Table 10).
Table 8. Mean bird use days at Great Salt Lake by year, 1998-2001.