Habitat Use

All count data for the years representing high and low lake conditions (1999 and 2001, respectively) show patterns of abundance for the following suites of species (Appendix 3). Ducks and dowitchers that favor fresh water in association with emergent wetlands were more abundant in 1999. Gulls, avocets/stilts and small sandpipers were more abundant during the low lake year of 2001. These groups prefer exposed shoreline and mudflats for nesting and foraging. Phalaropes were also more abundant in 2001. Personal observations by the authors noted more abundant brine fly production during this low water year, which may have contributed to the larger numbers of phalaropes, gulls, and sandpipers. The survey year 2001 was also a better year for brine shrimp production than 1999. Counts at point samples did not always reflect these same patterns. Of 19 point samples, 74% had a greater ratio of species to habitat types in 1999 over the drier year of 2001 (Table 11 and Table 12).

Table 11. Comparison of species and habitat diversity at point samples in 1999 and 2001.
The values listed are ratios of the number of species to number of habitat types.

Point 1999 2001
3a 2.3 1.7
3b 2.4 1.8
6.1 0.6 1.1
6.2 2.1 1.0
6.3 3.2 1.6
8a.1 4.0 3.7
8a.2 3.4 2.9
8a.3 4.5 5.8
9b 3.8 2.7
11.1 4.0 3.6
11.2 3.8 3.0
11.3 5.7 2.8
18.2 2.1 2.6
18.3 2.4 3.8
15.1 2.3 3.8
15.2 2.2 1.8
34a.1 3.8 1.1
34a.2 4.3 1.8
34a.3 4.1 2.0

Table 12. Comparison of waterbird density (birds/ha) by suite at point samples
and corresponding shoreline areas. Point sample data were averaged through time and
across samples. Data from the following shoreline areas were used to calculate mean
birds per hectare for a point sample and the entire block of respective areas:
3a, 3b, 6, 8a, 9b, 11, 18, 34a.

Suite Name Mean density at a point sample Mean density at GSL shoreline survey areas
1 Gulls 5.77 2.46
2 terns 0.20 0.01
4 Dabbling Ducks 0.94 0.19
5 Diving Ducks 0.24 0.01
6 All Ducks 7.07 0.20
7 Herons and egrets 0.08 0.00
8 Avocets and stilts 3.56 1.54
9 Small sandpipers 1.81 0.20
10 Dowitchers 0.30 0.00
11 Yellowlegs 0.07 0.00
13 Plovers 0.24 0.03
14 Phalaropes 1.29 0.41
15 Large sandpipers 0.13 0.02
16 Ibis 0.21 0.01
17 Pelicans 0.96 0.04
18 Eared grebes 1.62 0.14
19 Coots 0.90 0.05
20 Geese 0.73 0.05
21 Cormorants 0.09 0.00
22 Cranes 0.04 0.00
23 Medium sandpipers 0.49 0.01
24 Soras and rails 0.02 0.00
25 Other grebes 0.14 0.00
26 B.B. plovers and red knots 0.51 0.01
All birds 27.42 5.40

Go to Previous Section (Survey Area Descriptions) • Go to Next Section (Discussion)...