The 6 Lakes (Clear, Eagle, Almanor, Thermalito, Davis and Antelope)
Grebe Survey Summary
- Max Adults: N/A
- Year: N/A
- Most Recent Adults: N/A
- Year: N/A
- Survey Type: N/A
- Most Common Threats Reported: N/A
- Lake name:
- The 6 Lakes (Clear, Eagle, Almanor, Thermalito, Davis and Antelope)
- Location:
- California
- Region associations:
- Clear Lake; Eagle Lake; Almanor Lake; Thermalito Afterbay; Lake Davis; Antelope Lake
- Comments:
- This is a summary of the 6 Lakes (Clear, Eagle, Almanor, Thermalito, Davis and Antelope).
Surveys (2)
Survey Citation:
Kyle, K., D. Arsenault, N. Lunder, M. Waits, F. Hayes, S. Overlock, J. Patten, and R. Martin. 2013. Conservation of Aechmophorus grebe colonies at six northern California lakes. Final report. Oakland, California, USA.
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Time period
N/A -
Source
Report -
Both Western and Clarks?
N/A
| Count Type | Range | Max | Year |
|---|---|---|---|
| Max Adults | N/A | N/A | N/A |
| Most Recent Adults | N/A | N/A | N/A |
| Max Nests | N/A | N/A | N/A |
| Most Recent Nests | N/A | N/A | N/A |
| Max Chicks | N/A | N/A | N/A |
| Most Recent Chicks | N/A | N/A | N/A |
Comments:
This entry for some population stats of the 6 surveyed lakes overall (or the 4 major ones: Clear, Eagle, Almanor, Thermalito). Estimated population at these 6 lakes is over 70% of the breeding grebes and 76% or more of total nesting Aechmophorus grebes in CA (Ivey 2004). About 5.6% of global population of Aechmophorus grebes is supported in Nothern CA. Eagle, Clear and Lake Almanor together "supported more than 13,000 grebes in 2012" (Kyle 2012) and rank 1st, 3rd, and 4th in breeding lakes "among select CA Lakes" (Ivey 2004). Averaged 65 surveys/year across these 6 lakes for 4 breeding seasons from 2010 to 2013. Steady increase in # adults until 2013 for all lakes except Eagle Lake (likely due to low water levels). Observed active nests also increased through study period except collapse at Eagle Lake. Estimated average productivity (young:adult) was 0.19 for all 6 lakes. If Eagle Lake was excluded due to no reproduction 2012 to 2013, productivity of the other 5 lakes was 0.27. The Audubon chapters conclude from the disturbance surveys that in most years, natural predation, water flux, food availability (not measured) have more impact on the grebes than human disturbance (boats, kayaks, dog walkers, planes). The report also states that water level fluctuations is one of the major factors impacting grebe reproductive success and water level management protocals are urgent. They hope to negotiate with power producers to include grebes into water management plans for the summer/breeding season. These chapters do extensive outreach into the communities, including signage, education, and other ways to advocate for grebes.
Survey Citation:
Loggins, D. 2015. Conservation of Aechmophorus grebe colonies at six northern California lakes. Semi-annual financial and programmatic report. Audubon California, Sacramento, California, USA.
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Time period
N/A -
Source
Report -
Both Western and Clarks?
N/A
| Count Type | Range | Max | Year |
|---|---|---|---|
| Max Adults | N/A | N/A | N/A |
| Most Recent Adults | N/A | N/A | N/A |
| Max Nests | N/A | N/A | N/A |
| Most Recent Nests | N/A | N/A | N/A |
| Max Chicks | N/A | N/A | N/A |
| Most Recent Chicks | N/A | N/A | N/A |
Comments:
Number of grebes for each lake is similar to prior years but reproduction was less on all lakes in 2015 compared to prior years. No data table of count numbers for this report. Modified Gericke et al. (2006) protocol similar to the last five breeding seasons and included nest initiation surveys (weekly), nest monitoring surveys, disturbance surveys (weekly), and population and brood surveys (1-2 times a month until October).