Nesting Bald Eagle Population Sites
This indicator measures the number of active bald eagle nests in the Tahoe Region. The bald eagle (Haliaeetus leucocephalus) is the national symbol and an iconic species that is exceptionally important to the public. Bald eagle reproductive success in the Tahoe Region may be affected by human activity such as boat access or other recreational uses in nesting territories, and the loss of nesting habitat including large trees in close proximity to surface water. Regional programs such as protecting large snags and limiting recreation around known nests aim to protect bald eagles in the Tahoe Region. Potential nesting bald eagle habitat and known nests are monitored each year by various wildlife agencies in the Region.
Status
Total number of nesting bald eagle pairs in the Tahoe Basin that were active from 1996 through 2023. Threshold standard is one nest. The trendline was estimated using a linear regression model.
Surveys conducted for nesting bald eagles are done throughout the summer by NDOW and CA State Parks, with some help by TRPA. Access detailed datasets on Tahoe Open Data, including: Buffered Bald Eagle Nest Locations and Annual Nest Counts (This data is defined as "Bald Eagle- nesting" under Wildlife Species column).
Evaluation Map
Approximate locations of known bald eagle nesting areas from 1996 to 2023 in the Tahoe Basin. Not all known nest locations are active every year. The nest at Sugar Pine point was last active in 2019.
2023 Evaluation
- Status
- Considerably Better Than Target
- Trend
- Rapid Improvement
- Confidence
- High
Applicable Standard
W4: Provide a minimum of 1 Bald Eagle (Nesting) population site.
W11: Provide disturbance zones and influence zones for Bald Eagle (Nesting).
Key Points
- Four nests were found in 2023, the most in nearly 30 years of annual monitoring.
- Since routine monitoring began in 1996, the number of nesting bald eagle pairs has increased an average by 0.08 nests per year.
- There is high confidence that the number of bald eagle nests in the region has been increasing.
- Protective measures are in place for projects like trail construction and forest fuels reduction that minimize disturbance to nesting bald eagles and nesting habitat.
About the Threshold
- The bald eagle (Haliaeetus leucocephalus) is the national symbol and an iconic species that is exceptionally important to the public. In the lower 48 states, bald eagles were considered threatened under the Endangered Species Act until they were de-listed in 2007. They are still protected by the federal Bald and Golden Eagle Protection Act and Migratory Bird Treaty Act, which prohibits the harming, killing, or possession of bald eagles, or their eggs or nests.
- Bald eagle reproductive success in the Tahoe Basin may be affected by human activity such as boat access or other recreational uses in nesting territories (Laves and Romsos 2000), and the loss of nesting habitat including large trees in close proximity to surface water (Laves and Romsos 2000). TRPA’s Code of Ordinances and enforcement limit disturbance in buffers surrounding nest sites. Fish mortality from spawning, disease, or catch and release fishing can impact the amount of available carrion, which can affect nesting bald eagles (Jackman, Hunt, and Hutchins 2007; Beauchamp et al. 1994). In other areas, weather conditions affect the reproductive success (Gende, Wilson, and Jacobsen 1997), although it is unknown to what degree weather affects nesting success in the Tahoe Basin.
Delivering and Measuring Success
EIP Action Priorities
-
Acquire Environmentally Sensitive Lands for Restoration and Protection
Public land acquisition preserves open and wild spaces.
-
Restore and Protect Native Fish and Wildlife
Enhancing the biologic integrity of ecosystems to improve the environmental conditions necessary for the full range of species to help compensate for past degradation.
Monitoring Programs
Rationale Details
- Considerably better than target. The status was determined based on the number of active nests in the Tahoe Basin over the evaluation period. The average number of active nests from 2019-2023 was 3.25. Therefore, the current status is considerably better than target.
- Rapid improvement. The annual increase since 1996 is 7 percent, therefore, there is a trend of rapid improvement.
Confidence Details
- High. All potential nesting habitat is surveyed each year using standardized protocols and frequent observations.
- High. The estimated growth is positive. The lower bound of the 95% confidence interval is 3.9% annual growth and the upper bound is 11.5% annual growth. The 99% confidence interval is 2.6%-12.8 % annual growth. The confidence intervals do not overlap with zero and the p-value is 0.000285, therefore, there is high confidence in the nesting bald eagle pair population growth.
- High.
Additional Figures and Resources
No photos available.
No documents available.