Indicator
Peregrine Falcon Population Sites
2019 Evaluation
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This indicator measures the number of active peregrine falcon nests in the Tahoe Region. Peregrine falcon (Falco peregrinus anatum) populations declined precipitously across the country in the mid-1900s. Peregrine falcons were recorded in the Tahoe Region in the early 1900s, but were not observed naturally occurring in the Region between 1960 and 2007. Their recovery is a result of banning DDT and similar chemical contaminants, and active species reintroductions. In the Tahoe Region, recreation such as climbing and hiking near nests is one of the threats to the species. Programs to reduce these recreation impacts aim to protect peregrine falcons. Peregrine falcons are monitored across the Region by TRPA and other partners. 

Peregrine Falcon Population Sites.JPG
Status

Total number of active peregrine falcon nests recorded in the Tahoe Basin during years when formal surveys were conducted relative to the threshold standard of two population sites. Surveys were conducted four times between 1994 and 2008 but no confirmed nests were observed until 2009. 

2019 Evaluation
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Status
Considerably Better Than Target
Trend
Moderate Improvement
Confidence
High
Applicable Standard
W6: Provide a minimum of 2 Peregrine population sites. W13: Provide disturbance zones and influence zones for Peregrine.
Key Points
  • Peregrine falcons have made a remarkable recovery in the Tahoe Region since they first reappeared in 2009.
  • Active nests continue to grow, and as of 2019, there were five active nests in the Tahoe Region.
  • Years of monitoring at the Castle Rock nesting site revealed impacts from hikers resulting in nest failures. Multiple EIP partners worked together to discourage hiking and climbing near the nest site during the nesting period. Due to this effort, nesting success occurred in 2019.
  • The disturbance zone standard for Peregrine falcons has been implemented by TRPA and other partner agencies.
Evaluation Map
Description

Active peregrine falcon nest sites within the Tahoe Basin from 2015 to 2019.

About the Threshold
Peregrine falcon (Falco peregrinus anatum) populations declined precipitously across the country in the mid-1900s (USFWS 2003). Peregrine falcons were recorded in the Tahoe Basin in the early 1900s (Orr and Moffitt 1971), but were not observed naturally occurring in the basin between 1960 and 2007 (J.S. Romsos, Schlesinger, and Manley 2000; Zanetti 2015; California Department of Fish and Wildlife 2007). In the mid-1980s, several juveniles were re-introduced, but left the basin the same year (U.S. Forest Service 2009). The species was federally listed as endangered under the Endangered Species Act until it was removed in 1999 due to an overall increase in the population. They were, however, considered endangered by the State of California until 2009. Their recovery is a result of banning DDT and similar chemical contaminants, and active re-introductions (USFWS 2003). They are still protected by the Migratory Bird Treaty Act, which prevents harming peregrine falcons or their nests.
In some areas peregrine falcons have shown reduced reproductive success when nesting cliffs are used by rock climbers (Mearns and Newton 1988; Cade, Enderson, and Linthicum 1996). Within the Tahoe Basin, some of the cliffs with nests are used by rock climbers, which could affect nesting success. However, at the two sites in the basin with rock climbing activity, the species has successfully reproduced every year since 2011, suggesting that these birds are not disturbed by the current rock climbing activity (U.S. Forest Service 2015b). An evaluation of potential peregrine falcon habitat in the basin concluded that potential nesting habitat exists, but it is of marginal quality, which may limit the total number of active nests the Region can support (Boyce and White 1980). Some peregrine falcons nesting in the basin may migrate to Central or South America for the winter, where they could be affected by contamination from organochlorine pesticides (e.g. DDT) (USFWS 2003).
Delivering and Measuring Success

Example EIP Projects

  • Castle Rock Peregrine Falcon Habitat Protection

    Organizations working to harmonize wildlife protection and responsible recreation to protect peregrine falcons while allowing access to hiking and climbing routes near the birds’ nesting sites.

Monitoring Programs

Rationale Details
Current status was determined by the number of active nests in the most recent monitoring year. In 2019, there were five active nests, which is 250% of the standard. Therefore, the current status is considerably better than target.
Trend was determined using simple linear regression on the number of active nests. From 2008-2019, the number of nests grew by an annual 23%, therefore, the trend is considered to be moderate improvement.
Confidence Details
High. Standardized protocols were utilized.
High. Standardized protocols were used and enough years of data exist to establish a trend.
High.
Additional Figures and Resources

No photos available.

No documents available.