Measuring the health of Mt. Tam
Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.
One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?
The overall condition of riparian-associated birds is Good.
Point Blue Conservation Science analyzed patterns of abundance from 1996 to 2013 and in riparian-specific studies from 1997 to 2011 to determine the trends for as many individual species as possible (see References below). Trends were determined for six of the seven riparian-associated species.
The vast majority of birds in this group are doing well and data was sufficient to assess condition with high confidence. One species of concern, the Warbling Vireo, is increasing in the One Tam area of focus despite decline trends elsewhere in the Bay Area and statewide. Poor reproductive success has been implicated in this vireo's decline elsewhere so perhaps the breeding conditions in the One Tam area are of higher quality (e.g., fewer cowbirds and other nest predators).
Cormier, R.L., Seavy, N.E. & Humple. D.L. (2014). Abundance patterns of landbirds in the Marin Municipal Water District: 1996 to 2013. Point Blue Report. Available here.
Gardali, T., Ballard, G., Nur, N., & Geupel, G. R.. (2000). Demography of a declining population of Warbling Vireos in coastal California. The Condor, 102(3), 601-609. Available from: http://www.jstor.org/stable/1369791.
Gardali, T. G., & Jaramillo, A. (2001). Further evidence for a population decline in the western Warbling Vireo. Western Birds, 32:173-176. Available from: https://www.westernfieldornithologists.org/archive/V32/32(3)%20p0173-p0176.pdf.
Humple, D. L., & Porzig, E. L. (2012). Riparian landbird monitoring in Golden Gate National Recreation Area and Point Reyes National Seashore: analysis report through winter 2011-12. Petaluma, CA: Point Reyes Bird Observatory (PRBO). Available here.