Research

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This page is still under development

Dr. Harry Thiers and Dr. Dennis Desjardin have compiled an extensive list of the fungi in the Yuba Pass area. Such knowledge of the fungi prompted researchers investigating the fungal connection between parasitic flowering plants and their host plant to choose this area to gather samples for genetic analyses.

Dr. James Kelley has been collecting baseline data on the physical properties of the lakes in the Lakes Basin area. This database will allow us to analyze future impacts.

Dr. Robert Patterson and Dr.Thomas Parker have compiled lists of the flora of the Sierra Buttes and surrounding areas. Jim Steele has collaborated with Bill and Nancy Harnach of the Sierra Valley Herbarium towards the goal of producing a flora of Sierra Valley.

Dr. Peter Busher and Earthwatch volunteers have examined small mammal populations within Spotted Owl roosting areas.

Jim Steele and John McCormick are investigating Neotropical Migratory Bird populations. This project has been funded by the U.S. Forest Service for the past 5 years. A special emphasis has been on dispersal patterns as a function of elevation. A brief summary of this work is presented below.

Land managers must evaluate what constitutes critical habitat for species of concern. For migratory passerine birds, the breeding grounds and wintering grounds are characterized as critical habitat. For waterfowl however land managers distinquish among three critical habitats: breeding grounds, molting grounds and wintering grounds. Our research suggests that some passerines rely on three critical habitats similar to waterfowl.

Orange-crowned Warblers in the Sierra Nevada breed mostly below 3500 feet elevation. After fledging young in May and June, they disperse to higher elevations. They begin and complete molt away from their breeding grounds. Adults may remain at a higher elevation site upwards to 70 days if conditions are favorable while they molt. Individuals return to these sites the following year, similar to the site fidelity shown for their breeding grounds. However in dry years where conditions are not favorable, adults will move out to different habitat, apparently at higher elevation. Nonetheless it appears that they become sedentary at these new sites. Hatching year birds do not show the same sedentary behavior during this time and become concentrated in great abundance in sites at higher elevations than the adults. The become particularly concentrated in meadows dominated by willow.

Both adults and hatching year birds depend on habitats at elevations above the breeding grounds for more than two months.This is the time between fledging young and the beginning of migration. Thus it appears that this species depends on one habitat for breeding and another for post-breeding needs and molting and that adults and hatching year birds rely on different habitat.

Below are two graphs that depict when adults shift to higher elevations after breeding. Dark blue represents individuals caught that had not begun to molt. Light blue indicates individuals in the process of molting. Red indicates individuals that have completed molt. The number of individuals in each of these categories of molt are indicated for three elevations. Low elevation is a site at 3000 feet, the mid elevation site at 5000 feet, and the high elevation site is 6700 feet.

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