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Monthly Public Programs at Sonora Library & Zoom

Wednesday, March 20, 2024, 7:00 pm

Geology & Birds

Presented by Jeff Tolhurst

Our chapter is very fortunate in that it encompasses an elevation range from under 1,000ft. to over 10,000 ft. which provide many different habits from grasslands through oak woodlands and on up to alpine forests. Varied habitats offer opportunities for different bird (and other wildlife) species to adapt and survive, thereby reducing direct competition for resources. For example, the Clark’s Nutcracker resides up at the higher elevations where part of its survival strategy is to cache up to as many as 30,000 nut seeds (mostly whitebark pine) every year in many dispersed locations that it can recover as winter takes over. To do that efficiently, it has adapted by evolving a special pouch under its tongue that it uses to carry seeds long distances, along with a prodigious memory that allows it to recover many or perhaps most (but not all) of those seed caches. In other words, species evolution has gone hand-in-hand with the evolution of landscapes and their varied habitats.

The question that Jeff will address this evening is how the geologic processes over time produced the Sierra Nevada as we know it with such a variety of habitats and ecotones that facilitated the evolution of species with their many survival adaptations and strategies. For example, we have the Red Hills complex with its serpentine soil that supports several endemic species, and not far away is Table Mountain with a vastly different ecological complexion. In addition to habitat formation, Jeff will also briefly touch on how geology relates to migration patterns, climate and weather influence, nesting sites, birds and the fossil record, resource availability, and the impact of natural disasters on birds.

Jeff Tolhurst recently retired after teaching geosciences and geospatial technologies at Columbia College, in Sonora, CA, and has over 31 years of teaching experience. He also worked for the U.S. Geological Survey (USGS), and for Trinity Restoration Associates (TRA), doing surface and groundwater studies, for another 6 years. He has a Ph.D., M.S., and B.A. in geological sciences and continues to learn more about the earth in retirement.

This program will be in-person at the Sonora library and on Zoom

Zoom link: https://us02web.zoom.us/j/89307683859

 

Board Meetings

Our board meetings usually are the third Wednesday of the month, September through May, and are at 3:30pm.  Audubon members are welcome to attend these meetings. For information on next meeting you may call Tom Parrington, President, at (209) 928-3835 or email him at tepgjtuo@gmail.com