Archive for February, 2010

Are We in the Midst of the Sixth Mass Extinction? A view from the world of amphibians
Guest Speaker: Vance Vrendenburg
Thursday February 18th, 7:30pm

sierran frog

Many scientists argue that we are either entering or in the midst of the sixth great mass extinction. Intense human pressure, both direct and indirect, is having profound effects on natural environments. SF State Professor, Vance Vrendenburg presents a view from the world of amphibians.

The amphibians—frogs, salamanders, and caecilians—may be the only major group currently at risk globally. A detailed worldwide assessment and subsequent updates show that one third or more of the 6,300 species are threatened with extinction.

This trend is likely to accelerate because most amphibians occur in the tropics and have small geographic ranges that make them susceptible to extinction. The increasing pressure from habitat destruction and climate change is likely to have major impacts on narrowly adapted and distributed species. Dalamanders on tropical mountains are particularly at risk.

A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease.

Our data for frogs in the Sierra Nevada of California show that the fungus is having a devastating impact on native species, already weakened by the effects of pollution and introduced predators.

Vance Vrendenburg, SF State Professor, presents a general message from amphibians is that we may have little time to stave off a potential mass extinction. Learn more about his work at his website: http://web.me.com/vancevredenburg/Vances_site/Home.html

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Last thursday night, Jan 28th, Camilla Fox showed us how coyotes are already out there living among us. In particular she told some amazing stories about the 2000 some coyotes who live in Chicago. What’s amazing isn’t the number that are there per se, but how little conflicts there actually are between them and us.

Since 1890, the Coyote has expanded into three times the amount territory and has come to be the keystone predator in a lot of ecologies. As that they provide ecosystem services — controlling other predators like feral carts, raccoons; controlling rodents and lagomorphs; and cleaning up carrion.

Contrary to myth, even in cities, domestic animals don’t make up a large portion of their diet, and a certain times of the year, fruits and berries become part of their diet. They are the ultimate flexitarian.

Camilla gave an intro to coyote biology ecology and noted how and where conflicts can occur: often as coyotes are protecting their young in their dens (as were two coyotes who were killed in golden gate park), and as unattached juvenile coyotes disperse in search of new groups to join. Camilla’s organization Project Coyote tries to educate the public and their governments how to better manage Coyote populations.

Coyotes often come into conflict with humans in cities when they have been accustomed to taking food from humans, and when they are sick (often with mange). Feeding coyotes is often a death knell for them. One strategy for us is to make sure the Coyotes are properly wary of people. Scare them off if you can.

The other reason paying attention to coyote biology is important is how control strategies can fail. Some scientists think that control efforts have led to an increase in population of smarter coyotes. Usually groups have a single breeding pair, but deaths of that pair can lead to a pack that is suddenly all having cubs.

Despite the war that humans have waged on coyotes possibly as many as 400,000 year are killed. Coyote populations remain strong (other interesting things are happening as well, like coyotes interbreeding with wolves and dogs). Removing coyotes can also lead to an increase in populations of raccoons and feral cats which have repercussions down the food chain.

Stable packs though maintain territory, keep out the young juveniles (or absorb them presumably) and have a more stable population.

Camilla left us with a video documenting the Coyotes arrival in San Francisco, and more information about how they cope in Chicago.

Learn more at http://www.projectcoyote.org/

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