Ravens: the new desert blight

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Jim_b
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Ravens: the new desert blight

Post by Jim_b » Thu Mar 17, 2011 12:51 pm

"Wildlife biologists now estimate that raven populations have increased" in southern California desert areas "by about 1,000 percent in the past 35 years." Ravens "have earned a villainous reputation among naturalists in the California deserts -- they have been identified as one of the main predators of desert tortoise," a threatened species found on various areas managed by BLM-California. Among solutions: "Keep a lid on all garbage receptacles, cover and store food if you leave your campsite during the day, do not feed any wildlife...."

http://www.vvdailypress.com/articles/lo ... avens.html
Last edited by Jim_b on Sun Mar 20, 2011 2:05 pm, edited 1 time in total.

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Re: Ravens: the new desert blight

Post by reptilist » Thu Mar 17, 2011 2:18 pm

Ravens expand their presence with mankind leading the way.

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Re: Ravens: the new desert blight

Post by Guz » Thu Mar 17, 2011 8:38 pm

Yep. And covering our trash etc is a double edged sword. They cant find the easy food then its tortoise for dinner. Why not declare open season on them? Give ducks and quail a break for a year or two...just sayin'

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Re: Ravens: the new desert blight

Post by gordon » Sun Mar 20, 2011 1:22 pm

I am all for an open season on them.

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Re: Ravens: the new desert blight

Post by lara » Sat Mar 26, 2011 8:16 am

NOT ALL RAVENS ARE BAD RAVENS

Cumulative Effects and Implementation of a Desert Tortoise Recovery Plan Task
Dr. Danny C. Reinke Edwards, AFB, CA Judy Hohman USFWS, Ventura, CA

http://www.iaia.org/IAIA08Calgary/docum ... Study2.pdf

•Basic assumption - Raven predation on desert tortoises is a learnt behavior – target only ravens known to prey on desert tortoises
•Removing a relatively small number of ravens has the potential to substantially reduce predation of desert tortoises

••••••••••••••••••

•Alternatives Considered and Dismissed – all alternatives suggested by public were addressed in detail and the evaluation explained

•Examples of alternatives recommended by the public • Establish a hunting season and/or bounty for permitted hunters
• Establish an Adopt-a-Raven Program •Trap and Relocate Ravens •Provide Another Food Source for Ravens •Implement Visual or Auditory Aversion for Ravens •Conditioned Taste Aversion (CTA)
•Introduce a Predator for Ravens •Implement a Birth Control or Chemical Sterilization Program •Allow Diseases (e.g., WNV and Newcastle’s Disease) to Reduce the Raven Population •Control/Reduce Human Population Control •Modify all utility poles and towers to preclude raven perching or nesting

••••••••••••••••••

Summary
• Responsibilities:
– Lead agency is the US Fish and Wildlife Service
– This was a joint level Desert Managers Group
(DMG)
• Goal: – TheEA allows us to remove ravens where we
find evidence of predation on desert tortoises

– Key Point -- The goal is not to remove all ravens, but to remove the minimum number of ravens needed to stop desert tortoise predation.
• When: – Final USFWS EA - March 2008 – Edwards Adoption EA FONSI – June 2008
– Publication of USAF FONSI/Adoption and waiting
period ended 3 July 2008

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Re: Ravens: the new desert blight

Post by lara » Sat Mar 26, 2011 8:18 am

Jim_b wrote:"Wildlife biologists now estimate that raven populations have increased" in southern California desert areas "by about 1,000 percent in the past 35 years." Ravens "have earned a villainous reputation among naturalists in the California deserts -- they have been identified as one of the main predators of desert tortoise," a threatened species found on various areas managed by BLM-California. Among solutions: "Keep a lid on all garbage receptacles, cover and store food if you leave your campsite during the day, do not feed any wildlife...."

http://www.vvdailypress.com/articles/lo ... avens.html
as usual the daily press did not do their research to find out all ravens are not predators of tortoises. i would not use them as a source of reliable information. they simply used a press release story from the NPS - another source i would not trust totally as they usually have their own agenda.

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Re: Ravens: the new desert blight

Post by gordon » Thu Mar 31, 2011 3:59 pm

The problem I see with the removal of specific tortoise predating ravens is that remove one and others are going to fill their spot very quickly. Ravens are very opportunistic feeders and are very efficient predators. Although I have not seen them personally taking large numbers of baby tortoises I have seen more than my share of shells. I had a good number of images however they have been lost due to lousy backups and a theft of my computer the images were on. However I have seen them very effectively hunt and kill lizards up to the size of fully mature desert iguanas. They think more like predators and I suspect that the "it moves and can't eat me so I can eat it" mentally is more hardwired in than most people think. I am afraid that the numbers need more than a minor thinning to reduce the threat to the tortoises and other animals they are feeding on. Where once you were lucky if you saw one of two ravens it is very common to see 50-100. I had really hoped that WNV would have a greater impact on them than it did, as it did on crows in the Los Angeles basin. however the lack of standing water even in relatively rainy years means very few mosquitoes to vector the disease. Dont get me wrong I think ravens as a species are wonderful birds and am in no way suggesting we eliminate them entirely but the numbers really do need to be reduced to manageable levels.

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Re: Ravens: the new desert blight

Post by Borrego Linda » Sat Apr 02, 2011 9:12 am

My German Shepherd goes nuts when she sees them on the telephone poles here in Borrego Springs. She wants to climb up and get them! They tease her but sometimes she "scares" them into flying away. There are a lot of them.

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Re: Ravens: the new desert blight

Post by kswaby10 » Fri Apr 15, 2011 3:06 pm


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Re: Ravens: the new desert blight

Post by reptilist » Fri Apr 15, 2011 3:22 pm

Grilled slowly with some lemon pepper, and served with wasabi, they would be great table fare.

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