Where are the Corvids?
Posted: 24 September 2006 08:25 PM
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Where are all the Corvids?

The past 2 months I have not seen any of my friendly Ravens, where are they?  I have lived on a kelp cove on the Pacific Ocean for the last 8 years and have always enjoyed 6-8 raven soaring on the bluffs year round, but none lately. I even have a recent carcass of what I believe to be a Raven on my yard.

I recently read an article that said that corvids—ravens, crows, scrub jays are very susceptible to West Nile Virus.  According to http://goliath.ecnext.com/  “Since 2000, surveillance for West Nile virus (WNV) in dead corvids has been the cornerstone of the early warning system for this virus in the Canadian public health system.”

Does anyone know if that is the SMC thinking on the cause, or what other reasons might explain the disappearance of the ravens? My neighbors have also found several bird carcasses.   

Question…  Do West Nile Virus carrying mosquito breed in wetlands?

Terry Gossett

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Posted: 25 September 2006 09:47 AM   [ # 1 ]
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Fear not, the ravens have not disappeared.  They’re over in the pines in Montara.  We saw fewer in our neighborhood in Montara last year than in previous years but they are back this year.  I guess they were in Moss Beach vacationing last summer. ;-)

Regarding WNV, corvids are quite susceptible.  As are potentially robins (http://www.cnn.com/2005/HEALTH/07/29/westnile.robins.ap/) and squirrels.  If you discover a dead bird, you should collect it and report it at either http://westnile.ca.gov/dead_bird_report.php or http://vector.ucdavis.edu/cfm/deadbird2.cfm or by calling the hotline: 877-WNV-BIRD.

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Posted: 25 September 2006 09:52 AM   [ # 2 ]
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Didn’t we vote ourselves into the Mosquito Abatement District sometime in the last few years? Perhaps someone from the district could tell us what is being done about abatement locally.

Might be good if folks from different areas of the coastside kept an eye out for changes in corvid population/activity. I have been away so haven’t noticed way up here in the back of beyond.

Earlier I think I remember reading that we were supposed to report dead birds to someone, but I don’t remember who. Do they come and pick them up for autopsy? Does anyone know?

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Posted: 25 September 2006 02:55 PM   [ # 3 ]
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The SM County Health Dept. has posted a “Fight the Bite” page with all kinds of info on Mosquito Control and reporting dead birds. Here’s the tiny url for the County page:

http://tinyurl.com/fkf7u

This link lets you to report a dead bird online:

http://westnile.ca.gov/dead_bird_report.php

Corvids are very active in town (HMB), near 92.

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Posted: 25 September 2006 07:54 PM   [ # 4 ]
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Thanks Suzanne—

I did the online report of the bird carcass that you provioded to us…and they responded within 2 hours, but unfortunately the carcass was mostly dessicated so they advised me to double wrap in plastic with gloves, and dispose in trash, so I was too late to see if it was West Nile Virus on my Raven..

also glad to hear that ravens are still around on coastside..

thanks

terry gossett

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Posted: 25 September 2006 11:38 PM   [ # 5 ]
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I have also been wondering about but the birds, but about the hawks, not the ravens. After the heavy rains of last winter I noticed that the hawks were scarce. Also noticed that the rodents (voles?) at the Poplar bluffs were gone—drowned/forced out I assumed.

Is this is yearly cycle here or did the rains give the food cycle here on the coast a bit of a shock?

—Darin

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Posted: 26 September 2006 12:42 PM   [ # 6 ]
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I called the Humane Society when we found a dead raven in our yard, and they advised us to wrap it in a garbage bag using gloves etc. and they would come get it when they could .  They came about two days later, but we never heard the reason for the death.

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Posted: 29 September 2006 09:30 PM   [ # 7 ]
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Lots of raptors and ravens on Montara Mountain, as usual, this summer. Aerial shows have been excellent.

Carl May

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Posted: 03 October 2006 04:18 PM   [ # 8 ]
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Big flock of more than two dozen turkey vultures on and above the lower slopes of Montara Mountain in McNee Ranch this morning. They must be the envy of every glider pilot. We only had a quick look, but there was no obvious carcass attracting them to the area. Seeing more of the bobcat who hangs out in the area these days, and more deer making their annual appearance lower on the mountain. Be especially watchful for deer on Highway 1 this time of year—or end up with the front end of your car looking like my truck.

Carl May

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Posted: 04 October 2006 09:24 AM   [ # 9 ]
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Getting back to the topic of corvids, Ox Mountain started covering up their site after work and this may have directly impacted ravens’ ability to forage, so they may be more dispersed as a result. I still see them everywhere when I’m out walking.

We’ve got a new corvid in rapidly growing numbers—the American crow. I saw the first one on a wire near Burger King on a February morning four years ago. A year later I noticed two in the same spot. Last year I spotted a couple near the fire department and a pair up in Miramar by the Coastal Trail. This summer I’ve seen a two different flocks of about fifteen birds each, one in the State Park at the end of Kelly and the other on my street on Terrace Ave. They are now a local resident and can be seen anywhere along the Coastal Trail.

Thirty years ago the only ravens around here were few and far between flying along the ridges of the hills—I’d only see them when out hiking. After Ox Mountain became the county dump and began its inexorable expansion, the raven population expanded as well. They tend to group in large numbers during the winter with upwards of four hundred in some of the rural canyons and ranches south of town. During the annual bird count last December. we saw them fairly evenly distributed all along the coast to Santa Cruz. And, of course, there are dozens hanging along the beach where Pilarcitos empties into the ocean, and in the nearby Monterey Cypress in the campground on the bluff.

The logaritmic increase of corvids in expanding suburban areas like this goes hand in hand. These birds spell havoc for the resident songbird population because corvids are primary preditors of eggs and young birds. The crows in my neighborhood scooped up the pair of Allens humingbird young that I’d watched grow to adolescence from my den window.

Simple law: corvid numbers up, other species down, maybe even out. That’s the changing ecology of suburbanization. West Nile Virus, while unwelcome because it affects most bird species, impacts the larger ones more so may have the benign effect of restoring some balance, but I would not count on it.

Watching all of this play out supports a Buddhist outlook where you don’t have judgments or laments, just take it in because change is constant. There are micro events affected by macro forces that humans seem ill prepared to deal with being imperfect as we are. Call it the effects of original sin or plain hubris, we are seeing a rapid extiction of species and the jiggering of a few hardier ones like the adaptable corvids.

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Posted: 10 October 2006 09:04 PM   [ # 10 ]
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Ken King - 04 October 2006 04:24 PM

These birds spell havoc for the resident songbird population because corvids are primary preditors of eggs and young birds.

Do they eat hawk eggs as well? A few months back I was suprised to see a Crow and a Red-tailed Hawk jumping from branch to branch in the trees at George and Birch in Montara—the crow had a large egg in its mouth, the Hawk seemed angry—seemed like it was the Hawk’s egg, though maybe he was just hungry, too.

—Darin

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Posted: 11 October 2006 10:15 AM   [ # 11 ]
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I’m pretty sure you saw a raven in the tree and not a crow because I doubt the crows are that far north yet. The difference between Ravens and crows is Ravens are four inches longer in overall length from tip of the beak to tail end. When you aren’t sure about the size of the bird, they can be told apart by whether the end of the tail is tapered and wedge-like (raven) or squared off (crow).

Ravens are slightly larger than Redtailed hawks and often pursue and drive them away. They’d eat their eggs if they spotted an unoccupied nest, and working in pairs could ingeniously lure a parent off the nest by attacking it and being chased while the other raven makes off with an egg or young. Of course the hawk would be upset but could not do anything once the egg is out of the nest. Normally you think of hawks being on top of the food chain, but ravens are the biggest “song bird” in North America.

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Posted: 11 October 2006 05:19 PM   [ # 12 ]
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Corvids are probably not the reason for the endangered status of the Marbled Murrelets but they’re a very real threat to finishing them off in San Mateo County.  They’re efficient nest predators and the reduced old growth nesting habitat of the Murrelets creates a dual danger.  Corvids learn quickly that hanging around humans creates feeding opportunities. That’s why the Coastal Commission staff recommended denial of the PCA campground right next to a habitat.  The Commission itself, however, was willing to accept airy conditions such as “kids can’t eat outdoors, keep garbage cans covered, and keep kids quiet” and approved it. The final permit hasn’t been issued yet. 
There’s a lawsuit that’s been filed by some Southcoast residents but I don’t know the status of that.

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