Thursday, June 30, 2011

Saga of Screech and the Raven

My neighbor called a few days ago to let me know that they had seen a Common Raven take down a Western Screech Owl in their backyard.  They had seen a scuffle in the redwoods, and then saw the Raven on the ground pecking at something and heard peeping.  They debated for a bit on whether to intervene, or if it was just nature taking course, but ultimately decided to do save the peeper.  Much to their surprise, after shooing off the Raven, they came up to a small owl with his head feathers plucked off.

Location of the incident, redwood and madrone
They picked up the little bird with the intent to take him to Wildcare, and the owl just laid there completely still with it's talons clenched and eyes open, not even visibly breathing.  They thought it was dead, but Wildcare said to bring it in anyway.  Sometimes the owls go catatonic (play 'possum) in response to trauma.  Much to my neighbor's surprise, the little owl sprang to life at Wildcare.  Wildcare initially hoped to release the owl the next day, in case it was nesting, but the injuries were to much and it had to stay longer.

Ravens are well established nest predators, and are also know to take adult birds.  This was an issue for the heron and egret colony at Audubon Canyon Ranch, where one year a Raven pair decimated the young of the colony (in full view of tourists none-the-less!).  There was a detailed study of Raven ecology and predation habits that resulted from that (see references below).  I was curious if there was any documentation about how often ravens went after screech owls, but I didn't find anything addressing that specifically.  

As I mentioned in the My Side of the Mountain post, this is the first year that I've seen raven's here.  Given the frequency that I have seen and heard them this spring, I believe they have a nest just over the ridge.  These ravens are not shy around human residences.  I've seen one of this pair walking along my fence, eyeing my cat as he rolled in the sun on the deck.  It quickly departed when I opened the door, and my neighbors said that it quickly departed when they waved to shoo it, even from a long distance away.

Although Ravens have been relatively rare to the developed areas of eastern Marin in post gold rush days, their population here is increasing as they develop a taste for the food humans inadvertently provide (i.e. garbage).  This can be devastating for rare species that are vulnerable to predation by Ravens.   The human supplied food can support the Ravens populations at a higher level than the prey species would otherwise.  This means that Ravens can completely decimate a prey species, without being regulated by it's decline.  This is known as "subsidized predators".  Bay Nature did a very nice article on the Ravens in this area, including covering this phenomenon.  So it's quite possible that by intervening in this predation, they just helped correct the affects of an anthropogenically enhanced predator.

Keep tuned for updates on Screech's recovery.

References and additional articles:
www.egret.org/sci_cont.../Kelly_and_Roth_2001_raven_update.pdf
www.egret.org/sci_cont_pdfs/ACR.../Kelly_2002_raven_mgt.pdf
http://baynature.org/articles/jul-sep-2002/the-raven-returns

Monday, June 20, 2011

Nuttal Neighbor

In the first My Side of the Mountain post, I mentioned that there is a Nuttal's woodpecker who drums on an old oak out back.  Here is a brief video of the habitat, and you can hear the drumming at the start and end of the video.
video


Although the dominant tree species shown here is California Bay Laurel, there are a few overshadowed oaks in the middle of all that.  Nuttal's is a small woodpecker, with a black-and-white, barred back, confined primarily to the oak woodlands of California.   Interestingly, although Nuttall's Woodpeckers are nearly confined to oak woodlands, they do not eat acorns, instead going for insects and arthropods, and some fruit.

Although I couldn't get a clear photo through the foliage, I was able to glimpse the distinctive features of the Nuttall's, at least enough for identification.  Nuttall’s color pattern is distinct from other woodpecker species in this area, easily distinguishable at a glance due to the barring on the back and the single red patch.  The other two species here from the same genus, Picoides, are the hairy woodpecker and the downwoodpecker.  Although they both also have the single red patch on the rear crown, they also have a broad white patch on their back instead of the barring of the Nuttall's. 

This watershed supports 7 species of woodpeckers, from 5 different genus’s of the family Picidae. Additional woodpecker species seen locally include: acorn woodpeckerLewis’s woodpeckerred-shafted northern flickerRed-breasted sapsucker, and a personal favorite - the pileated woodpecker.  There is a pair of pileated woodpeckers which frequent the local area, and I'll have a post on them in the future.   

References:

Cornell Lab of Ornithology - http://www.allaboutbirds.org/
Cornell Lab of Ornithology - The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:http://bna.birds.cornell.edu/bna/species/

Tuesday, June 14, 2011

Odd Odocoileus

This sorry fellow showed up yesterday.  He has a deformed antler, still in velvet, that makes him appear a bit like a flop-eared dog.

I originally assumed that he may have broken the antler mid-growth.  Maybe trying to spar a little to soon?  Or possibly a car accident?  But after chatting with a biologist/deer hunter (thanks Vic) and a quick peruse of Google, it turns out that there are many possible alternative causes for deformed antlers, ranging from damaged testicles to "trophic memory" of old injuries, and many are not immediately intuitive.

One of the most interesting I found is that injury to a rear leg may cause reoccurring abnormal development of the antler on the opposite side!  Last year there was a young deer with an injury on a rear leg, but I didn't think to get any photographs or record the date or side of the injury.  It would be fascinating if it is the same deer.  However, the drawings of those deformed antler deer don't show it looking quite as broken as this one does.  

An article from the Mule Deer Foundation points out some really interesting side notes"Besides direct trauma to the growing antler, injuries to a large skeletal structure such as a broken leg bone often causes a misshapen rack the next antler cycle. If the front leg is injured, either side of the rack may be affected. However, if the rear leg is injured the opposite side of the rack is usually misshapen." I originally thought that I may be able to figure out if it was trauma to the antler directly if it grew normal next year, but then I read "If one pedicle is injured severely, that side or both sides will be malformed during the next antler cycle. In addition, the nerves may “remember” the injury and reproduce nontypical antlers for several years. This “trophic memory” only occurs when the injury is substantial and occurs in the early stages of antler growth when there is a high density of nerve connections in the growing antler tissue. "

There are many interesting anecdotes about what may cause malformed antlers, but nothing conclusive about this particular situation.  However, it appears to most closely resemble the following description "If an antler tine breaks completely while still in the velvet phase it may stay attached to the rack via the velvet skin and re-fuse with it leaving a pendulous (hanging) tine that usually has a large rounded tip."

This deer is a regular here.  He travels with a companion who has distinctive ear injuries, so I can at least confirm the companion is the same individual.  Here is an image of both of them, taken one month earlier.  I hadn't noticed at the time, but in this image, the Odd Odocoileus (on the left) appears to have a smaller antler starting on the side that is very deformed now.  But it may just be the angle of the photo.



Does anyone have any additional thoughts on this?

______________________
References and Additional Information:

  • Stable URL: http://www.jwildlifedis.org/cgi/reprint/8/4/311.pdf
  • Stable URL: http://www.jstor.org/stable/1376120 - 1959. W. Leslie Robinette and Dale A. Jones. Antler Anomalies of Mule Deer. Journal of Mammalogy Vol. 40, No. 1 (Feb., 1959), pp. 96-108 
  • http://www.muledeer.org/news/magazine_articles/2009/JulAug09_NotYourTypicalAntlers.html


Thursday, June 9, 2011

Habitat Helper for Hummingbirds

We recently got a visit from a hummingbird to a nesting material station that I set up about 2 months back.  I no longer wanted to support the local rodent populations with the spilled remains of bird feeders, but I enjoy encouraging the local birds to come down for closer observation.  I was watching one of the local songbirds yank coco fiber from the liners on hanging baskets, and it dawned on me I may be able to encourage the birds to come down, at least during the spring/summer, by providing some nesting material.  I'd also often see birds up by the horses, taking off with some of the long mane hairs left on the fence line, so it could work.

I took down one of the suet baskets, and filled it up with natural cotton balls, which seemed like they would make good lining material, and hung it up outside with high hopes.  Then watched it, and watched it, and watched it - but it didn't get touched for the better part of two months.  Granted, it's been uncharacteristically pouring rain and cold most of that time.  The cotton balls held up well through the weather, and it looked like I'd just put them up fresh most of that time.

The weather just got nice this week, and low and behold, today I saw a hummingbird spending a lot of time buzzing around the cotton cage, and it finally dawned on me it may actually be using it.  I started watching with no small amount of anticipation, and I saw the little guy taking small tufts of cotton out through the wire!  After watching him dart up through the trees with a beak full of fluff, I realized that the cotton through the whole cage now had a frizzy look, from having bits of it tugged out.


I do not yet have images of birds removing the cotton, I will try and get a camera trap set up on it soon, but I wanted to share this post in case any one else wanted to try this out this season.

Saturday, June 4, 2011

Coyotes Close - My Side of the Mountain

We have a resident pack of coyotes here.  I occasionally hear them yipping up the hill and night, and despite knowing the stats about what a low risk they are, the sound still makes the hair on the back of my neck stand up. It is definitely a very wild sound, and much more welcome than car alarms.  The local coyotes are a regular trigger for the camera traps, but I have never seen one here in person until yesterday morning.  Just out our kitchen window, trotting smoothly across the hill up behind our neighbors house, was a healthy looking red coyote.  The neighbor had mentioned seeing one out there a week or so ago.  This morning, it went trotting by just at the opportune time my camera was taken apart for downloading pictures.  I think I'll name the coyote Murphy...

Luckily I have some images from the set up the hill, it is very nearby, and likely the same individual, or at least from the same pack.  Most of the images from that spot are black and white IR night shots, but I have one from during daylight where you can see the nice coat color.  The coyote looked a little shaggier when the photo was taken a few months ago, it looked almost brushed out now.

This individual was inspecting the camera after a curious human passer by had unsuccessfully tried to remove it from a tree, and left it at ground level.  Bushnell isn't great on the close focus, but very nice on the anti-theft options!

I do have to wonder if the coyote's new bold appearance has anything to do with the new neighbor recently letting their four coyote-naive cats outdoors.  Although cats don't make up a large part of the coyote's diet, they are not one to pass up on that opportunity.   The timing was uncanny.

Hopefully someday I'll be lucky enough to discover where these residents are denning, and attempt to get some shots like these amazing images captured by RandomTruth (Warming: incredibly cute).  Until then, I'll be happy with some nice pics of the adults.  The two sightings were both during daylight hours, so I'm hopeful for some additional color shots.

References and articles:
http://www.projectcoyote.org/
http://www.nytimes.com/2010/09/28/science/28coyotes.html?_r=2&ref=science&pagewanted=1
http://www.mnh.si.edu/mna/image_info.cfm?species_id=29
http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-079-01-0001.pdf

Thursday, June 2, 2011

Calling Quail

I've seen more quail this spring than I have in the past 5 years.  Maybe it's from all the rain this year and last.  I've seen a number of pairs or small coveys, and I'm looking forward to the next phase of fuzzy little ping-pongs running through the grass after the adults.  A single brood has been known to have as many as 28 young, and multiple broods are frequently raised communally, so that it a lot of tottering fuzz.

When I was a kid, I volunteered at the Sonoma County Bird Rescue Center. Every spring, well meaning folks would see the precocial babies running on the ground, and assume they had fallen from a nest.  Or sometimes some of the young would actually get separated from parents by the insurmountable barrier of a curb.  Folks would scoop up the entire brood and bring them to the rescue center.  All of the chicks brought in would get placed together in big tubs of cute to be raised by volunteers and staff.  I'm sure our local Wildcare experiences a similar seasonal influx.

Usually all I hear is the quick "pit-pit-pit" alarm call as the rolly polly birds dive for the bushes along a trail, or the distant "Chi-ca-go". This morning I came across a very vocal male letting the world know where he stood with an "advertisement" call.  On a fence post... at the trailhead to Smith Ridge Fire Road.

video

The other call you hear in the foreground is my son mimicking the calls, and much to his delight (and the quails possible confusion), getting answered.

Here are some still shots as he calls, and composed himself between announcements.



References:
http://www.allaboutbirds.org/guide/California_Quail/lifehistory
http://bna.birds.cornell.edu/bna/species/473/articles/introduction
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