Showing posts with label forensics. Show all posts
Showing posts with label forensics. Show all posts

Saturday, January 29, 2011

CSI West Kennebunk

A couple of weeks ago I wrote about finding evidence of a large bird having landed near some of our feeders and wondered if a hawk was haunting the area. These suspicious were confirmed last weekend. 

Around noon on Sunday, January 23, I looked out a second-floor window onto the feeding area and saw more marks made by large wing feathers in the snowbank; they're barely discernible in lower center right of this shot [click on it to bring up a larger copy of the image]:


Here's a close-up shot, taken from ground level:


Once I got a good look at the wing marks I began searching for further evidence. There was nothing right there under this feeder, but back up on the path  in front of the house there was plenty of it--lots of feathers in the path and in the snow banks:





There was one largish feather sticking out of the snow in a bank near the house:


I dug around it a bit and quickly uncovered a small trove of others:


Judging from the color, and the spots on some of them, I think the victim was most likely a Mourning Dove. Of which there are plenty around here. The photo on the Cornell site shows feather spots like quite clearly.

I kept looking around for more evidence and noted an odd depression in the snow on the opposite side of the path, on the lawn. I trudged through the knee-deep snow to get a better look and was rewarded by finding a very clear imprint of a large bird:


He or she came down facing the house, and had probably approached from one of the trees in the middle of the front lawn. I didn't think to measure the print but the most likely culprit was a Cooper's Hawk. It was definitely much larger bird than a Sharp-shinned Hawk like the one that crashed into the house in late December.

After gathering what evidence I could I made mental plans to do a blog post about what I'd found, but before I had the chance to do so the hawk struck again! On Wednesday afternoon, about 3:15, I again looked out at the feeder area from the upstairs window--I check the area frequently to see what visitors we're hosting--and saw what looked like a couple of feathers underneath the large bottle feeder. I went out to investigate, and, sure enough, it was a small tuft of feathers, this time with a bit of bloody flesh attached. These had a reddish tinge to them, so I suspect that a female Northern Cardinal was the victim this time. 

I again walked back towards the front of the house and again found the marks of large wings in the snowbank. [NOTE: The late-afternoon light was very poor for taking pictures so I've cranked up the contrast in this and the following shots to exaggerated, grossly unnatural levels in order to bring out the detail.]:


I went back in the house, thinking that I'd seen all that was to be seen, but when I looked out a second-story window at the front of the house I was surprised to again see a strange imprint in the snow. I went back out, camera in hand, and again trudged through the deep snow to get a better look. There, not ten feet from where the earlier imprint had been, and in much the same orientation, was clear evidence of another crash-landing by a large bird:


I don't quite know how to interpret the marks up near where the head was; it almost looks as though a Pterodactyl was here! The bird must have been thrashing around and those marks are tracks left by its beak.

This time I had the presence of mind to bring out a tape measure in order to give some sense of scale:



Again, click on the images to bring up a larger copies and to make the numbers on the tape readable. The spot where I placed the end of the tape was probably not where the top of the bird's head actually was, so the reading of 24" is probably too long. The Sibley guide gives 16.5" as the average length of a Cooper's Hawk; the Cornell site gives 14.6-15.4" as the average length for a male and 16.5-17.7" for a female -- females of most raptor species are generally larger than the males. If my bird really was nearly 2' long from stem to stern, that would suggest a Northern Goshawk. Not impossible, but Goshawks are birds of the deep woods. Unless and until I actually get a good look at our local predator, I'm going to assume that it's most likely a female Cooper's Hawk.

Since finding the second set of evidence I've been more vigilant about monitoring activity outside the house. So far there's been no further sign of the hawk. Thinking back, however, I recall that on the day before the second kill I'd noted some odd behavior from a male Hairy Woodpecker. Hairys are a nearly-constant presence at our suet, so it was not at all surprising to see one clinging to the tree just under one of the suet feeders. What was surprising was that when I checked again, several minutes later, he was still there, in nearly the same spot. I made subsequent checks over the course of several minutes, and though he moved a bit, he never got far from the position in which I first saw him. It was almost as if he was frozen to the tree. I finally went out to check on him, thinking there might be something wrong with him, but upon my approach he flew away very quickly. I wonder now if the "frozen" bird was adopting that posture to avoid being spotted by a hawk?

Thursday, January 13, 2011

Winter

This is the first full winter we've spent in the Maine house, so we've been anticipating some new visitors to the feeders and woods. So far, though, we've mostly had the Usual Suspects. There have been, and still are, a few Tree Sparrows around, and a couple of Red-breasted Nuthatches have been here semi-regularly. There seem to be more White-breasted Nuthatches than usual--I've seen as many as four at one time.
They're always fun to watch, but because the Red-breasted are less common around here it's always more of a treat to see them. After not seeing many Goldfinches for awhile, they've come back in fairly good numbers. Even in their subdued winter plumage they're lovely little things. It's great to have plenty of Juncos around, and there also seem to be a few more Blue Jays than we've had in the past.

Although there's pretty constant traffic to the suet feeders, we aren't replacing the cakes as often as we were a few months ago. Hairy and Downy Woodpeckers are around most of the time, helping themselves to the suet, but Black-capped Chickadees, Tufted Titmice, and even our resident Crows patronize the suet at different times. 
 Today I saw a single Common Redpoll, probably a female, but it did not seem to hang around long. Odd to see just one, since they seem to be quite the flockers. We had quite a few here in February of 2009, along with a few of their Hoary cousins, but saw none at all last year. Apparently this is not unusual; the info on the Cornell site indicates that they typically are seen in the northern U.S. every other year.

In the meantime, other folks on the Maine bird list are reporting lot of Bohemian Waxwings, White-winged Crossbills, Evening Grosbeaks, as well as Redpolls in various parts of the state. I hope that some show up here!

We have had a bit of avian excitement here, however. We got our first substantial snow of the winter just after Christmas, on December 27, to be exact. It was not a huge storm, but we got maybe 8" or so. As I was shoveling off the back deck that morning I was surprised to see a lot of feathers sticking out from under the snow. I brushed the snow off with my hands and was astonished to find not just some feathers, but an entire Sharp-shinned Hawk buried there, quite dead, and quite frozen!


It appears as though he broke his back. He was lying on his back when I found him. He must have run into the house, presumably in pursuit of a smaller bird, and perhaps confused and with his vision impaired because of the snow. The snow began sometime in the late afternoon the day before, and the collision must have happened soon after it started; he was completely covered by the snow. One odd thing about this is that we've never happened to see a Sharp-shin around here before. There's been one [or more] Cooper's Hawks around on occasion, and certainly Sharp-shins are not at all uncommon, but we'd just never seen one in the yard before.

So, now that I have this hawksicle, what am I to do with it? My understanding is that it's illegal for individuals to possess specimens of migratory birds [and I trust that nobody who reads this will bust me!], so I'd love to find a good home for him/her in some educational program. I offered the hawk to Wells Reserve for their education programs, but got a polite turn-down. Meanwhile, he resides in our freezer, in a very large zip-loc bag. 

We may have had another hawk in our yard early this morning. Yesterday was our heaviest snowfall of the winter. White stuff came down all day and there were still some flakes in the air when we went to bed last night. This morning, though, all was clear and we had a bright, sunny day. When I first peered out the bedroom window this morning into the yard where most of the bird feeders are, I was pleased to see all the tracks in the snow from all those Early Birds we always hear so much about.



All of these marks were probably made by the Chickadees, Juncos, Jays, etc. that feed here all the time. But I was puzzled by another set of marks nearby:

That claw-shaped mark in the left center of the shot was particularly intriguing [click on the image to get a larger copy of it]. It wasn't until later in the day, after we'd shoveled out the paths to the feeders and thus disturbed some of these marks that it finally hit me what that was--the pattern of the primary feathers on the end of a bird's right wing! A fairly sizable bird at that...possibly a Crow, but more likely a hawk of some sort. There's no obvious evidence of a kill, but there's certainly lots of other markings there in the snow. That hook-shaped pattern in the lower part of the shot is curious, and is something I still haven't quite figured out. To the right of center there is what could be marks made by the large bird's left wing. I regret that I did not tumble to what I was seeing sooner than I did, or we could have given the site a more thorough examination, with an eye to gathering forensic evidence, than we did!