February 27, 2017 at 7:52 am (birds, geology, mammals)
Tags: Berberis thunbergii, great horned owl, hooded warbler, Japanese honeysuckle, kame, St. James Farm, tree cavity, whitetail deer
by Carl Strang
This has been a relatively slow winter at St. James Farm Forest Preserve. There has been little snow, so my tracking has been limited. Coyotes have been covering the preserve, and the relatively few deer tracks have not revealed a consistent pattern. That in itself suggests buck group, and eventually in January I saw them: a huge buck, a good-sized but clearly subordinate forkhorn, and a newly minted buck fawn. Since that first sighting, I have spotted them twice more in widely separated parts of the preserve.
The boss buck
As I mentioned in an earlier post, the great horned owls’ nest tree of last winter was a casualty of the autumn’s controlled burn. My practice is to wait until mid-February to do the annual nest search. I had my inventory of candidate cavities, made last winter, but it didn’t take long to find the incubating female on last year’s red-tailed hawk nest. In a related note, I spotted a newly available candidate cavity along one of my monitoring routes. The top of an old oak recently broke off, leaving an open top of sufficient diameter that great horneds might consider it. A forest this old probably has some equilibrium of candidate cavities as old ones are lost and new ones form.
The new candidate nesting cavity
With that task out of the way, I decided to see if I could find a little nest in the area where the hooded warbler had his territory last summer. He has been a regular there in recent years, but as far as I know, no one has seen a female or young. I found that his territory has scattered bush honeysuckles and lots of Japanese barberries, bad for forest quality but probably good from the warbler’s viewpoint. Descriptions of hooded warbler nesting suggest that barberry would be an ideal platform. I didn’t find a nest, and ended the search when I found a dense thicket of barberries, with a few multiflora roses mixed in, at least 100 feet in diameter, worthy of Brer Rabbit.
Part of the thorny tangle
As I circumnavigated this patch, which is in a part of the forest with relatively dramatic surface relief, I noticed a few tipped trees whose fall had turned up rounded stones in the soil.
Rounded stones exposed by a tipped tree’s root tangle
This suggests that the preserve’s forested hills may in fact be kames, places within the melting continental glacier where the meltwater piled its flow-rounded stones into mounds. St. James Farm is very close to the western edge of the Valparaiso Moraine.
May 12, 2011 at 6:01 am (birds)
Tags: eastern bluebird, imprinting, Morton Arboretum, nesting, purple martin, tree cavity
by Carl Strang
I was taking a walk at the Morton Arboretum a couple days ago when a male bluebird landed in a small tree nearby.
He allowed a close approach.
Soon his mate appeared.
Females look similar, but their colors are not as bright.
They were going in and out of a natural tree cavity.
The cavity was big enough that the bird completely disappeared when entering.
This was exciting, for me. I have been concerned that bluebirds may be going the way of purple martins, recognizing only bird houses provided by people as suitable nest sites. This pair may or may not use that cavity in the end, but the fact that they are considering it is a positive sign. They, at least, have not irreversibly imprinted on nest boxes as candidate nest sites.
April 6, 2010 at 5:53 am (mammals, methods)
Tags: canine distemper, Mayslake, raccoon, tracking, tree cavity
by Carl Strang
Recently I was in the South Savanna at Mayslake Forest Preserve, making a photographic record of a tree cavity at the broken top of a living red oak. That hole had been a candidate for the great horned owl nest, but I finally concluded it was too small.
Nearby I found another cavity I hadn’t noticed earlier, in a dead red oak.
Something was stuck to the edge. There were a few tufts of fur, the size, color and coarseness of raccoon hair.
There were just a few toenail scratches on the trunk. These were fresh, and with a raccoon’s size and spacing, but too few to indicate regular use of the cavity as a den.
Furthermore, there had not been a raccoon trail leading to that tree. Such a trail would be present at a frequently occupied den tree. However, not too far away I found this:
The raccoon had not been there the last time I’d been through that area, a day or two before. It had no marks of injury, but the face seemed contorted by a snarl.
My best guess is that the animal died of canine distemper, the most common disease of local raccoons. That illness affects the central nervous system, resulting in disorientation, clumsiness, and facial muscle spasms. Perhaps the raccoon was strong enough to take refuge in that nearby tree cavity, spending some days there as the disease took its toll. Eventually, near death, it managed a final rally, clumsily exiting the tree and losing some hair in the process, perhaps falling to the ground, perhaps taking a final drink from nearby May’s Lake, and dying as it attempted to return to its shelter (the body was facing the dead oak).
All of this is speculative, but the tufts of fur were gone from the cavity within two days, which further associates them in time with the raccoon’s death.