Handiwork of a hunter

On my way from the second den site to the feeding location, the trail that I was following went down a rocky slope to a little creek, which the hemlocks were growing beside. Though the rocks were covered with snow, the slope was still steep, and the hard crust made footing uncertain, so I was keeping an eye on my step and not really paying attention to the surrounding woods. About halfway down I noticed a feather that had blown across my path. I stopped to pick it up; it was pretty, so I took a photo. Then I noticed another, and took a photo of that one, too. Then a couple more. As I looked, I realized they seemed to be originating from the top of the slope I’d just started down.

I climbed back up (just a short distance, a few feet), and discovered, at the top of the rocks, probably less than 2 meters (6 feet) from where I’d been walking, this mess of feathers left over from somebody’s meal. How I missed that, I don’t know. I was really focused on finding out where that porcupine went, I guess.

I identified the victim as a Ruffed Grouse by the tail feathers, whose thick, dark band is characteristic of the species. This was not a surprising find for me. On my walks in the 100-acre woods, as well as farther back from our house in the woods behind our back fields, grouse are the number one bird species I encounter. I don’t come across many, but I still have more meetings with them than I do with anything else, and that includes the ubiquitous chickadees.

I checked out the feathers for evidence of damage caused by the predator, either tooth marks from a mammal or crushed quills from a raptor, but couldn’t see anything definitive. I was about to just leave and label it “unknown” when I noticed the above: a very clear, very distinctive bit of whitewash that had blended in with the snow when I first examined the scene. The poop would have been left by the predator as it departed, and very clearly eliminates a mammal from consideration. A number of raptors will take grouse if given the opportunity, but the grouse’s biggest threat comes from either Great Horned Owls or Northern Goshawks, which probably account for the largest proportion of adult mortality.

There are a few reasons that I think this is a hawk kill and not an owl kill. The first, and primary one, is simply that the bird was plucked. Goshawks always pluck their prey, but I’ve found mixed reports on whether Great Horns do or not. Online there seem to be some references to the behaviour, but nothing consistent. I couldn’t see anything in the Birds of North America (BNA) account on the species indicating whether they do or don’t, although it does note that the Great Horn “Dismembers larger prey before swallowing… Dismembers larger mammals and birds with feet and bill; swallows the pieces. Generally discards head and feet of larger prey.” Nothing about plucking.

The way the poop is a line rather than a blob also suggests hawk to me, although I admit I have no experience with how owl poop looks when the bird is on the ground, not on a branch. I also don’t know whether owls defecate as they depart; I don’t recall ever having seen the behaviour in owls, though I have occasionally seen it in hawks. This may simply be a function of the greater frequency of observing hawks than owls. Third, though Great Horns will hunt in the forest, the BNA account suggests they prefer open areas, either woodland clearings, forests with open understories, or forest edges for hunting. Goshawks, meanwhile, are quite at home in denser woods. Although I wouldn’t exactly call the woods there dense, neither are they especially open. Finally, according to the BNA birds only make up about 10% of a Great Horn’s diet, on average, while they compose a much greater percentage, in some studies up to half, of a goshawk’s. Interestingly, the illustration in the goshawk account of hunting behaviour showed a goshawk chasing two Ruffed Grouse through the woods.

I don’t know if it’s possible to know for certain who the hunter was. I know there are Great Horns around here, but goshawk isn’t an impossibility – they’re uncommon but present year-round throughout most of Ontario. They were recorded in the square immediately north and the one immediately east of us, as well as others in the area, during the recent Ontario Breeding Bird Atlas. And I actually thought I might have seen one cruise by the house one day a few weeks ago, but it was gone before I could get a good look.

I was amazed by the variety of patterns present in the feathers, and I took photos of many, all so beautiful. Can you figure out where on the bird they’re from? Here’s a tip: the ones with the squared off ends usually tend to be breast/belly feathers, while the ones that are longer and more rounded are typically from the back and shoulders.