Roughie caching

I'm aware that many species cache food and I have witnessed it in woodpecker, titmice, chickadees and great horned owls and more.

Yesterday Ron Dudley and I happened across what appears to be an "open" larder for a Rough-legged Hawk, which I found interesting and thought I would share. I apologize in advance for the image quality not being up to my normal standards, this Roughie was nervous in our presence and did not allow a close approach, so the image with the roughie in it is a large crop, it is only 25% of the original image.

In the first image the roughie was on the metal post, by the feet there are two rodents.

The second image shows those same rodents on the post, the roughie was approximately 20 feet from the post but on a different perch. This image was taken one hour 5 minutes after the first image.

The third image shows just one rodent on the post, it was taken 39 minutes after the second image. The Roughie was not visible at the time the third image was taken.

I'm not sure this is caching, though it most likely is. I had not seen this behavior in Roughies before.

Image #1

Image #2

Image #3

Very interesting Mia, thanks for sharing.

With the seemingly high density of raptors in the area though - I'm surprised it would leave its hard won food out in the open. Couldn't a Harrier or Red-Tailed swoop in and steal it?

- Luke

Thanks for posting that, it's fascinating. I did a little research, and I did find a reference to Broad-wings caching, but I didn't find any other Buteos.

If you can find anyone to listen, this should probably be submitted as a field note to somebody. I feel hypocritical saying that, as it has often been said to me, and I have never done so.

Mia -

I forwarded a link to your posts to NPN member Ted Swem. Ted has done the definitive studies of breeding Rough-legged Hawks along the Colville River on the North Slope of Alaska. He might disagree, but I regard him as the most knowledgeable person in North America on Roughies. Here's his response:

The BNA species account for rough-legs says "caching not reported." I can't remember offhand whether or not I've seen them cache prey on the Colville near nests. Many raptors do, but offhand I can only remember seeing it in falcons and owls, not buteos. I'd guess that they sometimes do it near nests, but I can't remember seeing it now that you raise it. They certainly stack up uneaten prey in nests, but that's not really caching.

The behavior photographed probably doesn't qualify as caching. I think caching implies that the bird takes the prey to a location with the intent to leave it, often involves some degree of hiding it, and presumably also is done with the intent that it will be retrieved later. In the case of the voles on the fence posts in Mia's images, we can't know if it intended to retrieve them later, but I'd guess that the bird just took the prey to the fence post to eat and then just didn't finish eating the whole thing. Presumably, there was an abundance of readily available prey, and it caught slightly more than what was needed. The mechanisms that cause a bird to quit foraging when it's full are probably a bit imprecise at times, and this might just have documented some of that slop. I'd guess it took the prey to the fence post to consume it, then either got too full to finish it or ended up leaving less desirable portions of the vole after eating the more desirable portions. Some work in Ohio showed they nearly invariably take prey to perches to eat, and 46% of those observed used fence posts as a platform for eating.

So, I'm not sold that these photos document caching. To use that old expression, probably its eyes were just a bit bigger than its stomach (or crop, in this case).

My thanks to Mia for interesting documentation, and to Ted for taking time to answer the question.

Jim,

Thanks for sending the link to Ted and for his response on these images. If I witness some thing like this again with Roughies or any other buteo I'll be sure to document it!