As I write this there is a young mule deer buck in my forested backyard with two magpies sitting peacefully on his back, apparently grooming him. He seems not bothered at all, and they obviously find him a source of some kind of food, perhaps ticks?
Oops, now there are three, two on his back and another waiting its turn on an adjacent branch. What makes this unusual is that magpies normally avoid our forest. We see them in a more open area perhaps 200 yards down the road, but not here.
It seems clear the deer is the attraction bringing these large, slightly clumsy birds into the aspen forest. There appears to be no open wound on the deer's back and he's happily foraging on aspen leaves.
If you web search "magpies grooming deer" you will find several pictures on the Internet. Apparently this behavior is common and well-tolerated by the deer. Who knew?
I guess it works out well for both deer and bird. It's the first time the DrsC have seen it, and we've spent 16 summers sharing this forest with the deer, watching fawns lose their spots and grow.
See photos at the other DrC's blog: cruztalkingtwo.blogspot.com.