While stalking on Friday morning, I found myself high up on a steep face of granite and heather overlooking a single sitka spruce tree. This ground was all burnt out in 2012, and the scorched tree is now little more than a black gallows in a world of fresh young heather and blaeberry. A crow’s nest was easily visible in the top of this tree, and as I watched, the occupant dropped off her nest and flew noisily into combat with a gang of seven immature crows which had come drifting off the moorland margins. Her partner joined her, and the two of them took part in a vicious aerial exchange which ultimately saw off the youngsters. Ten minutes later, a buzzard was battered into submission by these two extremely territorial birds, and when a raven passed by, it was also hounded out of sight. I watched them for an hour, and I can honestly say that I’ve never seen a gamekeeper do such an efficient job of seeing off corvids.
It occurred to me that having this breeding pair on the hill could potentially serve as an excellent natural predator control mechanism. As long as they had a vested interest in keeping other birds out, the local grouse only had to worry about one pair of crows. I had made a note to destroy the nest while I was on the hill, but then I started to waver. Without eggs to protect, these crows would allow open access for all other predators and the net effect of removing the nest might even be negative. Perhaps they were serving an important purpose.
That was until I remembered that territorial breeding crows are without question the worst egg thieves of all. Studies have shown that the huge majority of nests are raided by dominant, territory-holding birds which acquire the skills to find sitting birds over many years of practice. Juvenile crows certainly eat eggs, but they are so much more transient and nomadic that they rarely spend the time looking for nests or hunting like their mature peers. On balance, I think it’s safer to have a dozen young crows on the hill than a single pair of territorial birds, and my mind was made up when I finally reached the bottom of the tree and found shards of grouse egg scattered across the moss.
Like a black bear, I clumsily hauled myself up thirty feet into the dry old branches until I reached the nest, pushing it out from below and catching a single egg as it fell from the densely packed pad of roe hair and sheep wool. I carefully opened the shell and found that the clutch would have hatched within a day or two. Seconds later, I slipped calamitously and the other three green eggs fell out with a clatter onto the stones below me. As I had been in the tree, one of the pair had come to call loudly in protest, and it circled high up above me on the edge of sight.
It’s not a very nice job and it would have been good to have caught both of them in a trap before disposing of the nest, but this is such a remote, obscure spot that I can only do what is possible with limited time and resources. It may be too late for them to sit again this year, and at least it’s an improvement to ensure that they are not raking the heather, looking to feed four extra hungry mouths over the next few weeks. And if they do sit again, their chicks should be so late that the grouse will hopefully have grown up enough to be out of harm’s way.