Monday 3 February 2014

Sparrowhawks and Magpies

I have a post about fungi and foxes in the works, but I want to write about something I saw a few days ago in my garden. There was a sudden commotion of birds outside, with flocks of small birds bursting out of the trees and Rooks and Black-headed Gulls swirling up above, and then suddenly a large, brown Woodpigeon-sized blur whooshed into the garden at top speed and disappeared into one of the trees. The garden was suddenly empty of birds, and that made me almost certain that the blur that arrived wasn't a Woodpigeon (well, that and the speed it arrived at!), but a Sparrowhawk!

I kept watching, and sure enough a female Sparrowhawk soon hopped into view, and sat in the tree. I expected her to leave pretty quickly, but she actually stayed about 2 hours. She was left in peace for a little while, and then all of a sudden a pair of Magpies arrived in a flurry of tailfeathers and landed in the same tree. Magpies are an unusual visitor in my garden, probably more so than Sparrowhawks, but they are the corvid that currently visits most often.

The Magpies began to hop around the tree, not getting too close to the hawk but obviously intending to bother her. They were fluffing their feathers, flaring their tails and making sudden movements. They were also hitting the tree branches with their beaks, especially when they were near the hawk. I kept trying to convince myself it was a feeding behaviour but the longer I watched the more it seemed like a sort of intimidation tactic aimed at the Sparrowhawk, as if saying 'look how sharp and powerful our beaks are and how strong we are!' I later saw a Magpie sitting on another tree pecking the ends off branches, but that time it was clearly picking something off the tree (early buds? Who knows but anything's possible this winter!), and this was different from the branch hammering. Has anyone else seen Magpies pecking branches as an intimidation tactic? I may be totally off with this theory. ^^

The Sparrowhawk didn't budge at all, but kept turning her head to keep an eye on the Magpies, occasionally preening or tucking her foot into her breastfeathers. It was interesting to see how the Magpies avoided going close to her, and it made me realise I'd never seen a mobbing situation happen in a tree before, only in flight. I knew mobbing in trees happened because it's a known method for finding roosting owls, as you can see smaller birds making a commotion around the area in the tree where the owl is. I've heard Jays making an appalling screeching at Tawny Owls before (didn't see either of them but heard some irate hooting!), but never been able to see the mobbing actually happening. It was very interesting to see a tree mobbing incident.

I've seen in-flight mobbing many times (though I believe I've only written about it once: the Sparrowhawk mobbing Goshawk incident in Germany), and seen crows and Rooks mobbing Buzzards all the time at my patch, and the corvids often fly daringly close to the Buzzard, even provoking it to swing its talons so they have to dodge out of the way. I'm sure birds of prey do occasionally manage to kill birds that are mobbing them, but it's clear that being in flight means the birds can use their maximum flying agility to dodge. But perched, they are at a high risk of the hawk suddenly scratching with a talon and inflicting a dangerous wound that could potentially be fatal. It's a similar principle to why Red Deer avoid attacking each other with their antlers during the rut unless they have to-when there's sharp objects involved, it has to be really, really worth it! I'm sure that's why the Magpies avoided going too near, even though the hawk wasn't moving at all.

The Magpies stopped trying after a while and left, and the hawk was sitting as tight as ever. The small birds were starting to regroup and were all keeping an eye on her; flocks of Chaffinches, Goldfinches and Chaffinches and the Blue Tit pair were all watching that Sparrowhawk with caution, as well as a Grey Squirrel that had begun to climb into her tree but turned back quickly when it spotted her!

Then suddenly the Magpies were back, but they'd brought reinforcements in the form of two more Magpies. A fifth one was also at the back of the garden- this was more Magpies together than I'd ever seen in my garden before! The four Magpies continued to bounce around the tree, trying to intimidate the hawk. At one point they all flew back to join the single Magpie in the back tree, before suddenly flying back to the hawk's tree in a rush, as if trying to intimidate her with numbers, which was comical to watch. The hawk continued to sit tight, until she seemed to become fed up with being surrounded by Magpies. She made a sudden movement, jumping from her branch to an upper branch, and the Magpies scattered. What's more, they did not return. Their hassling had had no effect, but the Sparrowhawk had got rid of them in one swoop!

Magpies are confident, bossy birds and it was interesting seeing them be intimidated in this way. I don't know why the Sparrowhawk wanted to sit in our garden, whether she was digesting a meal or thinking of doing some hunting, but whatever it was she obviously didn't feel like being bothered. As far as I know my garden isn't part of Magpies' territory (or if it is, as I've said before, they don't visit my garden very much- I don't think they like that it's quite a confined space), so I guess they decided it was too risky to continue their attempt to shoo her away. If you have any stories of Magpies or other corvids bothering predators, whether the corvids persisted or were driven away by the predator, please send me a comment or email me and tell me all about it! :)

I wrote before about a female Sparrowhawk visiting the garden but I don't think it was the same bird as I saw a few days ago. The bird the above post is about had a little orange-red barring on her upper breast instead of the usual dark grey female barring, while the bird from last October had only dark grey baring. Male Sparrowhawks have orange-red barring all over the breast, and I have seen a few females with a little reddish barring too, but have never seen this explained in a bird book. Its impossible for the birds with a little reddish barring to be males because females are so much bigger. Does it mean these female birds are first-winters? That's the only thing I can think of but it seems wrong somehow, because why would young female Sparrowhawks moult into a brighter plumage before getting their adult feathers? It's possible there's no reason for it and it's just natural variation. If anyone can confirm either of these or knows the real reason, please do contact me. I'd love to find out more.

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