Saturday, 28 November 2009

The sitting blackbird

Given my blogging name, and my liking for the bird, I have been trying to get a half decent blackbird shot for a while. Blackbirds display a milder version of the 'berry tree guarding behaviour' I described in my previous post for the Mistle Thrush. The just sit on their chosen bush - cotoneaster or rowans being favourites - and chase away other blackbirds that come their way, but basically, they just spend a long time doing just that, sitting. A couple of years ago I witnessed the squirmishes between the sitting male and the determined female that kept skulking in the bush to feed. This was my chance, and Blackbird got the Blackbird.

Thursday, 26 November 2009

The Yew Thrush

Mistle Thrush on a Yew
A closer shot of a Mistle Thrush
The Yew tree is laden with bright red, soft berries at the end of a church garden. On top of it is a bird, with a ratchety voice, guarding the precious sweet load, a Mistle thrush. Individual Mistle Thrushes become territorial during the winter months and defend their tree of intruders, either conspecifics or other thrush species. They eat their berries economically, feeding on the ground when possible, and leaving the berries for frosty days. The tree, thus, retains its bright berries for most of the winter. Only in very cold winters, will the Mistle Thrush be unable to enforce his possessions and must relent to the flocks of other hungry thrushes that want to feed. They are seen to defend Ivy berries, Mistletoe and, preferentially Holly trees.
Yew Berries. The only non-toxic part of the tree is the red aril surrounding the seeds, which thrushes help disperse.

More information

Barbara Snow & David Snow (1982) Long-term defence of fruit in Mistle Thrushes, Turdus viscivorus.  Ibis, 126: 39–49. doi: 10.1111/j.1474-919X.1984.tb03662.x

Friday, 13 November 2009

Dancing Gulls

I went for a long walk the other day and passed next to some grassy sport grounds. Several Herring Gulls and a Woodpigeon were on it. The Woodpigeon and some of the gulls were lazily dozing on the ground, enjoying the early morning sun. Two of the gulls were doing something more interesting. They were patting the ground moving their feet rapidly, as if running on the spot. After a little while, they stopped and looked into the grass intently, only to start their tap dance-and-watch sequence all over again. Their sustained interest indicated this behaviour was related to obtaining food. Occasionally they pecked the ground, but if they caught something it was small and I coudn't see it. In any case they did not seem to catch any good size earthworms. I took some photos and a very poor quality video. Yesterday I saw the same thing in the local park grass, but this time it was a Common Gull. I got a few answers in The Last Word, the Question and Answer section in the New Scientist. I also found some better quality than mine:

Here, the gull is seen actually catching a couple of worms. It is quite an intriguing behaviour reminiscent of the facts behind the World Worm Charming Championships, which take place in the village of Willaston (Cheshire, U.K.) since 1980. Participants must encourage worms to the surface of the ground by vibration means only (no digging allowed!). The current record is impressive: 567 worms in 30 min from a 3 sqm plot. I was also wondering if the gull behaviour arose when they feed in puddles in the beach and when adopting it on grass, found by chance it actually encourages worms to surface. I can only say, Blackbirds, learn!
Common Gull checking for the effect of its dance