Sunday 20 December 2009

Woodpigeons



Woodpigeons fill their crop with large meals and then they spend long periods resting and digesting.
I have recently discovered Woodpigeons' love of berries. Partly through reading a treasure-trove of a book "Birds and Berries" by Snow and Snow (1988), which I recommend to any bird-watcher. Since starting reading it I see things I missed before, just by paying more attention and 'expecting' things. While they carried out their detailed research on the interaction between berry-producing plants and berry-eating birds of the British Isles, the Snows discovered that Woodpigeons actually disperse many berry seeds. It was previously thought that pigeons crushed seeds in their muscular gizzards, together with grit they ate, and therefore acted as 'seed predators'. Although this can be true, it likely depends on the diet of the pigeon. Woodpigeons feeding on berries apparently do not ingest grit and many, if not most seeds are found intact in their droppings - and some at least have been proven to germinate after this. The Snows documented 711 bouts of berry feeding in Woodpigeons in 10 species of native plants. More than half of these were on Ivy (a total of  476), and many in Haws, Elder and Holly. Woodpigeons took both ripe and unripe Ivy and elder.
  I have been watching Woodpigeons feed on an ornamental hawthorn and a Cotoneaster near to where I work. There are a couple of sibling juveniles that feed on them and they are very funny to watch, doing acrobatics to reach the berries.
This one is almost upside down.
Ornamental Hawthorn berries

Tuesday 8 December 2009

December songs

Spot the Blackbird subsinging
The sun shone today, a mild December day. A couple of Blue Tits busily searched through the thinner branches of the lime tree in front of the house, while a Great Tit sang enthusiastically between feeding on the trunk and thicker branches.
Later in the day I heard the beautiful, melancholic phrases of a Robin singing. Robins, being territorial, sing almost year round. And then, a mystery song. Quiet, almost whispered twitter coming from well inside a bush. I searched, a male Blackbird, hiding, singing to himself. During spring and summer, Blackbirds sing proud from top of trees, buildings, aerials - which must feel like singing from the top of the world for the Blackbirds of Hull. Somehow the birds in winter have this desire to sing, but cannot/won't do it in its usual way. This song is called 'subsong' and it is not completely understood why they do it. Some people argue it is the start of territory defence, with pair starting to form; others argue the birds are  practicing, as it can happen from young birds. It usually happens when there is plenty of food, and some time to spare, and what better to do with your time than a bit of music?
A singing blackbird in May

Tuesday 1 December 2009

Magpie Roost

The last few days in the afternoon I've spotted one or two Magpies in a tree in the street. Not that Magpies are not common around here, a few weeks ago there were no less than eight on a tree nearby - apparently the collective name is a 'tidings' of Magpies, bearers of good news.
It just called my attention every time they were in the same tree, an almost bare Maple. Today that happened again, so I went out when it got dark to check the tree. A full moon night, and there! the black and white bellies of two roosting Magpies!

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