Wednesday, 21 May 2014

The female Tawny Owl flew into the lime tree where she parks her owlets during the day, carrying prey. She had mangled it severely, so it was hard to tell what it was, but probably some unfortunate fledgling. No sooner had she arrived than a Jay flew in and started screaming at her, so she moved to the adjacent plane tree, as seen in this picture.

When things had quietened down she returned to the lime tree and divided the food among her three owlets, which were making a tremendous noise in anticipation. Two of them were perched together. First the one at the back was fed ...

... then the front one. Their mother was hidden, and all you could see was the leaves moving as a large bird swept through them.

The male Little Owl was in the chestnut tree where the pair's nest is.

Not far away on the grass, a Magpie was feeding one of its young, which is on the left of this picture. They don't look much different from adults except that their tail feathers are not grown to full length.

There is a heavy growth of green water plants around the Coots' nest near Peter Pan, and the Mute Swans brought their cygnets to eat it. The Coots were alarmed by this intrusion, and the male bravely sallied out and attacked the female swan, who drove him off with one peck.

These Coots have lost their chicks, almost certainly to gulls, but still have some eggs left to hatch. However, any subsequent chicks are likely to go the way of the first lot. It was a rotten place to build a nest.

The people at Bluebird Boats report seeing a lot of dead and dying crayfish -- in the boats they get a good view straight down into the water. The last time this happened was in 2008 when workmen cleaning the Diana fountain accidentally flushed water contaminated with algicide into the lake; this killed all or almost all the crayfish, as well as the tiny Daphnia that play such a vital role in keeping the water clean. It's not clear what has happened now.

They have found dead crayfish in their boats, dropped in by gulls. And where they find them, they also find these mysterious little whitish oval objects, usually two of them. They appear to be made of something like bone or shell, and are about ¼ inch, 6 mm, along their long diameter.

Does anyone know what they are? Sorry about the low quality of this picture, which was the best I could manage without a close-up lens.


  1. Hi Ralph,

    I saw this response to an old question on a website by someone called ATP-Man, I was wondering if the photo was of the calcium tablets they mention. I also understand that after they have moulted the crayfish will hide and stay still until the shell has hardened some have thought theirs had died not sure if this is what is happening. I guess that they are also more susceptible to the birds while their shell is soft. I am no expert so this is possibly totally wrong just a guess. Keep up the great work with the Blog.

    "Crayfish contain an exoskeleton which means it needs to get rid of it in order to grow in size. This is called molting. If the food is abundant they will molt several times quite often early in life. The crayfish hides and crawl out of its exoskeleton through a slit along its dorsal surface. It will and wait for a while until the new skeleton hardens.
    In preparation for molting the crayfish withdraws most of the calcium from its shell, and stores it in two white "tablets"in the sides of its head. Calcium is a major hardener in the crayfish shell, as it is in strong human bones and teeth."

    1. Thank you very much for this fascinating information. What a remarkable process.

    2. Never seen or heard of this process before, quite interesting.... after a bit of Googling I found this site that would seem to concur Chris Hinton's comments...

    3. Also found this interesting article

    4. Thanks. Will look at these.

  2. Hello Ralph I got a decent shot of a reed warbler at The Lido.

    How can I send it to you?

    John Mealyer

  3. Hi Ralph,

    Do you think it is eutrophication which is happening in the serpentine? And which party is monitoring the quality of the water body of Royal Parks? Eutrophication can directly lead to death of fishes and crayfish.

    1. I think the Serpentine is in reasonable shape. There is a certain amount of nitrate and phosphate runoff from the surrounding grass -- which could be reduced if they stopped dumping leafmould on it. The lake gets algae and the hair-like plants whose name I have forgotten because it's shallow, and a few days' sunshine warms it. As for monitoring the water quality, I think this is restricted to occasional panics, for example before the Olympics, when the management suddenly hire quacks such as Plocher and Phoslock to dump magic sludge in it, which is totally ineffective. The things for bubbling air through the water probably reduce the amount of oxygen overall, because they stir up sludge from the bottom. But, as city lakes go, it's not too bad -- far better than the St James's Park lake, for example.

    2. Thanks for the analysis! The Amey people told me that they call it XXX pond weed and they remembered the 2008 incident saying during that incident people put air lines underneath the water. Is it that they have left the air line in the lake and working ever since?
      I have seen a group of four chicks of Egyptian Duck resting at the lakeside with no parents around. I stood there for about five to ten mins eventually the mother duck came back and alarmed her chicks to swim away from my staring. This intrigues me a lot. Does mother duck normally dump her chicks for a short period?

    3. Egyptian Geese seem to vary. Some are as vague as Mallards, some are as vigilant as proper geese. You'd think that the natural selection caused by this would have made them cleverer and cleverer, but evidently not. Reversion to the norm, I suppose.