Four families of Blackbirds today, a good number. After an influx of Blackbirds last autumn, numbers seem to be holding up, so the rapid decline in population that has affected this park uniquely may be arrested or even reversed. One of the families was enjoying the dark red plums on a tree beside the little path that leads down from the Triangle car park to the Serpentine. Normally people pick these plums, which are small but tasty; but this year they are behind the Olympic barrier and only birds can reach them. There was a Song Thrush in the same tree.

Here a female Blackbird emerges from the shrubbery to have a rest from feeding her young and attend to her feathers. She is well camouflaged among the leaf litter.

One doesn't normally think of Grey Herons as birds that use camouflage: their way of remaining unnoticed is to stand stock still. But here are three herons in the fallen horse chestnut tree in the Long Water, and they are remarkably difficult to see.

Both families of Great Crested Grebes at the Serpentine island are doing well.

They will probably have to move when the wild rumpus starts on the lake. There are now plenty of small fish in the Long Water, but they will have to take the territory of the pair near the bridge who have not nested, but are behaving quite fiercely -- see yesterday's picture. The grebe nesting on the fallen poplar bravely remained on her nest yesterday when the man operating the weed-clearing machine came recklessly close to them, and I am glad to say that the pair are are still there today.

The family of Greylag Geese were efficiently begging for food at the Lido restaurant.

Note: Elizabeth mentioned yesterday that she had rediscovered how to enlarge the photographs on this blog for a better view. For any readers who don't know, all you have to do is click on any picture. You will be taken to a page with a black background, and can view all the day's pictures by scrolling up or down with the mouse wheel, or clicking on the thumbnails at the bottom. To close this page and return to the text, click the X in the top right corner.

The Reed Warblers on the Long Water near the bridge have a family. I saw and heard them moving around in the evergreen trees across the path from their reed bed, and had quite enough sight of them to be certain what they were. Their scratchy calls are much as you would expect after hearing the male Reed Warbler's harsh, clattering song.

A little farther up the lake, two Great Crested Grebes were enjoying a territorial fight when a couple of Coots thought it would be amusing to join in. The grebes gave up immediately, dived, and surfaced some distance away in their respective territories. Grebe fights look savage but are actually wresting matches in which no one gets hurt. The idea is to get a grip on the opponent and hold his head under water so that he submits (or her head: boths sexes fight, sometimes two on two). Coots fight to injure, so their intervention was spoiling the fun.

The Little Owl was calling repeatedly from a tree in the leaf yard. As usual, it remained invisible. But it is good to know that this elusive bird is still with us. There has been no sign of any family, but we would be unlikely to find out if there were one.

A pair of Moorhens nesting in a well hidden place in the reed bed below the Italian Garden have just hatched five chicks, and were feeding them on the edge of the filter under the ornamental fountain.

Here is a closer shot of a baby Moorhen's curious red and blue head. It is strange that newly hatched Moorhens have black feathers and red beaks but, as they grow larger, they change to shades of drab brown all over. When adult, they become black again and regain their red beaks.

And here two bees gather nectar from an Australian bottlebrush flower (Callistemon) near the Lido.

A young Jay made an appearance in the hazel thicket at the bottom of the leaf yard. It is just growing its adult face, with a fierce painted-on moustache like a Kathakali dancer, but still has that tatty, elderly look of an adolescent bird. Birds start off grey; we end up grey.

Both families of Great Crested Grebes from the island were out on the water. Here a parent bird with young on its back is passed by the Greylag Goose family.

The two grebe families were in sight of each other and, as always when this happens, started squabbling about territory. But there are plenty of small fish and it was too hot to quarrel, so they just exchanged a few insults and threatening gestures, backed off from the borderline, and went on feeding their chicks.

Here one of the Coots at the outflow of the lake climbs up his newly made ramp. The plaintive cries of chicks could be heard echoing in the cavernous space behind, but so far they have not emerged. And why should they? They are safe from gulls and their parents are feeding them.

The Black-Headed Gull with the ring mentioned here on 18 July came close enough for me to take photographs. It was obliging enough to shift its stance, allowing almost the whole number to be seen. It is almost certainly EX63693, only the last figure being unclear because of the angle.

This is one of several gulls that Roy Sanderson ringed in Hyde Park in December 2011. If the last figure is 3, it was seen later in Bushy Park before it headed off to its breeding site, probably in the Netherlands or Scandinavia, and here it is back home for the winter.

A reminder: if you get even a partial view of a gull's ring number, please put it in the comments here and Roy may be able to tell you about it.

It was time for the monthly bird count: a pretty low total. Many birds are keeping well away from the noise and disturbance as the Olympic preparations gather pace, or have simply left. I don't know whether I shall be able to get into Hyde Park at all once the games have started. About a sixth of the two parks is now covered with construction. This is the most damaging event that the parks have suffered in their entire history.

The weed-chopping machine was on the Long Water, stirring up a good deal of mud and making the water murky. The algae here have mostly died, and have been succeeded by a true plant, a species of Najas which, although not very pleasing to look at, is purifying rather than polluting the water, and should have been left to grow to keep the water in the Serpentine clear. So, as usual, human attempts to clean up the lake are making things worse.

But amid the destruction and noise, there were cheering sights. A pair of Great Crested Grebes from the other, west, end of the Serpentine island has produced two very young chicks from an unsuspected nest somewhere behind the wire plant baskets.

In Kensington Gardens near the bridge, a young Wren was calling noisily for food while its mother explored the bushes for insects.

There was another kind of dragonfly on the edge of the Long Water. I looked it up, and it is apparently a White-Tailed Skimmer, though why this mainly pale blue insect should have that name is a mystery to me.

And in the shrubbery near the Rudolf Steiner memorial bench, a fox was taking no notice of anyone.

Update: Gino confirms that the plant is Najas guadalupensis. He also points out that cutting it up and leaving bits strewn over the water surface will cause it to spread faster.

The Moorhens in their hidden nest in the top of the willow near the bridge have at least one chick, seen here on a branch of the tree.

After I had taken this picture they climbed down from their unusual habitat and took to the water like any other Moorhens.

I need not have worried about the Coots nesting in the outflow of the Serpentine. Someone -- probably Malcolm, the Royal Parks Wildlife Officer -- has kindly made them a little wooden ramp so that they can climb out over the weir. I heard the chicks calling from inside the outflow and waited for a bit to see if any of them came up the ramp, but none did.

The Reed Warbler nearby was singing from a patch of reeds a few yards away from his usual place. In the patch where he is usually found, I thought I could hear faint scratchy calls like nestlings waiting to be fed. I listened for a while, but the noise of the park made it impossible to hear more. Will keep an ear on this spot.

The Great Crested Grebe family from the Serpentine island have now come right across the lake, where their parents were feeding the chicks on tiny fish with great efficiency. Here one of the chicks stretches out a leg, giving a good view of a grebe's unique turbine-blade toes that make it the fastest of all foot-propelled swimming birds. (Penguins are faster, swimming with their wings. These modifications come at a price: penguins can't fly, grebes can hardly walk.)

In the Dell, a Grey Heron was enviously eyeing some carp far too big for it to catch.

There is a family of Robins in the bushes behind the Albert Memorial. Here, one of the young birds waits for a parent to bring food.

When about to be fed, a young Robin vibrates its entire body violently, like a tiny high-speed version of a dog coming out of the water. 

The territorial battle of the Mute Swans continues on the Long Water. This time the male at the Lido turned up before the rest of his large family and confronted the lone resident male at the line of posts that is the current frontier of their territories. He then crossed the line and made efforts to push the other swan back to the next line, which is marked by a fallen horse chestnut tree sticking into the water.

These are both big birds, about equal in strength. Normally an intruder on to another swan's territory would lose, but this one has a family, which gives him considerable status in these confrontations. King David got this right:

Like as the arrows in the hand of the giant,
Even so are the young children.
Happy is the man that hath his quiver full of them;
They shall not be ashamed when they speak with their enemies in the gate.

(Psalm 127:4-5)

Nearby, a female Tufted Duck was foraging among the algae.

You can see that the Long Water is still fairly clear, though there are mats of dead green algae which, if the weather remains warm for the next few days as forecast, will be overgrown with toxic blue-green algae. However, the Serpentine is as murky as oxtail soup. The algae are nourishing a good growth of young fish -- these are mostly roach with a few bream. (Thank you, Gino, for telling me this when I was taking the picture.)

But the water is really in a pretty bad state. The murkiness is due largely to the work on the Olympic jetty, and careless use of motor boats, stirring up mud from the bottom. The top two feet of the heavy growth of algae has been cut back with a curious machine looking like a cross between a combine harvester and a tank -- it actually has tracks, which propel it on both water and land. This has also churned up a lot of mud. Once it comes up, it takes days to subside.

But even before this, the lake had been badly disturbed. Last year, when a triathlon was held in the lake as a trial run for the Olympics, the lake was also weedy, though not nearly as bad as it is now. So they poured thousands of gallons of hydrogen peroxide into it, which killed the algae but seems to have knocked the ecosystem badly out of kilter. This spring, many tonnes of mineral sludge were dumped in the lake in an effort to absorb the nitrates and phosphates that nourish algae -- it consisted mainly of fine clay with some compound of lanthanum (a radioactive element). Soon after this, although the weather was cold and no algae would normally have been expected, there was a strong growth of three kinds of green algae, which has not abated.

At the same time, all the Little Grebes left the lake and have not been seen since. In Regent's Park, where the water has not been mucked about with, there are plenty of Little Grebes and they have bred.

I would not want to swim in this water, and feel sorry for the athletes who will have to.

To return to more cheerful matters, here is a white dove that has managed to avoid involvement in the opening ceremony.

And here a purple loosestrife plant has escaped from the planting in the Italian Garden and is decorating a nearby fence, to the delight of a young photographer.

A sunny Sunday and the park was full of people, and the shyer birds had retreated. Of course many of the park birds are completely blasé about crowds. Here a moorhen feeds her chick unconcernedly in the middle of the pavement near the Bluebird boat hire cabin, unworried by photographers. 

And here a Greylag Goose explores the edibility of the hedge plants, on a narrow path with people a few inches away.

And of course, all the usual geese, swans, ducks and pigeons were efficiently following people with bags of bread, and are now joined by increasing numbers of Black-Headed Gulls. The experienced park birds can spot the telltale carrier bag and stance on the edge of the water from a distance of 300 yards, and instantly head for the spot from all directions.

The Coots nesting in the Italian Garden, having completely wrecked the clump of plants they nested in, have now started chewing up the plants in the other clumps. Here one returns form an expedition with a stem of purple loosestrife and climbs the wire netting around the nest to present it to its mate.

Fond as I am of letting birds do their thing, it is a pity the Coots are making such a mess of the attractive new water plants in the Italian Garden. The flowering rushes have just come into bloom.