The Mute Swans nesting at the east end of the Serpentine have only one cygnet, which must be a disappointment for them but they are looking at it all the more carefully, not letting it stray more than inches away from them. Here the young bird enjoys a meal of algae.

I am always surprised that big, active birds such as geese and swans can get all their energy from grass and algae. Unlike cows, they don't have complex digestive systems that can extract the last drop of nourishment from this poor diet. They have to spend hours a day eating.

Algae were sustaining this Pied Wagtail in a different way. It was light enough to walk over the algal mat on the Round Pond without sinking in, and collect the insects that cluster on it.

Occasionally one of its feet would break through, but a slight flutter was enough to let it recover its footing.

The young Great Crested Grebe at the west end of the island was chasing its mother closely and begging noisily for food -- so loudly that passers-by with no particular interest in birds stopped to  see what the fuss was about. Here the mother looks below the surface to see if there is anything edible swimming about.

This young Blue Tit was also loudly demanding food in a tree near the Serpentine.

I could hear other young Blue Tits calling in several parts of the park, and also from inside yet another lamp post at the southeast corner of the Serpentine. The half dozen lamp posts I know to have Blue Tit nests in must be only a small part of the total.

There were Swifts all over the place, visible not just in the park but in the adjoining streets. The two Common Terns were still on the Long Water. They paid a brief visit to the Round Pond, but didn't like it so much and returned to the Long Water within a few minutes.