The House Martins at their colony on the water tower are well into their nesting season. Of the eight nests which I am watching six have got young, and one appears to be unoccupied, though I suspect that a sparrow may have claimed it. Although I have not seen a bird enter it, I have seen bits of straw poking out, which makes me suspicious. The final nest is still being built, probably by a young bird or birds in their first season. They started from just about scratch - there was a small smear of mud on one side of the tile, and they have gradually added to it over the past three or four weeks until it is now about three-quarters built. It has been fascinating to watch them flying in with small blobs of mud, which they then press and mould into the structure. I can't wait to find out if they will actually use it when it is finished.
The remaining six nests contain young in various stages of development. Nest no. 1 seems to contain just one large nestling, which must be about to fledge. It is assiduously fed by its parents, and sits at the entrance in full view. Now and again the nestling turns its rear end towards the entrance and neatly excretes its droppings well away from the nest. The other nests contain between two and four young, though it is quite difficult to be sure of the numbers since they are so high up. I use a telescope to watch them, and on cold or windy days (of which there have been many) the nestlings hunker down out of sight and only appear briefly when the parents visit.
The literature says that the clutch size is "usually four or five eggs, but varies between two and six", and the nestlings come to the nest entrance to beg when they are about nine days old. The weather this June has not been kind: a lot of rain, a lot of wind, quite cool, so the parents may be having difficulty finding enough insects to feed their brood, which would result in lower numbers fledging. From what I have seen so far I would predict that this will be quite a poor season.