Wednesday, 3 June 2009

June is bustin'

June is an interesting month. It's not really spring any more, but the birds are still singing and there are still migrants arriving. It's probably the best month for flowers and for insects, especially since we expect a dry summer to come. In fact, the lush greenness of spring is already fading and we have some seriously scorched areas where the soil is thin.

So; birds first. All of our summer breeders have arrived from Africa. The last breeders to arrive are probably spotted flycatchers, but we hardly see them these days. The first to arrive, in March, were sand martins, so why do they wait until the end of May to nest? After poking around at every possible site (and there are many at Paxton) they finally decided to nest in a newly dug clay pit at Diddington. Now, each day, we get arrivals of waders that should be breeding in the high Arctic. Species such as grey plover, sanderling, knot, turnstone and dunlin should be in Greenland, Baffin Island, or even mainland Canada; so why are they still here? I guess they don't need to be there yet. The Arctic summer is so short that these birds arrive at the last minute, pull off one brood and then start back. Some will be "non-breeders". I find this to be a derogatory term, as though, by not flogging it all the way to Hudson Bay at the age of one or two years, these birds are failures. I suggest that these "vacationers" are the insurance policy for the species. If this year's arctic breeding season is a complete disaster, these birds may be the hope for the future.

The insect story is no less dramatic. This year has already produced two dramatic insect phenomena. First, we have had a huge influx of painted lady butterflies. They emerged from their pupae in Morocco in March, passed through Spain in April and reached us, battered and faded, in late May. Most have just carried on north, and may reach Iceland. Others will stay and lay their eggs on thistles. After going through the egg, caterpillar and chrysalis stages, they will emerge in August and we should see huge numbers in our gardens then. All of the survivors will head south, back to North Africa for the winter.

The second spectacular insect event can be viewed from the River Viewpoint. If you look across the river to the island you will see some bird cherry trees that have become completely defoliated. They look dead, but you can see that they are covered in cobwebs. This is the result of a major infestation of moth caterpillars (called bag-worm in the USA). They are probably brown-tail moths. Bird cherries have their flowers and leaves very early and so they may be able to store enough energy in spring to get them through such a major attack on their foliage.

This year's caterpillar population seems to be exceptionally high, and they have made the national news, not because of their effect on trees, but because of their effect on people. The caterpillars have many small hairs that irritate the skin and eyes. Because there are so many of them this year, the hairs are affecting people downwind of the largest colonies and causing a lot of visits to the doctors' surgeries.
In the plant world, every year is different. This time we have a lot of spotted orchids on the meadow trail, but we may not have such a good season for the later showing species such as pyramidal and bee orchids, unless we get some more rain.