Community Wildlife Area – April 2020

View from The Wildlife Patch

I was looking round the patch today. It is wet, cold and at first sight inhospitable. Yet there is lots going on really.

We have 4 Blue Tit boxes on the patch and at least one is occupied. The prospective occupants were twittering angrily at me as I took a close look at the box. This indicates they have decided to take up residence there again. These Birds almost entirely depend on the larvae of the Winter Moth (Operophtera brumata).

This moth is an interesting species in itself. The sexes differ in that only males have wings, the females being entirely flightless. As the name would suggest adults are only active in winter having developed means of generating heat from inside their bodies. The female hatches from the pupae in Late Autumn/Early Winter. She emits a Pheromone (aerial hormone) which wafts through the cool air to attract an eager male. After mating she lays eggs at the base of the buds of many species of deciduous trees. The Larvae hatch in early spring. They feed first in the expanding buds, then on the leaves of the same plant. They pupate in Late May to hatch in Late Autumn. These are the Small Green Caterpillars that are often seen hanging from mature trees and shrubs in Late Spring.

Being unable to fly could mean that these would struggle to distribute their species to new locations and areas. These caterpillars overcome this by a means of Aerial distribution. They let out a silk thread from their tail end. When this becomes long enough to be caught by a breeze, the caterpillar lets go of earth to fly as if on a parachute. Of course they have no means of steering or governing height but it works for them.

Many species of invertebrates use this form of Aerial distribution. Spiders, mites as well as Lepidoptera all “fly” in this manner. So many in fact that different species accumulate in the air to form a sort of “Ariel Plankton”. A reduction in the volume of this Plankton Layer must surely be a factor in the shortage of Swallows, Swifts etc. we are experiencing today.

Now back to Blue Tits. In Late Winter/ Early spring these birds can be seen in parties of 6 or more pecking at the Buds of deciduous trees. When they do this they are thought to be searching for Winter Moth Eggs. It is believed that the amount of eggs consumed by the birds has an effect on the amount of eggs the Tits lay in that the more moth eggs the birds eat, the more eggs the birds lay. Moreover, it is thought that Blue Tits are so closely tied in with Winter Moths that they react to a substance in the developing Moth egg that stimulates the birds breeding behaviour. This enables the birds to have an abundant source of food timed to feed the hatchlings at the right time.

One more thing. If anyone fancies making a couple of Hedgehog Hotels (plans on the internet) we can find good home for them on The Patch.

Dave Musson 07942 674867

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