Derek – Friday 5th March 2021

Forest Gate Community Garden is planning for when we can open for visitors. This month, volunteers will be tidying the garden, planting, and generally sprucing up for what we hope will be our April opening, as lockdown eases due to the roll out of the vaccine programme. We have all been too cut off these last months, and who can not look forward to being social beyond Zoom, which is always a second best.

There’s frog spawn in the pond, which is a hopeful sign, always enjoyed by visitors, children especially, as the spawn swells and the tadpoles hatch, feed and develop over the spring months. Tadpole mortality is high, but a few will make it to frogs, and hopefully return to spawn, and renew the cycle.

I am frequently peering into hedges trying to see the cheeping sparrows, and often can’t see them. This is an example of concealment by disruptive colouring. The sparrow has a broken pattern of brown lines, lighter and darker, which make the bird very hard to see in a bush against the twigs. Even when I can hear them, sometimes I can’t find them.

Colour in animals has one of three functions: concealment, advertisement, or mimicry.

Concealment is illustrated by the sparrow, by a greenfly on a leaf, the green lacewing or a cricket. The latter eager to hide from birds. A grey rabbit can be difficult to spot if stationary in a field, its colour merging into the background of soil and vegetation. There’s the stick insect, so like a stick, we only spot them when they move.

Advertisement is when the animal wants to be seen. It could be the robin with its red breast saying to another male robin, this is my territory, clear off! Or there’s sexual advertisement, which we have in the peacock’s brilliant wings to attract the peahen, or the male mallard’s green, black and white colouration. Sexual selection is the reason why male birds have all the colours, and the choosy females are often quite plain.

I find mimicry quite fascinating. A hoverfly acquires the colouration of a wasp, to make it less palatable to a bird. It is often called Batesian mimicry after the naturalist Henry Walter Bates from his work in the Brazilian rainforests in the 1850s. He noted that some butterflies mimicked unrelated varieties which were toxic to birds. A well known mimic is the cuckoo, which copies the colour of, for example, the eggs of the reed warbler, so its offspring are brought up by the host bird.

I began writing this a few days before the David Attenborough series began on colour in nature, *Life in Colour*. I thought of leaving this piece a while, but then had a rethink. Spring awakens our sense of colour in nature, with the flowers and new leaf. And such things bear repeating.

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