Nature Notes – December 2018

After I mentioned Redwings and Fieldfares last time, several people got in touch to tell me that they had seen Fieldfares only a few days later (early November). These were all in small groups and did not stay around. Presumably these birds were passing through, perhaps heading further West. No doubt there will be others to be seen and heard as the winter progresses, so look and listen out for them.

The large clump of hibernating ladybirds in Sweffling Church (they are the recent colonist, the Harlequin Ladybird) has grown even larger, but I have learnt that this is not unusual. Hibernating ladybirds are found in other churches and church towers, even, although it is hard to imagine, inside the bells themselves. These are typical examples but find them on the south-west window in church.

At the end of October many other insects were busy feeding on the Ivy flowers, some preparatory to themselves hibernating. Among these were a couple of Comma butterflies, which are a bright golden-brown, very conspicuous in the autumn sunshine. They have jagged, scalloped edges to their wings, the only one of our butterflies to have this feature. This, when the wings are closed,
makes them look very much like a dead leaf, all the more so because of the dark colour of the underwings. The dead-leaf mimicry must be important to them when hibernating, as they do not seek the cover of hollow trees or buildings like the other winter butterflies, but hang outside in the partial cover of brambles or other shrubs. Incidentally, the underwing also shows the clear, white, comma-shaped mark from which this insect gets its name. Hanging outside in the open in a cold winter raises the question of why Commas do not freeze to death. Apart from cold reducing all the body functions to zero, actual damage and death occur due to ice crystals forming in the body. Commas, along with many other insects, have chemicals in their body fluids which allow them to fall to temperatures as low as -15 degrees without freezing. Many even contain glycerol or other compounds which allow ‘supercooling’, where their temperature can fall even lower, commonly as low as -30 degrees or less, without ice crystals forming at all. I have only once found a hibernating Comma, but they must be around so do look for them.

Garden birds are coming more frequently to the bird feeders now. I am particularly keen to help the House Sparrows, which nationally are not doing well but are still common in many of our gardens here. They like seeds, including peanuts and sunflower seeds, and the ever- popular sunflower hearts (expensive but better value for weight). In winter the males have undergone a change in plumage – quite subtle but worth looking for as an exercise in birdwatching skills. The neat black bib of the breeding plumage has almost disappeared, changing to pale fawn. However, underneath their fawn tips, these breast feathers are still black. As winter progresses these pale tips wear away, revealing an increasing amount of black until the spring plumage is regained.

Geoffrey Abbott