What's Happening in November 2011

Even though the clocks have been put back and shortening day length heralds the approach of winter, there is spectacular colour to be enjoyed in the tree leaves of late autumn as we experience more than our fair share of mild sunny days. Take a walk in an urban area to see the developing colours on street-planted trees such as Red oak and Norway maple or Japanese maples in local gardens.

Turning colours

Similarly within the wider countryside trees such as birch, ash, field maple, and sycamore are turning and oak will follow later. Chlorophyll, the green pigment used by the leaves to capture energy from the sun to manufacture sugars, is broken down in this process and by autumn is used up, exposing the orange-yellow carotenoids previously masked by the chlorophyll.

The additional reds and purples of some trees so admired in autumn are due to pigments called anthocyanins which are actively produced in the autumn, particularly during bright sunlight, through the breakdown of sugars. The function of these bright colours, produced just before the leaves fall, is still uncertain.

Crop collection

Also falling from trees at this time of the year are their seeds. Some, including maple and ash, are attached to ‘keys’ which enable them to sail some distance from the parent whereas others, including huge numbers acorns from oak trees simply fall to the ground. In this case part of the crop is then collected, dispersed and buried by jays and grey squirrels.

The sweet chestnut, almost certainly introduced to Britain by the Romans, is common in Dorset and often forms an impressive tree, although it is sometimes grown as coppice. The nuts, inside spiny seed-cases, rarely seem to attain the size of those imported from mediterranean countries.

Beech trees are also widespread and beech nuts or ‘mast’ was eaten by grazing animals in the past. The crop varies greatly from year to year but in good ‘mast’ years large flocks of brambling, which breed in mixed woodland in northern Scandinavia and Russia, can appear to exploit this food source.

Obvious residents

Another bird which arrives from the same area to enjoy our relatively mild winters is the fieldfare. This striking member of the thrush family is somewhat larger than the redwing, another winter visitor, with which it often forms mixed flocks. The memorable ‘chack-chack-chack’ of the fieldfare becomes more familiar as temperatures drop and the birds feed on rowan and holly berries or take fallen apples from garden fruit trees.

One of Dorset’s most famous resident birds, the dartford warbler, came through the severe weather of last winter with a reduced population. If some of the predictions of another cold winter are fulfilled, then they will be very dependant on the numerous spiders in gorse which provide their major winter food source.

Watch out for hedgehogs

And finally, if you are planning to celebrate Guy Fawkes night with a bonfire in your garden, don’t forget to check for hedgehogs before setting it alight. To a hedgehog, such piles of vegetation and discarded wood may provide insects and slugs or a shelter where hibernation nests can be constructed.

Written by John Wright
Dorset Wildlife Trust Member & Volunteer

Japanese maple by John Wright

Grey squirrel by Ken Dolbear

Brambling by Ken Dolbear

Fieldfare by Ken Dolbear

Hedgehog by Nikkii Hesketh-Roberts