The extreme cold is having a huge impact on survival and hibernation
A LITTLE Scandinavian thrush with chestnut flanks has been the first notable casualty of the big freeze in Ireland, its feather-light corpses scattered widely along icy roadsides and in frozen fields.
Redwings are among the huge flocks of birds from northern Europe which fled west as temperatures fell.
Some winter migration to Ireland is normal, but the scale of the influx, of everything from blackbirds and chaffinches to lapwing and snipe, has been phenomenal.
The clouds of redwings and fieldfares (another, bigger, Scandinavian thrush) arriving to carpet coastal fields at some stretches of the west have not been seen in decades. Many are prey not only to hunger and cold, but hunting by peregrine falcons, kestrels and stoats.
Migrant ducks and swans have found their winter wetlands frozen and, while waterfowl try to keep patches of water open, many must be starving or caught in ice.
Human disturbance by skaters and walkers with dogs takes a toll on their energy and many have moved to coastal estuaries. Most shooters know half-starved birds are not worth a cartridge.
A desperate search for food has made many “wild” birds tame, allowing close approach by people, or has brought them into gardens and to nut feeders.
While tits, finches and sparrows are being sustained in this way, other tiny birds with exceptional heat-loss, such as insect-hunting wrens, will have died.
Many insects overwinter as eggs, pupae or larvae in the soil, and snow may actually be an extra insulation. Others, such as queen bumblebees and wasps, hibernate in deep crevices, protected by chemicals such as glycerol that prevents their cells from freezing.
This protects even butterflies, such as peacocks and lesser tortoiseshells, which hibernate as adults. However the freeze will decimate many insect pests, such as woolly aphids, whose survival through mild winters has become so unwelcome.
Among Ireland’s mammals, the native stoat and hare are thought to have survived the last final cold snap of the last Ice Age. Neither of them hibernates, nor do pine martens and squirrels, but hedgehogs and badgers – normally only intermittent hibernators in the mild Irish winter – are likely to stay put, such as bats in caves and roof-spaces.
The hedgehog lowers its temperature in its winter hideaway, only gently reviving its metabolism to fend off total freezing, while the badger draws on its fat reserves in its cosy, grass- lined chambers underground.
The smallest Irish mammal, the pygmy shrew, cannot stop hunting for beetles and woodlice. Even on an averagely cold winter’s day, it must eat up to twice its weight in insects and a couple of hours without food can prove fatal.
The fox, on the other hand, sheltering in conifer plantations and urban thickets, should generally do well for food, given the widespread death of birds.
Their eerie barking on January nights has more to do with sex than hunger.
