The absence of wrens could spell bad news

ANOTHER LIFE:THE WORST of the winter, as I write, has stayed beyond the hill. On this side, shielded from the north and basking in the ocean's glitter, the harsh night frosts are mainly what menace our feathered refugees. Opening the door to another pink dawn, I spark an eruption of redwings from the interior of a big escallonia bush. They fan away past what is left of the moon, trailing a thin, sighing twitter as they fly to fields along the shore. I can only apologise for the disturbance: all flight costs energy, and flying in alarm even more.

This is worth bearing in mind by stoical human wanderers, out for mufflered walks with the dog. Putting up flocks of waterbirds and waders from frozen lakes is a casual unkindness. Next weekend, as it happens, brings an international census of whooper and Bewick's swans, including those wintering in Ireland, and observers will need to be specially stealthy – and well-wrapped up (more at birdwatchireland.ie). All the birds are now stressed from hunger and windchill, and millions must already have died across Europe in the massive spilling out of polar cold. Looking back through Another Life, I found the bitter winter of 1985, when "the cats were lining up [redwing] corpses on our doorstep in threes", while others were washed up with dead golden plover along the shore. We no longer keep cats, but at this New Year John Sweeney of Achill reported redwings and fieldfares arriving "in clouds" to carpet the island's fields – migrants from Scandinavia pushed west to the edge of Europe.

Redwings are the little thrushes with rufous flanks and a creamy collar and stripe over the eye. Fieldfares are thrushes, too, but bigger, more poised, and affectingly elegant: crisp grey and brown above and a glowing ochre bib. Their flocks keep a distance from people, but redwings have been bouncing in the leaves on our unmown, soggy lawn, stabbing hopefully for worms, and hunger can compel a rare perch at garden feeders.

Just before Christmas we went to the co-op for a hessian sack of peanuts from Argentina, a whole winter’s supply, and have already had to dig deep to satisfy our daily dozens of birds.

We like to think that some, at least, are “ours”, but know, in reality, that whole successions of tits and finches pass through the garden, ­ some delaying, no doubt, for the food and close shelter.

The house sparrows are ours, I’m sure, for once overwhelmed in a brilliant, squabbling mix of goldfinches and siskins.

A song thrush feeds nervously just beyond the window as I write, fleeing from robins and blackbirds between turns at a box of goose fat and oatmeal. It is fluffed up beautifully against the cold and the first flakes of a snow shower lie on her back without melting.

I haven’t seen a wren for many days and that could be bad news.

Hunters after spiders, pupae and cocoons, hibernating flies and butterflies, wrens get no special winter help from humans. They may take over a tits’ nest-box as a communal roost at night (50 in one box seems to be the current record). Last February, a reader in Co Antrim sent a photograph of wrens, eight or nine of them, snuggled head-down in a swallow’s nest in her porch.

They’ve been doing it for years, and the colder it is the more wrens push in. Once they settle, little heads pressed together in the dark and breathing warmer air, no one is allowed to use the front door.

Of all living things, only mammals and birds can maintain a constant body heat no matter how cold the air. For some of the tinier warm-blooded creatures, the extra activity is scarcely worth the trouble.

Their large body surface in relation to their size sets up a heat loss that demands a high metabolic rate to burn fuel faster. The colder the winter, the stronger grows the obsessive need for food.

Birds in general have the highest body heat of any animals.

Even on a frozen lake, a swan maintains 105 degrees Fahrenheit [40.5C], a temperature which in humans would be fever. A goose will roost on snow if it has to, beak tucked into the warm air beneath the feathers on its back.

Birds also warm up the venous blood returning from their extremities by passing it through a coil of warm arterial blood before it reaches the body core.

Before the winter, I was wondering how soon Iceland’s whooper swans might, given global warming, choose not to bother migrating to Ireland for the winter. Next weekend’s census may tell us many interesting things, but maybe not much about that.

Eye on Nature

On December 12th a friend found a corncrake on the side of the road. He took it home and placed near the heat. Next day it was in excellent condition and we released it at a suitable location, but the severity of the weather since then did not bode well for it.

J Carmody, Kilrush Co Clare

A mystery. All corncrakes should have returned to Africa by September.

At Woodbrook Golf Club I recently saw a strange fish lying on the 12th tee box overlooking the sea. It was like a piece of bamboo, about one foot in length, with light and dark brown mottled colours, a small fin-shaped tail and a head with a long narrow snout resembling seahorse. We suspected a bird may have dropped it.

M O’Shea, Lea Rd, Dublin, 4

It sounds like a pipe fish which belongs to the same Order as the seahorses.

A sparrowhawk has been in our garden every day feeding on apples near the bird-feeder. He chases away the birds on the ground, but does not swoop on the birds at the nut-feeder. They are not frightened of him now and merely hop a little way from him.

Liam Boyle, Clonmel, Co Tipperary

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. viney@anu.ie. Please include a postal address.