For birds, spring starts here
23 January 2006
When the weather is cold, grey and miserable, it can be hard to imagine when winter will finally end and spring will begin.
The birds in your garden and in your local park can't afford to sit around, feeling glum and wishing the sun would come out. There's important work to be done - breeding!
Perhaps the most noticeable evidence of birds getting geared up for the new breeding season is the increase in birdsong that occurs from mid-January onwards.
While some birds, such as robins, sing throughout the winter (indeed, both males and females sing to protect their territory), others recommence singing at this time of year, both to attract potential mates and to signal to other birds the boundaries of their ‘patch’.
'the crossbill can lay eggs in January... surely they should wait until spring has arrived?'
At your local park, you may notice wildfowl displaying. Ducks are notably early to begin courting and don’t waste any time in staking their claim to breeding partners. You could see male mallards paying very close attentions to females, or male teals showing off their fine plumage by stretching themselves into rather odd, pointy shapes.
Male goldeneyes contort themselves by throwing back their heads into an uncomfortable-looking position that looks painful but impresses females. Though they can be seen in all over Britain in winter, they breed in Scandinavia (with small numbers in Scotland). They start their breeding preparations early.
To attract the best possible mate, birds have to look their best. This is why black-headed gulls get their ‘hoods’ back. In autumn and winter, they have white heads with a dark smudge behind the eye, but for the breeding season, they grow dark brown feathers on their head (never black!).
Keeping eggs warm in sub-zero temperatures
Amazingly, for a small bird (only just bigger than a house sparrow), the crossbill can lay eggs in January. You could ask why on earth they want to do that - surely they should wait until spring has arrived and the weather is kinder?
The answer lies in food. For the same reason that blue tits time their egg-laying so that the hatching of their chicks coincides with the appearance of all those tiny caterpillars, crossbills time their offspring’s arrival into the outside world so that the availability of food is at its peak. For crossbills, that means pine seeds, extracted from cones by the parents’ specially-shaped bills.
Pigeons and doves, such as the woodpigeon and collared dove, have no qualms about breeding young at any time of year. Nesting has been recorded in every month. It’s hardly surprising, given the year-round easy availability of food on garden bird tables.
Getting an early start
Sometimes, birds can be induced to start building nests and laying eggs by unseasonally high temperatures. In Brighton, a brood of song thrushes left the nest in early January 2005 – meaning the eggs were laid in December 2004.
Is this a precursor of things to come, with climate change having an detrimental effect on our wildlife? Already, eggs are being laid earlier in the year, and summer visitors are arriving earlier and leaving later.
Climate change could cause real problems for some species unable to keep pace with the rate of change. Upland breeding birds such as Scottish crossbills (found only in Scotland), ptarmigans and snow buntings could soon find their habitat disappearing from beneath them.