The number of goldcrests in the country is about to shoot up, with the arrival of loads of birds from Norway, Sweden, Finland and even Russia, writes the BTO’s Graham Appleton.
They will join local birds, looking for small insects and other invertebrates amongst the needles of fir trees.
Often their presence is betrayed by a high-pitched call, as they keep contact with each other in small, loose flocks. If you catch sight of one, look out for the yellow crest of the female or the flame-orange crest of the male. Goldcrests can be told apart from the only other kinglet, the firecrest, as this much rarer species has a strong white eyebrow.
A goldcrest is tiny. A fat one, preparing to cross the North Sea, weighs up to 8 grams (the same as a 50 pence piece) but a newly-arrived bird on the East Anglian coast may weigh less than 5 grams (equivalent to a 20 pence piece).
On an October morning, especially if the weather is unkind, exhausted birds can be found in bushes along the coast, hungrily looking for insects or nectar to replenish their energy reserves. These are the lucky ones, of course; in these circumstances many other birds will have failed to complete the sea crossing.
Years ago, there was a rumour that goldcrests travelled across the North Sea on the backs of woodcocks; both species arrive at the same time and presumably people could not believe that these tiny scraps of feather could fly here on their own.
Goldcrests live life at a fast pace. The longevity record is only just over four years – which is much less than blue tit (nearly 10 years) or a blackbird (over 14 years) – and an adult will typically not be alive to breed in more than one or two years. If there is a high chance of dying, then the survival of a species is dependent upon parents producing as many chicks as possible. In good years a pair of goldcrests will have two broods, each of six to eight chicks, raised in a woven basket of moss, lichen and cobwebs, lined with feathers, and hanging from a branch of a fir tree. Even allowing for losses, it is easy to see how the number of birds in a population can become five times as big in just four months.
Here in Britain, even with our relatively mild climate, winters can be tough for goldcrests, susceptible as they are to wind-chill, wet weather and icy conditions.
This is one species that does not really benefit from the extra food that people put out for birds; they are best helped by spray-free gardening and perhaps by hanging a roosting pocket in a leylandii tree.