Disastrous Breeding Season

Bird On! News
14th June 1996

Reports from round the UK are that our small birds are having a very bad breeding season - despite the recent warming of the weather. Many species have had a very hard time during May - the coldest for 74 years - and it takes more than a few days of good weather for their food supplies to improve.

Birds like Blue and Great Tits and Chaffinches which are dependant on the caterpillars on native trees like Oak and Beech have been badly caught out. The cold weather has delayed the caterpillars and many of the birds have either failed to hatch their eggs or have had the chicks die of starvation.

David Glue, of the British Trust for Ornithology, said:

'Reports from all over the country have been very gloomy. Literally millions of eggs of these birds will have been laid this year and will have failed to produce chicks. Experienced nest recorders reckon it is the latest tit breeding season for ten years and that the chicks that are fledging are very poor, half-starved individuals.'

Professor Chris Perrins, of the Edward Grey Institute of Oxford University agreed:

'Until the last few days the tits that were able to fledge were very light and sickly. The warm weather has helped but the chicks are still rather smaller than normal.'

Aerial migrants - the Swifts, Swallows and martins - have been very stressed. The Swifts arrived late. Roy Overall, who has been studying the University Tower Colony in Oxford for more than 30 years, found no eggs laid in May. There were even four birds dead, apparently from starvation. He said:

'This is the first time in my experience that egg laying has not started in May. There were 56 eggs on Saturday (8th June) and there is still time for them to have a brood provided the summer weather continues uninterrupted.'

Although the Swallows and martins arrived early, very few started nesting until the last few days. Many have spent up to six weeks waiting for the weather to improve.

Not all is doom and gloom and this year is exceptionally good for breeding Barn and Tawny Owls. Their chicks are feasting on the abundant small mammal populations. Broods of four and five owlets are common.

It is advisable to continue feeding garden birds. Food provided for the garden birds at this time of year can keep the adult tits and finches fit and healthy. They can then spend extra time finding naturally occurring food for their chicks.

Black sunflower seeds and peanut kernels (fed in small mesh feeders so that the parents cannot choke their chicks on whole nuts) are ideal. Providing live food like mealworms can directly help the chicks too. When they fledge the parent birds are very likely to bring them along to such food.

Recent research by the British Trust for Ornithology has shown that gardens where there was summer feeding had more birds in the following autumn (October to December). This was particularly the case with Greenfinch (twice as often recorded) but was quite marked for Blue Tit, Great Tit and Chaffinch. Of the top ten birds, only Blackbird and Robin showed no difference and they are often in gardens only for the naturally occurring foods.

A study in Sussex showed that the Greenfinches preferred to nest near a birdfeeder and the nestlings hatched near a feeder were heavier, at five or six days, than those hatched further away. Males with more than one female were closer to feeding stations than monogamous ones.

As expected the food offered was used by the adults to keep themselves in good trim and the youngsters were fed natural food until they were about ten days old. Other studies have proved that supplementary food can cause the birds to be able to lay earlier, increase their clutch size and fledge more young.

Postscript

Some readers of Bird-On! may have seen an article in the Sunday Times (UK) about birds dying because of Salmonella. This was a travesty and the quotes were not acknowledged by the people concerned. There has been rather more Salmonella this spring than in previous years but it has certainly not reached epidemic proportions. Sensible hygiene at the feeder is the answer. There is also hardly a problem with aflatoxin in peanuts any more since regulations are stopping infected cargoes being imported.