Birds breeding for the first time are rarely successful in raising young, and reproductive success increases with age, as older birds breed earlier in the breeding season, and fledge more young.
Birds breeding include skylark, cuckoo, song thrush, spotted flycatcher, dunnock, house sparrow, linnet, and bullfinch.
The cold spring weather the UK is experiencing now is affecting garden birds' breeding patterns, Johnson added.
Among more than 170 species of birds breeding in the floodplain are grouse, partridge, goose, and duck.
The study by two Finnish ecologists, reported in the journal Nature, showed that the birds' breeding success improved over seven years as emissions of heavy metals were reduced.
And over the past few years, George has come to believe that the warmer Arctic climate is changing not only his birds' breeding habits but also the species in a far more profound way.
After a shaky start, when over-enthusiastic visitors almost wrecked a site called Gypsy Cove by trampling over the birds' breeding grounds (which are known as rookeries), penguin numbers are increasing.
Conservation actions designed to stop or reverse these processes will be especially beneficial to birds breeding in bottomland forest ecosystems.
Unlike most British birds of prey, red kites are social birds, breeding in loose colonies and feeding together.
Habitat fragmentation, the draining of wetlands, and stream channelization may act synergistically to elevate rates of nest predation for those birds breeding in forested wetlands.
It has run in Dumfries for a number of years and claims to have seen the number of adult birds breeding in the town decline "considerably".
