The behaviour and ecology of a population of Long-tailed Tits in Wytham Great Wood, Oxford, were studied between October 1970 and June 1971. Flocks were found to have a stable composition in autumn, and to occupy fairly discrete territories which they defended against other flocks.

In spring the population was reduced by about 50% and in the pre-nesting period flocks formed only in cold weather or just before going to roost. These flocks occupied the same territories as the autumn flocks and the individuals composing them eventually nested within the flock territory.

Predation of nests was heavy, increasing to a peak in the first half of May. Only nine pairs out of 36 managed to rear young successfully. At six out of these nine nests, supernumerary birds helped to feed the young, but it seems unlikely that this increased their success, since all young hatched fledged successfully. The presence of supernumerary birds at the nest was accompanied by frequent hover-displays by all the adults.

The distribution of nests in relation to habitat shows that there is a preference for scrub rather than mature woodland, although the latter is used extensively for feeding during the winter. There appears to have been a radical change in the height of nest-sites in Wytham Great Wood between 1955–57 and 1971, and this is probably due to predation.