Activity patterns of parent Great Tits Parus major feeding their young during rainfall

The influence of rainfall on the foraging patterns of Great Tit Parus major parents while feeding chicks at the nest was investigated using automated nest monitoring with electronic balances and photography. Great Tit females significantly reduced their visit rate to the nest during all vain intensi ties, while male feeding frequency did not significantly change. The female response was probably due to increased brooding requirements of young sinc e the reduction ill visit rate was most apparent at early nestling stages. At this rime the chicks are incapable of thermoregulation and females signi ficantly increased their nestbox occupancy time during rain. There was no i ndication that parents were compensating for periods of female inactivity d uring rainfall: there was no significant increase in visit rate following r ainfall and no significant increase in prey size delivered to the nest duri ng periods of rain. An analysis of data from six consecutive years revealed that the proportion of wet hours within the first week Of the nestling per iod significantly influence fledging weight in this species.