FOOD AVAILABILITY AND THE MALES ROLE IN PARENTAL CARE IN DOUBLE-BROODED TREECREEPERS CERTHIA-FAMILIARIS

The aim of this work was to examine differences in paternal and matern al care in a double-brooded, monogamous species, the Treecreeper Certh ia familiaris, in relation to food availability. As a measure of paren tal care, rye recorded the hourly feeding activity of parents when the nestlings from their first and second breeding attempts were 7 and 12 days old, Feeding frequency of the first brood increased with the age of the nestlings and also with the brood size when 12 days old, While the feeding activities of the females were similar with respect to th e first and second broods, the males were less active and failed to pr ovide any food to their nestlings in 15 cases out of 28 second broods. In spite of this, the fledglings from the second broods were heavier than those in the first, Such a pattern of male behaviour was possible without being a disadvantage to the chicks because the food supply in creased during the breeding season and the female could provide food f or the young alone, Thus paternal care was particularly important in t imes of poor food supply, i.e, during the first brood, where the exten t of these males' activity in feeding the 7-day-old nestlings was posi tively correlated with the average mass of the nestlings, Our results support the idea that the mate of monogamous, altricial bird species o ften makes important contributions to raising the young, especially du ring periods when it is difficult for the female to do so alone, Males show flexibility in their pattern of parental care, and male Treecree pers change their contribution to the first and second broods within t he same season.