Many bird parasites reduce their hosts' fitness and, as a consequence,
anti-parasite behaviour such as preening and nest sanitation has evol
ved. These activities are time consuming and, during the day, compete
directly with time devoted to foraging and food provisioning to nestli
ngs. Moreover, infested hosts may have to allocate extra time to forag
ing in order to compensate for the energy loss that ectoparasites impo
se on the nestlings and parents. Alternatively, brooding females could
, at the expense of sleeping, allocate more time to preening and nest
sanitation at night. If sleeping has a short-term restoring function,
one may then expect a reduction in feeding efficiency of sleep-deprive
d females. In this study, the effect of a haematophagous ectoparasite,
the hen flea, on the activity budgets of breeding female great tits d
uring the day and at night was investigated experimentally. Time alloc
ated to nest sanitation increased only slightly from 0.6 % of daytime
in ectoparasite-free nests to 2.8% of daytime in infested nests, thus
demonstrating the higher priority given to food provisioning than para
site control. Females in infested nests reduced their sleeping time si
gnificantly (73.5% of night-time in parasite-free nests versus 48.1% i
n infested nests). The time freed from the reduction of sleeping time
was mainly used for nest sanitation (8.3% of night-time in parasite-fr
ee nests versus 27.1% in infested nests). Despite this strong decrease
in sleeping time, there was no effect of ectoparasites on the females
' rate of food provisioning to nestlings. (C) 1996 The Association for
the Study of Animal Behaviour