Data from: Grooming time parallels molt intensity in wild-caught feral Rock Pigeons

Feathers are critical for locomotion, communication, thermoregulation,
waterproofing, and protection from UV radiation. To maintain these
functions, birds care for their feathers by grooming, which consists of
preening with the bill and scratching with the feet. Grooming cleans and
arranges feathers, distributes preen oil and powder down, and removes
ectoparasites. Birds devote considerable time and energy to grooming, to
the exclusion of other activities, such as foraging. All else being equal,
birds should aim to minimize their grooming time. Seasonal changes in
grooming have been documented, with some species of birds grooming more in
summer than winter. The higher rate of summer grooming may be caused by
molt; however, the relationship between the dynamics of grooming and molt
have been quantified only in captive birds subject to other manipulation,
such as induced molt in poultry, or access to mates in Zebra Finches. We
conducted an eight-month study of wild-caught feral Rock Pigeons (Columba
livia) to compare rates of grooming and molt. We found that the intensity
of grooming parallels the intensity of molt throughout the molt cycle.
Pigeons more than double their grooming time at peak molt, consistent with
patterns observed in wild birds. Our results suggest that molt may be more
energetically costly than previously realized, given concomitant increases
in grooming.