The functional
response, i.e. the change in per capita food intake rate per time unit with
changed food availability, is a widely used tool for understanding the ecology
and behaviour of animals. However, waterfowl remain poorly explored in this
context. In an aviary experiment we derived a functional response curve for
teal (Anascrecca) foraging on rice (Oryzasativa) seeds. We found a linear
relationship between intake rate and seed density, as expected for a
filter-feeder. At high seed densities we found a threshold, above which intake
rate still increased linearly but with a lower slope, possibly reflecting a
switch from filter-feeding to a scooping foraging mode. The present study shows
that food intake rate in teal is linearly related to food availability within
the range of naturally occurring seed densities, a finding with major
implications for management and conservation of wetland habitats.