Habitat use of Amazonian birds varies by age and foraging guild along a disturbance gradient

Patterns of habitat use directly influence a species’ fitness, yet for
many species an individual’s age can influence patterns of habitat use.
However, in tropical rainforests, which host the greatest terrestrial
species diversity, little is known about how age classes of different
species use different adjacent habitats of varying quality. We use long
term mistnet data from the Amazon rainforest to assess patterns of habitat
use among adult, adolescent (teenage), and young understory birds in
forest fragments, primary, and secondary forest at the Biological Dynamics
of Forest Fragments Project in Brazil. Insectivore adults were most common
in primary forest, adolescents were equally likely in primary and
secondary forest, and all ages were the least common in forest fragments.
In contrast to insectivores, frugivores and omnivores showed no
differences among all three habitat types. Our results illustrate
potential ideal despotic distributions among breeding populations of some
guilds of understory birds where adult insectivores may competitively
exclude adolescent individuals from primary forest. Secondary forest
recovery appears to hold promise as breeding habitat for frugivore and
omnivore species but only as pre-breeding habitat for insectivores, but as
the forest ages, the demographic structure of bird populations should
match that of primary forest.