When foods are scarce, individual birds tend to specialize in one food source (e.g., seeds) or another (e.g., insects) depending on the size and shape of their beak.
(foods; are; scarce) (individual birds; tend; to specialize in one food source (e.g., seeds) or another (e.g.; T:When foods are scarce) (individual birds; to specialize e.g.; in one food source) (insects; depending; on the size and shape of their beak)
foods individual birds individual birds insects
are tend to specialize e.g. depending
scarce
to specialize in one food source (e.g., seeds) or another (e.g. T:When foods are scarce
in one food source
on the size and shape of their beak