Geospiza adults use their bills to crack seeds for food; however, seed cracking ability is not as important in young fledglings because adults continue feeding them after they leave nest [32].
Some have heavy, blunt beaks for cracking seeds open.
The nestlings are unable to crack seeds and so are usually fed insects.
Their name is derived from the French gros bec, or "thick beak," which is adapted to cracking seeds with ease.
Each beak appeared to be specialized for a task, such as cracking seeds or drinking nectar.
Three species, the ground finches, have stout bills for cracking seeds; the other three, the cactus finches, sport the slender, pointed bills needed for retrieving nectar.
For example, if the mean beak size in an adult population of birds was 10 centimeters before selection and 13 centimeters after selection (because individuals with smaller beaks could not successfully crack seeds to eat in the current environment and therefore died before mating), the selection differential would be +3 centimeters.
The species collected in New York, Pheidole morrisi, normally has two types of worker ants, according to Abouheif: minor workers, which are responsible for foraging, nursing, feeding eggs and larvae, and taking care of the queen; and soldier ants, which defend the nest and use their big mandibles to crack seeds harvested by the minor workers.
Baby cockatiels cannot crack seeds until their beak becomes stronger.
We saw one another there every day — when we had our morning coffee, still in our bathrobes; when we wrung and hung the laundry at midday; when we smoked an afternoon cigarette; when we watered the plants at sunset; and when we cracked sunflower seeds and gossiped at night.
