a) dodo - became extinct due to overhunting for use as a food source for early sailors. May also have lost eggs due to introduction of rats to its island.
b) passenger pigeon - loss of habitat, over-hunting, and use of its feathers for fashionable clothes.
c) Carolina parakeet - loss of its forest habitat which caused it to switch to feeding on crops. Farmers then killed it as a pest. Many were caught and kept as pets. The feathers were used for fashionable clothes.
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