(1) They also eat fruits, berries, twigs, leaves, catkins , and seeds.(2) Live oaks produce male flowers called catkins that bloom in hanging clusters.(3) In winter, they are most readily observed feeding in trees with catkins , such as birch and alder.(4) Pin oaks produce drooping wind-pollinated male flowers called catkins ; the female flowers come in groups of one to three just as the leaves begin to unfold.(5) Some varieties shed pollen from the male catkins before the female flowers are receptive, and so require pollen from another variety with a later pollen maturation date.
