Reserva Ecológica Costanera Sur

A spinetail with a featherless tail
It is strange to see a bird with a featherless tail. Generally one or two feathers may be missing when birds are molting but not all of them at the same time. This massive feather molt may occur as a response to the fact of being grabbed by the tail by a predator. The bird sacrifices its tail, but saves its life. It is believed that there must be a relaxation of the muscles holding the feather which causes its detachment. As the whole piece is lost, the feather grows back right away. This molt is known as shock molt or fright molt. This phenomenon has also been reported in cases with birds being handled and has been registered after catastrophic events. CR

Two martin fledgelings wait for their parents to bring some food. A fledgeling is a young bird which has left the nest. It is feathered but is still cared for by the parents. An evident characteristic is the enlarged oral flanges at the base of the bill. This structure is enlarged integumentary tissue which passerine chicks have when they hatch and decreases as the young grows. It is normally yellow and it will be more or less bright depending on how well lit the nest is. It is believed to arouse parents to feed the young and to serve as a food target to place it properly. They differ in colour from their parents. Fledgelings are grayish whereas the adult is brown.
CR

© JST (J. Simón Tagtachian) – © RU (Rosana Ursino)