08 December 2009

There are two types of young

PRECOCIAL--are covered with down; eyes open, alert; legs strong, can walk in few hours; nest on ground, almost never in trees.

ALTRICIAL-- naked, can't regulate temperature; eyes closed at hatching; weak, can't stand up; mouth lining variable, often conspicuous, bright; nesting is variable, all tree nesters are altricial except the Hoatzin.

There is really a gradient from precocial to altricial.

Northern Waterthrush

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