bird's nest vs covert

bird's nest

• A structure built by a bird as a place to incubate eggs and rear young. 

• Any of several plants having some resemblance to the typical nest of a bird, eg, wild carrot (Dauca carota) 

• Any tangle of fibers resembling a typical nest of a bird. 

covert

• A feather that covers the bases of flight feathers. 

• A covering. 

• A disguise. 

• Area of thick undergrowth where animals hide. 

• A hiding place. 

• Under coverture. 

• Secret, surreptitious, concealed.