 The red warbler is a small passerine , measuring 12 @.@ 5 – 13 @.@ 5 cm ( 4 @.@ 9 – 5 @.@ 3 in ) in length , and weighing from 7 @.@ 6 to 8 @.@ 7 g ( 0 @.@ 27 to 0 @.@ 31 oz ) . As an adult , it is red overall , with either a white or dark gray ( depending on the subspecies ) auricular patch on each side of its head . Its slightly darker wings and tail are edged in pinkish @-@ red . Its legs are flesh @-@ colored , and its flesh @-@ colored bill shows a dark tip . The feathers of this species contain alkaloids , which render the bird unpalatable ; humans find it inedible . 
