Wednesday, 2 October 2013

Butcherbirds

Adult male Pied Butcherbird - there is a reason for the glove, see below
Last weekend I was on a bird-banding trip to the Weddin Mountains, run by Richard Allen. There were seven of us altogether to set up and maintain vigilance over the numerous mist nets we had placed throughout a patch of wooded, partially-cleared pastureland adjacent to the nature reserve. Most of the birds in the area seemed to be local breeders, which was reflected by the catch of adult birds of a wide variety of species, but no high numbers of any one species other than White-plumed Honeyeater, which were abundant and breeding. One pair had a nest in the tree branches above the banding station. And we also found nests Spotted Pardalote, Speckled Warbler, White-winged Chough and Pied Currawong. 

The glossy black hood and wide white collar indicate that this is an adult male bird,
some of the bird's black feathers have faded to brown under almost
 a year of sunlight since it probably moulted and grew that set  
Butcherbirds are never abundant in any area as the pairs guard their territories well, excluding all others. So it was doubly opportunistic for us to catch two species, Pied Butcherbird Cracticus nigrogularis and Grey Butcherbird Cracticus torquatus. And as they were breeding, we had a chance to compare and note features of the two species' full adult plumage. The Pied Butcherbird illustrated here is an adult male, the distinguishing features for an adult being: the blue-grey bill with a black tip, juvenile and  immature birds have grey/brown bills through to dull blue, each with a dark grey tip; his hood is black rather than brown/grey of an immature bird. Adult females have less white on the outer wing coverts, less glossy black in the hood and grey on the back. 

Butcherbirds have a well defined hook on their bill tip
The Grey Butcherbird is very like the Pied and could perhaps be most quickly described as a similar bird, but of of duller plumage. As its name describes, it is grey overall. The adult male has a black hood, but white throat unlike the Pied's black bib. As with the Pieds, these adults also have blue bills with black tips, while the young birds have grey-brown ones with darker tips. The bird illustrated here is an adult female as she has a grey-brown hood and a distinct patch of off-white feathers in the lores, complete between the eye and bill; the male has a distinct white spot on the lores which does not extend to the eye.  

Adult female Grey Butcherbird
Great care should be taken when handling butcherbirds of any species as they can bite...

The hook on the tip of a butcherbird's bill is well adapted for gripping

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