Large-billed Crow – sex differentiation

16 Nov 2012   in Crows, Morphology-Develop. 1 Comment »
Contributed by Dato’ Dr Amar-Singh HSS

“The common crow in the country is the House Crow (Corvus splendens) but it is not native. It was brought over from India in the early 1900s to deal with pests in Selangor (caterpillars in the coffee plantations). From there they discovered the nearby town (Klang), which since has been ‘crow capital’. It has progressively spread through some of the major cities of the west coast of the peninsula.

[The images above and below show the presumed male. Notice the 'notched-tipped throat feathers' (Wells 2007) which have a blue-green sheen best seen in imaged 1a. Also the violet-blue in wings.]

“We have yet to get clear sightings of the House Crow in my area. But the Large-Billed Crow (Corvus macrorhynchos macrorhynchos) does occur, with increasing frequency in the past 10-15 years. Previously seen at the outskirts of the city and fringe of the jungle, now I have 15-20 that fly over our home daily to go to feeding grounds and return in the evening.

“Wells, D.R. (2007) ‘The birds of the Thai-Malay Peninsula: Vol. 2 (Passerines)’ suggest that there is sex differentiation. Three features are listed for the female: slightly smaller build, less graduated tail and upper mandible less strongly arched (above). This pair seems to fit the description.”

[The composite image below shows the male above and the female below.]

Dato’ Dr Amar-Singh HSS
Ipoh, Perak, Malaysia
4th November 2012

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  • One Response to "Large-billed Crow – sex differentiation"

    1. Am says:

      The problem is, you won’t know what a “less strongly arched” mandible is, unless you have something to compare it to. Which means, if you saw a bird on its own, it would be difficult to identify it unless there was another of the opposite sex next to it.

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