John Holmes

10th Nov 2016   Tai Sang Wai   7D2 + 500mm f4

subbuteo

Thanks John- good to have a comparison like that! It looks like Northern has a deeper fork in the tail and a more extensive, cleaner white rump- any thing else to look for?

Dylan

lpaul

John, do you have photos of the underparts of both you can add?

John Holmes

Hi Dylan and Paul

- here are some shots of the underparts - only one of the Northern House Martin, then four of what I think is Asian.

Asian is more compact, and, as you know, often is darker on the flanks and rest of the body, but this is a variable feature.  (and according to "The Avifauna of HK" there are two possible AHM races to occur here..!)

[ Last edited by John Holmes at 18/11/2016 07:42 ]

lpaul

John,

I think your photos show both taxa of Asian House Martin that occur in HK.

Note that all your birds are first-winter birds based on the white tip to the tetials.

The two Asian House Martin taxa that occur (nigrimentalis from se China and Taiwan) and nominate dasypus (ne China, Korea, eastern Russia)can generally be separated on size, structure and plumage.  The former is much more sullied below and on the rump and is smaller which a shorter more shallowly forked tail (as per the 2nd and 3rd images in your second post).  Nominate dasypus is much cleaner below and on the rump, is larger and has a longer and more deeply forked tail (4th and 5th images).