Please take a look of the comment by Paul LEADER one year ago.
http://www.hkbws.org.hk/cgi-bin/yabb/YaBB.pl?board=BirdingTips;action=display;num=1144158702
Thanks for the links, but (as ever with photos on the net) be aware that many of these are misidentified, although is not surprising given the confused taxonomy of the Sand and Pale Martin complexes and the lack of references which deal with them in sufficent detail.
The easiest way to separate them is structure with Pale Martin having wings longer than the tail at rest and a very shallow fork to the tail (recalling Asian House Martin), whereas on Sand Martin the wings are about the same length (or shorter) than the tail at rest and the tail has a deep fork, rather like a juvenile Barn Swallow.
In general Pale Martin is the most widespread in China with three or four different and quite distinct subspecies occuring. Sand Martin would appear to be largely restricted to eastern China. Author: cgeoff Time: 27/04/2007 12:41 Subject: cropping photos
Many of the photos on the site are crops from larger images. While this is perfectly understandable, and in most cases desirable, please could photographers be careful not to crop out parts of the bird. I've noticed this on a few occasions recently. In particular, the second of the martins above has had the tip of the tail cropped out, and it is not possible to see the full length. As Paul has pointed out, tail length is very important in identifying these birds (as well as a number of others).
Geoff Author: sammysam Time: 27/04/2007 21:58
Geoff,
As the birds are nearly fit the whole frame, there are no cropping at the tail part of the original photos.
Sammy
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