Searching a Little Stint among hundreds of Red-necked Stints is always a challenge to birdwatcher in HK. We always say body/bill shape are the most accurate clues for bird ID. However, I think it's too difficult to see the different in HK as most of time we see Little Stint is from a far far distinct and hiding behind crowds of similar waders.
I think we can search a Little Stint in Spring HK by looking at these features:
1. bright orange tertials and greater coverts
2. White throat
3. White V-shape on mantle
My approach is searching the flocks of stints for a "golden" individuals, and then confirm it with white throat an white V-shape(Beware of the yellow legged Long-toed Stint).
I think there are few of them at Mai Po at this period of time and I've just got a record photo.
Little Stint on left and Red-necked Stint on right.
Having say so, I think your photo is a Red-necked Stint.
A nice close-up photo for this species anyway.
Gary
