June 2025

2024/10- Island Ringing: Hill Blue Ahead!
by hkbwsofficial

A fairly slow autumn season for us, but not without its highlights!

A bird we don’t catch so often, in the form of the gorgeous Hair-crested Drongo! This is one of our more conspicuous residents, found flitting around open areas with their distinctive long tails trailing behind them!

But, at the risk of sounding like a broken record, it is another resident that we do not know much about the moult of (although realistically they probably carry out Summer Complete moults in both adults and juveniles). Therefore, we must leave this individual unaged for now, as a 1st calendar year or older.

Another uncommon capture for us this month was this beautiful little Two-barred Warbler! As mentioned previously, this species can be differentiated from the similar Arctic Warbler by their significantly longer Primary 1 (outermost). Ageing these guys is actually similar than their doppelgangers, with adults and juveniles both carrying out very restricted summer partial moults. However, adults’ wings are typically significantly more worn than juveniles. This is partially due to the feathers being much older than juveniles (almost a year old versus just a couple of months old), and partially due to interspecies variation- i.e. some species just don’t keep their feathers in as good condition as others.

For us, this means that, because the wing is rather fresh, we can tell this is a 1st calendar year bird!

And finally, I may have saved the best for last. By now, you probably have realised that the vast vast majority of the blue flycatchers we catch in Hong Kong are Hainan Blues. So, imagine our surprised when, just at the end of this month, we pulled out an individual that most certainly was not a Hainan Blue! It turned out to be a gorgeous Hill Blue Flycatchers, which is potentially the first ever capture of this species in Hong Kong!

This individual appeared to show a moult limit in the tertials, and between the GCs and PCs (the GCs being denser, darker and with that rich blue hue). Though it is possible for this to be 1st calendar bird have carried out a fairly extensive summer partial moult, the lack of knowledge on the moult strategy and the extent of the moult in this species leaves it best to be aged as a 1st calendar year or older for now!

Daily Totals

SpeciesOriginalRecapture
Black-browed Reed Warbler10
Common Emerald Dove21
Common Tailorbird10
Dusky Warbler80
Greater Coucal10
Hair-crested Drongo10
Hill Blue Flycatcher10
Oriental Magpie Robin10
Pale-legged Leaf Warbler52
Red-whiskered Bulbul10
Sakhalin Leaf Warbler10
Siberian Blue Robin10
Siberian Rubythroat20
Two-barred Warbler20
Yellow-bellied Prinia11
Grand Total294

*Please note that all wild birds, their nests, and eggs are highly protected (under Wild Animals Protection Ordinate, Cap. 170) in Hong Kong. It is an offence to wilfully disturb, take, remove, or injure wild birds or their nests/eggs. The actions described here were undertaken by trained professionals holding the necessary licenses and permits issued by the AFCD.*

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