Today was much quieter than yesterday, with just 4 new birds and 2 recaptures. We are now capturing just residents, and, with the lack of moulting ecology we have on them, they are making our attempts at ageing them pretty difficult!

First up was a Swinhoe’s White-eye with a fairly worn wing, but no obvious moult limits. Must be aged as a 2nd calendar year or older.

Next up was a couple of recaptured Common Tailorbirds. Both were originally ringed in 2021, meaning they are at least 2nd calendar year birds.

The individual above was ringed in September 2021 as a 1st calendar year bird, meaning that it must be a 2nd calendar year now. Typically we do not age our birds based on the original capture (for fear of bias), but instead with the characteristics we see in the bird on every capture.

In the bird above we can see a potential moult limit between the PCs and the GCs, with the PCs being more brown, worn and less dense. This could be a moult contrast between juvenile PCs and post-juvenile GCs, but we need more individuals to be sure of this.

Click to enlarge.

The young birds continued with a 2 1st calendar year Red-billed Leiothrixs! Again, due to the lack of information on their moulting, we use their irises for ageing.

Irises can be difficult to photograph, so here we have enhanced the brightness of the photos to show the difference between an adult bird (left) and juvenile (right). Juveniles have a typically more brown iris, vs the adults that show a more red iris. As aforementioned, we must be careful in using solely the iris for ageing, as we need the information for when the first juveniles begin to show an adult-type iris- something we do not have for many Hong Kong species.

Daily Totals

*Please note that all wild birds are protected under Hong Kong Law. All ringing activities are conducted with the necessary permits issued by the AFCD. Handling and processing of birds is only carried out by experienced individuals.*