On the evening of March 28 saw me arriving at Nam Kham Nature Reserve in Chiang Saen, Chiang Rai Province with my friends who are also bird ringers. They had to prepare poles and nets for the following morning, so I went into one of the hides to see if there’s any bird at the pool made for birds to come and bathe. To my surprise, as I stepped into the hide, the rare Chestnut-crowned Bush Warbler was already bathing, as well as a male Siberian Rubythroat. They quickly flew into the bush as they noticed me but came out shortly afterwards.
The Chestnut-crowned Bush Warbler came down to the pool 3 times until it got completely dark, but I could only get a few ok-ish shots. This is a rare and quite mysterious species that overwinters in northern Thailand. We only knew that it spends the winter in lowland reed beds just a few years back when Nam Kham was established. On the other hand, it moves up to high montane forest to breeding during breeding season.
While the bush warbler was away, I was entertained by a family group of the colourful Chestnut-capped Babbler. Two parent birds and two juveniles came to enjoy evening bath for more than 10 minutes. Both of the parents were ringed just like the bush warbler and most birds here. Another bird which came to the pool was the lovely Baikal Bush Warbler, but it was already too dark for me to get any good shot.
On the following morning, I joined a ringing session where we caught some really nice birds. The first one that I saw was a smart adult Chestnut-capped Babbler followed by a very brightly coloured Yellow-bellied Prinia. A beautiful male Siberian Rubythroat was also caught as well.
But the highlight of the session was a single Blyth’s Reed Warbler, one of the rare Acrocephalus warblers in Thailand. Few records have beeb reported from Nam Kham Nature Reserve and Bung Boraphet in Nakhon Sawan Province.
We also caught 2 Blunt-winged Warblers, a rather common but extremely difficult to see species, so we had a really nice opportunity to compare the two species closely together. The best way to distinguish the two is by looking at the primary projection. Blunt-winged Warbler has shorter primary projection than Blyth’s making the wings look shorter and rounder, hence the name Blunt-winged. Apart from the primary projection, I also noticed that the iris of the two species were slightly different; Blyth’s having a lighter and more rufous colouration than Blunt-winged which has a cold brown tone to it.
Since there had been no confirmed photo of Blyth’s Reed Warbler taken in Thailand in the wild, I prepared to take photos of it after being released. The above shots were already my best effort. Unfortunately some part of the bill is hidden in both shots but at least the long primary projection is still visible confirming that it is not a Blunt-winged nor Paddyfield Warbler.
I then took a walk around the reed maze and came across 2 singing Acrocephalus warblers in tall reeds. Since one of them was so close, I tried recording the song using my iPhone and played back. Quite amazingly, despite the very low volume, the bird still responded and came out to perch on reed top for few seconds, enough for me to snap some shots before it flew out. One of the shots shows wing formula which seems to suggest that it’s a Blunt-winged Warbler (relatively long P1).
Before leaving Nam Kham, I spent about an hour sitting in the hide waiting for birds to come and bathe. Only a Baikal Bush Warbler showed up briefly. I guess it was the same individual that showed up in the earlier evening. It was still in a non-breeding plumage, showing no sign of grey on breast nor dark lower mandible which are characteristics of breeding plumage.