The female of all three are distinct and unmistakable, if a pair is seen together, their ID should be readily confirmed.
The males, on the other hand, are a different story, they look puzzling at first but there are subtle features to tell them apart as described below.
Bornean Blue Flycatcher
The identification features of male Bornean Blue Flycatcher are lack of dark chin and a bright shiny turquoise blue down its mantle and back as indicated in the above image.
This species is endemic to Borneo.Mangrove Blue Flycatcher
You can see that Mangrove Blue does have dark chin, contrary to the plate in Susan Myers, however, its mantle and back lacks the bright and shiny turquoise blue of the Bornean Blue. Its upperparts are also more uniformly colored.
Large-billed Blue Flycatcher
This image is courtesy of Kong Ket Leong
Large-billed Blue Flycatcher, on the other hand has relatively more saturated and extensive rufous orange underparts, the legs look paler on birds that I have photographed.
It has more extensive dark chin than Mangrove Blue. Its back is dull blue in contrast to the darker mantle, whereas Mangrove Blue has the back uniformly colored with the mantle.
Large-billed Blue Flycatcher is only found on Borneo and Sumatra.
It has more extensive dark chin than Mangrove Blue. Its back is dull blue in contrast to the darker mantle, whereas Mangrove Blue has the back uniformly colored with the mantle.
Large-billed Blue Flycatcher is only found on Borneo and Sumatra.
In Summary, the key to separate them is as follows:
1. If no dark chin = Bornean Blue Flycatcher.
2. If has dark chin
2A, back and mantle uniformly colored = Mangrove Blue Flycatcher.
2B, mantle dark and back dull blue = Large-billed Blue Flycatcher.
It is not that hard, is it?
Happy birding.
Photodocument of the wild birds of Borneo.
Standard References for my blog.