
Photo: Matt Felperin · CC BY 4.0 (May be cropped or resized)
Anas acuta
Size
Males 59–76cm; females 51–64cm
Wingspan
80–95cm
Weight
Males 450–1,360g; females 454–1,135g
The northern pintail is a fairly large duck with a wingspan of 80 to 95cm. The male is 59 to 76cm long and weighs 450 to 1,360g, considerably larger than the female, which is 51 to 64cm long and weighs 454 to 1,135g (Wikipedia, general species account).
The only source opened for the Bhutan guide gives these measurements and nothing else, with no plumage, range, diet or breeding detail, so none is stated. The entry is kept short rather than borrowing from other accounts.