
Photo: Julien Renoult · CC BY 4.0 (May be cropped or resized)
Oenanthe isabellina
Clutch size
4–6 pale blue eggs, usually unmarked, sometimes with reddish speckles
The Isabelline wheatear lays four to six pale blue eggs, usually unmarked but sometimes with a scattering of reddish speckles; the average egg size is 22.16 by 16.6mm (Wikipedia, general species account).
That is all the source read for the Bhutan guide gives. No plumage, size, range, habitat or diet information was found, so none is stated, and its occurrence in Bhutan is flagged for checking.