Patten, D. B. D. E, Paine, A. R. J, Campbell, J. D. O. W. D, Heubeck, M, Glover, E. M. R. J. F. B, Clark, F, McNeil, D. A. C, Oreel, G. J, Britton, D, King, B & Vittery, A / March 1981 – vol. 74, issue 3, pp 146–151 Undertail-coverts of Little Grebe According to the literature, one important distinction between Pied-billed Grebe Podilymbus podiceps and Little Grebe Tachybaptus ruficollis is the white undertail-coverts and vent of the American species. In BWP, the undertail-coverts of Pied-billed are described as 'conspicuous white', but those of Little Grebe as 'grey-brown' in breeding plumage and 'pale grey-br... This article is only available to registered users.To read more, please log in or purchase a subscription.