Muir, R. C, Lawton, J, Clafton, F. R, Clafton, F. R & Mylne, C. K / December 1959 – vol. 52, issue 12–435 Birds drinking the sap of a birch tree.--On 13th April 1958 I was watching a Marsh Tit (Parus falusiris) feeding at the edge of a deciduous wood at Minsmere in Suffolk when I noticed it return several times to the same place on a tree. At first I thought it was taking insects, but then I realized that the bird was drinking the sap oozing out of a broken twig. Three times the bird flew off to feed ... This article is only available to registered users.To read more, please log in or purchase a subscription.