THE PALATABILITY OF ARCTIC WILLOW FOR GREATER SNOW GEESE - THE ROLE OF NUTRIENTS AND DETERRING FACTORS

Temporary feeding on willow buds and leaves by nesting greater snow ge ese provided us with an opportunity to test the relative importance of nutrients and deterrents in affecting the palatability for geese of a food plant with a high phenol content. Protein, total phenol and fibe r (neutral and acid detergent fiber, and lignin) were analyzed in clos ed and open buds and in rolled and open leaves. Geese feed on willows at the open-buds and rolled-leaf stages but not at the closed-bud and open-leaf stages. Protein content was higher in open buds and rolled l eaves (25-27%) than in closed buds and open leaves (19-21%). Phenol co ntent increased during leaf emergence but was already high (14%) in ro lled leaves. All plant fibers were very high in closed buds but declin ed rapidly during leaf emergence. The increase in phenol:protein ratio appeared to be more important than phenol concentration alone in expl aining the cessation of feeding by geese on willow leaves whereas the high fiber content of closed buds may explain why they were not eaten. Our results illustrate the value of a multifactorial approach in the study of the food selection process in herbivores.