VOLLMER A, BOTH C & TINBERGEN J (2007) Sea Buckthorn Hippophae rhamnoides berries as winter food of Great Tits Parus major. LIMOSA 80 (2): 68-75.

It has been long known and studied well that Beech mast is an important food source for Great Tits in winter. The situation in the Lauwersmeer area in the northern Netherlands is different though: there are no Beeches here, but Sea Buckthorn shrubs are very common. Could these conspicuous and nutritious berries play a role in the life of a Great Tit? Great Tits sleep in the winter in their nestbox, where they produce faeces. We were able to link the colour of the faeces (orange vs. dark brown/black) to the consumption of buckthorn berries and thereby gained more insight in the diet of the Great Tits. Furthermore we found out that the availability of the Sea Buckthorn shrubs influenced the dispersal of the birds in winter. With a higher berry density both the consumption of berries and the number of birds present were higher. The probability that a bird was found in a wood where it was born or had bred was independent of the amount of Sea Buckthorn nearby. However young birds that had switched between woods and birds that had come from somewhere else were more likely to be found in a wood with more berries.

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