Effects of bird ingestion on seed germination of Vaccinium cylindraceum (Ericaceae), an endemic species of the Azores archipelago1This article is part of a Special Issue entitled “A tribute to Sam Vander Kloet FLS: Pure and applied research from blueberries to heathland ecology”.

Abstract

In this paper we investigate the effects of bird ingestion on Vaccinium cylindraceum Smith seed germination characteristics and the effect of a lack of bird dispersal on seed germination in the field. To test the effect of bird ingestion on seed germination, we carried out laboratory germination trials using ingested seeds and manually depulped seeds. To test the effect of a lack of bird dispersal on seed germination, we carried out germination trials using intact fruits above or under a cap of dead leaves under field conditions. The number of damaged seeds per fruit differed between species. Nearly 92% and 70% of the seeds ingested by, respectively, Erithacus rubecula and Turdus merula passed intact through the birds’ digestive tracts, and the germination characteristics of these seeds were not significantly affected. Only 16% of the seeds ingested passed intact through the digestive tract of Fringilla coelebs , and the germination ability of these seeds was significantly reduced. Uncovered intact berries in the field cracked, exposing the seeds to light, thus resulting in 18% of germination. Our results suggest that E. rubecula, T. merula, and F. coelebs can act as seed dispersers of V. cylindraceum. Also, V. cylindraceum seeds do not need to be ingested to germinate, but seed germination is enhanced as a consequence of seed exposure to light.