Effects of fruit ingestion by Taiwan Barbet (Megalaima nuchalis) on seed germination of four native tree species in Taiwan

To clarify the effects of gut passage and feces of the Taiwan Barbet, Megalaima nuchalis, on seed germination, bird feeding and germination experiments were conducted for 4 native and commonly distributed tree species, Ficus microcarpa, Ficus superba var. japonica, Bischofia javanica and Cinnamomum[?] camphora, between November 2012 and February 2014. The experiment consisted of 4 treatments including washing the pulp, washing the pulp and scarifying the seed coat, not washing the feces, and washing the feces after the seeds had passed through the bird's gut. Intact fruits were used for the control. Seeds and fruits of the 4 tree species were separated into 2 different germination temperatures of 30/20 and 25/15°C, except that those of C. camphora were only treated at 30/20°C. Ficus superba var. japonica and B. javanica had high germination percentages and short germination times in a wide range of temperatures, i.e., 30°C during the daytime to 15°C at night. On the other hand, F. microcarpa had a lower germination percentage and longer germination time at 25/15°C compared to 30/20°C. Compared to intact fruits, washed seeds of B. javanica at the 2 germination temperatures, F. microcarpa at 30/20°C, C. camphora at 30/20°C, and F. superba var. japonica at 25/15°C exhibited significantly higher abilities to germinate. The results indicated an inhibitory effect on seed germination from the pulps of the 4 tree species. Compared to washed seeds, seeds passing through Taiwan's barbet's gut showed no significantly different germinability, except that fewer C. camphora gut-passed seeds germinated than washed seeds. The results indicate that the Taiwan Barbet's gut may remove pulp from around seeds of these 4 tree species and minimize the inhibitory effect of the pulp on seed germination. Compared to washed seeds, the germinability of washed and scarified seeds was higher for C. camphora, which indicated that the seed coat of C. camphora precluded the seeds from germinating. The Taiwan Barbet's gut apparently did not change the seed coat of C. camphora, which was suggested by the germinability of seeds passing through the barbet's gut being lower than that of washed and scarified seeds. To sum up, seed germination of F. microcarpa, F. superba var. japonica, and B. javanica was inhibited by their pulp, and that of C. camphora was inhibited by the pulp and the seed coat. Passage through the Taiwan Barbet's gut may facilitate seed germination of these 4 tree species by eliminating the inhibitory effect of the pulp but not by scarifying the seed coat. The bird's feces had no apparent effects on seed germination of F. microcarpa, F. superba var. japonica, or B. javanica; however, a possible fertilization effect on seeds of C. camphora should not be neglected, which suggests the need for a follow-up study.