The dispersal of fruits and seeds of Poison-ivy, Toxicodendron radicans, by Ruffed Grouse, Bonasa umbellus, and squirrels, Tamiasciurus hudsonicus and Sciurus carolinensis

A study was conducted to determine the dispersal potential of seeds and fru its of Poison-ivy (Toxicodendron radicans (L.) Rydb.) by mammals and birds in a study plot near Stonewall, Manitoba, Canada. Puffed Grouse (Bonasa umb ellus) and Red Squirrels (Tamiasciurus hudsonicus) and Grey Squirrels (Sciu rus carolinensis) were the most common visitors to feeders containing fruit s and to fruit-bearing plants. Squirrels acted as seed predators by removin g the exocarps and mesocarps from fruits and eating the seeds. However, the y often dropped individual fruits or entire infructescences that they had b een carrying to dining or caching sites and because of this they were effec tive dispersal agents for the seeds. Ruffed Grouse behaved as frugivores by eating the fruits and excreting intact seeds. Germination in seeds extract ed from grouse faeces was not significantly different from seeds from fruit s taken directly from the plants. Germination of seeds from within intact f ruit was higher but, not significantly, than that from seeds from which the exocarps and mesocarps had been removed. These results show that the fruit and seeds of Poison-ivy are food resources for Ruffed Grouse and squirrels , respectively. Both kinds of animals are effective seed dispersal agents f or seeds of this species.