Animal vectors of Arceuthobiumamericanum seed in Manitoba
Long-distance dispersal of Arceuthobiumamericanum Nutt. ex Engelm. seed by animals was investigated in Grand Beach Provincial Park, Manitoba, where passerine migration routes traverse stands of dwarf mistletoe infected Pinusbanksiana Lamb. Small mammals appear to be insignificant as vectors in Manitoba as no seeds were found on any of the 193 individuals trapped. In contrast, 5.5% of 146 birds netted in 1986 and 5.1% of 59 netted in 1987 carried seed. Three species are reported carrying seed for the first time: brown creeper (Certhiaamericana), Swainson's thrush (Catharusustulatus), and red-breasted nuthatch (Sittacanadensis). Seeds were also found on five gray jays (Perisoreuscanadensis) and three dark-eyed juncos (Juncohyemalis), species for which numerous records of dwarf mistletoe seed transport already exist. Swainson's thrushes and dark-eyed juncos are potential disseminators of A. americanum seed into jack pine stands in northern Ontario and the Great Lakes States during years when seed discharge and migration overlap.