Bird Dissemination of Dwarf Mistletoe on Ponderosa Pine in Colorado

Publisher Website
Google Scholar
Abstract
Dwarf mistletoe [A. v. ssp. cryptopodum (Engelm.) Hawksworth and Wiens] distribution and the role of birds as vectors of the parasite were studied in a Colorado ponderosa pine (Pinus ponderosa Laws.) forest. Occurrence of the parasite at distances from a source greater than those attributable to explosive seed discharge was erratic and infrequent. In 24 cases, ages of initial infections in single or multiple tree infection centers were determined. Age analyses indicated that long-distance seed transmission followed by successful infection occurred on an average once every 4 yr in 150 ha of healthy ponderosa pine. A total of 411 birds representing 21 spp. were trapped in an infected pine stand during dwarf mistletoe seed dispersal in 1974-1976. Mountain chickadees (Parus gambeli Ridgway) and pygmy nuthatches (Sitta pygmaea van Rossem) were primary vectors of the parasite. Field observations and laboratory experiments suggested that birds ingested dwarf mistletoe seeds infrequently but such seeds were not viable when voided in feces. Viable seeds apparently were transported by birds only when they adhered to feathers and were transferred to foliage at birds subsequently foraged.

This publication has 2 references indexed in Scilit: