The potential of bird feeders to be used for ecological monitoring of vectors for Phytophthora ramorum in garden and woodland environments

Abstract

Bird feeders were investigated for their use in determining whether birds are vectoring the tree disease Phytophthora ramorum, and whether feeders are acting as nodes of spore transfer. This was done by studying feeders at residences in Keele University and in Olderwood and Denham Woods, Devon. Keele borders a P. ramorum managed woodland and the Devon sites had past confirmations of the disease and ongoing control management. The feeders were tested for P. ramorum using swabs in combination with rapid diagnostic test kits, and no positive results were detected. Surveying the households produced data showing the potential use of feeders for ecological monitoring, including avian Phytophthora vectors. Questions included frequency of cleaning the feeders and 48% reported less than once per year. The range of birds reported were predominantly common passerine species and 76% reported regular use by Grey Squirrels. Observations and camera traps were used to study feeders in woodland environments. A total of 14 bird species were observed and 4 species of mammal. Based on visitation numbers, feeders took between 1.5-3 weeks to become established in these woodlands. Preferences for hanging feeders were found for Great Tit, Coal Tit, Blue Tit and Siskin, whereas Marsh/Willow Tit, Nuthatch and Robin showed preference for ground feeders. All the species seen on the feeders were resident species, although migrants were observed in the same environment. Few correlations were found between feeder visits and environmental variables, and unmeasured factors may have determined the differences observed in visitation rates across the study period. Camera traps recorded behaviour not captured by observations, indicating time preferences by species. Conversely observations provided information not gained through camera traps, displaying merit in a joint approach to monitoring feeders. The data collected is used to create recommendations for future study using feeders and avian Phytophthora dispersal.