On the Enviroweeds List Server, a request was recently made for information on the bird species that feed on English Ivy fruit, and the possible distance that they spread the seed.
Respondents listed Blackbirds and Pied Currawongs as culprits, but limited information was presented. Pied Currawongs can disperse seed up to 20 km, while Blackbirds seed dispersal is less than 100 m.
I have been able to find very little information on the specific bird species that disperse our serious weed seeds. Carr (1993) has published a table showing 53 different environmental weed species in Victoria that are dispersed by various animals, including birds, following ingestion of fruit or seed. However most of the information in the table is from personal observations, not from exhaustive research projects, and many serious weeds such as English Ivy and Blue Bell Creeper are not listed. The most common bird dispersal agents listed were Blackbirds, Pied Currawongs and Red Wattle Birds.
An interesting research report on the dispersal of olive seed is available on Google (Spennemann and Allen 1998). Starlings are a major pest in olive orchards. They are known to fly up to 40 km from their roosts for feeding, which permits large scale dispersal of seed. Carr (1993) lists Starlings as a dispersal agent also for Coast Wattle (Acacia longifolia var. sophorae), which is closely related to Sallow Wattle (Acacia longifolia var. longifolia) arguably the worst environmental weed on the Surf Coast. I am not sure whether Starlings are common in Anglesea, or whether a range of other birds also disperse Sallow Wattle seed.
I think it would be very valuable information if we knew which animal species disperse the major environmental weeds on the Surf Coast. It could make a very interesting citizen or community based research project.
Reference: Carr, G.W. 1993, Exotic flora of Victoria and its impact on indigenous biota. In D.B.. Foreman and N.G. Walsh (Eds.), Flora of Victoria Volume 1. Introduction. Inkata Press,
Spennemann Dirk H.R. and Allen L. Richard 1998, The Spread of Olives on Wagga Wagga Campus, Charles Sturt University The Johnstone Centre, Report No. 101