Microbial impact of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus) on aquatic ecosystems.

Quantitative and qualitative analyses of the intestinal bacterial flora of Canada geese and whistling swans were carried out with the finding that wild birds harbor significantly more fecal coliforms than fecal streptococci. The reverse was typical of captive and fasting birds. Neither Salmonella spp. nor Shigella spp. were isolated from 44 migratory waterfowl that were wintering in the Chesapeake Bay region. Enteropathogenic Escherichia coli were detected in seven birds. Geese eliminated 10(7) and swans 10(9) fecal coliforms per day. Results of in situ studies showed that large flocks of waterfowl can cause elevated fecal coliform densities in the water column. From the data obtained in this study, it is possible to predict the microbial impact of migratory waterfowl upon aquatic roosting sites.

A mallophaga, Trinoton anserinum, as a cyclodevelopmental vector for a heartworm parasite of waterfowl.

The biting louse Trinoton anserinum serves as the intermediate host in the life cycle of the filarial heartworm, Sarconema eurycerca. Microfilariae, second-, and third-stage larvae were dissected from 39 of 89 lice infesting whistling swans, Cygnus columbianus columbianus, in North America and mute swans, Cygnus olor, in the Black Sea, U.S.S.R. Infective third-stage larvae obtained from lice collected from heartworm-parasitized whistling swans were injected subcutaneously into each of two hand-reared, nonparasitized mute swan cygnets. Both of these birds developed heartworm infections, one becoming microfilaremic at 14 weeks. The results of this study provide conclusive evidence that a mallophagan serves as a natural cyclodevelopmental vector of a filarial parasite.