Disease patterns in the Detroit Zoo: a study of the avian population from 1973 through 1983

A retrospective study was conducted to evaluate disease patterns in birds at the Detroit Zoo from 1973 through 1983. Data were derived from the zoo's medical and animal census records; the mean (+/- SD) population of birds during the study period was 469 +/- 42. Overall annual morbidity rates were 12.5% to 21.5%, with spring months having the highest morbidity rates. Annual mortality rates were 3.1% to 15.2%; 23.9% of the deaths were caused by microbial agents (particularly Erysipelothrix rhusiopathiae, hemolytic Escherichia coli, Salmonella spp, Aeromonas spp and Proteus spp), 15.4% by trauma, and 42.5% by nondetermined causes. The mute swan (Cygnus olor), mallard duck (Anas platyrhynchos), common gallinule (Gallinula chloropus), common rhea (Rhea americana), and red-billed hornbill (Tockus erythrorhynchus) were the 5 species most frequently affected of the 1,032 deaths from 1973 through 1983. The most frequently isolated parasites were Microtetramere spp, coccidian species, Diplotriaena spp, and Trichomonia spp.