Zebra fecal egg counts
In wildlife, endoparasite burden can be strongly affected by host life-history stage, environmental conditions, host abundance, and parasite co-infections. We tested the effects of these factors on gastrointestinal parasite infection in plains zebras (Equus quagga) in the Serengeti ecosystem, Tanzania, using fecal egg counts of two nematode families (Strongylidae and Ascarididae) and on the presence/absence of cestode (Anoplocephalidae) eggs. We predicted higher egg counts of Strongylidae and Ascarididae and increased likelihood of Anoplocephalidae infection in individuals 1) during energetically costly life history stages when resource allocation to immune processes may decrease and in young zebras after weaning because of increased uptake of infective stages with forage, 2) when climatic conditions facilitate survival of infective stages, 3) during times of large aggregations when forage contamination with infective stages increases, and 4) in individuals co-infected with more than one of these parasites, as this may indicate reduced immune competence. Strongylidae egg counts were higher and occurrence of Anoplocephalidae eggs was more likely in bachelors than in band stallions, whereas Ascarididae egg counts were higher in band stallions. Strongylidae and Ascarididae egg counts were not affected by lactation in adult females or by age class in young. In adult males, adult females, and young, Ascarididae infections were more likely in wet conditions. Co-infections did not affect Strongylidae egg counts. Ascarididae egg counts in adult females were higher when individuals were co-infected with Anoplocephalidae. We present evidence that parasite burdens in plains zebras are affected by life history stage, environmental conditions, and co-infection.