Health assessment of seabirds on isla genovesa, galápagos Islands

A multispecies colony of seabirds was studied on the island of Genovesa, in the northern part of the Galpagos archipelago, Ecuador, in 2003, to establish baseline health parameters and to test specifically for Chlamydophila psittaci, known to exist elsewhere in the archipelago. Twenty-three Red-footed Boobies (Sula sula), 24 Great Frigatebirds (Fregata minor), 25 Nazca Boobies (S. granti), and 19 Swallow-tailed Gulls (Creagrus furcatus) were hand-restrained for venipuncture and collection of lacrimo-choanal-cloacal combination swabs. White blood cell (WBC) counts, differentials, and packed cell volumes were obtained and plasma chemistry analyses performed on the blood samples. Presence-absence and parasitemias of circulating hemoparasites were determined by microscopic evaluation of peripheral blood smears. Haemoproteus-like hemoparasites were found in three of the seabird species sampled. Prevalences were 29.2% (7 of 24) in Great Frigatebirds, 15.8% (3 of 19) in Swallow-tailed Gulls, and 8.7% (2 of 23) in Red-footed Boobies; none of the Nazca Boobies were infected. Parasitemia levels were relatively low within each of the infected species. Individual Great Frigatebirds with Haemoproteus infections also exhibited significantly higher heterophil-to-lymphocyte concentration ratios than birds not infected with Haemoproteus, an indication that birds infected with Haemoproteus were also physiologically stressed or, alternatively, that they were actively fighting the infection. Haemoproteus prevalences within Great Frigatebirds on Genovesa were not significantly different from those previously reported from conspecific hosts in the Hawaiian Islands. To compare seabird hemoparasite data with those for a sympatric terrestrial species, Galapagos Doves (Zenaida galapagoensis) were sampled on Genovesa in 2004 and screened for Haemoproteus previously reported in Galapagos Doves on other islands. Prevalence in this terrestrial endemic was high (42.3%; 11 of 26), and several birds exhibited relatively high parasitemia levels. Chlamydophila psittaci was not found in any birds by either serology or antigen detection methods.