Hematozoa are reported from 1,361 members of the Passeriformes representing 101 species and 22 families, all from Colorado. Some parasitemia was observed in 693 birds (51%). The parasites and their incidences were: Plasmodium (all species), 43 (3%); Haemoproteus, 229 (17%); Leucocytozoon, 273 (20%); Trypanosoma, 401 (29%); Haemogregarines sensu lato (Hepatozoon and Lankesterella), 40 (2.9%); microfilaria, 174 (13%). Seventy-one new host-parasite associations were encountered. Two papers on the hematozoa of Colorado birds have been published by Stabler and Holt (1963, 1965). This third in the series deals with 1,361 members of the Passeriformes, representing 101 species and 22 families. MATERIALS AND METHODS All birds were from Colorado, the majority being from east of the Continental Divide. The period of collection extended from 1948 to 1969. Blood from those captured alive was obtained from a snipped toenail and from the body cavity of those which were shot. Following staining with Giemsa, the blood films were first scanned under low dry magnification (150 X ) and then searched under oil immersion (1,455 X) until we felt that all hematozoan types had probably been detected. The femoral marrow from many of the dead birds was examined in physiological saline for trypanosomes. RESULTS The results are summarized in Table I. Of the 1,361 birds examined, 693 (51%) showed some parasitemia. The parasites and their incidences were: Plasmodium (all species), 43 Received for publication 22 July 1969. (3%); Haemoproteus, 229 (17%); Leucocytozoon, 273 (20%); Trypanosoma, 401 (29%); Haemogregarines sensu lato (Hepatozoon and Lankesterella), 40 (2.9%); microfilaria, 174 (13%). Of the 401 infections with Trypanosoma, only 91 had the organism in the circulating blood. Seventy-one new host-parasite associations were encountered. The common redpoll appears to have been examined parasitologically for the first time. DISCUSSION The complete hematological picture of some of the 1,361 passeriforms has already been published (Stabler, 1961). These birds constitute less than 10% of the total, are all magpies, and are included here for the sake of completeness. Table I bears a column headed "Hg sensu lato" (Haemogregarines sensu lato). It includes parasites similar to those described by Wood and Herman (1943) and Clark and Swinehart (1966) as Hepatozoon (32 cliff swallows, 1 plain titmouse, and 1 western blueTABLE I. Hematozoa from Colorado Passeriformes. Hg sensu Bird Total No.+ Pr Pc Pr-c Pp Pv Pn Ph H L T lato M Tyrannidae Eastern kingbird 10 4 2 2 1 Tyrannus tyrannus Western kingbird 16 9 1* 1' 2 7* Tyrannus verticalis Ash-throated flycatcher 2 1 1* Myiarchus cinerascens Say's phoebe 10 2 1* 1 Sayornis saya Western flycatcher 4 4 2* 4 Empidonax difficilis Western wood pewee 9 5 4 1* Contopus sordidulus Vermillion flycatcher 1 0 Pyrocephalus rubinus Genera and species names are listed according to the fifth (1957) edition of the AOU Check-list. Abbreviations: Pr, Plasmodium relictum; Pc, P. cathemerium; Pr-c, P. relictum-cathemerium; Pp, P. polare; Pv, P. vaughani; Pn, P. nucleophilum; Ph, P. hexamerium; H. Haemoproteus; L, Leucocytozoon; T, Trypanosoma; Hg sensu lato, Haemogregarines sensu lato; M, Microfilaria; *, New host-parasite records. 12 This content downloaded from 207.46.13.71 on Sat, 22 Oct 2016 06:17:57 UTC All use subject to http://about.jstor.org/terms STABLER AND KITZMILLER-HEMATOZOA FROM COLORADO PASSERIFORMES 13