Ferruginous Pygmy-Owls: a new host for Protocalliphora sialia and Hesperocimex sonorensis in Arizona.

Publication: Wilson Bulletin

Publication Date: 01-JUN-05

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COPYRIGHT 2005 Wilson Ornithological Society

Cactus Ferruginous Pygmy-Owls (Glaucidium brasilianum cactorum, hereafter pygmy-owl) are secondary obligate cavity nesters that require mature trees, including large columnar cacti, for nesting (Proudfoot and Johnson 2000). In March 1997, the U.S. Fish and Wildlife Service listed the pygmy-owl as endangered in Arizona (U.S. Fish and Wildlife Service 1997). In 1999, only 41 adult pygmy-owls were known to exist in Arizona. In 2000 and 2001, population sizes in Arizona were 34 and 36 adults, respectively (U.S. Fish and Wildlife Service 2003).

On 2 June 2002, during a cooperative study of nesting ecology and phylogeography of pygmy-owls in Arizona, we removed three dipteran larvae from the right wing of one pygmy-owl nestling. Larvae were incidentally discovered and then removed during routine banding of nestlings. The larvae, later identified by T. L. Whitworth as P. sialia (Diptera: Calliphoridae), were on the wing margin between secondary remiges number 5 and 6, 6 and 7, and 10 and 11. We preserved larvae in 95% ethanol and vouchered samples as study specimens at the Texas Cooperative Wildlife Collection at Texas A&M University in College Station. Subsequent examination of the infested nestling's siblings revealed no additional ectoparasites. To the best of our knowledge, this is the first record of P. sialia parasitizing pygmy-owls.

The nest cavity was 3.5 m above ground level in a saguaro cactus (Carnegiea gigantea) in the Altar Valley southwest of Tucson, Arizona. The entrance diameter (7.5 x 9.0 cm) was large enough to remove nestlings and nest material by hand. After the nestlings fledged, we removed and examined nest material for additional P. sialia; none were found. However, we did collect 119 Hesperocimex sonorensis (Hemiptera: Cimicidae), another hematophagous parasite. To the best of our knowledge, this is the first published record of H. sonorensis infesting a pygmy-owl nest cavity. Due to funding and time limitations, nest material was not examined from any other pygmy-owl nest cavities.

The Calliphoridae mostly comprise...

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