[453] The Condor 105:453–464  The Cooper Ornithological Society 2003 BACTERIA IN THE REPRODUCTIVE TRACTS OF RED-WINGED BLACKBIRDS GINA HUPTON 1,3 ,SUSANA PORTOCARRERO 2 ,MELISSA NEWMAN 2 AND DAVID F. WESTNEAT 1,4 1 Department of Biology and Center for Ecology, Evolution, and Behavior, 101 Morgan Building, University of Kentucky, Lexington, KY 40506-0225 2 Department of Animal Sciences, University of Kentucky, Lexington, KY 40546 Abstract. We identified bacteria collected from the ejaculates and cloacae of male Red- winged Blackbirds (Agelaius phoeniceus) and from the cloacae of their mates during two breeding seasons and at three geographic locations with two distinct breeding habitats in each. In all, 42% of 233 ejaculates contained at least one bacteria species. Analysis of control samples suggested that some bacteria come from contamination during collection, but most are either carried within the ejaculate or are present on the male cloaca. As in an earlier study of Agelaius phoeniceus, we recorded many different species with considerable diver- sity between samples. We tested several explanations for this diversity. We found no overlap in either the presence of bacteria or the species found in multiple ejaculates obtained from the same male. We also found no association between bacteria in the ejaculate and those in the cloaca from the same male, or in samples collected from a male and those from the females nesting on his territory. Surveys of ejaculates from three locations, Kentucky, New York, and Wisconsin, yielded similar patterns of prevalence and diversity. Ejaculate samples from males inhabiting relatively dry upland habitats contained a similar number of bacteria and array of species as males inhabiting relatively wet, marshy territories. Many of the isolated bacteria are probably benign, but pathological effects of some species have been recorded in some circumstances. Our results suggest that acquiring pathogenic bacteria rep- resents a potential cost to multiple mating by females, but the potential benefits of some microbes may offset these risks. Key words: Agelaius phoeniceus, bacteria, extra-pair copulations, microorganisms, mul- tiple mating, Red-winged blackbirds, sexually transmitted diseases. Bacterias en el Sistema Reproductivo de Agelaius phoeniceus Resumen. Identificamos bacterias aisladas del semen eyaculado y de las cloacas de ma- chos de la especie Agelaius phoeniceus y de las cloacas de sus parejas hembras durante dos estaciones y en tres a ´reas geogra ´ficas, con dos tipos de ha ´bitat en cada a ´rea. En general, el 42% de las 233 muestras de eyaculaciones presento ´ por lo menos una especie de bacteria. El ana ´lisis de las muestras control sugiere que algunas bacterias provienen de contaminacio ´n ambiental durante la colecta, pero la mayorı ´a de las bacterias provienen del semen o esta ´n presentes en la cloaca del macho. Al igual que en un estudio anterior con Agelaius phoe- niceus, registramos muchas especies distintas, con bastante diversidad entre las muestras. Pusimos a prueba algunas hipo ´tesis que podrı ´an explicar esta diversidad. No encontramos coincidencia ni en la presencia de bacterias ni en las especies encontradas entre mu ´ltiples muestras obtenidas de un mismo macho. Tampoco encontramos correspondencia entre las bacterias presentes en las muestras de semen y de la cloaca de un mismo macho, ni entre las muestras colectadas de los machos y de las hembras que se encuentran anidando en su territorio. El estudio de muestras de eyaculaciones provenientes de tres localidades, Ken- tucky, New York, y Wisconsin, produjo patrones similares de prevalencia y diversidad. Muestras de semen de machos que habitan ambientes relativamente secos en tierras altas presentaron nu ´meros de bacterias y especies similares a las muestras colectadas de machos que habitan territorios pantanosos. Probablemente, muchas de las bacterias son benignas, pero en ciertas circunstancias se han registrado efectos patolo ´gicos de algunas especies. Nuestros resultados sugieren que adquirir bacterias patolo ´gicas es un posible costo del apa- reamiento mu ´ltiple de las hembras, pero los posibles beneficios de algunos microbios po- drı ´an compensar estos riesgos. Manuscript received 22 November 2002; accepted 21 April 2003. 3 Present address: Department of Ecology, Evolution, and Behavior, University of Minnesota, Ecology Build- ing, St Paul, MN 55108. 4 Corresponding author. E-mail: biodfw@uky.edu Downloaded from https://academic.oup.com/condor/article/105/3/453/5563251 by guest on 14 October 2022