The research focus of the program concerns the relationship between environment, demography, and mating system. The study organism is a small, insectivorous passerine bird, the red-backed fairy-wren Malurus melanocephalus. US PIs have studied this species in dry schlerophyll forests of eastern Australia since 1997 (with a hiatus from 2000 – 2003). The proposed IRES research builds upon this previous work to address a question with broad relevance for behavioral ecologists: how do underlying ecological conditions affect social organization, mating behavior and the strength of sexual selection? To do so, we exploit the considerable flexibility red-backed fairy-wrens exhibit in social organization, expression of sexual signals, and mating behavior (Webster et al. 2010) and a study area in which ecological conditions vary in a patchwork manner. By characterizing the degree to which red-backed fairy-wrens use flexible behavioral and physiological strategies to negotiate the ecological and social environment that they experience, and comparing this reproductive flexibility with other tropical and temperate species (Macedo et al. 2008, Stutchbury & Morton 2001, 2008), we expect this research to further our understanding of avian mating systems and how they respond to anthropogenic activities (Caro & Sherman 2010).
Red-backed fairy-wrens live in cooperatively breeding groups in which male offspring from previous breeding seasons often delay dispersal from their natal territory and assist their parents with subsequent reproductive efforts as auxiliary males (Schodde 1982, Rowley and Russell 1997, Varian-Ramos et al. 2010). Groups are therefore often composed of a dominant, breeding male and female and one or more socially subordinate, non-breeding auxiliary males (females typically disperse before their first breeding season). Male breeding phenotype is a phenotypically plastic trait that is regulated by androgens and affected by male condition and perhaps social status (Karubian 2008, Lindsay et al. 2009, Webster et al. 2010, Karubian et al. in press): males in better condition and/or with access to mates acquire showy red/black nuptial plumage in the pre-breeding season molt, whereas younger males and auxiliaries often retain brown, female-like plumage even though they are reproductively capable. Red-backed fairy-wrens exhibit extremely high rates of sexual promiscuity (Karubian 2002), and ornamented males have higher fitness than unornamented males (Karubian et al. 2008, Webster et al. 2008, Karubian et al. 2009).
Discrete student projects may include the following:
(1) Fire and habitat quality. Students will measure vegetative structure, conduct standardized insect collection, and monitor nesting success in relation to fire history .
(2) Demography & social organization. Students will measure adult condition and survival, population density, nesting phenology, nesting success, group composition and distribution of male phenotypes (followed by data analysis upon return to US).
(3) Sexual promiscuity. Students will monitor nesting attempts, quantify parental care, and collect blood samples from nestlings and fledglings (followed by molecular analyses of paternity upon return to the U.S.).
(4) Visual signals. Students will collect feather samples from the carotenoid-based red patch on the back of nuptial males (followed by spectrometer-based measures of feather color upon return to the U.S.).
(5) Acoustical signals. Students will use recording equipment to obtain standardized recordings of males in different habitat types (followed by analyses using Raven software upon return to the U.S.).
(6) Mapping. Students will use GPS units to map fire history and red-backed wren breeding activity (followed by use of remote sensing images to create predictive MAXENT models upon return to U.S.).
(7) Aviary experiments. Students will capture birds away from the core study population and assist with animal husbandry and aviary-based experiments to determine the role of social status on male phenotype (followed by data analysis upon return to the U.S.).
