Feather coloration and patterning are major signals influencing mate choice within and between species. However, most studies of the role of plumage in mate choice have focused on colorful species with obvious sexual dichromatism. To better understand how achromatic plumage might influence hybridization, we quantified plumage variation between and within two achromatic songbirds that occasionally hybridize, Black-capped (Poecile atricapillus) and Mountain (P. gambeli) chickadees. We collected feathers from 43 live birds and photographed 155 prepared museum specimens to measure overall plumage color and the size of the throat and cheek patches.
Figure 1: Distribution of museum specimens (A) and live birds (B) sampled for this study. Museum specimens were sampled from across Colorado and live birds from in and around Boulder, CO. Dotted line in (A) designates the latitudinal divide between northern and southern quadrants (~39°N). Quadrants were divided longitudinally by the Front Range mountains (~105°W): rather than the longitudinal divide being linear, individuals were binned into quadrants based on geography (i.e., mountains or plains). In (B), live birds were collected from Boulder (dotted, right box), Sugarloaf Mountain (dashed, middle box) and the Mountain Research Station (solid, left box). Black-capped Chickadee sample locations are coral points and Mountain Chickadee sample locations are navy. Chickadee drawings by Jessica French.
Using principal component analyses and generalized linear mixed models, we characterized plumage patterns within and between Black-capped and Mountain chickadees from Colorado to examine plumage color variation and differences in throat and cheek patch size. We found that Black-capped Chickadees (1) were less achromatic and had brighter plumage with more color contrast than Mountain Chickadees, (2) had smaller throat and cheek patches than Mountain Chickadees, and (3) were not sexually dimorphic.
To learn more about this project, check out my published work: open-access or online library
Or my poster presented at the Front Range Student Ecology Symposium: click here
Or my presentation for all-career ecologists and evolutionary biologists: click here