We are all familiar with the “to the death” struggles between males of certain mammal species to determine social status within their group. However, such dramatic confrontations are not the only methods for animals to ascertain a dominance hierarchy.
Adult yellow-crowned sparrows (Zonotrichia atricapilla) have a brownish back streaked with darker brown and greyish brown underparts. Their most unmistakable marking is a yellow head patch on a black head. The black feathers resemble a stripe on either side of the yellow patch. In winter, the black and yellow coloration is less distinct. Both sexes look the same as adults.
Yellow-crowned sparrows winter in flocks, often with other species, and return to the same wintering site each year. According to research by Chine and her associates (2011), the size and color of the yellow crown patch helps determine the bird’s status within the flock. When two yellow-crowned sparrows have yellow head patches the same size and color intensity, the appearance of the black stripes on either side of the yellow patch appears to come into play and provides an additional determining factor for social status. Using these visual cues to determine a bird’s position in the flock reduces the injury and energy expenditure that results from actual physical confrontation.
These yellow-crowned sparrows were photographed earlier this month near the fish trap at Crystal Lake (Shasta County CA). Before long they will begin their migration to breeding grounds in the tundra, stunted boreal forests and brushlands of Alaska and Western Canada.