white females solicit EPCs and engage in brood parasitism, leaving their eggs in another's nest to be raised and fed. Mating with the opposite morphs and using alternative reproductive strategies helps maintain competitive equilibrium. This behaviour has been described genetically to follow from the chromosomal inversion of a supergene which acts as an extra pair of sex-determining genes, resulting in four phenotypes that reproduce in a disassortative mating pattern. Wintering and migration In winter, this species migrates to the southern and eastern United States. They are differential migrants with females migrating farther, increasing the proportion of females at lower latitudes in the Atlantic flyway. Females are smaller so they would not perform as optimally at colder, higher latitudes, and females avoid competition with the dominant males of the winter hierarchies by migrating farther. There is also no benefit for females to be among the first to return after winter, so migrating farther allows the males to return and establish territory a few weeks before their arrival. It stays year round in the Atlantic provinces of Canada. This bird is a rare vagrant to western Europe. Alongside some other species such as the cardinal, dark-eyed junco, song sparrow and chickadees, this species ranks among the most abundant native birds during winter in eastern North America. Despite a high level of con-specific rivalry within white-throated sparrows, this species is often dominated by other seed-eating winter residents, even those that are no larger than itself like the song sparrow, and thus may endure high levels of predation while foraging since restricted to sub-optimal sites at times by competition. Not to mention numerous mammalian carnivores, at least ten avian predators often hunt them and they are among the most regular prey species for some smaller raptors, i.e. the sharp-shinned hawk and eastern screech-owl. Diet These birds forage on the ground under or near thickets or in low vegetation. They mainly eat seeds, insects and berries, and are attracted to bird feeders. Song and calls White-throated sparrows produce song laterally through the left side of their syrinx, and control of their syrinx involves both their central and peripheral nervous systems. After damage to motor control of the left side of the syrinx, individuals were still able to produce sound but their song pattern was distorted, indicating the left side chiefly controls their production of song. There are at least two distinct songs sung by this