Male and female are similar, although female is paler. The plumage is slate gray except the belly and the feathers on each side of the tail which are white. The beak is pale pink. The junco measures on average 15.5 centimeters, has a wingspan of about 23 cm and weighs about 20 grams, the weight of a mushroom! It can live up to 10 years!

The Dark-eyed Junco is primarily seed-eating when adult. The chicks are fed with insects, which is why we often see adults foraging insects. Juncos make their nest on the ground, it is mainly the female who builds it. When moving, they run and hop on the ground. They are able to make leaps of more than 30 cm! The junco is faithful to its companion.