They’re back.
I have wondered what has taken them so long. Last year they were here in late September. This fall I saw the first ones at my feeder Oct. 12 and as the weather gets colder, more will be coming.
Just as the American robin is a sign of spring, the dark-eyed junco is a sign that winter is on the way.
The juncos are one of Iowa’s most common winter birds from October to April. In spring they fly north to nest in the spruce and fir forests of Canada and the northeastern part of the U.S.
The juncos in our area have several common names. They are more correctly called
dark-eyed junco, but they are also called the slate-colored junco, snowbird and junco. Ornithologist place them in the finch family.
They are sparrow-sized birds, about six inches long. The males are a slate-gray color
on their back, head, throat and the upper half of their breast. The bottom half of their breast and belly is white.
The females are very similar in color to the males but have a slightly brownish tint on their head and wings. From a distance, it is difficult to tell the sexes apart.
Both the males and females show white outer tail feathers when they fly, and both have a pinkish colored bill.
Because they nest in Canada, we seldom get to hear the bird’s song. It is a high-pitched,
non-distinct trill. This time of the year in Iowa, we do hear their alarm call, which is a metallic clicking sound.
William Rowan, a Canadian scientist, used this species in a very famous experiment in the 1920s. He wanted to find out the cause of bird migration and breeding behavior. He used juncos in his experiments to prove that the trigger for these behaviors was the amount of sunlight to which the birds were exposed.
Bird banding studies have also shown an interesting pattern in their migration.
The adult females migrate the greatest distance south in the winter. They fly to the southern parts of the United States and into northern Mexico.
The juncos in Iowa are probably older males and young females. The young males show the least amount of migration, they stay in the northern part of the Great Lake States.
Scientist speculate that the shorter migration helps the young males claim preferable nesting territory when the breeding season occurs.
Juncos exhibit a very strong flocking behavior. Banded birds have proven that the flocks stay together for years at a time.
The flock also has a definite pecking order. Some members do not eat until the dominant birds have eaten.
They are very useful birds because one-third of their diet consist of ragweed seeds. They also eat thistle, grass and other weed seeds.
At a bird feeder, they will eat millet, cracked corn and bread crumbs. They prefer to eat on the ground, eating the seeds that other birds have spilled from the feeder.
According to several ornithologists, the population of juncos has declined over the past few years. This population decline is attributed to the increased use of pesticides and herbicides that destroy the bird’s natural food supply.
These handsome winter birds should be appreciated for their role in the environment as consumers of noxious weed seeds. When you see juncos this winter, think about those little birds helping to reduce hay fever pollen next summer.
