by John Shackford
The Fox Sparrow (Passerella iliaca) is definitely one of my favorite sparrows. When I first see one my first thought is usually “possible Hermit Thrush”, because of both species’ rich reddish-brown coloration. When it turns out to be “only” a Fox Sparrow, I am not that disappointed—Fox Sparrows are not all that common either. So I am very happy with either result. At least one other observer I read later in Bent’s Life Histories noted that a fleeting glimpse of the Fox Sparrow evoked the same reaction in him. We usually find a number of Fox Sparrows each year on our Christmas Bird Count (CBC), but the species is not always a sure bet—we are on the western and northern edge of the winter range of the species.
In reading Life history of the Fox Sparrow, by Bent, he suggests, I believe, that the species is quite strict in the dates it migrates, more so than most other small species. This can cause major problems for the species when unusually snowy—particularly icy—weather hit during its spring migration northward. There are accounts of thousands being starved and frozen during harsh weather in the eastern United States during such periods. It is believed that this is the major threat to Fox Sparrow populations, rather than any particular predator, and the species usually recoups its numbers in the next several years.
During our CBC I usually see the species in rather thick brush along the river below Lake Overholser. At first I generally see it low in the vegetation (probably on the ground) and then it moves upward in the trees to maybe 8-20 feet high. Sometimes I hear its song as it sits there, which is very pleasing. It also has a “check” note which can be identified by careful observers (not me yet). On the breeding ground it is a vociferous singer, it does not matter whether the day is sunny or cloudy.
In feeding, the species scratches the ground with both feet at the same time. It has been noted that the bird must have great balance to not pitch forward to the ground during this feeding activity. Most of its food during migration and winter is vegetable matter. In one study 127 stomachs were found to contain 86% vegetable matter—ragweed and smartweed seeds being favorites—while 14% animal. On the breeding ground its diet is believed to be much more animal matter, especially what they feed the young.
The Fox Sparrow nests across Canada to Alaska, from east coast to west coast of the continent, and there are considerable plumage color difference between eastern birds (the “red” form) and western birds, (grayish birds in the Rocky Mountains of the west, to sooty-colored birds toward the west coast). There is some debate if these different forms should be considered separate species, so let’s discuss the species now, before someone decides to split it! The only birds I remember seeing in Oklahoma are the “red” form.
- C. Bent has an interesting quote on the Fox Sparrow: “The one outstanding requirement for the fox sparrow’s breeding habitat is dense, bushy cover where the birds can nest and scratch for food while well screened from view” (1968, Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies). It seems to particularly like stunted forest woodlands for breeding habitat.
Sometimes researching a Bird of the Month can result in some surprising information. At the time of the writing of Bent’s life history on this species, there was not much known about Fox Sparrow behavior during the breeding season, apparently due largely to the retiring nature of the species. Gaps of information like this indicate a need for more basic research to fill in our knowledge and understanding of a species: we assume—erroneously sometimes—that everything has already been worked out. There is still a need for close observation (perhaps a lot has been figured out on the Fox Sparrow since Bent wrote his life history in 1968; I do not have ready access to the North American Bird Life Histories released in recent years.)
I think this habit of being a retiring species on the breeding ground also informs us of the nature of the bird during winter here. They do seem to be retiring; when the weather gets bad in winter in Oklahoma—like ice and snow bad—we see one or two show up on the ground below our feeders, always a treat. But when the weather is moderate, they seem to find enough food elsewhere, instead of depending on feeders.