Hi there! My mother, Camilla suggested that I write a series of posts about birds on my blog since I’ve been talking about them and learning about them. Please let me know if you have any bird books, CDs, or a website you’d recommend! Here is the part about American Tree Sparrows.
American Tree Sparrows are small, round-headed birds that often fluff out their feathers, making their plump bodies look even chubbier. Like other sparrows, they have fairly small bills and long, thin tails. Their color pattern is a rusty cap and rusty (not black) eyeline on a gray head, a streaked brown back, and a smooth gray to buff breast in both male and female American Tree Sparrows give an overall impression of reddish-brown and gray. A dark smudge in the center of the unstreaked breast is common.
Small flocks of American Tree Sparrows hop about on the ground, scrabbling for grass and weed seeds, calling back and forth with a soft, musical twitter that might make you twitter, sing, or dance. A single American Tree Sparrow may perch in the open top of goldenrod stalks or shrubs, or on low tree branches. Look for small flocks of American Tree Sparrows in the winter in weedy fields with hedgerows or shrubs, along forest edges, or near marshes except for Reno, NV. They readily visit backyards, especially if there’s a seed feeder.
American Tree Sparrows breed in the far north and are hardly seen south of northern Canada in the summer. 4-6, usually 5. Pale bluish or greenish, with brownish spotting often concentrated at larger end. Incubation is by female, 11-13 days; male visits nest often, but does not incubate. Young: Both parents feed nestlings. Young leave nest at age 8-10 days, when flight feathers not yet fully grown.
Parents may lure them away from nest by offering food. Young are able to fly at about 14-15 days after hatching; parents continue to feed them for about 2 more weeks. 1 brood per season, but may attempt to renest if 1st attempt fails. Diet in the winter is almost entirely seeds, from grasses, weeds, and other plants; also a few insects and berries.
In the summer, they eat mostly insects and other small invertebrates, plus a few seeds. Young are fed mostly insects. Pairs form shortly after birds arrive on breeding grounds. Male actively defends territory, chasing away other members of same species.
Nest site is on or near ground, in grass clumps beneath shrubs. Sometimes on hummock in open tundra; rarely up to 4′ above ground in willow or spruce. Nest is an open cup of twigs, grasses, moss, lined with fine grass and with feathers (usually ptarmigan feathers). Female builds nest in about 7 days.
All wintering areas are well to the south of breeding areas. Migrates relatively late in fall and early in spring. Apparently, migrates mainly at night. On average, females winter somewhat farther south than males.
The American Tree Sparrow is a small sparrow with a long notched tail. The adult has a streaked back and wings, with two white wing bars, but is otherwise unstreaked, while the juvenile is streaky overall. Adults have an unstreaked gray-brown breast and belly, with a dark spot in the center. The tail, rump, and nape of the neck are all solid gray.
The upper mandible of the bill is dark and the lower is yellow. The head is mostly gray, with a rufous crown and eye-line. American tree sparrows (Spizella arborea) breed throughout almost all of Alaska, the Yukon and Northwest territories, the very north of Manitoba and Ontario, all of Labrador, and in northern Quebec. Their winter range includes a very small part of southern Canada and all of the United States except for the western most 250 miles, the southern most 450 miles and all of Florida.
American tree sparrows usually breed near the tree line in open scrubby areas with willows, birches, alder thickets or stunted spruce. They may also breed in open tundra with scattered shrubs, often near lakes or bogs. They spend the winter in open forests, gardens, fields, and marshes. Baumgartner followed birds for the first 22 days of development.
Order of hatching was not dependent on the order of laying. Earlier hatched birds took the lead in development. During the nine and one-half days in the nest, the four feather tracts of the birds (dorsal, ventral, alar, caudal) go from completely bare to the back covered, lower belly slightly bare, wings 2/3 grown, and tail still a stub, and the birds grow from 1.62 gm to 16.7 gm, while their length goes from 33 mm to 75 mm during the same period. They lose 1.5 gm the first day out of the egg but have gained 3 gm by day 21 (Baumgartner, 1968).
On the second day after hatching the young were able to stretch for food. On the fourth day their eyes were half open, after the fifth day, wide open. The first sounds were made on the fifth day but were very soft. Fear was acquired between 7.5 and 8 days as demonstrated by their raucous calls when touched by humans.
During the first 12 days of the fledgling period (which lasts until about a month after leaving the nest in (Spizella arborea) the birds showed a steady increase in both tail length (14-47mm) and wing length (46-68mm). At the end of the first 21 days the wings were still slightly shorter and the tails about 2/3 the length of mature birds. A tree sparrow was observed to fly 30 or 40 ft fifteen days after hatching, and a little before one month after hatching, the birds could fly all around their territory. American tree sparrows are monogamous (one male mates with one female).
Males and females form breeding pairs after they arrive at the breeding sites in the spring. Both males and female sing to attract a mate. Females become excited when males come to sing nearby. They call back to the male, making a “wehy” sound.
Males may show off for females by spreading their wings and fluttering them or darting to the ground in front of the female, then flying back up to a perch. American tree sparrows breed between May and September. They raise one brood of chicks each year. The females builds the nest alone.
The nests are built on the ground out of moss, grasses, bark and twigs. They are lined with fine grass and feathers.The female then lays about 5 eggs. She lays one egg each day.
She incubates the eggs for 10 to 14 days and broods the chicks after they hatch. The chicks are altricial (helpless) when they hatch, so they rely on the female to protect them and keep them warm. Both parents feed the chicks until 2 to 3 weeks after the chicks leave the nest (called fledging). The young fledge from the nest about 9 days after hatching.
In late summer, the families join larger flocks. We do not know when young American tree sparrows begin breeding.
American tree sparrows breed once per year. Females incubate the eggs and brood the chicks after they hatch.
Both parents feed the chicks until they are about 22 days old. The oldest known American tree sparrow lived at least 10 years and 9 months. Most American tree sparrows probably live about 2.3 to 3.4 years. American tree sparrows are migratory.
Though they are usually active during the day (called diurnal), they migrate at night. American tree sparrows are territorial during the breeding season. Males sing to claim territories and they defend their territories from others. Females occasionally chase intruders too.
American tree sparrows do not defend winter territories. During the winter, they form large flocks that forage together. Within these flocks, some birds are dominant over other birds. American tree sparrows move by hopping on the ground and on branches, and by flying.
They do not swim or dive, but they do bath frequently. They roost alone trees or shrubs, haystacks, cornfields, and marshes. In the winter, they might take shelter together under the snow. American tree sparrows are omnivorous; they eat many different seeds, berries and insects.
During the winter, American tree sparrows mainly eat grass and weed seeds. During the summer, they mostly eat insects and spiders. American tree sparrows search for food among plants on the ground and the branches and twigs of shrubs and trees. In Massachusetts, they are often seen in flocks, feeding at bird feeders.
American tree sparrows need to drink a lot of water each day. During the winter, they eat snow in order to get enough water. Known predators of American tree sparrows include northern goshawks, sharp-shinned hawks, screech owls, pygmy owls, Cooper’s hawks, American kestrels, weasels, foxes, and red squirrels. When approached by humans, American tree sparrows give a rapid series of “tset” calls.
It is unknown how American tree sparrows respond to other potential predators. American tree sparrows are very important members of the food chain. They eat many weed seeds and insects and spiders, and they are an important food source for their predators.