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American tree sparrow

Spizella arborea

What do they look like?

American tree sparrows are small, grayish-brown birds. They have a rusty-colored crown and a rusty-colored line behind each eye. They have a grey head, chin, throat, breast and belly and a rusty patch on each side of their breast. They also have a dark spot in the middle of their breast. Their tails are long, with a notch in the middle. Their beaks are dark on top and yellow on the bottom. Males and females look about the same. Young American tree sparrows look similar to adults, but have streaking on their sides and their breast.

Adult American tree sparrows weigh 18 to 26 g, and are 14 to 16.5 cm long. Their wingspans range from 21.6 to 24.8 cm. (Alsop, 2001)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    18 to 26 g
    0.63 to 0.92 oz
  • Range length
    14 to 16.5 cm
    5.51 to 6.50 in
  • Range wingspan
    21.6 to 24.8 cm
    8.50 to 9.76 in

Where do they live?

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. (Alsop, 2001)

What kind of habitat do they need?

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. (Naugler, 1993)

  • Aquatic Biomes
  • lakes and ponds

How do they grow?

Baumgartner (1938) 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 (Baumgartner, 1938).

How do they reproduce?

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. (Baumgartner, 1937c)

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. (Baumgartner, 1937c; Cornell Lab of Ornithology, 2003; CWBO, 1997; Naugler, 1993)

  • How often does reproduction occur?
    American tree sparrows breed once per year.
  • Breeding season
    American tree sparrows breed between May and August.
  • Range eggs per season
    4 to 6
  • Average eggs per season
    4
    AnAge
  • Range time to hatching
    10 to 14 days
  • Range fledging age
    8 to 10 days
  • Range time to independence
    2 to 3 weeks

Females incubate the eggs and brood the chicks after they hatch. Both parents feed the chicks until they are about 22 days old. (Baumgartner, 1937b; Baumgartner, 1938)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • male
      • female

How long do they live?

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. (Baumgartner, 1937a; Baumgartner, 1968; CWBO, 1997; Naugler, 1993)

  • Range lifespan
    Status: wild
    10.75 (high) years
  • Typical lifespan
    Status: wild
    2.3 to 3.4 years

How do they behave?

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 winter, they may take shelter together under the snow. (McNicholl, 1987; Naugler, 1993)

  • Range territory size
    0.005 to 0.0038 km^2

Home Range

We do not have information on home range for this species at this time.

How do they communicate with each other?

American tree sparrows communicate using sounds and body signals. Only male American tree sparrows sing, and each male sings only one song. Their songs are high, thin whistles and last 1 to 2 seconds. They are used to defend a territory and to attract a mate. Both males and females use calls to communicate. Each call seems to mean something different. Chicks also use calls to express hunger, discomfort, and fear. (Baumgartner, 1938; Cornell Lab of Ornithology, 2003)

What do they eat?

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. (Baumgartner, 1937b; Cornell Lab of Ornithology, 2003; Hamilton, 2000; Knappen, 1934)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

What eats them and how do they avoid being eaten?

Known predators of American tree sparrows include northern goshawks (Accipiter gentilis), sharp-shinned hawks (Accipiter striatus), screech owls (genus Otus), pygmy owls (genus Glaucidium), Cooper's hawks (Accipiter cooperii), American kestrels (Falco sparverius), weasels (family Mustelidae), foxes (family Canidae) and red squirrels (Tamiasciurus hudsonicus).

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. (Naugler, 1993)

What roles do they have in the ecosystem?

American tree sparrows are 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. (CWBO, 1997)

  • Ecosystem Impact
  • disperses seeds

Do they cause problems?

We do not know of any way the American tree sparrows harm humans.

How do they interact with us?

American tree sparrows may help farmers by removing weed seeds from their fields. (Baumgartner, 1937b; Baumgartner, 1968)

Are they endangered?

American tree sparrows are abundant and widespread. There are approximately 26,000,000 American tree sparrows throughout their range. American tree sparrows are protected by the US Migratory Bird Treaty Act, but have no special status under the U.S. Endangered Species ACT or CITES. (Kaufmann, 1996; Naugler, 1993)

Some more information...

Two geographic races are recognized based breeding location. Spizella arborea arborea breeds from the Atlantic coast all the way to the east of the Yukon. Spizella arborea ochracea breeds around and in the Yukon and Alaska.

Spizella arborea ochracea was first recognized as a subspecies in 1881 by William Brewster. He describes them as:

"The ground color of the back is decidedly paler than the eastern examples, bringing out the dark streaks in sharper contrast, which is heightened by the absence of their usual chestnut edging; ash of throat and sides of head is much fainter, in many places replaced by brownish fulvous; the underparts, especially the sides and abdomen, are more strongly ochraceous; and the broad ashy crown patch gives the head a very different appearance."

Males of both races generally winter farther north than females.

Spizella arborea arborea is sometimes called "eastern tree sparrow", "winter chippy" and "Canada sparrow". (Baumgartner, 1968; Forbush and May, 1939)

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Kari Kirschbaum (author, editor), Animal Diversity Web.

Ernest Travis (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

References

Alsop, F. 2001. Birds of North America, eastern region. New York, NY: DK Publishing, Inc.

Baumgartner, A. 1968. Tree Sparrow. U.S. National Museum Bulletin, 237: 1137-1165.

Baumgartner, M. 1938. A study of development of young tree sparrows at Churchill, Manitoba. Bird-Banding, 9(2): 69-79.

Baumgartner, M. 1937a. Enemies and survival ratio of the tree sparrow. Bird Banding, 8(2): 45-52.

Baumgartner, M. 1937b. Food and feeding habits of the tree sparrow. The Wilson Bulletin, 49(2): 65-80.

Baumgartner, M. 1937c. Nesting habits of the tree sparrow at Churchill, Manitoba. Bird Banding, 8(3): 99-108.

CWBO, 1997. "Chipper Woods Bird Observatory: American Tree Sparrow" (On-line). Accessed 03/03/04 at http://www.wbu.com/chipperwoods/photos/treesparrow.htm.

Cornell Lab of Ornithology, 2003. "American Tree Sparrow" (On-line). Cornell Lab of Ornithology, All About Birds. Accessed March 04, 2004 at http://birds.cornell.edu/programs/AllAboutBirds/BirdGuide/American_Tree_Sparrow.html.

Forbush, E., J. May. 1939. A natural history of American birds of eastern and central North America. USA: Houghton Mifflin Company.

Hamilton, T. 2000. Winter Population Trends of Six Species of Sparrows. Bird Observer, 28(3): 154-163.

Kaufmann, K. 1996. Lives of North American Birds. USA: Houghton Mifflin.

Knappen, P. 1934. Insects in the winter food of the tree sparrow. Auk, 51: 93.

Lima, S. 1995. Back to the basics of anti-predatory vigilance: the group-size effect. Animal Behaviour, 49: 11-20.

McNicholl, M. 1987. Communal sheltering under snow by American Tree Sparrows. Ontario Birds, 5(3): 111-113.

Naugler, C. 1993. American Tree Sparrow (Spizella arborea). Pp. 1-12 in A Poole, F Gill, eds. The Birds of North America, Vol. 37. The Academy of Natural Sciences, Philadelphia, and The American Ornithologist's Union, Washington, D.C.

 
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Travis, E. 2002. "Spizella arborea" (On-line), Animal Diversity Web. Accessed September 24, 2018 at http://www.biokids.umich.edu/accounts/Spizella_arborea/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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