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Henslow's sparrow

Ammodramus henslowii

What do they look like?

Henslow’s sparrows are one of the smallest sparrows, measuring just 11 to 13 cm long. They weighing about 13 g and their wingspan is around 20 cm. Their feature that looks most different from other sparrows is their head. It is large, olive-colored, relatively flat, and has dark stripes. Henslow's sparrows have streaks on their chests, wings that are a little bit reddish-brown, and short tails. Males and females look the same, but young are colored like clay and have black streaks on their back and head. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; DNR, 2012; Herkert, 2007; Pearson, 1936)

There are actually two subspecies, a western one that lives anywhere they do, and and eastern one that lives on the coast of the Atlantic ocean. However, some scientists think the eastern subspecies might be extinct. ("Henslow's Sparrow status assessment", 1996)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    10 to 15 g
    0.35 to 0.53 oz
  • Average mass
    13 g
    0.46 oz
  • Range length
    11 to 13 cm
    4.33 to 5.12 in
  • Average wingspan
    20 cm
    7.87 in

Where do they live?

Henslow's sparrows are native to North America. They travel every year between summer and winter locations. They spend summers breeding in New England, southern Ontario, and across to eastern south Dakota. This makes up an area of about 1,100,000 sq km. They travel north between early March and mid-May. They travel south for the winter between July and late October. They they live anywhere from Texas to Florida, and up the Atlantic coast. Scientists think they mostly lived on the prairies before the Europeans came. Now, Henslow's sparrows live and breed in grasslands, hayfields, and pastures that have replaced a lot of the prairies. They also have moved farther north and east as much of the prairies have been taken over by agriculture. (Alderfer, 2006; DNR, 2012; Herkert, 2007; Pearson, 1936)

What kind of habitat do they need?

Henslow's sparrows prefer grasslands and old farm fields that are bigger than 100 hectares. They like to have enough plant parts laying around to nest in. They also like to have tall, dense grass and plant stems they can perch on to sing. These singing perches are usually 30 to 61 cm off the ground. They are generally found in open fields and grassy meadows or hayfields that haven't been mowed. They also like places with lots of shrubs, especially if they are damp or near salt marshes. Henslow's sparrows are not usually found in areas where most of the grass has been eaten by farm animals. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; DNR, 2012; Hanson, 1994)

How do they reproduce?

Henslow's sparrows form mating pairs. When forming a pair, they make a special call, flutter their wings, and work together to judge possible nest locations. Male Henslow's sparrows return to breeding spots each spring and establish and defend territories by singing. They usually sing while sitting on dead plant stems shorter than 1 m tall. Their territories are about .8 acres. ("Henslow's Sparrow status assessment", 1996; Alderfer, 2006; DNR, 2012; Herkert, 2007; Robins, 1971)

Females start building nests in early May that are well-hidden and shaped like cups or domes. They are 1 to 3 inches above ground and right next to a thick clump of grass. They use coarse grass or dead leaves to build nests and line them with finer grass or sometimes hair. Usually, nests have a partial roof because they are attached to stems leaning over the main part of the nest. ("Henslow's Sparrow status assessment", 1996; Alderfer, 2006; DNR, 2012; Herkert, 2007; Robins, 1971)

Henslow's sparrows often raise 2 sets of young in the same year. They usually lay the first set of eggs by by mid to late May and start to build their second nests in July or August. Females lay 3 to 5 eggs and keep them warm, or incubate them, for about 10 to 11 days. Both male and female parents care for and feed the chicks while they are in the nest and for a little while after they leave it. After 9 to 10 days, they can fly. Males and females can have their own young after they are one year old. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Herkert, 2007; Pearson, 1936)

  • How often does reproduction occur?
    Henslow's sparrows may raise 2 broods per year, in early spring and late summer.
  • Breeding season
    First clutches are normally completed by mid- to-late May and second clutches are frequently initiated in July and August.
  • Range eggs per season
    3 to 5
  • Range time to hatching
    10 to 11 days
  • Average time to hatching
    11 days
  • Range fledging age
    9 to 10 days
  • Range time to independence
    - to - minutes
  • Range age at sexual or reproductive maturity (female)
    1 to 1 years
  • Range age at sexual or reproductive maturity (male)
    1 to 1 years

Females Henslow's sparrows watch over the eggs by themselves for 11 days. Females are mostly responsible for their young, but males become more involved after the chicks hatch. When the chicks are born, they are not able to move, feed, or take care of themselves. The young stay in the nest for 9 to 10 days after hatching. Females are largely responsible for their young during all periods of development, and males become more involved after hatching. ("Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Herkert, 2007; Pearson, 1936)

  • Parental Investment
  • altricial
  • male parental care
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

How long do they live?

Henslow's sparrows have a short lifespan, which is about 6.5 years. Their generations are 2 to 3 years long. ("Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Pearson, 1936)

  • Average lifespan
    Status: wild
    7 years

How do they behave?

Henslow's sparrows are social birds that live in small flocks. Their social organization is not rigid like herons or gulls, and they sometimes combine groups if they find a good habitat or one with a lot of food. They are found in small groups or alone in the winter and while migrating. They are active during the day, and they defend a territory during the summer. Henslow's sparrows are non-territorial during the winter and it is unknown if they exhibit site fidelity during this season. Henslow's sparrows are shy birds with a quiet, short, song that has two syllables. They are easier to hear than see because they are shy. If you disturb them, they often run instead of flying. They fly quickly and low to the ground in a drooping, zigzag way. Just after they take off, they twist their tail in a unique way. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Pearson, 1936)

  • Range territory size
    3035 to 4896.7 m^2
  • Average territory size
    3237.4 m^2

Home Range

In some areas, the number of Henslow's sparrows is decreasing. This is mostly due to loss of habitat, because they need large habitat areas to live. Their territory sizes vary and don't have very clear boundaries, but are about 0.8 acres in size. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; DNR, 2012; Pearson, 1936)

How do they communicate with each other?

Henslow’s sparrows communicate by songs and body language. They sing to attract mates, as a chorus, and to settle territorial disputes. They have different calls for predator alarms, courting, and calls of young in nests. The most common call is has two syllables and sounds like "zee-lick", almost like an insect. Nestlings can make a faint chirp while begging for food. They also communicate by a variety of wing fluttering. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Herkert, 2003; Herkert, 2007; Pearson, 1936)

What do they eat?

Henslow’s sparrows eat caterpillars, crickets, grasshoppers, beetles, spiders, bees and plant seeds they find on the ground. Young chicks eat grasshoppers or butterfly larvae about 80% of the time. Adults eat about 36% crickets and short-horned grasshoppers, 19% beetles 18% plants, and 29% is the other foods. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Herkert, 2003; Pearson, 1936; Robins, 1971)

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

What eats them and how do they avoid being eaten?

Snakes such as blue racers are known predators of Henslow's sparrows. Their young are eaten by thirteen-lined ground squirrels and feral cats. Predators are more likely to find their nests if they are near woods. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Alderfer, 2006; Pearson, 1936)

What roles do they have in the ecosystem?

Sometimes, 'brown-headed cowbirds Molothrus ater' lay their eggs in the nests of Henslow's sparrows. However, this does not happen often because Henslow's sparrows have adapted to resist them. Henslow's sparrows are also hosts to a number of parasites, such as red mites and lice. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Burhans, 2002; Herkert, 2003)

  • Ecosystem Impact
  • disperses seeds
  • creates habitat
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Henslow's sparrows don't have negative effects on humans.

How do they interact with us?

Henslow's sparrows may be used to judge the health and productivity of large grassland habitats in the areas they live, and the health of groundcover in certain forests. The grasslands where they live are some of the most rare kinds of environments in North America. ("Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; Herkert, 2007; Robins, 1971)

  • Ways that people benefit from these animals:
  • research and education

Are they endangered?

The IUCN Red List says that Henslow's sparrows are "near threatened." They are listed as "endangered" in Canada and 7 of the U.S. states where it lives, as "threatened" in 5 other states, and "special concern" in 4 more states. There are about 79,000 of them right now. Their numbers have decreased in the past 30 years, especially in the northeast. Humans taking over grassland for agriculture and breaking up large grasslands are the main reasons for their decline. They are counted by the North American Breeding Bird Survey and Christmas Bird Count to help with conservation efforts. In the south, their numbers have increased by a small amount, probably because the Conservation Reserve Program has created grassland habitat. ("COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada", 2011; "Conservation assessment: Henslow’s Sparrow", 2002; "Henslow's Sparrow status assessment", 1996; DNR, 2012; Herkert, 2007)

Contributors

Scott Thorson (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Jeremy Wright (editor), University of Michigan-Ann Arbor, Catherine Kent (editor), Special Projects.

References

Committe on the Status of Endangered Wildlife in Canada. COSEWIC assesssment and status report on the Henslow's Sparrow Ammodramus henslowii in Canada. x + 37 pp. Ottawa: COSEWIC. 2011. Accessed April 01, 2012 at www.sararegistry/.gc.ca/status_e.cfm.

U.S. Department of Agriculture, Forest Service. Conservation assessment: Henslow’s Sparrow. Gen. Tech. Rep. NC-226.. North Central: U.S. Department of Agriculture, Forest Service. 2002.

U.S. Fish and Wildlife Service. Henslow's Sparrow status assessment. -. Bloomington, Indiana: U.S. Fish and Wildlife Service. 1996.

Alderfer, J. 2006. National Geographic complete birds of North America. Washington, D.C.: National Geographic.

Burhans, D. 2002. Conservation Assessment--Henlow's Sparrow Ammodramus henslowii. General Technical Report, NC-222: 1-46. Accessed August 13, 2012 at http://nrs.fs.fed.us/pubs/gtr/gtr_nc226.pdf.

DNR, 2012. "Ammodramus henslowii" (On-line). Accessed February 08, 2012 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=ABPBXA0030.

Hanson, L. 1994. The Henslow's Sparrow of Minnesota: Population Status and Breeding Habitat Analysis. Mount Pleasant, Michigan: Central Michigan University.

Herkert, J. 2003. "Northern Prairie Wildlife Research Center" (On-line). Effects of management practices on grassland birds: Henslow's Sparrow. Accessed April 01, 2012 at http://www.npwrc.usgs.gov/resource/literatr/grasbird/hesp/hesp.htm.

Herkert, J. 2007. Evidence for a Recent Henslow's Sparrow Population Increase in Illinois. The Journal of Wildlife Management, Vol. 71, No. 4: 1229-1233.

Pearson, G. 1936. Birds of America. Garden City, N.Y.: Garden City publishing company, inc.,.

Robins, J. 1971. A Study of Henslow's Sparrow in Michigan. The Wilson Bulletin, Vol. 83, No. 1: 39-48.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Thorson, S. 2012. "Ammodramus henslowii" (On-line), Animal Diversity Web. Accessed September 24, 2014 at http://www.biokids.umich.edu/accounts/Ammodramus_henslowii/

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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