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Podiceps auritushorned grebe(Also: Slavonian grebe)

By Kari Kirschbaum and Bradley Handford

Geographic Range

Horned grebes are found in the Nearctic and Palearctic regions. They breed from Alaska and northern Canada south through the Canadian prairie provinces to Washington, Montana, South Dakota, and Wisconsin. Populations winter along the Pacific coast from Alaska to Mexico, along the Altantic coast from Nova Scotia to the gulf coast, and on large inland lakes such as the great lakes. They also breed and winter in Eurasia. (Bull and Farrand Jr, 1988; Farrand, 1988a; Farrand, 1988b)

Habitat

During the breeding season, horned grebes are found predominantly on prairie and boreal freshwater lakes with both open waters and marsh vegetation. They may also nest in marshes, small sloughs with weedy margins, ponds, and occasionally on rivers. Horned grebes overwinter in coastal saltwater habitats such as protected bays and exposed shores, and occasionally on large freshwater lakes. (Farrand, 1988b; Kaufman, 1996)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal

Physical Description

Horned grebes resemble small, compact ducks with short, pointed bills. They are 31 to 38 cm long and weigh 300 to 570 g. Breeding adults have a reddish neck, breast, and flanks. The back and throat are dark, and the head is nearly black. Conspicuous orange-buff to golden ear plumes distinguish the species from other grebes and give it its name. The bills of horned grebes are dark and the breast is white. The winter plumage of horned grebes is rather drab. The cheeks, throat, and breast are white, with a dark crown, nape, and back. The bill is duller than in the breeding plumage.

Male and female horned grebes are similar in appearance, but males are slightly larger, heavier and more brightly colored. Juveniles look similar to adults. (Farrand, 1988a; Godfrey, 1986; Stedman, 2000)

Horned grebes look like small ducks with short, pointed bills. They are 31 to 38 cm long and weigh 300 to 570 g. Breeding adults have a reddish neck, breast, and flanks. They have black heads, and dark throats and backs. They also have orange or golden plumes of feathers on the sides of their heads that look a little like horns. In winter, horned grebes are much duller. They have white cheeks, throat and breast, and a dark crown, nape and back.

Male and female horned grebes look alike, but males are slightly larger and more brightly colored. Juveniles look similar to adults. (Farrand, 1988a; Godfrey, 1986; Stedman, 2000)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • female more colorful
  • ornamentation
  • Range mass
    300 to 570 g
    10.57 to 20.09 oz
  • Range length
    31 to 39 cm
    12.20 to 15.35 in

Reproduction

Horned grebes begin breeding when they are 1 year old, and usually raise one brood per year. Pairs form in the winter or spring, and may breed together for more than one season. Like other grebes, horned grebes display complex courtship rituals that involve many different ceremonies and displays. Courtship displays involve posturing by both the male and the female. They rise up on the water to a vertical position, head feathers raised fully. They then dive together, and both come up with bits of weeds carried in the bill. They rush along the water, side by side, carrying the weeds (Kaufman 1996). (Kaufman, 1996)

Horned grebes begin breeding when they are 1 year old, and usually raise one brood per year. They breed between mid-May and early October, with peak activity occurring June through August. The nest site is located in shallow water among marsh growth. It is built by both sexes and consists of a floating mass of wet plant material with an indentation in the center for the eggs. The nest is anchored by standing vegetation (Kaufman 1996; Ransom 1981).

The female lays 3 to 8 (usually 5 to 7) eggs at a rate of approximately one every other day. The initially whitish to buff eggs quickly become stained red and brown from the nest material. Both parents incubate the eggs for 23 to 24 days. The precocial chicks are able to swim and dive immediately after hatching, but are commonly seen riding on their parent's back for the first week after hatching. The parents brood the young for approximately 9 days after hatching, and feed them for up to 14 days. Chicks become essentially independent at 20 to 25 days old, but cannot fly until they are 41 to 50 days old. (Bull and Farrand Jr, 1988; Collins, 1981; Kaufman, 1996; Ransom, 1981; Stedman, 2000)

  • Breeding interval
    Horned grebes breed once yearly.
  • Breeding season
    Horned grebes breed between mid-May and early October, with peak activity occurring June through August.
  • Range eggs per season
    3 to 8
  • Average eggs per season
    6
  • Average eggs per season
    4
    AnAge
  • Range time to hatching
    23 to 24 days
  • Average fledging age
    0 days
  • Range time to independence
    20 to 25 days
  • Range age at sexual or reproductive maturity (female)
    1 (low) years
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Range age at sexual or reproductive maturity (male)
    1 (low) years
  • Average age at sexual or reproductive maturity (male)
    1 years

Both adults build the nest and incubate the eggs. After the chicks have hatched, horned grebe parents carry them on their backs often for the first 10 days. They also feed the chicks for 10 to 14 days after hatching. (Stedman, 2000)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

The oldest known wild horned grebes lived at least five years and two months.

Behavior

Horned grebes are excellent swimmers and divers. During dives they may stay submerged for up to three minutes and travel 150-200 meters. They may also control their specific gravity in order to control how high they float in the water. Horned grebes are graceful on the water, but very awkward on land. Their legs are set so far back on their bodies, that they are hardly able to walk (Bull and Farrand Jr. 1988).

Like other grebes, P. auritus must run along the surface of the water in order to take-off. Horned grebes fly quickly with rapid wingbeats. Their feet and neck are outstretched during flight and their head is inclined downward (Ransom 1981).

Horned grebes are migratory, spending the breeding season on inland lakes and moving to the coast during the winter. They migrate at night, and typically alone.

Horned grebes are largely silent birds; however, during the breeding season, a variety of twitters, whines, shrieks, and chatter are given by birds with territories (Bull and Farrand Jr. 1988). (Bull and Farrand Jr, 1988; Ransom, 1981)

  • Range territory size
    10,000 (high) m^2

Home Range

During the breeding season, horned grebe home ranges typically range from 330 to 30,000 square meters. (Stedman, 2000)

Communication and Perception

Horned grebes exhibit very complex and varied physical displays that they use to communicate with one another. They also use vocalizations to communicate, particularly during the breeding season. Most of the vocalizations relate to the establishment and maintenance of the pair bond, and to territory and brood defense. Members of a breeding pair sometimes trill in duet. (Stedman, 2000)

  • Other Communication Modes
  • duets

Food Habits

The diet of horned grebes consists mainly of aquatic arthropods in the summer and fish and crustaceans in the winter. Leeches, tadpoles, salamanders, and some plant material may also be consumed on occasion. On the wintering grounds, mollusks may also be consumed. Horned grebes capture their prey by diving underwater. They swallow small items while underwater, but bring large items to the surface to manipulate before swallowing.

Like most other grebes, horned grebes swallow many feathers. These feathers presumably aid in digestions of sharp objects such as fish bones. (Kaufman, 1996; Stedman, 2000)

  • Animal Foods
  • amphibians
  • fish
  • insects
  • mollusks
  • terrestrial worms
  • aquatic crustaceans

Predation

Adult horned grebes do not have many predators. Incubating adults are vulnerable while on the nest, and may fall prey to mink or other predators.

Horned grebe eggs are taken by raccoons, crows, black-billed magpies, American coots and various gull species. (Stedman, 2000)

Adult horned grebes do not have many predators. Incubating adults are vulnerable while on the nest, and may be killed by mink or other predators.

Horned grebe eggs are eaten by raccoons, crows, black-billed magpies, American coots and gulls.

Ecosystem Roles

Horned grebes affect the populations of the animals that they eat. They also compete with some fish species for aquatic invertebrate prey. (Stedman, 2000)

Economic Importance for Humans: Positive

Horned grebes have no known affect on humans.

Economic Importance for Humans: Negative

Horned grebes feed on small fish, some of which may be economically important species.

Conservation Status

Populations of horned grebes appear to have declined in recent decades, but solid data is lacking (Kaufman 1996). Habitat loss and degradation are major threats to horned grebe populations. Drought-related loss of wetlands greatly affects horned grebes. Oil spills and pesticide accumulation in their aquatic habitats also negatively affect horned grebe populations. Other threats to horned grebes include ingestion of plastics and lead and entanglement in fishing nets. (Kaufman, 1996)

Contributors

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

Bradley Handford (author), University of Alberta, Cindy Paszkowski (editor), University of Alberta.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Bull, J., J. Farrand Jr. 1988. The Audubon Society Field Guide To North American Birds--Eastern Region. New York: Alfred A. Knopf.

Collins, H. 1981. Harper & Row's Complete Guide To North American Wildlife--Eastern Edition. New York: Harper & Row Publishers.

Farrand, J. 1988a. Eastern Birds--An Audubon Handbook. New York: McGraw--Hill Book Company.

Farrand, J. 1988b. Western Birds--An Audubon Handbook. New York: McGraw--Hill Book Company.

Godfrey, W. 1986. The Birds of Canada--Revised Edition. Ottawa: National Museums of Canada.

Kaufman, K. 1996. Lives of North American Birds. Boston: Houghton Mifflin Company.

Ransom, J. 1981. Harper & Row's Complete Field Guide To North American Wildlife--Western Edition. New York: Harper & Row Publishers.

Stedman, S. 2000. Horned grebe (Podiceps auritus). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, Vol. 505. Philadelphia, PA: The Birds of North America, Inc.

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