Geographic Range
Long-billed curlew (
Numenius americanus
) breeding areas range throughout the western United States and as far north as southern
Canada. Their breeding range extends from eastern New Mexico northwards to the western
Dakotas and into south Saskatchewan. Following grasslands and valleys in the Rocky
Mountains, long-billed curlews range southwards from Alberta, through Montana and
Wyoming into the Nevada Great Basin, and northwards through Oregon and Washington
to the Fraser Plateau in British Columbia.
Outside the breeding season, long-billed curlews range along the western coastline
of North America starting as far north as Cape Flattery and extending as far south
as El Salvador. They are also found across northern Mexico as far south as Mexico
City, and along the eastern Mexican coast from the Yucatan peninsula to Vermillion
Bay Louisiana. Other isolated ranges include midwestern Texas, and small Costa Rican
populations recorded in the Gulf of Nicoya, and the Golfo Dulce coastline between
Puerto Jiménez and Pavones.
- Biogeographic Regions
- nearctic
- neotropical
Habitat
The habitat of breeding long-billed curlews consists primarily of grasslands, with
the majority of individuals inhabiting shortgrass prairie, followed by pasture grasslands
and cultivated cropland. Curlews show no significant occupational tendencies between
dry and irrigated land, but tend to occupy wide-open areas with vegetation 4 to 15
cm tall. In winter they live primarily in intertidal areas and mudflats, as well as
foraging in nearby pastures.
- Habitat Regions
- temperate
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- Aquatic Biomes
- coastal
- brackish water
- Other Habitat Features
- agricultural
- estuarine
Physical Description
Long-billed curlews are long-legged shorebirds characterized by their long, decurved
bills. The plumage in adult curlews is brown to buff, and contains noticeable hints
of darker browns and pinks. Dark brown streaks and bars are present on their upper
body, with orange brown upper remiges and cinnamon-colored underwing coverts and axillaries.
Unlike many other curlew species, long-billed curlews have streaked rather than striped
crowns. In their species assessment, Dark-Smiley and Keinath (2004) note only a small
difference in size between sexes, with females slightly larger than males, but no
numerical data were reported.
Long-billed curlews weigh 490 to 950 grams and are 50 to 65 cm long. Their wingspan
is 62 to 101 cm long.
Juvenile long-billed curlews can be identified by their wing coverts, which have dark
brown centers. They also lack the dark brown barring and pale notches characterized
by adults. Juveniles can also be identified by their brighter coloration and shorter
beaks.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- female larger
Reproduction
Male long-billed curlews solicit mates by a combination of ground calls and vocal-bounding
flights consisting of perimeter or figure-8 patterned flights. These displays are
used to attract females to the males' territory. When females are present they then
will orient these flights around them. As females fly through a nesting area, these
displays intensify as all unpaired males rise and perform bounding flights. If a female
is unpaired, she will land in the nest field of one of the males, often wandering
through many territories over the course of several days until a mate is chosen. She
and her mate will then familiarize themselves with one another, mate, and form a monogamous
pair bond. If an unpaired female lands in an unpaired males nesting area, but does
not choose to remain and form a pair, then the male will spend less time soliciting
females and spend more time on the ground foraging.
- Mating System
- monogamous
Long-billed curlews breed once per year from late March to late July. Breeding females
lay their eggs in one clutch in June averaging 4 eggs per clutch. Their eggs are a
light beige or a pale blue-green color with chocolate colored splotches. Redmond (1986)
reports that long-billed curlew eggs are, on average, 65.3 mm long and 46.1 mm wide.
Breeding pairs take turns incubating the eggs, with the female sitting during the
day, and the male in the evening.
Long-billed curlew chicks hatch after an incubation period averaging 27 days. Chicks
start their pip hole (the hole which the chick enlarges during hatching to exit the
eggshell) 21 mm from the larger end of the egg, and all chicks in a clutch will typically
finish hatching within 5 hours of one another. Newly hatched chicks have a birth mass
between 44 and 66g. Chicks begin to fledge between 32 and 45 days of hatching, and
become independent 35 to 49 days after hatching, shortly after learning to fly. They
reach reproductive maturity after 2 years.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- oviparous
Long-billed curlews nest on the ground; both males and females form a nesting bowl by scraping and poking the ground into a small depression. The nests are lined with locally available insulating materials like leaves, grass, stems, and twigs. Notably, nests are only insulated depending on local availability around the nesting site, and nests in areas with more sparse vegetation have substantially less insulation than those in other areas. In the presence of a mammalian predator, long-billed curlews will display at the predator, and attempt to draw them away by feeding nearby while calling rapidly, but no effort will be made to drive them from the nest. They will, however, guard their eggs against avian predators, driving them away from the nest. Incubation of eggs occurs in shifts; typically females will sit on the eggs during the day, and males will take over in the early evening. Shortly after hatching, long-billed curlews defend against avian predators much more aggressively, and the remains of the eggshells are removed from the nest and deposited several hundred meters away from the nest. Their territoriality also narrows in scope, and at this point they evict other long-billed curlews in a radius around their chicks rather than from the entirety of their territory.
Long-billed curlews do not feed their young, and chicks hunt in a similar manner as
their parents. Both sexes watch over their young initially, and chicks are watched
closely despite their tendency to wander far from the rest of their brood. Chicks
can range as far as 100 meters away from a parent over the course of the day, before
being ushered back to the nest area by the observing parent to roost at night. After
2-3 weeks, female curlews will typically abandon the brood, leaving only the male
to care for the chicks. The juveniles fledge several weeks later, and after they have
learned to fly, they are considered independent.
- Parental Investment
- precocial
- male parental care
- female parental care
-
pre-hatching/birth
-
protecting
- male
- female
-
protecting
-
pre-weaning/fledging
- protecting
-
pre-independence
-
protecting
- male
-
protecting
Lifespan/Longevity
Redmond and Jenni (1986) suggest that long-billed curlews may live on average from
8-10 years, reporting a 15% mortality rate per year after they reach 2 years old.
However, it is more likely that their lifespan is much longer than that, as other
species in the genus
Numenius
can live between 23 and 32 years.
Behavior
Long-billed curlews are primarily diurnal, spending the majority of their time foraging.
They move between foraging sites by a combination of flight and short glides. Non-breeding
individuals are primarily solitary animals, although they often form mixed-sex flocks
during migratory flights and at winter roosts. Long-billed curlews typically remain
on their claimed territories, which they guard against other intruding individuals
and predators. They have been observed leaving their territories during the hottest
parts of the day, often foraging in cooler areas. During these periods of absence,
individuals from neighboring areas will commonly trespass and forage on the absent
curlew's territory.
Male long-billed curlews perform aggressive displays and antagonistic actions towards
one another at boundaries between individual territories. Despite this territorial
activity they also cooperate in mobbing activities to protect eggs and chicks when
a predator is present.
- Key Behaviors
- terricolous
- flies
- glides
- diurnal
- motile
- migratory
- solitary
- territorial
Home Range
Colwell et al. (2002) reported home ranges of 1.3 - 7.5 ha. across a 9-month study.
Long-billed curlews, on average, maintain home ranges of 3.0 ha during the summer,
and 2.3 ha during the winter. These ranges can deviate up to 70% depending on the
density of local prey populations, and individuals consuming a higher proportion of
crabs have been noted to maintain larger home ranges, possibly due to higher distance
between prey aggregations.
Communication and Perception
Long-billed curlews perceive their prey primarily by sight, and communication between
individuals typically consists of calls and displays. They produce a distinctive call
year-round consisting of a two-note whistle. This low-high whistle is observed in
both sexes and is both an anxiety tone and a contact call between members of the flock.
Their calls can vary seasonally, with some alarm calls observed only during the breeding
season between incubation and fledgling stages. Long-billed curlews use territorial
displays to remove intruders; these include flying directly at an intruder before
pulling up steeply, and crouch runs followed by an aerial chase. Communication during
breeding season also include acoustic displays like ground-calls, and visual flight
displays in males.
Food Habits
Long-billed curlews diet consists primarily of small invertebrates and wild fruits,
with those individuals inhabiting inland areas and grasslands mainly consuming a variety
of earthworms, spiders, grasshoppers, beetles, and caterpillars. In coastal areas,
they prey upon various bivalves, marine worms, mollusks, crustaceans, and some fish.
Some consumption of other bird’s eggs and nestlings has been observed as well. They
forage either singly, or in groups of up to 15 individuals by pecking food from the
ground or water with their long bills. They also probe loose ground, mud, and sand
in search of prey, and have exhibited some insect hawking behaviors. Curlews forage
almost exclusively during the day, and have little diet change seasonally within their
respective breeding and non-breeding ranges.
- Animal Foods
- fish
- eggs
- insects
- terrestrial non-insect arthropods
- mollusks
- terrestrial worms
- aquatic or marine worms
- aquatic crustaceans
- Plant Foods
- fruit
Predation
Adult long-billed curlew are preyed upon primarily by raptors like Swainson's hawk
(
Buteo swainsoni
) and the ferruginous hawk (
Buteo regalis
). Land predators like coyotes (
Canis latrans
), feral dogs (
Canis lupus familiaris
), and red foxes (
Vulpes vulpes
) prey upon hatchlings and injured or nesting adults. In the past, humans (
Homo sapiens
) were the primary predator of adult long-billed curlews, and drove them nearly to
extinction until hunting them was outlawed. Long-billed curlew eggs are more common
targets for predation, and after a nest is raided the parents abandon the clutch.
Redmond and Jenni (1986) found that the majority of eggs lost are consumed by coyotes
and feral dogs, followed by badgers (
Taxidea taxis
), and birds such as the common raven (
Corvus corax
) and black-billed magpie (
Pica hudsonia
).
Ecosystem Roles
Long-billed curlews compete for resources with other shorebirds on their winter ranges,
notably godwits
Limosa fedoa
and willets
Catoptrophorus semipalmatus
. They prey primarily on invertebrates (both terrestrial and marine) and are preyed
upon by hawks and canids.
Long billed curlews can be host to several species of lice, including
Austromenopon crocatum
,
Cummingsiella longistricola
, and
Lunaceps numenii numenii
. They may also be host to parasitic intestinal flatworms, including
Brachylaema fuscata
,
Dictymetra numenii
,
Dictymetra nymphae
,
Dictymetra paranumenii
, and
Dictymetra radiaspinosa
. Spiny-headed parasitic worms such as
Mediorhynchus papillosus
and
Mediorhynchus robustus
can inhabit their intestines. Parasitic flatworms (
Selfcoelum lamothei
) can be found in the air sacs of long-billed curlews.
- Lice Austromenopon crocatum
- Flatworm Brachylaema fuscata
- Lice Cummingsiella longistricola
- Flatworm Dictymetra numenii
- Flatworm Dictymetra nymphae
- Flatworm Dictymetra paranumenii
- Flatworm Dictymetra radiaspinosa
- Spiny-headed worm Mediorhynchus papillosus
- Spiny-headed worm Mediorhynchus robustus
- Lice Lunaceps numenii numenii
- Flatworm Selfcoelum lamothei
Economic Importance for Humans: Positive
Bird watching and ecotourism positively contribute to the economy both in travel costs
and bird watching equipment. Ecotourists observing shorebirds in their natural environment
would likely attempt to observe long-billed curlews, as they are one of the largest
sandpipers native to North America, and have very distinctive long, curved bills.
- Positive Impacts
- ecotourism
Economic Importance for Humans: Negative
There are no known adverse effects of long-billed curlews on humans.
Conservation Status
Long-billed curlews have no special status on the US Federal List or CITES. The IUCN Red List considers them to be a species of "Least Concern" despite a slightly negative population trend. They are protected under the US Migratory Bird Act. Despite their protected status, adult mortality rates indicate illegal hunting continues to be a problem. The U.S. Shorebird Conservation Plan categorizes them as "highly imperiled" due to their threatened habitat and persisting declines in population.
Though they were severely over hunted in the past, the greatest threat to their population is now the habitat loss from both urban growth and wetland drainage. There is little known about the effects of pesticides on long-billed curlews, but insecticides may affect them indirectly by reducing the abundance of arthropods.
The American Bird Conservancy has increased awareness of long-billed curlews threatened
habitat as a representative example of how losses of short grass prairie have affected
local species. Several protected grassland areas contain long-billed curlews, and
global population estimates have been proposed to identify threats to the species.
Additional Links
Contributors
William Bellamy (author), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Jacob Vaught (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- brackish water
-
areas with salty water, usually in coastal marshes and estuaries.
- agricultural
-
living in landscapes dominated by human agriculture.
- estuarine
-
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
- monogamous
-
Having one mate at a time.
- 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).
- 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
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- young precocial
-
young are relatively well-developed when born
- male parental care
-
parental care is carried out by males
- female parental care
-
parental care is carried out by females
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- solitary
-
lives alone
- 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
- acoustic
-
uses sound to communicate
- ecotourism
-
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
- carnivore
-
an animal that mainly eats meat
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
- 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.
- 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.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
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AnAge, 2016. "AnAge Data Survey - Numenius" (On-line). Accessed March 25, 2016 at http://genomics.senescence.info/species/survey.php?ids%5B%5D=01287&ids%5B%5D=01288&ids%5B%5D=01289&cmd=var .
Blend, C., N. Dronen. 2007. Selfcoelum lamothei n. sp. (Digenea: Cyclocoelidae: Cyclocoelinae) from the air sacs of the long-billed curlew, Numenius americanus (Scolopacidae), from the Galveston, Texas area, USA. Revista Mexicana de Biodiversidad , 79: 41-48.
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USDA Forest Service. Long-billed Curlew (Numenius americanus): a technical conservation assessment. None. Durango, Colorado: Ecosphere Ecological Services. 2006. Accessed March 24, 2016 at http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5182037.pdf .
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