Common Poorwill
Encyclopedia
The Common Poorwill is a nocturnal bird
of the family Caprimulgidae, the nightjar
s. It is found from British Columbia and southeastern Alberta, through the western United States to northern Mexico. The bird's habitat is dry, open areas with grasses or shrubs, and even stony desert slopes with very little vegetation.
Many northern birds migrate
to winter within the breeding range in central and western Mexico, though some remain further north. Remarkably, the Common Poorwill is the only bird known to go into torpor
for extended periods (weeks to months). This happens on the southern edge of its range in the United States, where it spends much of the winter inactive, concealed in piles of rocks. This behavior has been reported in California and New Mexico. Such an extended period of torpor is close to a state of hibernation
, not known among other birds. It was described definitively by Dr. Edmund Jaeger
in 1948 based on a Poorwill he discovered hibernating in the Chuckwalla Mountains
of California in 1946.
Jaeger's observations may have been influenced by earlier observations of torpor in the White-throated Swift
made by his acquaintance Wilson Hanna, a resident of the Riverside, California
area and noted oologist
.
In 1804, Meriwether Lewis
observed hibernating Common Poorwills in North Dakota during the Lewis and Clark Expedition
. Though these observations were recorded carefully in Lewis's journal, their significance was not understood. This was at least in part because the Common Poorwill was not then recognized as a species distinct from the Whip-poor-will
of eastern North America.
Native Americans of the Hopi
tribe were likely aware of the Poorwill's behavior even earlier—the Hopi word for the bird means "The Sleeping One".
This is the smallest North American nightjar
, about 18 cm (seven inches) in length, with a wingspan of approximately 30 cm (12 inches). It weighs 36–58 g. The sexes are similar, both gray and black patterned above. The outer tail-feathers are tipped with white, the markings slightly more prominent in the male.
The Common Poorwill is told from similar nightjars by its small size, short bill, rounded wings with tips that reach the end of the short tail at rest, and pale gray coloration. Like many other nightjar
s, the common name derives from its call, a monotonous poor-will given from dusk to dawn. At close range a third syllable of the call may be heard, resulting in a poor-will-low. It also gives a chuck note in flight.
Up to five subspecies are described, although these are all quite similar, and some may be of dubious validity.
Like other members of this family it feeds on nocturnal insect
s such as moth
s, beetle
s, and grasshopper
s. It ejects pellets of the indigestible parts, in the manner of an owl
. The Common Poorwill frequently takes prey off of the ground or by leaping into the air from the ground. It is reported to drink on the wing.
The nest of the Common Poorwill is a shallow scrape on the ground, often at the base of a hill and frequently shaded partly by a bush or clump of grass. The clutch size is typically two, and the eggs are white to creamy, or pale pink, sometimes with darker mottling. Both sexes incubate for 20–21 days to hatching, with another 20–23 days to fledging. There is usually one brood per year, but females may sometimes lay and incubate a second clutch within 100 m of the first nest while the male feeds young at the first site. The young are semiprecocial
. An adult disturbed on the nest tumbles and opens its mouth, hissing, apparently imitating a snake
.
Breeding is from March to August in the south of the range, and late May to September further north.
The genus name Phalaenoptilus is a compound of Greek phalaina, moth and ptilon, feather. The species name nuttallii honors English-born American ornithologist Thomas Nuttall
.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
of the family Caprimulgidae, the nightjar
Nightjar
Nightjars are medium-sized nocturnal or crepuscular birds with long wings, short legs and very short bills. They are sometimes referred to as goatsuckers from the mistaken belief that they suck milk from goats . Some New World species are named as nighthawks...
s. It is found from British Columbia and southeastern Alberta, through the western United States to northern Mexico. The bird's habitat is dry, open areas with grasses or shrubs, and even stony desert slopes with very little vegetation.
Many northern birds migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
to winter within the breeding range in central and western Mexico, though some remain further north. Remarkably, the Common Poorwill is the only bird known to go into torpor
Torpor
Torpor, sometimes called temporary hibernation is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds and some mammals such as mice and bats...
for extended periods (weeks to months). This happens on the southern edge of its range in the United States, where it spends much of the winter inactive, concealed in piles of rocks. This behavior has been reported in California and New Mexico. Such an extended period of torpor is close to a state of hibernation
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
, not known among other birds. It was described definitively by Dr. Edmund Jaeger
Edmund Jaeger
Edmund Carroll Jaeger, D.Sc. was an American biologist known for his works on desert ecology. He was born in Nebraska and moved to California in 1906...
in 1948 based on a Poorwill he discovered hibernating in the Chuckwalla Mountains
Chuckwalla Mountains
The Chuckwalla Mountains are a mountain range in the transition zone between the Colorado Desert—Sonoran Desert and the Mojave Desert, climatically and vegetationally, in Riverside County of southern California.-Geography:...
of California in 1946.
White-throated Swift
The White-throated Swift is a swift of the family Apodidae native to western North America, south to cordilleran western Honduras...
made by his acquaintance Wilson Hanna, a resident of the Riverside, California
Riverside, California
Riverside is a city in Riverside County, California, United States, and the county seat of the eponymous county. Named for its location beside the Santa Ana River, it is the largest city in the Riverside-San Bernardino-Ontario metropolitan area of Southern California, 4th largest inland California...
area and noted oologist
Oology
Oology is a branch of ornithology studying bird eggs, nests and breeding behavior. Oology can also refer to the hobby of collecting wild birds' eggs, sometimes called birdnesting or egging, which is now illegal in many jurisdictions.-As a science:Oology became increasingly popular in Britain and...
.
In 1804, Meriwether Lewis
Meriwether Lewis
Meriwether Lewis was an American explorer, soldier, and public administrator, best known for his role as the leader of the Lewis and Clark Expedition also known as the Corps of Discovery, with William Clark...
observed hibernating Common Poorwills in North Dakota during the Lewis and Clark Expedition
Lewis and Clark Expedition
The Lewis and Clark Expedition, or ″Corps of Discovery Expedition" was the first transcontinental expedition to the Pacific Coast by the United States. Commissioned by President Thomas Jefferson and led by two Virginia-born veterans of Indian wars in the Ohio Valley, Meriwether Lewis and William...
. Though these observations were recorded carefully in Lewis's journal, their significance was not understood. This was at least in part because the Common Poorwill was not then recognized as a species distinct from the Whip-poor-will
Whip-poor-will
The Eastern Whip-poor-will, Caprimulgus vociferus, is a medium-sized nightjar from North and Central America. The whip-poor-will is commonly heard within its range, but less often seen because of its superior camouflage...
of eastern North America.
Native Americans of the Hopi
Hopi
The Hopi are a federally recognized tribe of indigenous Native American people, who primarily live on the Hopi Reservation in northeastern Arizona. The Hopi area according to the 2000 census has a population of 6,946 people. Their Hopi language is one of the 30 of the Uto-Aztecan language...
tribe were likely aware of the Poorwill's behavior even earlier—the Hopi word for the bird means "The Sleeping One".
This is the smallest North American nightjar
Nightjar
Nightjars are medium-sized nocturnal or crepuscular birds with long wings, short legs and very short bills. They are sometimes referred to as goatsuckers from the mistaken belief that they suck milk from goats . Some New World species are named as nighthawks...
, about 18 cm (seven inches) in length, with a wingspan of approximately 30 cm (12 inches). It weighs 36–58 g. The sexes are similar, both gray and black patterned above. The outer tail-feathers are tipped with white, the markings slightly more prominent in the male.
The Common Poorwill is told from similar nightjars by its small size, short bill, rounded wings with tips that reach the end of the short tail at rest, and pale gray coloration. Like many other nightjar
Nightjar
Nightjars are medium-sized nocturnal or crepuscular birds with long wings, short legs and very short bills. They are sometimes referred to as goatsuckers from the mistaken belief that they suck milk from goats . Some New World species are named as nighthawks...
s, the common name derives from its call, a monotonous poor-will given from dusk to dawn. At close range a third syllable of the call may be heard, resulting in a poor-will-low. It also gives a chuck note in flight.
Up to five subspecies are described, although these are all quite similar, and some may be of dubious validity.
- P. n. nutalli breeds over most of the North American range.
- P. n. californicus, Dusky Poorwill, is darker and browner than the nominate race. It occurs in western California.
- P. n. hueyi, Desert Poorwill, is paler than the nominate race. It occurs in southern California.
- P. n. dickeyi, San Ignacio Poorwill, is smaller and less heavily marked than californicus. It is resident in Baja CaliforniaBaja CaliforniaBaja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
. - P. n. adustus, Sonoran Poorwill, is paler and browner than the nominate race. It occurs from extreme southern ArizonaArizonaArizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
to central SonoraSonoraSonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
.
Like other members of this family it feeds on nocturnal insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s such as moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, and grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s. It ejects pellets of the indigestible parts, in the manner of an owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
. The Common Poorwill frequently takes prey off of the ground or by leaping into the air from the ground. It is reported to drink on the wing.
The nest of the Common Poorwill is a shallow scrape on the ground, often at the base of a hill and frequently shaded partly by a bush or clump of grass. The clutch size is typically two, and the eggs are white to creamy, or pale pink, sometimes with darker mottling. Both sexes incubate for 20–21 days to hatching, with another 20–23 days to fledging. There is usually one brood per year, but females may sometimes lay and incubate a second clutch within 100 m of the first nest while the male feeds young at the first site. The young are semiprecocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
. An adult disturbed on the nest tumbles and opens its mouth, hissing, apparently imitating a snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
.
Breeding is from March to August in the south of the range, and late May to September further north.
The genus name Phalaenoptilus is a compound of Greek phalaina, moth and ptilon, feather. The species name nuttallii honors English-born American ornithologist Thomas Nuttall
Thomas Nuttall
Thomas Nuttall was an English botanist and zoologist, who lived and worked in America from 1808 until 1841....
.
External links
- USGS
- All About Birds – Cornell University
- Arizona State University
- Jaeger's discovery – several articles discuss history of observations of hibernation in the Poorwill
- San Bernardino County Museum – refers to Wilson Hanna, oologist
- Common Poorwill photo gallery VIREO