Made
famous in folk songs, poems, and literature for their endless chanting
on summer nights, Eastern Whip-poor-wills are easy to hear but hard
to see. Their brindled plumage blends perfectly with the gray-brown
leaf litter of the open forests where they breed and roost. At dawn
and dusk, and on moonlit nights, they sally out from perches to
sweep up insects in their cavernous mouths. These common birds are
on the decline in parts of their range as open forests are converted
to suburbs or agriculture.
At a Glance
Habitat
|
Food
|
Nesting
|
Behavior
|
Conservation
|
|
|
|
|
|
Open Woodland
|
Insects
|
Ground
|
Aerial Forager
|
|
Measurements
Both Sexes
Length
8.710.2
in
2226
cm
Wingspan
17.718.9
in
4548
cm
Weight
1.52.3
oz
4364
g
Relative Size
Smaller than a Chuck- wills-
widow; about the size of a
Common Nighthawk.
Other Names
Engoulevent bois-pourri (French)
Tapacamino cuerporruín-norteño
(Spanish)
|
Cool Facts
- Eastern Whip-poor-wills lay their eggs in phase with the
lunar cycle, so that they hatch on average 10 days before a full
moon. When the moon is near full, the adults can forage the entire
night and capture large quantities of insects to feed to their
nestlings.
- Eastern Whip-poor-will chicks move around as nestlings, making
it difficult for predators to rob the nest. The parent may help
by shoving a nestling aside with its foot, sometimes sending the
young bird tumbling head over heels.
- The male Eastern Whip-poor-will often will investigate intruders
near the nest by hovering in place with his body nearly vertical
and his tail spread wide, showing off the broad white tips of
the tail feathers.
- Eastern and Mexican Whip-poor-wills used to be considered
one species, simply called the Whip-poor-will. But in 2011 they
were split into two species based on differences in mitochondrial
and nuclear DNA. Eastern Whip-poor-wills give faster, higher-pitched
whip-poor-will calls and have more colorful eggs than their western
counterparts.
- The Eastern Whip-poor-will may locate insects by seeing the
bugs silhouettes against the sky. Its eyes have a reflective
structure behind the retina that is probably an adaptation to
low light conditions.
- The oldest recorded Eastern Whip-poor-will was at least 4
years old when it was found in Maryland in 1959. It had been banded
in the same state.
Eastern Whip-poor-wills breed in dry deciduous or evergreen-deciduous
forest with little or no underbrush, close to open areas. The forest
types they use include pine-oak with juniper, pine plantations,
pine flatwoods, northern hardwood forests, low-elevation white pine,
oak, aspen, birch, and scrubby woodlands with pitch pine, scrub
oak, and hickory. They seem to avoid large tracts of uninterrupted
forest with dense canopy. Their migration habitat is similar to
their breeding habitat. In winter, Eastern Whip-poor-wills prefer
broadleaf tropical or subtropical forest near open areas.
Eastern Whip-poor-wills feed exclusively on insects, including
moths, scarab beetles, click beetles, long-horned grasshoppers,
stoneflies, ground beetles, carrion beetles, tiger moths, ants,
bees, wasps, fireflies, long-horned beetles, measuringworm moths,
owlet moths, weevils, and scavenger beetles. They start foraging
30 minutes after sunset and continue until it gets too dark to see
their prey. At first light they resume feeding, stopping about 40
minutes before sunrise. When the moon is bright enough, they may
hunt all night long. During cold, rainy weather they will not try
to forage. Whip-poor-wills perch in trees (or sometimes on the ground)
and make short sallies to snag insects up to 15 feet off the ground,
or they may stay out on longer insect-catching flights. Their enormous
mouths allow them to swallow insects up to two inches long. They
sometimes search rotten logs and leaves for ants, caterpillars,
beetles, worms, and other insects.
Nesting
Nesting Facts
Clutch Size
2 eggs
Number of Broods
1-2 broods
Egg Length
1.11.3
in
2.73.2
cm
Egg Width
0.80.9
in
22.2 cm
Incubation Period
1921 days
Nestling Period
38 days
Egg Description
Cream-colored or grayish white,
marbled with lavender-gray,
yellowish-brown, or pale brown.
Condition at Hatching
Well developed and covered with
orange-tan down, but with eyes closed. |
Nest Description
Whip-poor-wills build no nest, though the weight of the incubating
adult may eventually create a slight hollow in the leaf litter. Despite
the absence of nest material, the eggs, nestlings, and adults are
all so well camouflaged that they are extremely difficult to see.
Nest Placement
The female Eastern Whip-poor-will lays her eggs directly on
the leaf litter of the forest floor, usually on the north or northeast
side of a small herb, shrub, or seedling that will shade the nest
from the hot afternoon sun. Whip-poor-wills occasionally nest on
bare ground, sand, or decayed wood. Its not known whether
males or females choose the site.
Behavior
Eastern Whip-poor-wills are nocturnal birds with loud, distinctive
voices. At night they fly slowly and silently, often wheeling around
180 degrees in between wing flaps. When nesting or roosting, whip-poor-wills
spend the day sitting motionless, becoming active only at dusk. They
can fly nearly vertically when chasing insects. They usually forage
in the semidarkness of early morning and early evening, but on moonlit
nights they chase moths and beetles all night long. Whip-poor-wills
appear to time their nesting so that chicks will hatch about 10 days
before the full moon, when the parents have more time (and moonlight)
to catch food for them. They regurgitate insects for their nestlings,
which may move from the nest site within days of hatching if a predator
comes to call. At about eight days old, the young molt into highly
camouflaged plumage and the female leaves them in the care of the
male, often starting a new clutch of two eggs nearby within the territory.
The male establishes and maintains his territory by calling along
the perimeter and by chasing off intruders while making aggressive
calls and hisses, with raised wings and mouth open. Males and females
feign injury to lead predators away from the nest. Whip-poor-wills
are generally solitary, forming loose flocks during migration.
Conservation
status via IUCN
|
|
Least Concern
|
Eastern Whip-poor-wills are still fairly common birds, but their
numbers declined by almost 3% per year between 1966 and 2015, resulting
in a cumulative decline of 75% during that time, according to the
North American Breeding Bird Survey. In some areas, parts of their
range seem to have become unoccupied. Partners in Flight estimates
a global breeding population of 2 million with 95% living part of
the year in the U.S., 5% breeding in Canada, and 43% wintering in
Mexico. The species rates a 14 out of 20 on the Continental Concern
Score. Eastern Whip-poor-will is on the 2016 State of North America's
Birds' Watch List, which includes bird species that are most at
risk of extinction without significant conservation actions to reverse
declines and reduce threats. It is also a U.S.-Canada Stewardship
species. The main problem Whip-poor-wills face is the loss of open-understory
forests. This can come from conversion to crops, pasture, urbanization,
or fire suppression leading to dense understories. Some habitat
may be being created as abandoned farmland reverts to forest. Because
Whip-poor-wills often fly over roads or sit on roadways while foraging,
they are also vulnerable to collisions with cars. Precise numbers
for this nocturnal species are difficult to obtain through daytime
surveyspeople can contribute data via the Nightjar Survey
Network.
|