Nashville warblers,, are found in North and Central America. As migratory warblers, their geographic range differs by season. They breed in the northern and western United States and some of southern Canada, usually near some type of water supply. In more detail, they will travel as far north into Canada as Saskatchewan and their range continues east past the James Bay and into the Gulf of St. Lawrence. Within the United States, these warblers are found all around the Great Lakes states and southward into northern Virginia following the Application Mountains. Additionally, they can also be found along the west coast starting as far north as Canada within the Thompson Plateau area southward into western Washington, northern Idaho, along coastal California, and inland California east of Sacramento southward into Fresno.
Nashville warblers are late migrants. In October, they depart their breeding locations to migrate south for the winter, traveling throughout multiple migratory pathways in the United States. They migrate into northern parts of Central America. These warblers can be found in central Mexico around San Luis Potosi and southward into Guatemala. A small population resides around San Salvador. The warblers will then migrate northwards in March, arriving back to their breeding ground in late April and early May. Furthermore, despite their name, Nashville warblers are only found in Tennessee during migration. (Birdlife International, 2016)
Breeding habitats of Nashville warbler vary across their wide geographic range, but generally, terrestrial areas. In Canada, they nest in black spruce (Picea mariana), balsam fir (Abies balsamea), birch (Betula), and poplar trees (Populus). In the northeastern United States, they have been found in mixed forests, along the edges of the forest and in fields. They use spruce-cedar bogs, aspen (Populus)-birch stands, and Jack pine (Pinus banksiana) stands. Further south along the eastern coast, they are found on mountain slopes, along the timberline. In the northwestern United States, the birds and their nests have been observed up to 2,134 m elevation in black oak (Quercus velutina). Additionally, nests were found in shrubby and brush habitats in the Cascade Range in Washington at an elevation of 984-1,312 m (Lowther, 2020). They are also seen at a lower elevation in ponderosa pines (Pinus ponderosa) and Douglas-fir zones (Pseudotsuga menziesii).
In eastern areas of their non-breeding range in North America, Nashville warblers are frequently found in deciduous trees, shrubs, or in open mixed forests. These nests are mid-canopy level at the edges of bushy woodlands close to meadows, roads, streams, ponds, swamps, or marshes. Within the Caribbean region, they are in the coastal areas, urban parks, and gardens. In the coastal areas of the Dominican Republic they are within the dry forest of Turks and Caicos Island and in the wet forest in Haiti. The western populations in North America are located in drier habitats, mainly in mountainous habitats. In Washington, they are found in the central Columbia Basin as well as in the southeastern part of the state in sagebrush-dominated landscapes. In Arizona, the warblers are found in the desert flats, desert wash, and creek bottom in the Chiricahua Mountains. Further south into Mexico, they utilize suburban gardens and the lower deciduous forests.
Their nests are built within 7-9 days by females. The males are not involved with building the nest or a part of the incubation period either. Their nest consists of a combination of fine fibers or grasses, strips of tree bark, and rootlets that are made into a cup-like mold. They are built on the ground, usually found on moss or at the base of shrubs. (Baicich and Harrison, 2005; Lawrence, 1948; Lowther and Williams, 2020)
Nashville warblers are about 12 cm long and weigh an average of 10 g. The adult males average weights of 8.9 g (range 7.0-13.9 g) and the adult females average 8.6 g (range 6.7-11.1 g). However, their weight does vary among the different seasons. Like other members of the genus Vermivora, their bills are thin and pointed. Nashville warblers lack wing-bars, tail-spots, or tail-patches. In southeastern Michigan, the wing length of the adult males ranged from 50.5 to 69.0 mm (average = 58.9 mm), while adult females ranged from 46.5 to 67.5 mm (average = 56.2 mm).
Adult Nashville warblers have a yellow chest, a gray forehead, with a white eye ring, olive-green on their back and scapular area, and a yellowish green rump. Adult Nashville warblers have black feet and a black or dark brown bill. However, females are less vibrant as the males and with barely a chestnut on the crown.
Juveniles have a dull yellow underneath, brown or gray head and neck, a white eye ring, dull green on their backs. Their feet and bill are pink and will become a dusty color as they get older. Juveniles will favor a female adult more so than a male. (Johnson, 1976; Lowther and Williams, 2020; Pearson, et al., 1936)
Nashville warblers breed seasonally, and Knapton (1984) suggests that they are monogamous within a season. The female builds the nest in the ground, which will take about 7 to 9 days. The male is nearby during this time and will often be singing. The nest is built compacted with fewer grasses and a cleaner appearance than other warblers. The males will guard the nest and their territory, chasing off the other males from their breeding territories. Lowther (2020) summarized male aggression and one mating observation. In this case, a male chased another male out of a shared territory. A female in the territory appeared receptive, making a "chink" call, causing the male to fly down to the female. Mating only lasted a few seconds, and the female exited to preen herself. There is little to no singing for days after the mating. (Baicich and Harrison, 2005; Knapton, 1984; Lowther and Williams, 2020)
The breeding season for Nashville warblers is in the spring, usually beginning between April and May. The female lays 4 to 5 eggs per nest, between 600 to 1000 h, and 1 egg per day. Eggs incubate for 11 to 12 days. The eggs are often white with brown speckles on them. At hatching, young weigh 0.4 to 1.25 g and will fledge at 9 to 11 days old. Until they are able to leave the nest, both parents equally feed them and keep them protected. The male is the protector of the nest, guarding the territory. By the time they depart their breeding locations in July, the young are fully independent. These warblers typically reach the age of maturity at age 1. Nashville warblers rarely will re-nest in a season, but they return annually same breeding site. (Baicich and Harrison, 2005; Lawrence, 1948; Pearson, et al., 1936; Reed, 1965)
Female Nashville warblers build the nest, which takes between 3 to 5 days. After the eggs are laid, females stay in the nest during the incubation period while the males feed them. The males will hover around the nest and will sing to keep it protected. Both sexes equally contribute to feeding the hatchlings. Less often, males show little to no effort to help feeding the young. The food source is found from the ground near the nest or the lower parts of nearby trees. The females stay with the hatchlings until they are able to fledge, which is around 9 to 11 days after hatching. Even after fledging, females continue feeding the young. Once the young reaches their mature age, usually 1 year old, they will begin breeding in their parents' breeding territory. (Baicich and Harrison, 2005; Birdlife International, 2016; Johnson, 1976; Knapton, 1984)
The longest recorded lifespan of a wild Nashville warbler was 10 years and 2 months. There were banded warblers that lived a little over 7.3 years when found dead. These birds are rarely studied in captivity and there is no known captive lifespan. (Budovsky, et al., 2013)
Nashville warblers forage diurnally, typically finding insects on branches and leaves. While foraging, they may flick their tails. Males typically sing at the tops of trees, usually bare trees.
In the breeding season, females are solely responsible for building the nest, which is concealed under foliage on the ground. When approached by a threat (e.g., humans), Lawrence (1948) reported a female faking a broken wing to draw the threat away from the nest. The female repeated this fake wing injury when her young were being banded by researchers.
Females incubate the eggs and their male partners feed them. Once the young hatch, both sexes euqally feed the young. There are some exceptions of males not feeding the young. Throughout the breeding season, they defend the nest - moreso after the chicks hatch. Females tend to be more aggressive and active protectors than males.
While the Nashville warblers travel to wintering grounds, they move in multispecies flocks (up to 20 species) in groups up to 100. At their wintering grounds, they are seen to be more active with each other and their singing. While in their breeding grounds, the males are territorial. They will form mixed-species flocks while at the wintering grounds. (Baicich and Harrison, 2005; Lawrence, 1948; Lowther and Williams, 2020; Pearson, et al., 1936)
Home ranges have been reported by Lowther and Williams (2020) as large as 1.1 ha in New Hampshire to 0.5 ha in an unreported location.
Lawrence (1948) briefly mentioned that a single Nashville warbler pair's territory was 0.4046 ha, or 4046 square meters. She described it as oval-shaped and including mainly forested areas. (Baicich and Harrison, 2005; Lawrence, 1948; Lowther and Williams, 2020)
Nashville warblers males produce songs that are two-parted with distinctive bell-like tones. The speed of their song is variable from slow to fast, and Lowther and Williams describes it as "see-bit see-bit see-bit see-bit ti-ti-ti-ti-ti-ti." The Nashville warblers are only singing the first half of their song during their spring migration period which is usually sung slowly. Some recent examples of this were documented in the Sierra Nevada Mountains in California and in the northeastern United States. Their flight song is similar to a standard song and is typically heard when they begin or end a flight. During the breeding seasons, both western and eastern populations were heard. The birds do not sing as much during incubation with their young in their nest. Once the young leaves the nest the singing begins to increase again. Their songs are similar to that of a Tennessee warbler (Leiothlypis peregrina) due to the closeness in the syllables.
Nashville warblers communicate through tactile and visual cues during the breeding season, with males feeding females on the nest and both parents feeding the young. Like all passerine birds, they can see in color. (Lowther and Williams, 2020)
Nashville warblers are insectivores, eating lepidopterans, flies, grasshoppers, locusts, and lice. They will capture their prey by gleaning or by hovering. However, during their breeding season, Nashville warblers will also feed on nectar and vegetation such as flowers on trees, parts of leaves, and twigs. They will feed on the nectar in their wintering grounds. They have been observed feeding on tubular blossoms of an Erythrina subumbrans tree while in Mexico and on a native plum (Prunus) in Minnesota. During spring, these warblers will nectar-feed when insects are scarce.
Knapton (1984) completed a diet study and found that male and female adults have 94% dietary overlap. Lepidopterans (butterflies and moths) comprised 88-90% of the diet by sex, and average prey size was 2.5 cm. The remaining 10-12% was comprised of spiders, beetles, and flies. Feeding of young was concentrated crepuscularly - early in the morning and again early in the evening. (Knapton, 1984; Lowther and Williams, 2020; Peter, 2008)
Little is known about the predation of Nashville warblers. Common predators for other warblers include snakes, foxes, and raptors. Blue Jays (Cynaocitta cristata), gray squirrels (Sciurus carolinensis), and red squirrels (Tamiasciurus hudsonicus) are suspected predators for Nashville warblers as they were seen in warbler nesting areas. (Lowther and Williams, 2020)
Ptilonyssus sairae are nasal mites that are found in one out of three Nashville warblers. Coccidia are apicomplexan parasites found in their intestinal tracts, occurring in up to 5% of tested warblers.
Another type of parasite is a nest parasite, brown-headed cowbirds (Molothrus ater). Brown-headed cowbirds will lay their eggs in the warblers’ nests and the adult Nashville warblers will raise them as their own. Cowbirds are known to reduce the survival of the young warblers. Lawrence (1948) described a situation where a single cowbird egg was laid in a Nashville warbler nest. Although the female used her bill to move the cowbird egg around, she did not remove it. Parents did feed the cowbird hatchling. (Lawrence, 1948; Spicer, 1987; Swayne, et al., 1991)
Birdwatching is a known positive economic effect of Nashville warblers in their migratory locations. They are known for their songs and they continue to sing while migrating. (Lowther and Williams, 2020)
There are no known negative economic effects of Nashville warblers on humans.
Nashville warblers are listed as a species of "Least Concern" on the IUCN Red List. They are listed as "protected" under the US Migratory Bird Act. This protection means they cannot be hunted, sold, taken, or otherwise killed. These warblers have no species status under CITES or the state of Michigan list.
Threats in the western United States include modification of riparian habitats and tree harvesting in tracts that these birds use. This habitat degradation may cause species decline. Declines also have been noted in the northeastern United States. Collisions with communications towers and with windows also have been documented in multiple studies. As is the case with many bird species, juveniles are more likely the victims of such collisions than adults, by a factor of 4 to 1.
Nashville warblers benefit from current forest management strategies like the use of prescribed fire. They are quick to move into and breed in second-growth forests if conditions are suitable. Although habitat loss is occurring in their wintering grounds, surveys suggest these warblers are adaptable to urban and suburban garden areas. Breeding Bird Survey data over the last 4 decades suggest these warblers may be slightly increasing in number. Therefore, no additional conservation efforts are in place. (Birdlife International, 2016; Lowther and Williams, 2020; U.S. Fish & Wildlife Service, 2020)
Amanda Bowman (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
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.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
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.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
an animal that mainly eats meat
uses smells or other chemicals to communicate
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.
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.
fertilization takes place outside the female's body
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly plants or parts of plants.
An animal that eats mainly insects or spiders.
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).
makes seasonal movements between breeding and wintering grounds
Having one mate at a time.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats nectar from flowers
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
Living on the ground.
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
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
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