Animal Diversity Web

Ge­o­graphic Range

Nashville war­blers, Ver­mivora ru­f­i­capilla, 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)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

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)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• scrub forest
• mountains

• Wetlands
• bog

• Other Habitat Features
• suburban
• riparian

• Range elevation

  0 to 2184 m

  0.00 to 7165.35 ft

Phys­i­cal De­scrip­tion

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)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male more colorful

• Range mass

  6.7 to 13.9 g

  0.24 to 0.49 oz

• Average mass

  10 g

  0.35 oz

• Average length

  12 cm

  4.72 in

Re­pro­duc­tion

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)

• Mating System
• monogamous

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)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• oviparous

• Breeding interval

  Nashville warblers breed once yearly.

• Breeding season

  April through May.

• Range eggs per season

  4 to 5

• Range time to hatching

  11 to 12 days

• Range fledging age

  9 to 11 days

• Average age at sexual or reproductive maturity (female)

  1 years

• Average age at sexual or reproductive maturity (male)

  1 years

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)

• Parental Investment
• altricial
• female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • male
    • female

Lifes­pan/Longevity

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)

• Range lifespan
  Status: wild

  7.3 to 10.2 years

Be­hav­ior

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)

• Key Behaviors
• terricolous
• flies
• diurnal
• motile
• migratory
• territorial
• social

• Average territory size

  4046 m^2

Home Range

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)

Com­mu­ni­ca­tion and Per­cep­tion

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)

• Communication Channels
• visual
• tactile
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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)

• Primary Diet
• carnivore
  • insectivore
• herbivore
  • nectarivore

• Animal Foods
• insects

• Plant Foods
• leaves
• wood, bark, or stems
• nectar
• flowers

Pre­da­tion

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)

Ecosys­tem Roles

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)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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)

• Positive Impacts
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive eco­nomic ef­fects of Nashville war­blers on hu­mans.

Con­ser­va­tion Sta­tus

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)

• IUCN Red List

  Least Concern

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Amanda Bow­man (au­thor), Rad­ford Uni­ver­sity, Logan Platt (ed­i­tor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor), Rad­ford Uni­ver­sity, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Baicich, P., C. Har­ri­son. 2005. Nests, Eggs, and Nestlings of North Amer­i­can Birds. Prince­ton, New Jer­sey: Prince­ton Uni­ver­sity Press.

Birdlife In­ter­na­tional, 2016. "Leio­th­lypis ru­f­i­capilla" (On-line). The IUCN Red List of Threat­ened Species 2016: e.T22721627A94718463. Ac­cessed Feb­ru­ary 02, 2021 at https://​dx.​doi.​org/​10.​2305/​IUCN.​UK.​2016-3.​RLTS.​T22721627A94718463.​en.

Bo­real Song­bird Ini­tia­tive, 2015. "Bo­real Song­bird Ini­tia­tive" (On-line). Nashville War­bler. Ac­cessed March 12, 2021 at https://​www.​borealbirds.​org/​bird/​nashville-warbler.

Bu­dovsky, A., T. Craig, J. Wang, R. Tacutu, A. Csor­das, J. Lourenco, V. Fraifeld, J. de Ma­g­a­l­haes. 2013. "Longevi­tyMap: A data­base of human ge­netic vari­ants as­so­ci­ated with longevity" (On-line). Trends in Ge­net­ics 29:559-560. Ac­cessed March 23, 2021 at https://​genomics.​senescence.​info/​species/​entry.​php?​species=Leiothlypis_​ruficapilla.

Farnsworth, A. 2007. Flight calls of wood-war­blers are not ex­clu­sively as­so­ci­ated with mi­gra­tory be­hav­iors. The Wil­son Jour­nal of Or­nithol­ogy, 119/3: 334-341.

Hamel, P. 1992. Land Man­ager's Guide to the Birds of the South. Chapel Hill, North Car­olina: The Na­ture Con­ser­vancy.

Janes, S., L. Ryker. 2016. Nashville war­blers use a sin­gle song type in south­west­ern Ore­gon with widely dis­trib­uted song vari­ants. The Wil­son Jour­nal of Or­nithol­ogy, 128/2: 412-418.

John­son, N. 1976. Breed­ing dis­tri­b­u­tion of Nashville and Vir­ginia's war­blers. The Auk, 93/2: 219-230.

Kelly, J. 2006. Sta­ble iso­tope ev­i­dence links breed­ing ge­og­ra­phy and mi­gra­tion tim­ing in wood war­blers. The Auk, 123/2: 431-437.

Kelly, J., R. Hutto. 2005. The east-west com­par­i­son of mi­gra­tion in north Amer­i­can wood war­blers. The Con­dor, 107/2: 197-211.

Knap­ton, R. 1984. Parental feed­ing of nestling Nashville war­blers: The ef­fects of food type, brood-size, nestling age, and time of day. Wil­son Bul­letin, 96/4: 594-602.

Lawrence, L. 1948. Com­par­a­tive study of the nest­ing be­hav­ior of chest­nut-sided and Nashville war­blers. The Auk, 65/2: 204-219.

Lowther, P., J. Williams. 2020. "Nashville War­bler (Leio­th­lypis ru­f­i­capilla), ver­sion 1.0." (On-line). In Birds of the World (A. F. Poole, Ed­i­tor). Cor­nell Lab of Or­nithol­ogy, Ithaca, NY, USA. Ac­cessed Feb­ru­ary 01, 2021 at https://​doi.​org/​10.​2173/​bow.​naswar.​01.

Pear­son, T., J. Bur­roughs, E. For­bush, W. Fin­ley, G. Glad­den, H. Job, L. Nichols, J. Bur­dick. 1936. Birds of Amer­ica. Gar­den City, New York: Gar­den City Pub­lish­ing Com­pany.

Peter, J. 2008. Nec­tar-feed­ing by a Nashville war­bler. On­tario Birds, 26/1: 68-71.

Reed, C. 1965. North Amer­i­can Birds Eggs. New York, New York: Dover Pub­li­ca­tions.

Simp­son, R., M. John­son, T. Mur­phy. 2015. Mi­gra­tion and the evo­lu­tion of sex­ual dichro­ma­tism: Evo­lu­tion­ary loss of fe­male col­oration with mi­gra­tion among wood-war­blers. Pro­ceed­ings of the Royal So­ci­ety B Bi­o­log­i­cal Sci­ences, 282/1809: 282. Ac­cessed Feb­ru­ary 02, 2021 at http://​doi.​org/​10.​1098/​rspb.​2015.​0375.

Spicer, G. 1987. Preva­lence and Host-Par­a­site List of Some Nasal Mites from Birds (Acarine: Rhi­nonys­si­dae, Speleog­nathi­dae). The Jour­nal of Par­a­sitol­ogy, 73/2: 259-264. Ac­cessed March 23, 2021 at www.​jstor.​org/​stable/​3282076.

Swayne, D., D. Getzy, R. Sle­mons, L. Kramer. 1991. Coc­cidio­sis As A Cause of Trans­mural Lym­pho­cytic En­teri­tis and Mor­tal­ity in Cap­tive Nashville War­blers (Ver­mivora ru­f­i­capilla). Jour­nal of Wildlife DIs­eases, 27/4: 615-620. Ac­cessed March 23, 2021 at https://​doi.​org/​10.​7589/​0090-3558-27.​4.​615.

Toews, D. 2017. Habi­tat suit­abil­ity and the con­straints of mi­gra­tion in New World war­blers. Jour­nal of Avian Bi­ol­ogy, 48/12: 1-10.

U.S. Fish & Wildlife Ser­vice, 2020. "Mi­gra­tory Bird Treaty Act Pro­tected Species (10.13 List)" (On-line). Mi­gra­tory Bird Pro­gram. Ac­cessed April 15, 2021 at https://​www.​fws.​gov/​birds/​management/​managed-species/​migratory-bird-treaty-act-protected-species.​php.