Dendroica discolor

Geographic Range

Prairie warblers ( Dendroica discolor ) have a wide range across North and Central America. The native breeding range of one prairie warbler subspecies, Dendroica discolor discolor , covers the eastern United States. Populations can be found from Georgia, west to northeastern Texas in the south, and to New York, Massachusetts, and southern Ontario in the north. Several isolated populations are located in Michigan, Iowa, and Kansas. This distribution is uneven, and as much as 96 percent of the prairie warbler population is estimated to breed in the southeastern United States. In winter, prairie warblers migrate to southern Florida and Caribbean islands in the Greater Antilles and the Bahamas. A smaller population is known to winter on the eastern coast of southern Mexico, going south through Honduras. Another subspecies, Dendroica discolor paludicola , has resident populations restricted to coastal Florida.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native

Habitat

During their summer breeding season, prairie warblers are found in pine forests, abandoned agricultural fields, the borders between forests and grasslands, and dune habitats. They are less common in denser forests. During winter, they live in desert washes, scrubs, pine forests, and mangroves. They are also found in citrus groves and coffee fields on some islands. This species is not generally found above 1220 m elevation. Florida prairie warblers ( D. d. paludicola ) are restricted to mangrove swamps year-round.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• scrub forest scrub forest

• Wetlands
• swamp swamp

• Other Habitat Features
• agricultural agricultural

Physical Description

Prairie warblers are small; they weigh between 6.4 and 8.8 g and are 11 cm long on average. Both sexes have yellow coloring on their faces and undersides, and olive coloring on their heads and backs. They often have chestnut streaks along their back as well. They have long white tail feathers and yellow wing-bars. Males have black markings on their faces, with notable semicircles below their eyes. Females are duller in comparison to males, with an olive color where males have black. Juvenile prairie warblers have duller pigmentation and weaker or absent markings on their body. Florida prairie warblers ( D. d. paludicola ) have less white on their tails. Prairie warblers are similar in appearance to other warbler species. Pine warblers ( Dendroica pinus ) are most similar, but pine warblers are bigger, have lighter markings, and do not have chestnut patches on their backs. Magnolia warblers ( Dendroica magnolia ) may be mistaken for juvenile prairie warblers, but magnolia warblers have gray heads and yellow rears.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• male more colorful

Reproduction

Every breeding season prairie warblers form mating pairs. After they migrate north, males establish territories and sing to attract females. Encounters between males and females may result in sexual chases, where males attempt to catch and pull the tail feathers of females. Female will either escape, or drive off males after 2 to 6 seconds of tail pulling. Males are always rejected at this stage. Alternatively, males will perform display flights during encounters with females. A behavior known as "pounce-on-female" is similar to a sexual chase, but ends with females turning around towards males, and entering a defensive posture. Males will then either leave or attempt to sing to otherwise entice females before leaving. This behavior becomes more common two or more days after pairs first meet. According to Nolan (1978), it is difficult to tell whether a pair will stay together until egg laying occurs, and females may abandon males even during nest construction.

• Mating System
• monogamous monogamous

Prairie warblers will breed up to two times per year. Their primary breeding season begins from April to May and ends between June and July. A second breeding attempt may occur in June or July and end in August. This happens if the first breeding event occurs early enough in the season, or if it fails. Females have an average clutch size of 4 eggs, which hatch an average of 12 days after being laid. Hatchlings weigh between 0.8 and 1.4 g at birth. Hatchlings fledge an average of 9 days after birth, after which they begin to leave the nest. Over the next 40 days, on average, fledglings stay with their parents, who provide them with food. Fledglings begin to forage for themselves after about 10 days and are able to fly and fully care for themselves after about 24 days. In total, fledglings become independent 34 to 55 days after they are born. Prairie warblers become sexually mature at approximately a year old. Female prairie warblers build a nest consisting of an outer layer of plant bark, a padding layer made of feathers, fur or soft plant seeds, and a lining made of grass, fur, feathers and/or ferns. Nests have an average outer diameter of 60 mm, with a 42 mm average inner diameter. Nests are sometimes reused by different females in subsequent years.

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

Paired prairie warblers help raise their young until they are independent – around 40 days after hatching. Females incubate the eggs while males forage for themselves and their mates. After eggs hatch, females spend time foraging instead of incubating. Newborn prairie warblers are unable to feed or care for themselves, so parents care for their young until they leave the nest. Once juveniles are independent, they often leave by themselves, but sometimes will be driven away by their parents.

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

Lifespan/Longevity

Little information is known about the lifespan of prairie warblers. The oldest-recorded bird was 10.3 years old. Survivorship and lifespan estimates are complicated by their migratory nature. No average lifespan data, either in the wild or captivity, is available as of 2015.

Behavior

Prairie warblers primarily travel by flying, but will hop when they need to move short distances along the ground. Prairie warblers are not usually social outside of breeding season, and generally hunt on their own. Males often engage in territorial fights, and will chase other males out of their territory. Males also fly into the territories of other males until chased out. Some fights may attract males and females from the surrounding area. Prairie warblers are active during the day and twilight, and sleep at night. They forage most intensely around dusk, but they hunt throughout the day. Tail-bobbing, preening, and bathing are commonly observed behaviors for this species.

• Key Behaviors
• arboreal arboreal
• flies
• diurnal diurnal
• motile motile
• migratory migratory
• territorial territorial

Home Range

During their breeding season, prairie warblers have territories averaging 15.6 square km. Territory sizes depend on local population density. Prairie warblers have been recorded with territory sizes as small as 2.4 square km and as large as 35 square km. Male prairie warblers claim territory as they arrive to breeding grounds after spring migration. They sing to establish the boundaries of their territories, and chase away male rivals in their territory. Males attempt to reclaim their territory from previous breeding seasons, and try to displace any rivals already present. Insufficient evidence exists on whether prairie warblers are territorial outside of breeding season.

Communication and Perception

Prairie warblers forage using sight. They also communicate to each other using songs, calls, and visual displays. Males have specific songs and calls for mate attraction and others for general social interactions, such as territorial conflicts. Songs are usually made up of 4 to 20 notes, while calls are usually one note. Prairie warblers use calls to establish contact between birds or warn of nearby predators. Female prairie warblers have been only rarely observed to sing. Males perform special display flights as part of their mating display. Both sexes give specific displays if threatened, crouching rigidly and facing the threat directly. Males also perform submissive displays, such as turning away from other males.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Prairie warblers are primarily insectivorous, eating a variety of arthropods. Less-frequently, they eat gastropods, seeds, and fruit. Prairie warblers hunt in a variety of locations within their habitats. They will feed on the ground, perched on tree trunks, or in the treetops. They are most commonly observed foraging on tree branches and fly-catching.

Stomach content tests on prairie warblers in their breeding range found that the animal matter in their stomachs consisted of 42% beetles ( Coleoptera ), 29% moths or butterflies ( Lepidoptera ), 8% flies ( Diptera ), 8% ants, wasps, or bees ( Hymenoptera ), 3% spiders ( Araneae ), 4% aphids or cicadas ( Homoptera ), and 1% other bug species ( Hemiptera ). There is less data available on their winter range diets, but present data suggest that they not change significantly from their summer range.

D. d. paludicola has the same general diet, but with a higher occurrence of spiders fewer beetles. Also, the prey species eaten by this subspecies of prairie warbler were more likely to be aquatic.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks

• Plant Foods
• seeds, grains, and nuts
• fruit

Predation

Prairie warblers are most at risk of predation before they hatch or while they are fledging. Adults are not generally subject to predation, although nesting females may be killed by nest predators. Frequent predators of nestlings and eggs include squirrel species ( Sciurus ), eastern chipmunks ( Tamias striatus ), raccoons ( Procyon lotor ), species of deer mouse ( Peromyscus ), and local snake species, such as mangrove water snakes ( Nerodia compressicauda ). Fledglings are also targeted by chipmunk species ( Tamias ) and snakes. Additional predators include red-winged blackbirds ( Agelaius phoeniceus ) and Norway rats ( Rattus norvegicus ).

Prairie warblers have behavioral adaptions to ward off predators. Adult birds sound alarm calls to warn nearby birds – especially fledglings – of predators. Groups of prairie warblers have been reported to mob snakes who get close to their nesting sites. Nesting prairie warblers also perform distraction displays at threatening animals. They do this by perching on branches away from their nests while performing a distracting display and making loud calls.

Ecosystem Roles

Prairie warblers hunt a variety of arthropod species. They serve as hosts for a variety of parasitic species, including northern fowl mites ( Ornithonyssus sylviarum ), harvest mites ( Trombicula ), rabbit ticks ( Haemaphysalis leporispalustris ), feather lice ( Menacanthus and Ricinus ), and scaly leg mites ( Knemidokoptes jamaicensis ). They also host unidentified nematode species.

Prairie warblers are also victims of brood parasitism from brown-headed cowbirds ( Molothrus ater ) and shiny cowbirds ( Molothrus bonariensis ). Up to 40% of prairie warbler nests may suffer from cowbird parasitism, with nests early in the breeding season having higher incidences of parasitism. Brown-headed cowbirds are a common source of nest failure in prairie warblers due to nest abandonment. Scaly leg mites ( Knemidokoptes jamaicensis ) have been linked to stress and muscle loss in warblers wintering in Jamaica. The prairie warbler subspecies D. d. paludicola is likely to suffer from brood parasitism in the future, as cowbirds (including shiny cowbirds) spread to southern Florida.

Economic Importance for Humans: Positive

As an insectivore, prairie warblers have been shown to help control agricultural pests. This was observed by Kellerman et al. (2008) in Jamaica, where prairie warbler presence was correlated with an increase in coffee production.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of prairie warblers on humans.

Conservation Status

Prairie warblers are considered a species of least concern on the IUCN red list and are not on the federal endangered species list. They are also not included in CITES appendices. Prairie warblers are protected under the U.S Migratory Bird Act. While they are currently experiencing population declines, these declines are not severe enough to warrant special status. Declines are due to natural succession of shrubby breeding habitats to unsuitable forested habitats. If steps are not taken to reduce the loss of breeding habitats, population declines will continue and prairie warblers may become a threatened species. Some regional populations are at immediate risk, and they are listed as endangered by the state of Michigan.

Additional Links

Encyclopedia of Life

Contributors

Brian Pratt (author), Radford University - Fall 2015, 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, Galen Burrell (editor), Special Projects.

References

Buerkle, C. 2000. Morphological variation among migratory and nonmigratory populations of prairie warblers. The Wilson Bulletin , 112/1: 99-107.

Faaborg, J., S. Latta. 2001. Winter site fidelity of prairie warblers in the Dominican Republic. The Condor , 103/3: 455-468.

Jackson, W., S. Rohwer. 1989. Within-season breeding dispersal in prairie warblers and other passerines. The Condor , 91/2: 233-241.

Kellermann, J., M. Johnson, A. Stercho, S. Hackett. 2008. Ecological and economic services provided by birds on Jamaican blue mountain coffee farms. Conservation Ecology , 22/5: 1177-1186.

Klimkiewicz, K., C. Klimkiewicz, A. Futcher. 1983. Longevity records of North American birds: Remizidae through Parulinae. Journal of Field Ornithology , 54/3: 293.

Latta, S. 2003. Effects of scaley-leg mite infestations on body condition and site fidelity of migratory warblers in the Dominican Republic. The Auk , 120/3: 730-743.

Morse, D. 1989. American Warblers: An Ecological and Behavioral Perspective . Cambridge, Massachusetts: Harvard University Press.

Nolan, V. 1978. The ecology and behavior of the prairie warbler, Dendroica discolor. Ornithological Monographs , 1/26: 1-595.

Nolan Jr., V., E. Ketterson, C. Buerkle. 2014. "Prairie warbler (Setophaga discolor)" (On-line). Birds of North America (on-line). Accessed September 23, 2015 at http://bna.birds.cornell.edu/bna/species/455/articles/ .

Pease, C., J. Grzybowski. 1995. Assessing the consequences of brood parasitism and nest predation on seasonal fecundity in passerine birds. The Auk , 112/2: 343-363.

Prather, J., A. Cruz. 1995. Breeding biology of Florida prairie warblers and Cuban yellow warblers. Wilson Bulletin , 107/3: 475-484.

Stephenson, T., S. Whittle. 2013. The Warbler Guide . Princeton, NJ: Princeton University Press.

Wells, J. 2007. Birder's Conservation Handbook . Princeton, NJ: Princeton University Press.

BirdLife International. 2012. "Dendroica discolor. The IUCN Red List of Threatened Species 2012 e.T22721725A39850788" (On-line). Accessed September 11, 2015 at http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T22721725A39850788.en .