Yellow Warbler
Encyclopedia
Dendroica petechia is a New World warbler
New World warbler
The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 or superspecies
Superspecies
A superspecies is a group of at least two more or less distinctive species with approximately parapatric distributions. Not all species complexes, whether cryptices or ring species are superspecies, and vice versa, but many are...

; the subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 group around D. (p.) aestiva is increasingly treated as good species Dendroica aestiva (Yellow Warbler) again. The name for the entire cryptic species complex
Cryptic species complex
In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each other—but whose morphology is very similar ....

 is Mangrove Warbler, and another group of subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 is known as Golden Warbler. Sensu lato, they make up the most widespread Dendroica
Dendroica
Dendroica is a genus of birds of the New World Warbler family Parulidae. It contains 29 species. The males in breeding plumage are often highly colorful...

 species, breeding in almost the whole of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and down to northern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

.

Description and taxonomy

Other than in male breeding plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

, all subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 are very similar. Winter, female and immature birds all have similarly greenish-yellow uppersides and are a duller yellow below. Young males soon acquire breast and, where appropriate, head coloration. Females are somewhat duller, most notably on the head. In all, the remiges
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

 and rectrices
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

 are blackish olive with yellow edges, sometimes appearing as an indistinct wing-band on the former. The eyes and the short thin beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

 are dark, while the feet are lighter or darker olive-buff
Buff (colour)
Buff is a pale yellow-brown colour that got its name from the colour of buff leather.Displayed on the right is the colour buff.EtymologyAccording to the Oxford English Dictionary, buff as a descriptor of a colour was first used in the London Gazette of 1686, describing a uniform to be "A Red Coat...

.

The 35 subspecies of D. petechia sensu lato can be divided into three main groups according to the males' head color in the breeding season. Each of these groups is sometimes considered a separate species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, or the aestiva group (Yellow Warbler) is considered a species different from D. petechia (Mangrove Warbler, including Golden Warbler); the latter option is the one currently accepted by the International Ornithological Congress
International Ornithological Congress
The International Ornithological Congress series forms the oldest and largest international series of meetings of ornithologists. It is organised by the International Ornithological Committee, a group of about 200 ornithologists...

 World Bird List.

The Golden Warbler (petechia group; 17 subspecies) is generally resident in the mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 swamps of the West Indies. Local seasonal migrations may occur. On the Cayman Islands
Cayman Islands
The Cayman Islands is a British Overseas Territory and overseas territory of the European Union located in the western Caribbean Sea. The territory comprises the three islands of Grand Cayman, Cayman Brac, and Little Cayman, located south of Cuba and northwest of Jamaica...

 for example, D. p. eoa was found to be "decidedly scarce" on Grand Cayman
Grand Cayman
Grand Cayman is the largest of the three Cayman Islands and the location of the nation's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles southwest of Little Cayman and 90 miles southwest of Cayman Brac.-Geography:Grand Cayman encompasses 76% of...

 and apparently absent from Cayman Brac
Cayman Brac
Cayman Brac is an island that is part of the Cayman Islands. It lies in the Caribbean Sea about 90 miles northeast of Grand Cayman and 5 miles east of Little Cayman. It is about 12 miles long, with an average width of 1 mile...

 in November 1979, while it had been a "very common" breeder in the group some 10 years before, and not frequently seen in the winters of 1972/1973; apparently, the birds disperse elsewhere outside the breeding season. The Cuban Golden Warbler (D. p. gundlachi) barely reaches the Florida Keys
Florida Keys
The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...

 where it was first noted in 1941, and by the mid-20th century a breeding population was resident. Though individual birds may stray farther north, their distribution is restricted by the absence of mangrove habitat.

They are generally smallish, usually weighing about 10 g (0.35273962105112 oz) or less and sometimes as little as 6.5 g (0.229280753683228 oz). The summer males differs from those of the Yellow Warbler in that they have a rufous crown, hood or mask. The races in this group vary in the extent and hue of the head patch.

The Mangrove Warbler (erithachorides group; 12 subspecies) measures 12.5 cm (4.9 in)and weighs 11 g (0.388013583156232 oz) on average. It is resident in the mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 swamps of coastal Middle America and northern South America; D. p. aureola is found on the oceanic Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

. The summer males differ from those of the Yellow Warbler in that they have a rufous hood or crown. The races in this group vary in the extent and hue of the hood, overlapping extensively with the Golden Warbler group in this character.

The Yellow Warbler (aestiva group; 6 subspecies breeds in the whole of temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 as far south as central Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 in open, often wet, woods or shrub. It is migratory
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...

, wintering in Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and South America. They are very rare vagrants to western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

.

Depending on subspecies, it may be between 10–18 cm (3.9–7.1 in) long, with an average wingspan of about 20 cm (7.9 in). They weigh 7–25 g (0.246917734735784–0.881849052627799 oz), varying between subspecies and whether on migration or not, globally averaging about 16 g (0.564383393681791 oz) but only 9–10 g (0.317465658946008–0.35273962105112 oz) in most breeding adults of the United States populations. The summer males of this group are generally the yellowest "warbler
Warbler
There are a number of Passeriformes called "warblers". They are not particularly closely related, but share some characteristics, such as being fairly small, vocal and insectivorous....

s" wherever they occur. They are brilliant yellow below and golden-green above. There are usually a few wide washed-out rusty-red streaks on the breast and flanks. The various subspecies in this group mostly in brightness and size as per Bergmann's
Bergmann's Rule
Bergmann's rule is an ecogeographic principle that states that within a broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been...

 and Gloger's Rule
Gloger's rule
Gloger's Rule is a zoological rule which states that within a species of endotherms, more heavily pigmented forms tend to be found in more humid environments, e.g. near the equator. It was named after the zoologist Constantin Wilhelm Lambert Gloger, who first remarked upon this phenomenon in 1833...

.

Vocalizations

The song is a musical strophe that can be rendered sweet sweet sweet, I'm so sweet, although it varies considerably between population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...

s. The call is a soft or harder chip or ship. This is particularly frequently given by females after a male has finishing his song. In territorial defence, they give hissing calls, while seet seems to be a kind of specialized cowbird
Cowbird
Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are brood parasitic New World birds which are unrelated to the Old World cuckoos, one of which, the Common Cuckoo, is the best-known brood parasitic bird....

 alert (see below). Other calls are given in communication between pair-members, neighbors, or by young begging for food. These birds also communicate with postures and perhaps with touch.

Ecology

Yellow Warblers breed in most of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 from the tundra
Tundra
In physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine...

 southwards, but they do not range far southwestwards and avoid the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

 coasts also. The Mangrove and Golden Warblers occur to the south of it, to the northern reaches of the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

. Yellow Warblers winter to the south of their breeding range, from southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 to the Amazon
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

 region, Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

 and Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

.

Yellow Warblers arrive in their breeding range in late spring – generally about April/May – and move to winter quarters again starting as early as July, as soon as the young are fledged. Most, however, stay a bit longer; by the end of August, the bulk of the northern populations has moved south, though some may linger almost until fall. At least in northern Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

, Yellow Warblers do not seem to remain on their breeding grounds longer than they did 100 years ago.

The breeding habitat of Yellow Warblers is typically riparian or otherwise moist land with ample growth of small trees, in particular willow
Willow
Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...

s (Salix). The other groups, as well as wintering birds, chiefly inhabit mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 swamps and similar dense woody growth. Less preferred habitat are shrubland
Shrubland
Shrubland, scrubland, scrub or brush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity...

, farmland
Arable land
In geography and agriculture, arable land is land that can be used for growing crops. It includes all land under temporary crops , temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow...

s and forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

 edges. In particular Yellow Warblers will come to suburb
Suburb
The word suburb mostly refers to a residential area, either existing as part of a city or as a separate residential community within commuting distance of a city . Some suburbs have a degree of administrative autonomy, and most have lower population density than inner city neighborhoods...

an or less densely settled areas, orchard
Orchard
An orchard is an intentional planting of trees or shrubs that is maintained for food production. Orchards comprise fruit or nut-producing trees which are grown for commercial production. Orchards are also sometimes a feature of large gardens, where they serve an aesthetic as well as a productive...

s and parks, and may well breed there. Outside the breeding season, these warblers are usually encountered in small groups, but while breeding they are fiercely territorial and will try to chase away any conspecific intruder that comes along.

These birds feed mainly on arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...

s, in particular 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. They acquire prey by gleaning
Gleaning (birds)
Gleaning is a term for a feeding strategy by birds in which they catch invertebrate prey, mainly arthropods, by plucking them from foliage or the ground, from crevices such as rock faces and under the eaves of houses, or even, as in the case of ticks and lice, from living animals. This behavior is...

 in shrubs and on tree branches, and by hawking
Hawking (birds)
Hawking is a feeding strategy in birds involving catching flying insects in the air. The term usually refers to a technique of sallying out from a perch to snatch an insect and then returning to the same or a different perch...

 prey that tries to fly away. Other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s and some berries and similar small juicy fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

s are also eaten, the latter especially by Yellow Warblers in their winter quarters. Caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...

s are the staple food for nestlings, with some – e.g. those of geometer moths (Geometridae) – preferred over others.

The predators of Yellow and Mangrove Warblers are those typical of such smallish tree-nesting passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

s. The odds of an adult Yellow Warbler to survive from one year to the next are on average 50%; in the southern populations, by contrast, about two-thirds of the adults survive each year. Conversely, less than one Yellow Warbler nest in three on average suffers from predation in one way or another, while two out of three Mangrove and Golden Warbler nests are affected.

Snakes, corvids and large climbing rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s are significant nest predators. Carnivores
Carnivora
The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...

, in particular Musteloidea
Musteloidea
Musteloidea is a superfamily of carnivoran mammals united by shared characters of the skull and teeth. Musteloids share a common ancestor with the pinnipeds, the group which includes seals....

 as well as the Red Fox
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...

 (Vulpes vulpes) and domestic or feral cat
Feral cat
A feral cat is a descendant of a domesticated cat that has returned to the wild. It is distinguished from a stray cat, which is a pet cat that has been lost or abandoned, while feral cats are born in the wild; the offspring of a stray cat can be considered feral if born in the wild.In many parts of...

s, prey on nestlings and fledglings as well as sick or distracted adults. These predators pose little threat to the nimble, non-nesting adults, but certain smallish and agile birds of prey do, especially the American Kestrel
American Kestrel
The American Kestrel , sometimes colloquially known as the Sparrow Hawk, is a small falcon, and the only kestrel found in the Americas. It is the most common falcon in North America, and is found in a wide variety of habitats. At long, it is also the smallest falcon in North America...

 (Falco sparverius) and Cooper's Hawk
Cooper's Hawk
Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...

 (Accipiter cooperii), and the Sharp-shinned Hawk
Sharp-shinned Hawk
The Sharp-shinned Hawk is a small hawk. In fact, "sharp-shins" or "sharpies" are the smallest to reside in USA and Canada, though some Neotropical species are smaller...

 (A. striatus) and screech owls (Megascops).

These New World warblers seem to mob predators only rarely. An exception are cowbird
Cowbird
Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are brood parasitic New World birds which are unrelated to the Old World cuckoos, one of which, the Common Cuckoo, is the best-known brood parasitic bird....

s, which are significant brood parasite
Brood parasite
Brood parasites are organisms that use the strategy of brood parasitism, a kind of kleptoparasitism found among birds, fish or insects, involving the manipulation and use of host individuals either of the same or different species to raise the young of the brood-parasite...

s. The Yellow Warbler is a regular host of the Brown-headed Cowbird
Brown-headed Cowbird
The Brown-headed Cowbird is a small brood parasitic icterid of temperate to subtropical North America. They are permanent residents in the southern parts of their range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or...

 (Molothrus ater), with about 40% of all nests suffering attempted or successful parasitism. By contrast, the tropical populations are host to the Shiny Cowbird
Shiny Cowbird
The Shiny Cowbird, Molothrus bonariensis, is a passerine bird in the New World family Icteridae. It breeds in most of South America apart from the most dense jungles, mountains and deserts , the coldest southernmost regions , and on Trinidad and Tobago...

 (M. bonariensis), but less than one nest in 10 is affected. Upon recognizing a cowbird egg in its nest, the warbler will often smother it with a new layer of nesting material. It will usually not try to save any own eggs that have already been laid, but produce a replacement clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...

. Sometimes, the parents desert a parasitized nest altogether and build a new one. Unlike some cuckoo
Cuckoo
The cuckoos are a family, Cuculidae, of near passerine birds. The order Cuculiformes, in addition to the cuckoos, also includes the turacos . Some zoologists and taxonomists have also included the unique Hoatzin in the Cuculiformes, but its taxonomy remains in dispute...

s, cowbird nestlings will not actively kill the nestlings of the host bird; mixed broods of Dendroica and Molothrus may fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...

 successfully.

Other than due to predation, mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 reasons are not well known. The maximum recorded ages of wild Yellow Warblers are around 10 years. A wintering Yellow Warbler examined near Turbo, Colombia
Turbo, Colombia
Turbo is a port town in Antioquia Department, Colombia. It is located at around . It is located on the coast of Gulf of Urabá, 340 km. north from Medellín...

 was not infected with blood parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

s, unlike other species in the study. It is unclear whether this significant, but wintering birds in that region generally lacked such parasites.

Breeding

As usual for New World warblers (Parulidae), they nest in trees, building a small but very sturdy cup nest. Females and males share the reproductive work about equally, but emphasize different tasks: females are more involved with building and maintaining the nest, and incubating and brooding the offspring. Most of the actual feeding is also done by them. Males are more involved in guarding the nest site and procuring food, bringing it to the nest and passing it to the waiting mother. As the young approach fledging, the male's workload becomes proportionally higher.

The Yellow and Mangrove (including Golden) Warblers differ in some other reproductive parameters. While the former is somewhat more of an r-strategist, the actual differences are complex and adapted
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

 to different environmental conditions. The Yellow Warbler starts breeding in May/June, while the Mangrove Warbler can be found breeding all year round. Yellow Warblers have been known to raise a brood of young in as little as 45 days, but usually take about 75 days. The tropical populations, by contrast, need more than 100 days per breeding. Males court the females with songs; a Yellow Warbler has been observed to sing more than 3,200 songs in one day. They are, like most songbird
Songbird
A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...

s, generally serially monogamous; some 10% of Mangrove Warbler and about half as many Yellow Warbler males are bigamous. Very few if any Yellow Warblers breed more than once per year; around one in twenty Mangrove Warbler females will do so however. If a breeding attempt fails, either will usually try and raise a second brood successfully though.

The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...

 of the Yellow Warbler is 3–6 (typically 4–5, rarely 1–2) eggs. Incubation
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 to hatching usually takes 11 days, but may take up to two weeks. The nestlings weigh 1.3 g (0.0458561507366456 oz) on average, and are brooded for an average 8–9 days after hatching, and leave the nest the following day or the one thereafter. Mangrove Warblers, on the other hand, have only 3 eggs per clutch on average and incubate some 2 days longer. Its average post-hatching brooding time is 11 days. Almost half of the parents (somewhat more in the Mangrove Warbler, somewhat less in the Yellow Warbler) attend the fledglings for some time after these leave the nest. This post-fledging care can extend for two additional weeks or more, and sometimes the pairs separate early, each accompanied by one to three of the young.

Some 3–4 weeks after hatching, the young are fully independent of their parents. They become sexually mature at one year of age, and attempt to breed right away. Only about one in four Mangrove Warbler nests successfully fledge any offspring, due to accidents and predation frequently causing total loss of the clutch. By contrast, 55% of all Yellow Warbler nestings are successful in raising at least one young.

Status and conservation

To humans, these birds are quite beneficial. For one thing, in particular the young devour many pest 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 during the breeding season. For another, the plumage and song of the breeding males have been described as "lovely" and "musical", and they can help to generate revenue from ecotourism
Ecotourism
Ecotourism is a form of tourism visiting fragile, pristine, and usually protected areas, intended as a low impact and often small scale alternative to standard commercial tourism...

. Adult Yellow Warblers are significant dispersers of plants via the ingested seeds, though this may of course spread any invasive weed whose fruits they find tasty. No significant negative effects of Yellow and Mangrove Warblers on humans have been recorded though.

These birds are generally common and occur over a wide range; consequently, the IUCN does not consider them a threatened species
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

. A local decline in numbers has been noted here and there. This is generally due to habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

, mainly by land clearance and herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

 and pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

 overuse of agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

, and sometimes overgrazing
Overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.Overgrazing reduces the...

. However, especially Yellow Warblers are prolific, and the stocks will usually rebound quickly if riparian habitat is allowed to recover.

The North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n populations are legally protected by the Migratory Bird Treaty Act. The Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...

 Golden Warbler (D. p. petechia) is listed as "Endangered Foreign Wildlife" by the United States' Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

 (ESA) since 1970; other than for scientific, educational or conservation purposes (for which a permit may be available) importing it into the USA is illegal. The Californian Yellow Warbler (D. p./a. brewsteri) and Sonoran Yellow Warbler (D.p./a. sonorana) are listed as "Species of Concern" by the ESA.

The Yellow Warbler is sometimes colloquially called the "Summer Yellowbird".

Further reading

  • Snow, D.W. (1966). '"Annual cycle of the Yellow Warbler in the Galapagos." J. Field Ornithology 37(1)

External links

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