Green heron
Template:Short description Template:Speciesbox The green heron (Butorides virescens) is a small heron of North and Central America. Butorides is from Middle English butor "bittern" and Ancient Greek -oides, "resembling", and virescens is Latin for "greenish".<ref name=job>Template:Cite book</ref>
It was long considered conspecific with its sister species the striated heron (Butorides striata), and together they were called "green-backed heron". Birds of the nominate subspecies (no matter which taxonomic arrangement is preferred) are extremely rare vagrants to western Europe—for example, a sighting in Pembrokeshire in 2018 was only the second recorded sighting in Wales;<ref>Template:Cite news</ref> individuals from the Pacific coast of North America may similarly stray as far as Hawaii.<ref name = HBW/><ref name=CLO/><ref name=ADW/>
DescriptionEdit
The green heron is relatively small; adult body length is about Template:Convert. The neck is often pulled in tight against the body. Adults have a glossy, greenish-black cap, a greenish back and wings that are grey-black grading into green or blue, a chestnut neck with a white line down the front, grey underparts and short yellow legs. The bill is dark with a long, sharp point.
Female adults tend to be smaller than males, and have duller and lighter plumage, particularly in the breeding season. Juveniles are duller, with the head sides, neck and underparts streaked brown and white, tan-splotched back and wing coverts, and greenish-yellow legs and bill. Hatchlings are covered in down feathers, light grey above, and white on the belly.<ref name = HBW/><ref name=CLO/><ref name=ADW/>
The green heron's call is a loud and sudden Template:Not a typo; it also makes a series of more subdued Template:Not a typo calls. During courtship, the male gives a Template:Not a typo call with wide-open bill, makes noisy wingbeats and Template:Not a typo calls in flight, and sometimes calls Template:Not a typo to the female before landing again. While sitting, an Template:Not a typo courtship call is also given.<ref name=CLO/><ref name=ADW/>
Measurements:<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
- Length: Template:Convert
- Weight: Template:Convert
- Wingspan: Template:Convert
TaxonomyEdit
As noted above, this species was formerly included in B. striata, which at that time was erroneously known as B. striatus. The Early Pleistocene B. validipes, whose fossil remains were discovered in Florida, might have been the ancestor of the green heron as the living species seems to replace the extinct relative in the fossil record.
Subspecies distinction is uncertain at best. The color variation between populations is less pronounced than between birds of the same population. Migratory populations are longer-winged than those resident year-round, but this cannot be used to delimit subspecies as it is quite obviously a consequence of differing habits and can be expected to undergo convergent evolution in unrelated populations of this species that just share the same habits. Thus, thorough molecular phylogenetic studies would be required to resolve the question of subspecies delimitation.
The following subspecies are commonly listed, though the validity of most of them is seriously disputed:<ref name = HBW/>
- Butorides virescens anthonyi (Mearns, 1895)
- Breeds in the United States west of the Rocky Mountains, south to northern Baja California Peninsula, Mexico. Some resident, most migrate to western Mexico in winter.
- Butorides virescens bahamensis (Brewster, 1888)
- Bahamas. Resident.
- Butorides virescens frazari (Brewster, 1888)
- Southern Baja California Peninsula, Mexico. Resident.
- Butorides virescens maculata (Boddaert, 1783)<ref name = "ITIS"/> – formerly maculatus
- Southernmost US through Central America to central Panama, Caribbean. Resident.
- Breeds from southeastern Canada to central and southern US east of the Rocky Mountains. Winters from southernmost US to northern South America.
Much of the dispute hinges upon the distinctness of the Caribbean and Central American populations, the second taxon in this species to be described. To describe the two most extreme views, some authors assemble the bulk of the mainland population in the nominate subspecies but treat the parapatric populations as distinct subspecies, while others place all resident populations in maculata and all migratory ones in virescens.
In Trinidad and Tobago and in central Panama, it overlaps slightly in range with the closely related striated heron and hybridizes with it; hybrids are intermediate between the two species, generally grayer below than typical green herons.<ref name="Tobago">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Panama">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
EcologyEdit
The habitat and foraging area of the green heron includes riparian zones, wetlands, ponds, and lakes, as well as human-made canals and ditches.<ref name="Moore-2016">Template:Cite journal</ref> Green herons do not exhibit a particular preference for diurnal or nocturnal foraging, often engaging in both.<ref name="Moore-2016" /> Shore-living individuals adapt to the rhythm of the tides.Template:Citation needed They mainly eat small fish, frogs and aquatic arthropods, but may take any invertebrate or vertebrate prey they can catch, including such animals like leeches, earthworms, dragonflies, damselflies, waterbugs, grasshoppers, spiders,<ref name="sta.uwi.edu">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> crayfish,<ref name="Butorides virescens Green heron">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> prawns,<ref name="sta.uwi.edu"/> mice, other rodents, lizards, tadpoles and snakes.<ref name="Butorides virescens Green heron"/> Some of the many fish eaten are: minnows, sunfish, catfish, perch, eels and, in urban areas, goldfish.<ref name="Butorides virescens Green heron"/> Green herons are intolerant of other birds – including conspecifics – when feeding and are not seen to forage in groups. They typically stand still on shore or in shallow water or perch upon branches and await prey. They are able to hover briefly to catch prey.<ref name="HBW" /><ref name="CLO" /><ref name="ADW" /> Green herons have been observed using captured prey (e.g. mayflies) or other objects (bread, feathers) to "bait-fish" – using a lure on the water's surface to attract fish.<ref name="Davis Jr.-1998">Template:Cite journal</ref> This bait-fishing behavior is common among herons.<ref name="Davis Jr.-1998" />
The northern population moves to its breeding ranges during March and April; near the northernmost limit of the green heron's range, breeding is well underway by the end of May. The migration to the winter quarters starts in September; by late October, the birds are absent from regions where they do not stay all year. At least the northward migration does not seem to be affected by global warming; birds appear in their breeding ranges at the same time they did 100 years ago.<ref name = HBW/><ref name=ADW/><ref name=Henninger/><ref name=OOS/>
Individuals of non-migratory populations abandon their territories after breeding season to roam about the region. They may or may not return to the previous year's breeding location, depending on whether they found better habitat during these wanderings. In these populations, the breeding season is determined by rainfall and consequent prey availability.<ref name = HBW/><ref name=CLO/><ref name=ADW/>
Green herons are seasonally monogamous. The pairs form in the breeding range, after an intense courtship display by the males, who select the nesting sites and fly in front of the female noisily and with puffed-up head and neck plumage. They nest in forest and swamp patches, over water or in plants near water. Nests are a platform of sticks, often in shrubs or trees, sometimes on the ground. Locations in trees are preferred, with some nests built up to Template:Convert off the ground although heights of several meters are more common. Rarely, large numbers of these birds congregate in heronries for nesting.<ref name = HBW/><ref name=CLO/><ref name=ADW/>
The clutch is usually 2–6 pale green eggs,<ref name=CLO>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> which are laid in two-day intervals (though the second egg may be laid up to six days later than the first).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> After the last egg has been laid, both parents incubate for about 19–21 days until hatching, and feed the young birds.<ref name = "SAS">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The frequency of feedings decreases as the offspring near fledging. The young sometimes start to leave the nest at 16 days of age, but are not fully fledged and able to fend for themselves until 30–35 days old. Sometimes – particularly in the tropical parts of its range – the green heron breeds twice a year.<ref name = HBW/><ref name=CLO/><ref name=ADW/>
Tool useEdit
Green herons are one of the few species of bird known to use tools. In particular, they commonly use bread crusts, insects, or other items as bait. The bait is dropped onto the surface of a body of water to lure fish. When a fish takes the bait, the green heron then grabs and eats the fish.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
GalleryEdit
- Green Heron nestlings.jpg
Nestlings
- Green Heron4.jpg
Subadult retaining some juvenile plumage
- Green heron (Butorides virescens virescens) young adult.jpg
Young adult B. v. virescens
- Green Heron at Dunes Golf Course, Sanibel.jpg
Breeding plumage, with neck retracted
- Green Heron Adult Prado Regional Park.jpg
Adult
- Green Heron With Crest Raised Key West 16 May 2020.jpg
Adult
- Green heron in PP (14296).jpg
Hunting in New York
- Green heron (Butorides virescens) in flight Peten.jpg
in Guatemala
- Butorides virescens 070506 GWADA.jpg
Subspecies B. v. maculata with neck extended
- 20230912 green heron point meadows keeney cove PND03302.jpg
Juvenile, Glastonbury, CT USA
- Juvenile Green Heron in Minnesota.jpg
Subadult in Minnesota
ReferencesEdit
External linksEdit
Template:Sister project Template:Sister project
- Butorides virescens – Green heron at Animal Diversity Web
- Green heron – Butorides virescens – USGS Patuxent Bird Identification InfoCenter
- Green heron at eNature.com
- Field Guide on Flickr
- {{#if:174793
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| url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=174793 | title = Butorides virescens | publisher = Integrated Taxonomic Information System }}