An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse grassland vegetation. Often flooded in the spring, and affected by drought in midsummer, alvars support a distinctive group of prairie-like plants. Most alvars occur either in northern Europe or around the Great Lakes in North America. This stressed habitat supports a community of rare plants and animals, including species more commonly found on prairie grasslands . Lichen and mosses are common species. Trees and bushes are absent or severely stunted.
25-406: The Burnt Lands is an alvar between Almonte and Ottawa near Upper Huntley, Ontario , Canada . It probably obtained its name from one of the forest fires that swept the area during early European settlement. It is possible that fires assist in creating or maintaining alvars. However, the shallow soil, with alternating drought and flooding, is likely the main factor. The main point is that in
50-447: A 75% decline was noted between 1966 and 2007. Originally, they were found in tallgrass prairie and other open areas with dense grass. Although hay fields are suitable nesting habitats, fields which are harvested early, or at multiple times, in a season may not allow sufficient time for young birds to fledge . Delaying hay harvests by just 1.5 weeks can improve bobolink survival by 20%. This species increased in numbers when horses were
75-485: A land that is typically covered in forest, alvars provide small area of open prairie-like conditions for plants that require such conditions. This alvar is one of the best examples of this habitat type in Lanark County and in southern Ontario. It has been the subject of numerous scientific studies. Because of its significance, The Ontario Ministry of Natural Resources has designated ca 610 hectares (1,500 acres) of
100-630: A natural pest control . In Florida, bobolinks feed most often on the Fall armyworm rather than the True armyworm, as the former is more common in the region. Males sing bright, bubbly songs in flight. During the 1800s the bobolink, like many birds, was slaughtered in large numbers for the meat trade. The numbers of these birds are declining due to loss of habitat . Bobolinks are a species at risk in Nova Scotia, and throughout Canada. In Vermont ,
125-655: A role. In Europe, grazing is frequent, while in North America, there is some evidence that fire may also prevent encroachment by forest. The habitat also has strong competition gradients, with better competitors occupying the deeper soil and excluding other species to less productive locations. Crevices in the limestone provide a distinctive habitat which is somewhat protected from grazing, and which may provide habitat for unusual ferns such as Pellaea atropurpurea . Bare rock flats provide areas with extremely low competition that serve as refugia for weak competitors such as
150-485: Is also a problem with jack pine trees, once planted by the Ontario Ministry of Natural Resources, that are now shading out some of the rare plant species; some experts suggest that these trees need to be removed. A fire in 1999 removed some of the encroaching forest and produced open meadows, which, in 2008 had nearly twice the number of plant species as in adjoining unburned areas. The alvar is protected within
175-408: Is always situated on the ground and is usually well-hidden in dense vegetation. Both parents feed the young. Bobolinks forage on or near the ground and mainly eat seeds and insects . They are nicknamed the " armyworm bird " because of their predation on large numbers of armyworms , including the true armyworm ( Mythimna unipuncta ) and the fall armyworm ( Spodoptera frugiperda ), acting as
200-609: Is declining elsewhere. Rare plants include Kalm's lobelia ( Lobelia kalmii ) , Pringle's aster ( Symphyotrichum pilosum var. pringlei ) , juniper sedge ( Carex juniperorum ), lakeside daisy ( Hymenoxys acaulis ), ram's-head lady's-slipper ( Cypripedium arietinum ) , and dwarf lake iris ( Iris lacustris ) . Also associated with alvars are rare butterflies and snails . The use of the word "alvar" to refer to this type of environment originated in Sweden . The largest alvar in Europe
225-631: Is from the Ancient Greek dolikhos , "long", and onux , "claw". The specific oryzivorus is from Latin oryza , "rice", and vorare , "to devour"; an old name for this species is "Rice Bird". The English "Bobolink" is from Bob o' Lincoln, describing the call. Measurements : Adults are 16–18 cm (6.3–7.1 in) long with short finch -like bills and weigh about 28 g (1 oz). Adult males are mostly black with creamy napes and white scapulars, lower backs, and rumps. Adult females are mostly light brown with black streaks on
250-478: Is located on the Swedish island of Öland . Here the thin soil mantle is only 0.5 to 2.0 centimeters thick in most places and in many extents consists of exposed limestone slabs. The landscape there has been designated a UNESCO World Heritage Site . There are other more local names for similar landforms, such as a pavement barren , although this term is also used for similar landforms based on sandstone . In
275-517: Is thought to have existed in some form since the end of the last ice age, since it has globally rare snails ( Vertigo hannai ) and even a kind of carabid beetle found nowhere else in the world. The CFS Carp Almonte Detachment (Almonte Antennae Yard), a decommissioned military radio receiver, was located in the alvar. Threats to the alvar include urban sprawl , subdivisions, quarries, illegal dumping of household trash and construction materials, illegal sand quarrying, and all-terrain vehicles. There
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#1732790232621300-505: The sandwort Minuartia michauxii and Micranthes virginiensis . In a representative set of four Ontario alvars, seven habitat types were described. From deep to shallow soil these were: tall grassy meadows, tall forb -rich meadows, low grassy meadows, low forb-rich meadows, dry grassland, rock margin grassland and bare rock flats. Alvars comprise a small percentage of the Earth's ecosystems by land extent. Although some 120 exist in
325-738: The Americas, the majority of records are from the British Isles . The species has been known in the southern United States as the "reedbird," or the "ricebird" from their consumption of large amounts of the grain from rice fields in South Carolina and the Gulf States during their southward migration in the fall. One of the species' main migration routes is through Jamaica , where they are called "butter-birds" and at least historically were collected as food, having fattened up on
350-497: The Burnt Lands Provincial Park. The park consists of two non-contiguous parcels of land, totaling 516 hectares (1,280 acres) of land. It is a non-operating park without any visitor activities or facilities. Alvar The primary cause of alvars is the shallow exposed bedrock. Flooding and drought, as noted, add to the stress of the site and prevent many species from growing. Disturbance may also play
375-475: The Galápagos have been found with seeds from Drymaria cordata , a plant native to the Galápagos but highly invasive elsewhere, entangled in their feathers, potentially spreading them to the mainland. Their breeding habitats are open grassy fields, especially hay fields, across North America . In high-quality habitats, males are often polygynous . Females lay five to six eggs in a cup-shaped nest, which
400-704: The Great Lakes region, in total there are only about 43 sq mi (110 km ) left across the entire Great Lakes basin, and many of these have been degraded by agriculture and other human uses. More than half of all remaining alvars occur in Ontario. There are smaller areas in New York, Michigan, Ohio, Wisconsin and Quebec. In North America , alvars provide habitat for birds such as bobolinks , eastern meadowlarks , upland sandpipers , eastern towhees , brown thrashers and loggerhead shrikes whose habitat
425-562: The United Kingdom the exposed landform is called a limestone pavement and thinly covered limestone is known as calcareous grassland . [REDACTED] Media related to Alvar at Wikimedia Commons Bobolink The bobolink ( Dolichonyx oryzivorus ) is a small New World blackbird and the only member of the genus Dolichonyx . An old name for this species is the "rice bird", from its tendency to feed on cultivated grains during winter and migration. The bobolink breeds in
450-605: The aforementioned rice. Bobolinks are the only species of land bird known to annually migrate through the Galápagos Islands , which are over 2,000 km from their primary migration route. A bobolink was collected in the Galápagos Islands by Charles Darwin in 1835. Bobolinks have been hypothesized to act as vectors for avian malaria-causing parasites arriving in the Islands. Additionally, bobolinks in
475-445: The alvar as an Area of Natural and Scientific Interest . A smaller parcel of several hundred hectares is protected within the Burnt Lands Provincial Park (Nature Reserve). It is a popular destination with local naturalists, including bird-watchers and photographers. Some of the distinctive plants found here include Cooper's milk vetch and Ram's-Head Ladyslipper . There are 82 breeding bird species and 48 butterfly species. The alvar
500-637: The back and flanks, and dark stripes on the head; their wings and tails are darker. The bobolink breeds in the summer in North America across much of southern Canada and the northern United States; from 1966 to 2015 the species experienced a greater than 1.5% annual population decrease throughout most of its breeding range, extending from the Midwestern United States to the Canadian Maritimes . The bobolink migrates long distances, wintering in southern South America. One bird
525-456: The musical Bloomer Girl : Evelina, won't ya ever take a shine to that moon? Evelina, ain't ya bothered by the Bobolink's tune? The bird is also one of the many important ornithological references in the poem " Pale Fire " by the fictional poet John Shade , part of Vladimir Nabokov 's novel of the same name. Sophie Jewett ends her poem "An Exile's Garden" (1910) with a reference to
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#1732790232621550-643: The primary mode of transportation, requiring larger supplies of hay. A 2021 study found that the reintroduction of American bison across the United States was detrimental to bobolink populations, with adult populations dropping as much as 62% and juvenile populations as much as 84%. This is presumed to be due to many new bison herds being managed more as livestock than wildlife, often kept in fenced pastures and protected from predation, which encourages overgrazing , trampling, and rapid multiplying. The study also found that lighter grazing by bison did not have
575-418: The same harmful effects, demonstrating that the two species could likely coexist under the right circumstances. Emily Dickinson penned many poems about or mentioning the bird. Edgar Allan Poe mentions the bird in "Landor's Cottage". William Cullen Bryant wrote about the bob-o'-link in his poem "Robert of Lincoln." The bobolink is mentioned in the song Evelina by Harold Arlen and Yip Harburg , from
600-543: The summer in the United States and Canada , with most of the summer range in the northern U.S. Bobolinks winter in southern South America , primarily Paraguay , Argentina , and Bolivia . Bobolink populations are rapidly declining due to numerous factors, such as agricultural intensification and habitat loss; they are considered threatened in Canada, and are at risk throughout their range. The genus name Dolichonyx
625-522: Was tracked migrating 12,000 mi (19,000 km) over the course of the year, often flying long distances up to 1,100 mi (1,800 km) in a single day, then stopping to recuperate for days or weeks. Bobolinks often migrate in flocks, feeding on cultivated grains and rice , which leads to them being considered a pest by farmers in some areas. Although bobolinks migrate long distances, they have rarely been sighted in Europe — like many vagrants from
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