The indigo bunting is a small seed-eating bird in the cardinal family, Cardinalidae. It is migratory, ranging from southern Canada to northern Florida during the breeding season, from southern Florida to northern South America during the winter, it migrates by night, using the stars to navigate. Its habitat is farmland, brush areas, open woodland; the indigo bunting is related to the lazuli bunting and interbreeds with the species where their ranges overlap. The indigo bunting is a small bird, with a length of 11.5–13 cm. It displays sexual dimorphism in its coloration; the male displays brightly colored plumage during the breeding season to attract a mate. Nest-building and incubation are done by the female; the diet of the indigo bunting consists of insects during the summer months and seeds during the winter months. The indigo bunting is included in the family Cardinalidae, made up of passerine birds found in North and South America, is one of seven birds in the genus Passerina, it was described as Tanagra cyanea by Linnaeus in his 18th-century work, Systema Naturae.
The current genus name, Passerina, is derived from the Latin term passer for true sparrows and similar small birds, while the species name, cyanea, is from the Latin word meaning dark or sea blue. The indigo bunting is a close relative of the lazuli bunting and interbreeds with the species where their ranges overlap, in the Great Plains, they were declared to form a superspecies by the American Ornithologists' Union in 1983. However, according to sequencing of the mitochondrial cytochrome-b gene of members of the genus Passerina, it was determined that the indigo bunting and lazuli bunting are not, in fact, sister taxa; the indigo bunting is the sister of a "blue" and a "painted" clade. This genetic study shows these species diverged between 7.3 million years ago. This timing, consistent with fossil evidence, coincides with a late-Miocene cooling, which caused the evolution of a variety of western grassland habitats. Evolving to reduce size may have allowed buntings to exploit grass seeds as a food source.
The indigo bunting is a smallish songbird, around the size of a small sparrow. It measures 11.5–15 cm long, with a wingspan of 18–23 cm. Body mass averages 14.5 g, with a reported range of 11.2–21.4 g. During the breeding season, the adult male appears a vibrant cerulean blue. Only the head is indigo; the wings and tail are black with cerulean blue edges. In fall and winter plumage, the male has brown edges to the blue body and head feathers, which overlap to make the bird appear brown; the adult female is brown on lighter brown on the underparts. It is faintly streaked with darker markings underneath; the immature bird resembles the female in coloring, although a male may have hints of blue on the tail and shoulders and have darker streaks on the underside. The beak is conical. In the adult female, the beak is light brown tinged with blue, in the adult male the upper half is brownish-black while the lower is light blue; the feet and legs are gray. The habitat of the indigo bunting is brushy forest edges, open deciduous woods, second growth woodland, farmland.
The breeding range stretches from southern Canada to Maine, south to northern Florida and eastern Texas, westward to southern Nevada. The winter range begins in southern Florida and central Mexico and stretches south through the West Indies and Central America to northern South America, it has occurred as a vagrant in Antigua and Barbuda, Denmark, Germany, Ireland, the Netherlands Antilles, Saint Pierre and Miquelon and the United Kingdom. The indigo bunting communicates through visual cues. A sharp chip! Call is used by both sexes, is used as an alarm call if a nest or chick is threatened. A high-pitched, buzzed zeeep is used; the song of the male bird is a high-pitched buzzed sweet-sweet chew-chew sweet-sweet, lasting two to four seconds, sung to mark his territory to other males and to attract females. Each male has a single complex song, which he sings while perched on elevated objects, such as posts and bush-tops. In areas where the ranges of the lazuli bunting and the indigo bunting overlap, the males defend territories from each another.
Migration takes place in April and May and again in September and October. The indigo bunting migrates during the night, using the stars to navigate. In captivity, since it cannot migrate, it experiences disorientation in April and May and in September and October if it cannot see the stars from its enclosure; these birds are monogamous but not always faithful to their partner. In the western part of their range, they hybridize with the lazuli bunting. Nesting sites are located in dense shrub or a low tree 0.3–1 m above the ground, but up to 9 m. The nest itself is constructed of leaves, coarse grasses and strips of bark, lined with soft grass or deer hair and is bound with spider web, it is constructed by the female. The clutch consists of one to four eggs, but contains three to four; the eggs are white and unmarked, though some may be marked with brownish spots, averaging 18.7 mm × 13.7 mm in size. The eggs are incubated for 12 to 13 days and the
Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, dikes, sills and volcanic necks. Intrusive rock forms within Earth's crust from the crystallization of magma. Many mountain ranges, such as the Sierra Nevada in California, are formed from large granite intrusions. Intrusions are one of the two ways igneous rock. Technically an intrusion is any formation of intrusive igneous rock. In contrast, an extrusion consists of extrusive rock. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons. Plutonic rocks form 7% of the Earth's current land surface. Coarse-grained intrusive igneous rocks that form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. Intrusive structures are classified according to whether or not they are parallel to the bedding planes or foliation of the country rock: if the intrusion is parallel the body is concordant, otherwise it is discordant.
An intrusive suite is a group of plutons related in time and space.. Intrusions vary from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite. Intrusions can be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes: Batholith: a large irregular discordant intrusion Chonolith: an irregularly-shaped intrusion with a demonstrable base Cupola: a dome-shaped projection from the top of a large subterranean intrusion Dike: a narrow tabular discordant body nearly vertical Laccolith: concordant body with flat base and convex top with a feeder pipe below Lopolith: concordant body with flat top and a shallow convex base, may have a feeder dike or pipe below Phacolith: a concordant lens-shaped pluton that occupies the crest of an anticline or trough of a syncline Volcanic pipe or volcanic neck: tubular vertical body that may have been a feeder vent for a volcano Sill: a thin tabular concordant body intruded along bedding planes Stock: a smaller irregular discordant intrusive Boss: a small stock A body of intrusive igneous rock which crystallizes from magma cooling underneath the surface of the Earth is called a pluton.
If the pluton is large, it may be called a stock. Intrusive rocks are characterized by large crystal sizes, as the individual crystals are visible, the rock is called phaneritic; this is as the magma cools underground, while cooling may be fast or slow, cooling is slower than on the surface, so larger crystals grow. If it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, it is called a laccolith. How deep-seated intrusions burst through the overlying strata causes intrusive rock to be recognized: Veins spread out into branches, or branchlike parts result from filled cracks, the high temperature is evident in how they alter country rock; as heat dissipation is slow, as the rock is under pressure, crystals form, no vitreous chilled matter is present. The intrusions did not flow. Contained gases could not escape through the thick strata, thus form cavities, which can be observed; because their crystals are of the rough equal size, these rocks are said to be equigranular.
There is no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. The minerals of each have formed in a definite order, each has had a period of crystallization that may be distinct or may have coincided with or overlapped the period of formation of some of the other ingredients. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect. Crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals; the former case is said to be idiomorphic. There are many other characteristics that serve to distinguish the members of these two groups. For example, orthoclase is feldspar from granite, while its modifications occur in lavas of similar composition; the same distinction holds for nepheline varieties. Leucite is common in lavas but rare in plutonic rocks. Muscovite is confined to intrusions; these differences show the influence of the physical conditions under which consolidation takes place.
Intrusive rocks formed at greater depths are called abyssal. Some intrusive rocks solidified in fissures as dikes and intrusive sills at shallow depth and are called subvolcanic or hypabyssal, they show structures intermediate between those of plutonic rocks. They are commonly porphyritic and sometimes vesicular. In fact, many of them are petrologically indistinguishable from lavas of similar composition. Ellicott City Granodiorite Guilford Quartz Monzonite Methods of pluton emplacement Norbeck Intrusive Suite Volcanic rock Woodstock Quartz Monzonite
Sprague's pipit is a small songbird in the family Motacillidae that breeds in the short- and mixed-grass prairies of North America. Migratory, it spends the winters in northern Mexico. Sprague's pipits are unusual among songbirds in that they sing high in the sky, somewhat like a goldfinch or skylark, it is more identified by its distinctive descending song heard from above than by being seen on the ground. Males and females are cryptically similar in appearance. Sprague's pipit summer habitat is native grasslands in the north central prairies of the United States and Canada. Found in mixed or short grass prairie throughout the central northern Great Plains of North America. In Canada, Sprague's pipit breed in southern Alberta, southern Saskatchewan, southwest Manitoba. In the United States, they breed in northeastern and central Montana and central North Dakota, northwest South Dakota, in the Red River Valley of Minnesota. Sprague's pipits winter in northern Mexico. In the United States it occurs from southern California, south-central and southeastern Arizona, southern New Mexico and eastern Texas found in southern Kansas, southern Oklahoma rarely in southern Missouri and northwestern Mississippi south through Arkansas and Louisiana.
In October 2016, an individual was found in Connecticut for the first time, suggesting that they could be vagrants to other places as well. In Mexico it is found in the interior from northeastern Sonora and Nuevo Leon south to Zacatecas and San Luis Potosi and along the Atlantic Coast from Tamaulipas to central Veracruz, it is uncommon in the Central Volcanic belt, rare in a vagrant to s Guerrero. Sprague's pipits were listed in 1999 by the Committee on the Status of Endangered Wildlife in Canada as “threatened”. Sprague's pipits were listed under the Species at Risk Act as “threatened” on 5 June 2003. In the United States, Sprague's pipits are a candidate for listing as “endangered” or “threatened” under the Endangered Species Act of 1973. Sprague's pipit is a ground nesting passerine and standing dead vegetation is used to build the canopy over the nest. Breeding continues until mid to late August. Nests are a small cup of grass found on the ground with standing dead vegetation folded over to create a canopy.
There is a single entrance to the nest. Four to six eggs are laid within the nests with an average incubation time of 13–14 days. Renesting and second broods have been documented for Sprague's pipit, as has polygyny. Sprague's pipit's eat various insects and sometimes seeds. During the breeding season the adults are entirely insectivorous and feed the young on insects as well. Campbell, RW, NK Dawe, I McTaggart-Cowan, JM Cooper, GW Kaiser, MCE GEJ Smith. 1997. Birds of British Columbia: Passerines: Flycatchers Through Vireos SNG and S Webb. 1995. A guide to the birds of Mexico and North Central America. Oxford University Press, New York. Jones, SL, JS Dieni, & PJ Gouse. 2010. Reproductive biology of a grassland songbird community in north-central Montana. Wilson Journal of Ornithology 122:455-464. Robbins, M. B. and B. C. Dale. 1999. Sprague’s Pipit. In The Birds of North America, No. 439. The Birds of North America, Inc. Philadelphia, PA. Sprague's Pipit Conservation Plan - U. S. Fish and Wildlife Service Sprague's Pipit Species Account - Cornell Lab of Ornithology Sprague's Pipit Anthus spragueii - USGS Patuxent Bird Identification InfoCenter Sprague's Pipit photo gallery VIREO
The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
Northern saw-whet owl
The northern saw-whet owl is a small owl native to North America. Saw-whet owls are one of the smallest owl species in North America, they can be found in dense thickets or conifers at eye level, although they can be found around 20 feet up. Saw-whets are in danger of being preyed upon by larger owls and raptors. Saw-whet owls are migratory birds without any strict pattern; the scientific description of one of the sub-species of this owl is attributed to the Rev. John Henry Keen, a missionary in Canada in 1896. Adults are 17–22 cm long with a 42–56.3 cm wingspan. They can weigh from 54 to 151 g with an average of around 80 g, making them one of the smallest owls in North America, they are close to the size of an American robin. The northern saw-whet owl has a round, white face with brown and cream streaks, they resemble the short-eared owl, because they lack ear tufts, but are much smaller. The underparts are pale with dark shaded areas, they are hard to spot. The northern saw-whet owl makes a repeated tooting whistle sound.
Some say they sound like a saw being sharpened on a whetstone. They make these sounds to find a mate, so they can be heard more April through June when they are looking for mates. Despite being more common in spring, they do vocalize year round; the northern saw-whet owl has a sophisticated hearing. It is due to different shape of the ear openings; because the sound reaches the ears at a different time and is of different intensity, the northern saw-whet owl can precisely localize its prey. Such accurate sound localization allows it to hunt in a complete darkness by hearing alone, their habitat is coniferous forests, sometimes deciduous woods, across North America. Most birds winter in mixed or deciduous woods, they love riparian areas because of the abundance of prey there. They live in old nests made by other small raptors; some are permanent residents, while others may migrate south in winter or move down from higher elevations. Their range covers most of North America including southeastern and southcentral Alaska, southern Canada, most of the United States and the central mountains in Mexico.
Some have begun to move more southeast in Indiana and neighboring states. Buidin et al. did a study of how far north the northern saw-whet owls breed and they found that they can breed northward to > 50° N, farther than recorded before. Their range is quite extensive and they can breed in the far north where most birds migrate from to breed, they are an adaptive species. Northern saw-whet owls lay about four or six white-colored eggs in natural tree cavities or woodpecker holes; the father does the hunting while the mother sits on her eggs. Females can have more than one clutch of eggs each breeding season with different males. Once the offspring in the first nest have developed their feathers the mother will leave the father to care for them and go find another male to reproduce with; this type of mating is sequential polyandry. They compete with boreal owls and squirrels for nest cavities and their nests may be destroyed or eaten by those creatures as well as nest predators such as martens and corvids.
Saw-whet owls of all ages may be predated by any larger species of owl, of which there are at least a dozen that overlap in range. They are predated by Accipiter hawks, which share with the saw-whet a preference for wooded habitats with dense thickets or brush; these birds wait on a high perch at swoop down on prey. They eat small organisms with a strong focus on small mammals in their diet. Swengel and Swengel reviewed ten studies that found northern saw-whet owls eating exclusively mammals, with most of the mammals being rodents. In their Wisconsin study, the Swengels counted Saw-whets as most eating deer mice and shrews. A similar study by Holt and Leroux in Montana found saw-whet owls eating more voles than other mammal species. Engel et al. found in the saw-whet owl a strong preference for small mammals, with 55% of prey being two species of voles. Holt and Leroux compared the eating habits of northern saw-whet owls to northern pygmy owls and found that they prey on different animals for their main food source, with saw-whet's diet 98% small mammals, while for pygmy owls over one-third of their prey was birds.
Their study concluded that these owls could adapt depending on the prey and with the other predators in the areas where they live. Engel et al. in Chain O'Lakes State Park, during the winter of 1987-88, compared Northern Saw-whet to long-eared owls. Engel confirmed the saw-whet owl's strong preference for small mammals, their diet appeared varied in the winter, was less tied to one mammal than was the long-earred owl. Other mammals preyed on include shrews, various other mice species, flying squirrels and bats. Supplementing the diet are small birds, with passerines such as swallows, sparrows and chickadees favored. However, larger birds, up to the size of rock pigeon can be taken. On the Pacific coast they may e
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, sleet, snow and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates", thus and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate. Two processes acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called "showers."Moisture, lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain occurs. A stationary front is present near the area of freezing rain and serves as the foci for forcing and rising air.
Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. The cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation is caused by convection; the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
Precipitation is a major component of the water cycle, is responsible for depositing the fresh water on the planet. 505,000 cubic kilometres of water falls as precipitation each year. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres, but over land it is only 715 millimetres. Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on other celestial bodies, e.g. when it gets cold, Mars has precipitation which most takes the form of frost, rather than rain or snow. Precipitation is a major component of the water cycle, is responsible for depositing most of the fresh water on the planet. 505,000 km3 of water falls as precipitation each year, 398,000 km3 of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective and orographic rainfall.
Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles, ice pellets and graupel; the dew point is the temperature to which a parcel must be cooled in order to become saturated, condenses to water. Water vapor begins to condense on condensation nuclei such as dust and salt in order to form clouds. An elevated portion of a frontal zone forces broad areas of lift, which form clouds decks such as altostratus or cirrostratus.
Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can form due to the lifting of advection fog during breezy conditions. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, evaporative cooling. Adiabatic cooling occurs when air expands; the air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain. Conductive cooling occurs when the air comes into contact with a colder surface by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath. Evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation; the main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet lan