Mindblowing Planet Earth

Wednesday 11 September 2019

Great Blue Heron Facts

Herons, egrets, and bitterns are medium to large wading birds with long necks and spear-like bills. Nearly all species feed primarily on aquatic animal life e.g., fish, frogs, crayfish, insects. The common along the margins of most freshwater and saltwater bodies and wetlands. Their long legs, necks, and bills are adapted for wading in shallow water and stabbing prey.

Most species build their nests in trees near their foraging habitat, and many nests colonially. Members of this group range in size from the least bittern 28-36 cm bill tip to tail tip to the great blue heron 106-132 cm tall. The sexes are similar in size and appearance.

The great blue heron (Ardeaherodias) is the largest member of the group in North America and feeds primarily on aquatic animals. It is widely distributed in both saltwater and freshwater environments. There are following subspecies in the United States and Canada:

h. wardi (Kansas and Oklahoma across the Mississippi River to Florida).
h. herodias (remainder of the North and Central American range).
h. fannini (Pacific coast of North America from Alaska to Washington).
h. occidentalis (extreme south of Florida)
h. occidentalis (the great white heron) is an all-white color morph that was formerly considered a separate species.

Body Size

Males average slightly heavier in weight than females. Northern continental herons are somewhat smaller than those found in the south determined a relationship between age and body weight for nestling great blue herons where BW equals body weight in grams and A equals age in days.

Great Blue Heron Habitat

Great blue herons inhabit a variety of freshwater and marine areas, including freshwater lakes and rivers, brackish marshes, lagoons, mangroves, and coastal wetlands, particularly where small fish are plentiful in shallow areas. They are often seen on tidal flats and sandbars and occasionally forage in wet meadows, pastures, and other terrestrial habitats.

Great Blue Heron Nest

Great blue herons tend to nest in dense colonies or heronries. The location of the heronry is generally close to foraging grounds, and tall trees are preferred over shorter trees or bushes for nest sites. They also may nest on the ground, on rock ledges, or on sea cliffs.

Great Blue Heron Food Habits

Fish are the preferred prey, but great blues also eat amphibians, reptiles, crustaceans, insects, birds, and mammals. When fishing, they mainly use two foraging techniques: standing still and waiting for fish to swim within striking distance of 2-3 Great Blue Heron slow wading to catch more sedentary prey (such as flounder and sculpin). To fish, they require shallow waters (up to 0.5 m) with a firm substrate.

Fish up to about 20 cm in length were dominant in the diet of herons foraging in southwestern Lake Erie, and 95 percent of fish consumed by great blues in a Wisconsin population was less than 25 cm in length. Great blues sometimes forage in wet meadows and pastures in pursuit of lizards, small mammals, and large insects.

In northern areas, small mammals such as meadow voles may be an important part of the diet early in the breeding season, possibly because some aquatic foraging areas may still be partially frozen when the herons arrive. Consumption of larger prey (fish, frogs, rodents) is often followed by drinks of water; terrestrial prey such as voles are usually dunked in water before they are swallowed.

Adult herons tend to deliver the same type and size of food to their nestlings that they consume themselves, but they deliver it well digested for young nestlings and less well digested as the nestlings grow. Adults tend to feed solitary, although they may feed in single or mixed species flocks where there are large concentrations of prey, fledglings are frequently seen foraging together.

Molt.

Adults undergo a complete molt in the late summer and fall and a partial molt of the contour feathers in the late winter and early spring. Young herons attain full adult plumage in the summer/fall molt at the end of their second year.

Great Blue Heron Migration

In the northern part of its range, most great blues are migratory, some moving to the southern Atlantic and the Gulf States to overwintering with the resident populations of herons, others continuing to Cuba and Central and South America. Most migrating herons leave their breeding grounds by October or November and return between February and April.

Breeding Activities and Social Organization

The male great blue heron selects the site for the breeding territory, and nests generally consist of a stick platform over 1 m in diameter. Great blues often use a nest for more than 1 year, expanding it with each use. Mean clutch sizes range from three to five in general, clutch size tends to increase with latitude.

Only one brood is raised per year; however, if a clutch is destroyed, great blues may lay a replacement clutch, usually with fewer eggs than the initial clutch. Both parents incubate and feed the young. During the breeding season, great blues are monogamous and colonial, with from a few to hundreds of pairs nesting in the same area or heronry. Colonies may be 2-4 Great Blue Heron & include other species, such as great egrets or double-crested cormorants.

Great Blue Heron Range

Breeding colonies are generally close to foraging grounds the distance between heronries and possible feeding areas in Minnesota lakes to range from 0 to 4.2 km, averaging 1.8 km. Another study found that most heroines along the North Carolina coast were located near inlets with large concentrations of fish, an average of 7 to 8 km away.

Fifteen to 20 km is the farthest great blue herons regularly travel between foraging areas and colonies. In the northern portion of their range, great blue herons often build nests in tall trees over dry land, whereas in the southern part of their range, they usually nest in swamp trees, including mangroves.

Each breeding pair defends a small territory around the nest, the size of which depends on local habitat and the birds' stage of reproduction. Herons in some areas also defend feeding territories. In other areas, great blues appear to be opportunistic foragers, lacking strict fidelity to feeding sites. A study shows that herons often returned to the same general areas, but different individuals often used the same areas at different times.

Population density. Because great blues nest colonially, local population density (i.e., colony density, colony size, and the number of colonies) varies with the availability of suitable nesting habitat as well as foraging habitat. On islands in coastal Maine, Gibbs and others found a significant correlation between colony size and the area of tidal and intertidal wetlands within 20 km of the colonies, which was the longest distance herons in the study colonies traveled on foraging trips.

In western Oregon, the size of heronries was found to range from 32 to 161 active nests; the area enclosed by peripheral nest trees within the colonies ranged from 0.08 to 1.21 ha. Population dynamics. Most nestling loss is a result of starvation, although some losses to predation do occur. In a study of 243 nests in a coastal California colony, 65 percent of the chicks fledged, 20 percent starved, 7 percent were taken by predators, and 7 percent were lost to other causes. Estimates of the number of young fledged each year by breeding pairs range from 0.85 to 3.1.

Based on banding studies, about two-thirds of the fledglings do not survive more than 1 year, although they may survive better in protected wildlife refuges. Values for later years indicate that about one-third to one-fifth of the 2-year-old and older birds are lost each year.

Similar Species

The great egret (Casmerodiusalbus) is almost the same size (96 cm length) as the great blue heron and is found over a limited range in the breeding season, including areas in the central and eastern United States and the east and west coasts. It winters in coastal areas of the United States and in 2-5 Great Blue Heron and Mexico and farther south. The great egret's habitat preferences are like those of the great blue heron.

The snowy egret (Egretta thula), one of the medium-sized herons (51 to 69 cm), shuffles its feet to stir up benthic aquatic prey. It is found mostly in freshwater and saltwater marshes but also sometimes follows cattle and other livestock as does the cattle egret. It breeds in parts of the western, southeastern, and east coasts of the United States and winters along both coasts of the southern United States and farther south.

The cattle egret (Bubulcusibis) is seen in agricultural pastures and fields, where it follows livestock to pick up insects disturbed by grazing. An Old-World species, it was introduced into South America and reached Florida in the 1950s. It reached California by the 1960s and has been continuing to expand its range.

The green-backed heron (Butorides striatus), one of the smaller herons (41 to 56 cm), breeds over most of the United States except for the northwest and southern Midwest. It has a winter range like that of the snowy egret and seems to prefer water bodies with woodland cover.

The tricolored heron (Egretta tricolor) (formerly known as the Louisiana heron) is common in salt marshes and mangrove swamps of the east and gulf coasts, but it is rare inland.

The little blue heron (Egretta caerulea) is common in freshwater ponds, lakes, and marshes and coastal saltwater wetlands of the Gulf Coast States. Juveniles are easily confused with juvenile snowy egrets. This species hunts by walking slowly in shallow waters, and its diet typically includes fish, amphibians, crayfish, and insects.

The black-crowned night heron (Nycticorax nycticorax), characterized by a heavy body, short thick neck, and short legs (64 cm), is a common heron of freshwater swamps and tidal marshes, roosting by day in trees. It typically feeds by night, predominantly on aquatic species, fish, amphibians, and insects. This heron is extremely widespread, occurring in North and South America, Eurasia, and Africa. It breeds over much of the United States and parts of central Canada and winters along both coasts of the United States and farther south.

The yellow-crowned night heron (Nyctanassa violacea) (61 cm) is similar to the black-crowned but is more restricted in its range to the southeastern United States. It roosts in trees in wet woods, swamps, and low coastal shrubs.

The American bittern (Botauruslentiginosus), another of the medium-sized herons (58 to 70 cm), is a relatively common but elusive inhabitant of freshwater and brackish marshes and reedy lakes. It is a solitary feeder, 2-6 Great Blue Heron & consuming fish, crayfish, reptiles, amphibians, insects, and even small mammals. Its breeding range includes most of Canada and the United States, although much of the southern United States is inhabited only during the winter.

The least bittern (Ixobrychusexilis), the smallest of the North American herons (33 cm), also is an elusive inhabitant of reedy areas. Its breeding range is restricted largely to the eastern half of the United States.

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Saturday 7 September 2019

The Snapping Turtle

Where Do Snapping Turtles Live

Snapping turtles are among the largest of the freshwater turtles. They are characterized by large heads with powerful hooked jaws. There are only two species of this family in North America. The snapping turtle, including both the common and Florida snapping turtles, and the alligator snapping turtle mostly found in lakes, streams, and freshwater where fish in abundance numbers.

The snapping turtle (Chelydra serpentina) is primarily aquatic, inhabiting freshwater and brackish environments, although they will travel overland. There are two subspecies recognized in North America that are primarily distinguished by range.

s. serpentine (the common snapping turtle, which is the largest subspecies, primarily occupies the United States east of the Rockies, except for the southern portions of Texas and Florida), and C.s. Osceola (the Florida snapping turtle, found in the Florida peninsula).

Snapping Turtle Size

An adult snapping turtle is large, 20 to 37 cm in carapace length. Although the male turtle attains larger sizes than females. In a large oligotrophic lake in Ontario Canada, adult males averaged more than 10 kg. Hence the female’s turtle is averaged 5.2 kg. In other populations, the difference in size between males and females often is less.

Snapping Turtles reach the sexual maturity at about 200 mm in carapace length. The cool, brief activity season in more northern areas results in slower growth rates and extended times to reach sexual maturity.

Snapping Turtle Habitat

In the east, snapping turtles are found in and near-permanent ponds, lakes, and marshes. However, in the arid west, the species is primarily found in larger rivers, because these are the only permanent water bodies.

They are often found in turbid waters with a slow current. They spend most of their time lying on the bottom of deep pools or buried in the mud in shallow water with only their eyes and nostrils exposed.

It is observed that young snapping turtles show a preference for areas with some obstructions that may provide cover or food. The turtle has the great ability to travel extremely long distances to find food or an appropriate area to lay their eggs.

What do Snapping Turtles Eat

Snapping turtles are omnivorous. In the early spring, when limited aquatic vegetation exists in lakes and ponds. They may eat mainly animal matter. Though, when aquatic vegetation becomes plentiful, they become more herbivorous. Also, young snapping turtles are chiefly carnivorous and like smaller streams where aquatic vegetation is less abundant.

Snapping turtles consume a wide variety of animal material. That is including insects, snails, crustaceans, clams, leeches, earthworms, tubificid worms, freshwater sponges, fish (adults, fry, and eggs), frogs, toads, salamanders, small snakes, small turtles, birds, small mammals, and carrion and plant material including several algae.

Snapping Turtle observed no difference between the diets of males and females who fed at the surface, mid pelagic, and benthic levels. The pharyngeal mechanism of feeding (i.e., drawing water with food objects into the mouth) prevents snapping turtles from ingesting food above the air-water interface.

Temperature Regulation and Daily Activities

Snappers are most active at night. During the day, they occasionally leave the water to bask onshore, but basking is probably restricted by intolerance to high temperatures and by rapid loss of moisture. It is found that the turtles were active in the early morning and early evening and basked in the afternoon but were rarely active at night.

Active turtles were found in deeper waters than inactive snappers. Cloacal temperatures of 18.7 to 32.6C were reported for snapping turtles captured in the water in Sarasota County, Florida, between May and October.

Snapping Turtle Hibernation

Snapping turtles habitually enter in the hibernation process at the end of October and emerge sometime between March and May. But it is all depending on latitude and temperature. Also, to hibernate, turtles burrow into the debris or mud bottom of ponds or lakes, settle beneath logs, or retreat into muskrat burrows or lodges.

The turtles have been seen moving on or below the ice in midwinter. Large congregations sometimes hibernate together. This turtle is incredible cold-tolerant; even remain active under the ice during the winter.

Snapping Turtle Breeding Activities

Mating occurs any time turtles are active from spring through fall, depending on latitude. Some investigators believe that male snapping turtles are territorial but doubt that males defend their home ranges against other males. Sperm may remain viable in the female for several years.

Nesting occurs from late spring to early fall, peaking in June. Snapping Turtles can travel long overland to reach a new destination. They do it because of pollution, food scarcity, destruction in habitat, overcrowding, and many other factors.

When do Snapping Turtles Lay Eggs

The older females nested earlier in the season than did smaller, younger ones. Females often move up small streams to lay eggs. The nest site may be in the soil of banks or in muskrat houses but more commonly is in the open on south-facing slopes and maybe several hundred meters from the water.

The turtle digs a 4-to 7-in cavity on dry land, preferably in sand, loam, or vegetable debris. The duration of incubation is inversely related to soil temperature. In more northerly populations, hatchlings may overwinter in the nest.

Home Range and Resources

Moreover, many turtles stay mainly within the same marsh or in one wide-ranging area from year to year. The summer home range includes a turtle’s aquatic foraging areas, but females may need to travel some distance outside of the foraging home range to find a suitable nest site.

The females tagged at their nesting site moved an average of 5.5 km from the nest site afterward. The 91.9 percent of the turtles in one population returned to the same nesting site a year after having been tagged there. Home ranges overlap both between and within sexes.

However, the young snapping turtles use different habitats than adults; they tend to remain in small streams until shortly before maturity when they migrate to habitats preferred by adults (e.g., ponds, marshes, lakes).

Population Density

The density of snapping turtles appears to be positively correlated with the productivity of the surface water body (e.g., density in a eutrophic surface water body is higher than in an oligotrophic lake). Specific habitat characteristics and intraspecific interactions contribute to the variability of observed population densities in snapping turtles.

Snapping Turtle Egg Incubation

Females do not begin laying eggs until age 6 to 19 year depending on latitude and when they reach an appropriate size (approximately 200 mm carapace). Males mature a few years earlier than females. However, females may lay 1 or 2 clutches per season.

Snapping turtle eggs incubation took around 90 days. However, it all depends on the average temperature during that time, hatch anywhere from 80 to 120 days after being laid. Clutch size increases with female body size calculated the relationship between clutch size and plastron length.

Clutch size has also been positively correlated with latitude the mammalian predators destroyed over 50 percent of the turtle nests. The undisturbed nests, hatchling success was less than 20 percent. Adult mortality is low, corresponding with the long lives exhibited by these turtles.

Snapping Turtles Predators

The eggs predators by crows, Foxes, mink, skunks, and raccoons. The hatch-lings and juveniles, most of the same predators will attack them as well as herons, as it is observed that mostly attacked by great blue herons, Yellow bitterns, fishers, hawks, owls, bullfrogs, large fish, and different snakes. The average lifespan is not known, but estimated life is more than a hundred years.

Similar Species

The alligator snapping turtle (Macroclemys temmincki) is much larger (16 to 68 kg; 38 to 66 cm carapace) than the common snapping turtle and is one of the largest turtles in the world. Its range is from northern Florida to east-central Texas and north in the Mississippi Valley.

Are Snapping Turtles Poisonous

Snapping Turtle biggest threat is to humans are their powerful bite and scratch. So be careful when you interact with him to avoid the danger of their bite and claws which are very sharp and lacerate the flesh of a person trying to calm them. The Snapping Turtle can also cause some serious bruise or even break the skin or break bones as well. CP

Read More – The Lesser Goldfinch (Spinus psaltria) / The Himalayan Cutia / The fire-tailed myzornis / Pando – The One Tree Forest

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Thursday 5 September 2019

American Kestrel (falcons)

American Kestrel Facts

Order Falconiformes, Family Falconidae - Falcons are the more streamlined of the raptor species, with long pointed wings bent back at the wrists and large tails that taper at the tips. They consume numerous kinds of animals including insects, reptiles, small mammals, and birds. It is also called sparrow hawk, although birds are not the main prey item. Falcons, in general, have long, pointed wings and long tails, like mourning dove (Zenaida macroura).

Falcons are found in a variety of habitats, from cities to the most remote areas. Strong fliers that achieve high speeds, falcons’ range in size from the American kestrel 27 cm bill tip to tail tip to the peregrine falcon 41 to 51 cm. It is one of the smallest and most widely distributed falcons in North America. In the first sight, kestrels are often confused with other small birds such as mourning doves.

Nest of American Kestrel

The American Kestrel seek ready-made nests, such as wild woodpecker excavated holes or nest boxes provided by humans. Especially- ready-made nest boxes support kestrels throughout the areas where there are few natural cavities. They prefer cavities in large trees, crevices in rocks, nooks in structures.

Mainly surrounded by large open areas covered with short ground vegetation with adequate hunting perches close by. The Kestrel used nest boxes, but competition from non-native European Starlings is a real problem. Once the Kestrels pair select the site for nesting, then they use it for many years.

Selected species

The American kestrel (Falco sparverius), or sparrow hawk, is the most common falcon in open and semi-open areas throughout North America. There are three recognized subspecies.

1. F.s. paulus (This is a year-round resident from South Carolina to Florida and southern Alabama).

2. F.s. peninsularis (it is a year-round resident of southern Baja California).

3. F.s. sparverius (It is widespread and migratory).

The Predators of the kestrel include large raptors such as great horned owls, golden eagles, red-tailed hawks, coyotes, bobcats, skunks, raccoons, ravens, and crows.

Body size of American Kestrels

The bird weighing slightly over one-tenth of a kilogram, the kestrel is the smallest falcon native to the United States. As for most raptors, females are 10 to 20 percent larger than males. Kestrel body weights vary seasonally, with maximum weight (and fat deposits) being achieved in winter and minimum weights in summer.

American Kestrels Habitat

Kestrels inhabit open deserts, semi-open areas, the edges of groves and even cities. In several areas, investigators have found that male kestrels tend to use woodland openings and edges, while females tend to utilize more open areas characterized by short or sparse ground vegetation, particularly during the winter. In other areas, however, investigators have found no such differentiation.

In Florida, kestrels appear to prefer sandhill communities particularly pine/oak woodlands. These areas provide high-quality foraging habitat and most available nest sites. Kestrels are more likely to use habitats close to centers of human activities than are most other raptors.

Territory size of American Kestrels in relation to relatively small mammal abundance at the trap site probably reflects a reasonable estimate of prey availability at all nearby sites. American Kestrels may not alter territorial boundaries once established, particularly if the original territory maximizes rates of prey capture while minimizing costs associated with territorial defense.

American Kestrels Diet

Kestrels prey on a variety of small animals including invertebrates such as worms, spiders, scorpions, bats, and beetles. The other large insects, amphibians, and reptiles such as frogs, lizards, and snakes, and a wide variety of small-to-medium-sized birds and mammals.

Large insects, such as grasshoppers, are the kestrels' primary summer prey. Although in their absence kestrels will switch to small mammals and birds. In winter, small mammals and birds comprise most of the diet. Kestrels usually cache their vertebrate prey, often in clumps of grass or in tree limbs and holes, to be retrieved later.

Invertebrate prey usually is eaten immediately. In Florida, where small mammals are scarce, and reptiles are abundant, lizards are an important component of the diet. Kestrels forage by three different techniques: using open perches from which to spot and attack ground prey, hovering in the air to spot ground prey, and catching insects on the wing.

Also, some favorite prey, like voles and mice, leave urine trails that show up in ultra-violet light. They use these trails to track the hapless rodents. Hence, after a hearty meal, Kestrel stash leftovers in clumps of grass, bushes, fence posts, tree limbs or tree cavities.

Molt

Females begin their molt during incubation and complete it by the end of the breeding season. Males, who are responsible for capturing most of the prey for the family, do not begin their molt until near the end of the breeding season.

Migration

The American kestrel is a year-round resident over most of the United States but is migratory over the northern-most portions of its range (National Geographic Society. Because of their late molt, males migrate and arrive at the wintering grounds later than females or immatures.

Breeding activities and social organization

Adult kestrels are solitary, except during the breeding season, and maintain territories even in winter. Kestrels typically build their nests in tree cavities but have used holes in telephone poles, buildings, or stream banks when tree cavities are not available.

Both parents participate in incubation, but the female performs most of the incubation, while the male provides her with food. Following hatching, the male brings most of the prey to the nestlings. After fledging, young kestrels remain dependent on their parents for food for at least 2 to 4 additional weeks.

Fledglings often perch and socialize with their siblings prior to dispersal. In Florida, resident kestrels (Paulus subspecies) maintain year-round pair bonds and joint territories. The resident pairs have a competitive advantage over winter migrants (sparverius subspecies) in their territories.

Home range and resources

Although some investigators have not noted territorial defense demonstrated that kestrels defend territories by introducing captured birds into other birds' territories. Winter foraging territories range from a few hectares in productive areas to hundreds of hectares in less productive areas.

Summer breeding territories probably follow the same pattern. Population density although much smaller than red-tailed hawks and bald eagles, reported kestrel breeding population densities can be similarly low 0.0003 to 0.004 nests per hectare.

Population Dynamics

Kestrels are sexually mature in the first breeding season after their birth. Scarcity of suitable nesting cavities probably limits the size of kestrel populations in parts of the United States. Three to four young may fledge per nest per year, but the mortality of juveniles in the first year is high (60 to 90 percent). Adult mortality can below 12 % per year.

Similar species

from general references, the peregrine falcon (Falco peregrinus), a rare resident of woods, mountains, and coasts, preys almost exclusively on birds. Though uncommon, they can be found wintering in most states, but rarely breeding. These large falcons are 38 cm) have been reintroduced in some areas in the United States and have nested in urban environments.

The merlin (Falco columbarius), larger (30 cm) than the kestrel, can be found in a variety of habitats but nests in open woods or wooded prairies. Wintering along coasts and near cities of the Great Plains, it primarily eats birds.

The prairie falcon (Falco mexicanus) also is a larger bird 39 to 50 cm than the kestrel and inhabits dry, open country and prairies. A year-round resident of the western United States, prairie falcons prey chiefly on birds and small mammals.

American Kestrels Call

American Kestrel (falcons) are quite vocal and have a limited set of calls. However, the familiar one is a repeated loud, thrilled series of 3-6 klee or killy lasting just over a second. The Kestrels call is distinctive and an excellent way to find these birds. Moreover, they do not need to drink free-standing water, as they need from the moisture of their prey.

Kestrel Take-Off and Landing

During take-off, the forward speed of the bird being low, the primary requirement of lift to overcome gravity is essentially provided by a fast flapping rate which is higher than in normal forward flight. The amplitude of flapping is also greater.

Similarly, during landing, the speed being low, the bird's wings must generate the required lift to uphold the weight and break the forward motion. Therefore, the wings are spread wide and the flapping motion adjusted. Kestrel also used "reduced span" upstroke in fast flight. The bird is having the habit of pumping their tail feathers up and down when perched, particularly after landing.

Sexes

The male kestrel has a rusty back, blue-gray wings and crown with a rusty cap, and distinguishing black facial stripes, and lightly spotted underparts. However, the female is alike, with a rusty back, wings, and breast streaking, but it does not have the blue-gray markings of the male. Source: CP

Breeding activities and social organization of American Kestrel

Home range and resources of American Kestrel

American Kestrel (falcons) are quite vocal and have a limited set of calls.

The American kestrel is a year-round resident over most of the United

Read More – The Lesser Goldfinch (Spinus psaltria) / The Himalayan Cutia / The fire-tailed myzornis / Pando – The One Tree Forest

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