Saturday, 3 February 2018
Friday, 2 February 2018
Thursday, 1 February 2018
Wednesday, 31 January 2018
28-3-2017 TARCOLES RIVER COSTA RICA - BARE THROATED TIGER HERON (Tigrisoma mexicanum)
The bare-throated tiger heron (Tigrisoma mexicanum) is a wading bird of the heron family, Ardeidae, found from Mexico to northwestern Colombia, with one recorded sighting from the United States in Hidalgo County, Texas. It is 80 cm (31 in) in length and weighs 1,200 g (42 oz).
This large species is found in more open habitats than other Tigrisoma herons, such as river and lake banks. It waits often motionless for suitable prey such as fish, frogs or crabs to come within reach of its long bill.
This is a solitary breeder, not normally found in heron colonies. The nest is a small flattish stick platform in a tree into which 2–3 green-tinged white eggs are laid.
The throat is bare and is greenish-yellow to orange in all plumages. The adult has black crown and light grey sides of the head, the sides of the neck and the upperparts otherwise blackish narrowly barred buff. The median stripe down the fore-neck is white-bordered with black; the remaining underparts are dull cinnamon brown. The juvenile is buff coarsely barred with black, more mottled and vermiculated on wings; the throat, median underparts, and belly are whitish.
The flight is heavy, and the call is a hoarse howk-howk-howk. Males also give a booming hrrrowwr! call, especially at sunset. During emission of the call, the beak opens wide and undulations can be seen along the course of the throat from mid-thorax caudally.
Tuesday, 30 January 2018
29-3-2017 TARCOLES RIVER, COSTA RICA - TURQUOISE BROWED MOTMOT (Eumomota superciliosa)
The turquoise-browed motmot (Eumomota superciliosa ) also known as Torogoz, is a colourful, medium-sized bird of the motmot family, Momotidae. It inhabits Central America from south-east Mexico (mostly the Yucatán Peninsula), to Costa Rica, where it is common and not considered threatened. It lives in fairly open habitats such as forest edge, gallery forest and scrubland. It is more conspicuous than other motmots, often perching in the open on wires and fences. From these perches it scans for prey, such as insects and small reptiles. White eggs (3–6) are laid in a long tunnel nest in an earth bank or sometimes in a quarry or fresh-water well. Its name originates from the turquoise color of its brow. It is the national bird of both El Salvador and Nicaragua, where it is known as "Torogoz" and "Guardabarranco" respectively.
The bird is 34 cm (13 in) long and weighs 65 g (2.3 oz). It has a mostly grey-blue body with a rufous back and belly. There is a bright blue strip above the eye and a blue-bordered black patch on the throat. The flight feathers and upperside of the tail are blue. The tips of the tail feathers are shaped like rackets and the bare feather shafts are longer than in other motmots. Although it is often said that motmots pluck the barbs off their tail to create the racketed shape, this is not true; the barbs are weakly attached and fall off due to abrasion with substrates and with routine preening.
Unlike most bird species, where only males express elaborate traits, the turquoise-browed motmot expresses the extraordinary racketed tail in both sexes. Research indicates that the tail has evolved to function differently for the sexes. Males apparently use their tail as a sexual signal, as males with longer tails have greater pairing success and reproductive success. In addition to this function, the tail is used by both sexes in a wag-display, whereby the tail is moved back-and-forth in a pendulous fashion. The wag-display is performed in a context unrelated to mating: both sexes perform the wag-display in the presence of a predator, and the display is thought to confer naturally selected benefits by communicating to the predator that it has been seen and that pursuit will not result in capture. This form of interspecific communication is referred to as a pursuit-deterrent signal.
The call is nasal, croaking and far-carrying.
The turquoise-browed motmot is a well-known bird in its range. It has acquired a number of local names including guardabarranco ("ravine-guard") in Nicaragua, Torogoz in El Salvador (based on its call) and pájaro reloj ("clock bird") in the Yucatán, based on its habit of wagging its tail like a pendulum. In Costa Rica it is known as momoto cejiceleste or the far-less flattering pájaro bobo ("foolish bird"), owing to its tendency to allow humans to come very near it without flying away.
28-3-2017 TARCOLES RIVER COSTA RICA - ROSEATE SPOONBILL (Platalea ajaja)
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The Roseate spoonbill (Platalea ajaja) is a gregarious wading bird of the ibis and spoonbill family, Threskiornithidae. It is a resident breeder in both South and North America. Plume hunting in the 18th and 19th centuries almost drove these beautiful birds to extinction.
Adult Roseate spoonbills have a bare greenish head and a white neck, back, and breast (with a tuft of pink feathers in the center when breeding), and are otherwise a deep pink. The colors can range from pale pink to bright magenta, depending on age, whether breeding or not, and location. Unlike herons, spoonbills fly with their necks outstretched, and they alternate groups of stiff, shallow wingbeats with glides.
Roseate spoonbills are resident breeders in South America mostly east of the Andes and in coastal regions of the Caribbean, Central America, Mexico, the Gulf Coast of the United States, and from central Florida's Atlantic coast at least as far north as South Carolina's Myrtle Beach. These birds inhabit coastal marshes, bays, lagoons, mangroves, and mudflats. They usually nest and roost in trees and shrubs near water.
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Roseate spoonbills are gregarious birds and prefer to feed and fly in groups. They are active during the day spending many hours foraging in shallow fresh or coastal waters. The birds feed by swinging their bill from side to side as they steadily walk through the water, often in groups. Their spoon-shaped bill allows them to sift easily through mud feeling and looking for prey. The bill has sensitive nerve endings and once the birds feel the prey touch their bill they snap it closed. Roseate spoonbills roost in colonies often with other waders. They sleep standing, often on one leg with their head hidden under a shoulder. These birds are usually silent but when alarmed they will produce a low-pitched 'huh-huh-huh'; when feeding they may utter a very low, guttural sound.
Roseate spoonbills are serially monogamous and stay with one partner during one breeding season. They nest in small colonies and males constantly defend their territories against intruders. Preferred nesting areas usually include shrubs, trees, or often mangroves. The nest is a large cup-shaped structure made with small branches and stems. The female lays 2 to 5 whitish with brown markings eggs and both parents incubate them for 22-23 days. The chicks are altricial. They are born naked, helpless, and blind. At 35-42 days after hatching the young leave the nest and begin to fly when they are 7-8 weeks old.
14-4-2017 GIBRALTAR - YELLOW LEGGED GULL (JUVENILE) (Larus michahellis)
The Yellow-legged Gull (Larus michahellis) is a large, robust seabird with a commanding presence. Its size can be quite variable, with the smallest females being scarcely larger than a Common Gull, and the largest males approaching the heft of a Great Black-backed Gull. Adults typically exhibit a grey back, a shade lighter than that of the Lesser Black-backed Gull, and their heads are notably whiter in the autumn months. A distinctive feature is their yellow legs, which give this species its common name.
When observing the Yellow-legged Gull, look for the yellow legs that contrast with the grey back and the white head, which becomes even whiter during the autumn. The wing tips are black with limited white spots, and adults have a red spot on the bill. The eye is surrounded by a red ring. Juveniles can be identified by their paler head, rump, and underparts, dark bill and eyes, and a black band on the tail.
This gull favors a variety of coastal environments, often nesting on sea cliffs, islands, and occasionally on buildings within urban settings. It is also known to breed on trees in some regions.
The Yellow-legged Gull has a breeding range centered around the Mediterranean Sea, extending to the Atlantic islands and coasts as far north as Brittany and west to the Azores. Its presence is also noted on the western side of the Black Sea.
The species is known for its adaptability, with many individuals remaining in the same area year-round, while others migrate to milder regions of western Europe or head south to areas such as Senegal and the Red Sea. Post-breeding dispersal can lead to increased numbers in regions like southern England from July to October.
The vocalizations of the Yellow-legged Gull are characterized by a loud, laughing call that is deeper and more nasal than that of the Herring Gull.
Breeding typically occurs in colonies, with nests constructed on the ground or cliff ledges. The nests are mounds of vegetation, and the species is known for its vigorous defense of its eggs, usually numbering three. Incubation lasts for 27–31 days, and fledging occurs after 35–40 days.
An opportunistic forager, the Yellow-legged Gull is omnivorous, feeding on a wide range of items from rubbish tips to field prey, coastal offerings, and even other seabirds' catches. Remarkably, during periods of food scarcity, such as the lockdown in Italy in 2020, these gulls have been observed preying on larger animals like rats and rock doves.
The Yellow-legged Gull is currently listed as Least Concern on the IUCN Red List, indicating that it does not face any immediate threat of extinction.
1-4-2017 MIAMI, FLORIDA - BROWN PELICAN (MALE) (Pelecanus occidentalis)
The back, rump, and tail are streaked with gray and dark brown, sometimes with a rusty hue. The male and female are similar, but the female is slightly smaller. The nonbreeding adult has a white head and neck, and the pre-breeding adult has a creamy yellow head. The pink skin around the eyes becomes dull and gray in the non-breeding season. It lacks any red hue, and the pouch is strongly olivaceous ochre-tinged and the legs are olivaceous gray to blackish-gray. It has pale blue to yellowish-white irides which become brown during the breeding season. During courtship, the bill becomes pinkish red to pale orange, redder at the tip, and the pouch is blackish. Later in the breeding season, the bill becomes pale ash-gray over most of the upper jaw and the basal third of the mandible. The Brown pelican is exceptionally buoyant due to the internal air sacks beneath its skin and in its bones. It is as graceful in the air as it is clumsy on land.
The Brown pelican (Pelecanus occidentalis) has been described as a comically elegant bird. Groups of these seabirds glide above surf along western and southern coasts, gracefully echoing the waves with their rise and fall. They plunge-dive from high up to feed, the force of impact serving to stun small fish, which they then scoop up. Today this species is fairly common - a good example of recovery from the pesticide pollution that once threatened them with extinction.
The Brown pelican is the smallest of the eight extant pelican species but is often one of the larger seabirds in their range nonetheless. Like all pelicans, it has a very long bill, measuring 280 to 348 mm (11.0 to 13.7 in) in length. The nominate subspecies in its breeding plumage has a white head with a yellowish wash on the crown. The nape and neck are dark maroon–brown. The upper sides of the neck have white lines along the base of the gular pouch, and the lower foreneck has a pale yellowish patch. The feathers at the center of the nape are elongated, forming short, deep chestnut crest feathers. It has a silvery gray mantle, scapulars, and upperwing coverts (feathers on the upper side of the wings), with a brownish tinge. The lesser coverts have dark bases, which gives the leading edge of the wing a streaky appearance.
The uppertail coverts (feathers above the tail) are silvery white at the center, forming pale streaks. The median (between the greater and the lesser coverts), primary (connected to the distal forelimb), secondary (connected to the ulna), and greater coverts (feathers of the outermost, largest, row of upperwing coverts) are blackish, with the primaries having white shafts and the secondaries having variable silver-gray fringes. The tertials (feathers arising in the brachial region) are silver-gray with a brownish tinge. The underwing has grayish-brown remiges with white shafts to the outer primary feathers. The axillaries and covert feathers are dark, with a broad, silver–gray central area. The tail is dark gray with a variable silvery cast. The lower mandible is blackish, with a greenish-black gular pouch at the bottom for draining water when it scoops out prey. The breast and belly are dark, and the legs and feet are black. It has a grayish-white bill tinged with brown and intermixed with pale carmine spots. The crest is short and pale reddish-brown in color.
The Brown pelican occurs throughout the Pacific, Atlantic, and Gulf Coasts of the Americas. Most brown pelican populations are resident (nonmigratory) and dispersive (moving from their birth site to their breeding site, or their breeding site to another breeding site); however, some populations migrate, depending on local conditions. Brown pelicans are strictly marine and coastal birds but occasionally follow large rivers during storms. They avoid the open sea and rarely occur far offshore, usually frequenting shallow waters along coasts, as well as estuaries and bays. They breed on the arid coasts of flat, bare, remote islands, or occasionally in mangroves. Brown pelicans can often be seen around fishing ports.
Brown pelicans, after bathing, use their beaks to spread oil from the uropygial gland over their feathers.
Courtship displays by Brown pelicans usually last 2-4 days, but sometimes as long as three weeks.
Brown pelicans incubate their eggs by means of their webbed feet, turning the eggs from time to time.
Brown pelicans are the only type of pelican that dive in order to catch prey. They glide low above the water and when they see a fish they fly to a height of 10 m (30 ft), fold their wings back, and plunge down into the sea.
Brown pelicans do exercises, including stretching and turning their pouch inside out to maintain its flexibility.
Brown pelicans are very gregarious and live throughout the year in flocks. They are diurnal but sometimes forage at night during a full moon. They sleep on land either while standing on both their feet or resting on their breast and belly, their head sideways on their shoulder with their beak tilted towards the side. This is the only pelican species that dives from height as the main method of obtaining food. Their air sacs enable buoyancy for them in the water. They do not swim under the water but plunge their head below the surface when catching prey. Brown pelicans are territorial during the nesting period. Threat displays, often carried out when another pelican is too close to an individual’s nest involve head swaying, indicating readiness to interact, and bowing and a "hrraa-hrraa" sound. Young pelicans who approach a nest too closely are often killed.
Brown pelicans do not have many natural enemies. Although nests on the ground are sometimes destroyed by flooding, hurricane, or other natural disasters, people pose the biggest threat to pelicans. In the early 20th and late 19th centuries, pelicans’ feathers were sought after to adorn women’s clothing, especially hats. Today tourists and fishermen threaten them by disturbing their colonies, especially in Mexico.
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