dendroica
libutron:

We see it blue, but how is it seen by his fellows? - Some facts about avian vision
No way to know really. Although we tend to be somewhat self-satisfied with our own color vision, it is not particularly well developed when compared with that of most vertebrates. The color vision of most humans relies on three types of retinal cone photoreceptors, all of them neurally integrated in the assessment of spectral radiances and thus in the perception of color, our colors are mapped in three-dimensional color space (we are “trichromatic”).
In contrast, most birds have four types of cone involved in their color vision and are likely to be tetrachromatic. The consequence of four cone pigments, and tetrachromacy in particular, is that birds see the world differently from humans and in a way for which it is hard to compensate because we simply lack the neural machinery.
There are also other additional physiological differences that limit our appreciation of a bird’s view of the world. First, most of the retinal cones of birds contain oil droplets with high carotenoid content that act as spectral filters and modify the spectral sensitivities of the cones. Second, birds are sensitive to ultraviolet (UV) wavelengths, whereas humans are not.
The differences between human and avian vision mean that, for many purposes, human vision, or standards derived from human psychophysics, are inappropriate for studying bird visual behavior.
In the case of the ‘bluest’ birds, those that have the highest percentage of blue feathers on the body, such as the Black-naped Monarch (Hypothymis azurea), it is known that these ornamental feathers reflect light maximally at the shortest wavelengths (UV), with the greatest intensity and the greatest contrast. 
References: [1] - [2]
Photo credit: ©Henry Koh | Locality: Kaen Krachan National Park, Thailand (2013)

libutron:

We see it blue, but how is it seen by his fellows? - Some facts about avian vision

No way to know really. Although we tend to be somewhat self-satisfied with our own color vision, it is not particularly well developed when compared with that of most vertebrates. The color vision of most humans relies on three types of retinal cone photoreceptors, all of them neurally integrated in the assessment of spectral radiances and thus in the perception of color, our colors are mapped in three-dimensional color space (we are “trichromatic”).

In contrast, most birds have four types of cone involved in their color vision and are likely to be tetrachromatic. The consequence of four cone pigments, and tetrachromacy in particular, is that birds see the world differently from humans and in a way for which it is hard to compensate because we simply lack the neural machinery.

There are also other additional physiological differences that limit our appreciation of a bird’s view of the world. First, most of the retinal cones of birds contain oil droplets with high carotenoid content that act as spectral filters and modify the spectral sensitivities of the cones. Second, birds are sensitive to ultraviolet (UV) wavelengths, whereas humans are not.

The differences between human and avian vision mean that, for many purposes, human vision, or standards derived from human psychophysics, are inappropriate for studying bird visual behavior.

In the case of the ‘bluest’ birds, those that have the highest percentage of blue feathers on the body, such as the Black-naped Monarch (Hypothymis azurea), it is known that these ornamental feathers reflect light maximally at the shortest wavelengths (UV), with the greatest intensity and the greatest contrast. 

References: [1] - [2]

Photo credit: ©Henry Koh | Locality: Kaen Krachan National Park, Thailand (2013)

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libutron:

Violet-backed Starling - Cinnyricinclus leucogaster

As you can see in these photos, in the African species Cinnyricinclus leucogaster (Passeriformes - Sturnidae) the sexual dimorphism is extreme in terms of coloration plumage. It means that both males and females are  phenotypically different  or have different appearance.

Males have head, neck, back and tail of brilliant purple. The underside is white. The female, however, is drab; the purple of the male is replaced by olive green feathers and the white underside is flecked with green dashes.

Reference: [1]

Photo credit: ©KS Kong | Locality: unknown (2013) | [Top] - [Bottom]

Birds Under Threat From Brown Tree Snake in Marianas
The Rufous Fantail (Rhipidura rufifrons mariae), a rare species found on Rota, Northern Mariana Islands, is one of the #birds at risk from brown tree snakes, which have devastated bird populations on Guam. Efforts to safeguard the Marianas’ remaining native birds, such as snake trapping and translocations of birds to islands without snakes, are underway. 
Read more: Yahoo News
(via: American Bird Conservancy)
Photograph by Jack Jeffrey

Birds Under Threat From Brown Tree Snake in Marianas

The Rufous Fantail (Rhipidura rufifrons mariae), a rare species found on Rota, Northern Mariana Islands, is one of the #birds at risk from brown tree snakes, which have devastated bird populations on Guam. Efforts to safeguard the Marianas’ remaining native birds, such as snake trapping and translocations of birds to islands without snakes, are underway.

Read more: Yahoo News

(via: American Bird Conservancy)

Photograph by Jack Jeffrey

ABC Bird of the Week:  Black Rail

The tiny, red-eyed Black Rail is only the size of a sparrow and is the smallest rail in North America. Like its South American relative, the Junin Rail, it is as elusive as a mouse, skulking and scurrying under the cover of dense marsh vegetation and rarely taking flight.

Despite their small size, Black Rails are fiercely territorial and call loudly and frequently during the mating season, a distinctive three-noted “kickee-doo.”

The Black Rail population has been declining steeply over the last 10-20 years, likely due to increasing development in coastal areas, which has caused habitat loss and degradation of suitable breeding areas…

(read more: American Bird Conservancy)

photos: Peter LaTourette and david Seibel

New Zealand pigeon or kererū (Hemiphaga novaeseelandiae)

… is a bird endemic to New Zealand. Commonly called wood pigeon.
The New Zealand pigeon is a large, 550–850 g (19–30 oz), arboreal fruit-pigeonfound in forests from Northland to Stewart Island/Rakiura, ranging in habitats from coastal to montane. The New Zealand pigeons are commonly regarded as frugivorous, primarily eating fruits from native trees. They play an important ecological role, as they are the only birds capable of eating the largest native fruits and drupes (those with smallest diameter greater than 1 cm), such as those of the taraire, and thus spreading the seeds intact…

(read more: Wikipedia)

photos: Kereru Discovery, Matt Binns, and Philip Poole

* FInd out more about Kereru conservation in New Zealand:

http://kererudiscovery.org.nz/

dendroica
libutron:

Tui - Prosthemadera novaeseelandiae
Endemic to New Zealand, the commonly named Tui,Prosthemadera novaeseelandiae (Passeriformes - Meliphagidae) is an important pollinator of native forest flowers. The flowers of the harakeke, or flax, are perfectly shaped to fit the tui’s beak. The yellow colouring on this tui’s forehead is a dusting of pollen from the harakeke flowers from which it has been feeding on nectar.
They are intelligent, aggressively territorial, and are said to be able to imitate the calls of nearly every other bird, as well as a vast array of other sounds.
References: [1] - [2]
Photo and text credit: ©Sid Mosdell | Locality: Waikawa, Marlborough, New Zealand (2011)

libutron:

Tui - Prosthemadera novaeseelandiae

Endemic to New Zealand, the commonly named Tui,Prosthemadera novaeseelandiae (Passeriformes - Meliphagidae) is an important pollinator of native forest flowers. The flowers of the harakeke, or flax, are perfectly shaped to fit the tui’s beak. The yellow colouring on this tui’s forehead is a dusting of pollen from the harakeke flowers from which it has been feeding on nectar.

They are intelligent, aggressively territorial, and are said to be able to imitate the calls of nearly every other bird, as well as a vast array of other sounds.

References: [1] - [2]

Photo and text credit: ©Sid Mosdell | Locality: Waikawa, Marlborough, New Zealand (2011)

libutron
libutron:

Rose-collared Piha - Lipaugus streptophorus
The Rose-collared Piha, Lipaugus streptophorus (Passeriformes - Cotingidae), is endemic to the spectacular and poorly explored tepuis of the Guianan shield. 
Both sexes are gray overall with pink undertail coverts, but the male has a bold pink collar as well. This sexual dimorphism is unusual among pihas, as is the Rose-collared’s habit of perching in the open at the forest edge. 
Currently this species is known only from the cluster of tepuis around the Gran Sabana on the borders of Venezuela, Guyana, and Brazil.
Reference: [1]
Photo credit: ©Marcelo Camacho | Locality: Bolivar, Venezuela (2012)

libutron:

Rose-collared Piha - Lipaugus streptophorus

The Rose-collared Piha, Lipaugus streptophorus (Passeriformes - Cotingidae), is endemic to the spectacular and poorly explored tepuis of the Guianan shield.

Both sexes are gray overall with pink undertail coverts, but the male has a bold pink collar as well. This sexual dimorphism is unusual among pihas, as is the Rose-collared’s habit of perching in the open at the forest edge.

Currently this species is known only from the cluster of tepuis around the Gran Sabana on the borders of Venezuela, Guyana, and Brazil.

Reference: [1]

Photo credit: ©Marcelo Camacho | Locality: Bolivar, Venezuela (2012)

astronomy-to-zoology
astronomy-to-zoology:

Silvery Grebe (Podiceps occipitalis)
…a species of grebe (Podicipedidae) which breeds in Argentina, the Falkland Islands, Chile and the western parts of Bolivia, Peru, Ecuador, and Colombia. It is also a known migrant in Paraguay and southern Brazil. Like all grebes, silvery grebes are water birds and typically inhabit freshwater lakes and ponds. In the Andes it is sometimes seen foraging on hypersaline lakes, and saline lakes in Patagonia. Silvery grebes will feed on a variety of aquatic invertebrates which are caught while diving under water. 
Class
Animalia-Chordata-Aves-Podicipediformes-Podicipedidae-Podiceps-P. occipitalis
Image: Patty McGann

astronomy-to-zoology:

Silvery Grebe (Podiceps occipitalis)

…a species of grebe (Podicipedidae) which breeds in Argentina, the Falkland Islands, Chile and the western parts of Bolivia, Peru, Ecuador, and Colombia. It is also a known migrant in Paraguay and southern Brazil. Like all grebes, silvery grebes are water birds and typically inhabit freshwater lakes and ponds. In the Andes it is sometimes seen foraging on hypersaline lakes, and saline lakes in Patagonia. Silvery grebes will feed on a variety of aquatic invertebrates which are caught while diving under water. 

Class

Animalia-Chordata-Aves-Podicipediformes-Podicipedidae-Podiceps-P. occipitalis

Image: Patty McGann

ABC Bird of the Week:  Swainson’s Hawk
This handsome western buteo, which occurs in both light and dark morphs (color variations), was named for British naturalist William Swainson. Some of its folk names—“grasshopper hawk” or “locust hawk”—reflect this bird’s tastes in prey. 
Starting in late August, nearly the entire population of Swainson’s Hawks migrates south to Argentina and Brazil in huge “kettles” or flocks. Over 800,000 Swainson’s Hawks can pass by single hawk-watching sites in Veracruz, Mexico, in a single fall day.
The species’ migration is a round trip of more than 12,000 miles—the longest of any North American raptor.
In the 1990s, Swainson’s Hawks showed an alarming decline in the western U.S., which was traced to heavy mortality on their wintering grounds. An estimated 35,000 birds had died in Argentina in one season alone, carpeting the ground with dead birds in some places…
(read more: American Bird Conservatory)
photograph by Ian Maton

ABC Bird of the Week:  Swainson’s Hawk

This handsome western buteo, which occurs in both light and dark morphs (color variations), was named for British naturalist William Swainson. Some of its folk names—“grasshopper hawk” or “locust hawk”—reflect this bird’s tastes in prey.

Starting in late August, nearly the entire population of Swainson’s Hawks migrates south to Argentina and Brazil in huge “kettles” or flocks. Over 800,000 Swainson’s Hawks can pass by single hawk-watching sites in Veracruz, Mexico, in a single fall day.

The species’ migration is a round trip of more than 12,000 miles—the longest of any North American raptor.

In the 1990s, Swainson’s Hawks showed an alarming decline in the western U.S., which was traced to heavy mortality on their wintering grounds. An estimated 35,000 birds had died in Argentina in one season alone, carpeting the ground with dead birds in some places…

(read more: American Bird Conservatory)

photograph by Ian Maton

Brant (Branta bernicla)
Brant are small, dark geese with large wings that give them their characteristic strong flight. They often nest in loose colonies in arctic North America and Russia using coastal tundra, islands, deltas, lakes, and sandy areas among puddles and shallows and vegetated uplands. 
To avoid predation, they build nests on small offshore islands, in small ponds or on gravel spits. Brant winter along the Pacific coast from Alaska to Baja California and mainland Mexico, and along the Atlantic coast from Massachusetts to North Carolina, primarily along lagoons and estuaries and on shallow bays.
Credit: U.S. Fish & Wildlife Service
(via: USFWS_Migratory Birds)

Brant (Branta bernicla)

Brant are small, dark geese with large wings that give them their characteristic strong flight. They often nest in loose colonies in arctic North America and Russia using coastal tundra, islands, deltas, lakes, and sandy areas among puddles and shallows and vegetated uplands.

To avoid predation, they build nests on small offshore islands, in small ponds or on gravel spits. Brant winter along the Pacific coast from Alaska to Baja California and mainland Mexico, and along the Atlantic coast from Massachusetts to North Carolina, primarily along lagoons and estuaries and on shallow bays.

Credit: U.S. Fish & Wildlife Service

(via: USFWS_Migratory Birds)