THE PLEURODIRA

 

The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differences between them, although anatomical and largely internal, are nonetheless significant, and the zoogeographic implications of them are substantial. The Pleurodira are known more commonly as the side-necked turtles and the name Pleurodira quite literally translates to side neck, whereas the Cryptodira are known as hidden-necked turtles.^[6] The Pleurodira turtles are currently restricted to freshwater habitats in the Southern Hemisphere, largely to Australia, South America, and Africa. Within the Pleurodira, three living families are represented: Chelidae, also known as the Austro-South American side-necked turtles, the Pelomedusidae, also known as the African mud terrapins, and the Podocnemididae, also known as the American side-neck river turtles.^[6][7] However, they are a cosmopolitan clade across the Cretaceous and Cenozoic, and even occurred in marine environments across the world.^[8][9]

 

Definition and description

 

 

 

 The Pleurodira are identified by the method with which they withdraw their heads into their shells. In these turtles, the neck is bent in the horizontal plane, drawing the head into a space in front of one of the front legs. A larger overhang of the carapace helps to protect the neck, which remains partially exposed after retraction. This differs from the method employed by a cryptodiran, which tucks its head and neck between its forelegs, within the shell.

The different methods of bending the neck require completely different anatomies of the cervical vertebrae. All extant turtles studied so far have eight vertebrae in the neck.^[10] In the Pleurodira, these vertebrae are narrow in cross-section and spool-shaped with biconvex centra on one or more of the cervicals.^[10] These centra act as a double joint, allowing a large degree of sideways movement and providing a means of folding the neck onto itself in the lateral plane. Conversely, in the Cryptodira, the neck bones are wide and flat. The biconvex centra in some of the cryptodiran cervicals allow the neck to fold onto itself in the vertical plane.^[10]

Pleurodirans also differ from cryptodirans in the emarginations of their skulls. Skull emargination provides room and anchorage for the jaw muscles. The connection points and the position of the emarginations relate to different bones of the skull.

Another difference is in the arrangement of the bones of the shell and the scutes overlaying them. Pleurodiran turtles have 13 scutes on the plastron of the shell, whereas cryptodiran turtles have only 12. The extra scute is called the intergular and is at the front of the plastron between the gular scutes. Pelomedusid turtles also possess mesoplastra, further differentiating this group.

 

Family: Chelidae

 

One of the three families that still lives in this suborder is the family Chelidae. This family contains 14 genera with a total of 61 species, and they are distributed among Australia, New Guinea, and South America.^[7] This group of Testudines characteristically have dorsoventrally flattened skulls and shells and are known for long snake like necks.^[7]

This family is unique for having a specially adapted strategy for catching prey. While the majority of the family Chelidae are omnivores there are 17 species that are carnivores.^[7] Those carnivores are Chelus fimbratus and species of the Chelodina genus.^[7] This special strategy is referred to as a gape-suck mechanism.^[7][11] This mechanism is when the turtle first opens its mouth little by little at first. Then, when the turtle is within striking range of the prey, it will open its mouth completely sucking in water at such a rate that the current into its mouth is too strong for prey to escape and engulf the prey within 0.004 seconds.^[11] This strategy also circumvents issues to quick capture of underwater prey. These issues include: resistance to rapid movement in water, pressure-waves due to rapid strike, and rapid water intake when feeding.^[11]

 

Taxonomy

 

 

 

 

 

 

 

THE BLACK- NECKED CRANE

 

 

The Black-necked Crane (Grus nigricollis) is a medium-sized crane in Asia that breeds on the Tibetan Plateau and remote parts of India and Bhutan. It is 139 cm (55 in) long with a 235 cm (7.8 ft) wingspan, and it weighs 5.5 kg (12 lbs). It is whitish-gray, with a black head, red crown patch, black upper neck and legs, and white patch to the rear of the eye. It has black primaries and secondaries. Both sexes are similar. Some populations are known to make seasonal movements. It is revered in Buddhist traditions and culturally protected across much of its range. A festival in Bhutan celebrates the bird while the Indian union territory of Jammu and Kashmir considers it as the state bird.

 At Bronx Zoo, New York, USA.

 

Description

 

 

This medium-sized crane is mostly grey with a black head and neck. The lores and crown are naked and dull red. A small patch of white feathers are present below and behind the eye. The tail is black and makes it easy to distinguish at a distance from the similar looking common crane which has grey tail.^[2]

 

Distribution and habitat

Copy of an illustration in Nikolai Przhevalsky's work where he gave the species its binomial name

From Phobjikha Valley, Bhutan.

The black-necked crane summers mainly in the high altitude Tibetan Plateau. The breeding areas are alpine meadows, lakeside and riverine marshes and river valleys. They also make use of barley and wheat fields in these areas. Wintering areas tend to be in sheltered valleys or lower altitudes. The largest populations are in China with smaller numbers extending into Vietnam, Bhutan and India.^[3] Small populations have been noted in northern Sikkim.^[4] A small group of 20 to 40 was once known to regularly visit the Subansiri area in the Apa Tani valley^[5] until 1975^[6] and vagrants have been recorded in Nepal.^[7]

In 1996 there were about 4,000 of the birds, most of whom spent their winters in Tibet in the valleys of the Nyanga, Lhasa and Pengbo rivers and the middle reaches of the Yarlung Tsangpo.^[8] The Hutoushan Reservoir in the Pengbo valley is an important winter resting place, with a 96 square kilometres (37 sq mi) Linzhou Black-necked Crane Preservation Zone established in 1993.^[9] Black-necked cranes also winter in small numbers in two valleys of western Arunachal Pradesh, India. These are Sangti and Zemithang.^[10][11][12]

 

Behaviour and ecology

 

Black-necked cranes forage on the ground in small groups, often with one bird acting as a sentinel. In winter, the groups arrive and leave the feeding grounds together, but may split into family groups, each group keeping their own small feeding territories in a big marshes or fields.^[6] They spend nearly 75% of the day foraging with peak feeding in the early morning and late afternoon.^[3] While foraging, they keep walking and they also walk long distances between the feeding spots. In this manner, they cover several kilometers a day while foraging.^[13] They feed on the tubers of sedges, plant roots, earthworms, insects and other invertebrates, frogs and other small vertebrates. They may also feed on fallen grains of barley, oats and buckwheat and will sometimes dig up and feed on potatoes, carrots and turnips.^[3][14] Their loud trumpeting calls are similar to those of other cranes.^[2]

 

 

A 1938 photograph of a flock in the Brahmaputra valley

These birds are very wary, but in some areas they are accustomed to the local people who do not disturb them. These cranes appear to be able to distinguish people in traditional dress and are especially wary of others.^[13]

100 odd of this species come to India every year for breeding. Photograph has been taken at Tso Kar, Ladakh, Jammu and Kashmir, India.

Like many other crane species, they are believed to form long-lasting pair bonds and dancing displays are made during the breeding season. The breeding birds are territorial and will chase away any intruders of the same species immediately, though they are generally tolerant of other species.^[13] The nest site is usually a pre-existing mud island inside a large shallow wetland, sometimes shared along with bar-headed goose. The nest varies from a scantily lined scratch in the ground to a structure made of grass, rushes and weeds with a depression in the centre, sometimes the eggs laid directly on the grass without any structure.^[15][16] Eggs are laid mainly in May and June. One or two eggs.^[2][17] The birds are relatively more wary when the young ones are small. Till the time when the young ones are able to fly, the family kept moving around the nesting location, but later the family started traveling far and wide in the course of a day. Though the young ones are able to forage independently, usually they accompany the parents during foraging. Short, subdued nasal "kurrr" calls are used by the family to keep in contact and also by adults to indicate availability of food to juveniles. The adults were found to feed the young ones mainly with fish in Ladakh, adults fishing like herons.^[13] They are endangered because of the hunters.

 

Status and threats

A couple of black-necked Tibetan cranes spotted in 2013 near Yamdrok Lake, Tibet Autonomous Region

The estimated population of the black-necked crane is between 8800 and 11000 individuals. These birds are legally protected in China, India and Bhutan. However habitat modification, drying of lakes and agriculture are threats to the populations. In many areas, dogs belonging to herders are a major threat to young birds. An incident of leopards preying on the roosting cranes during the night has been recorded from the Phobjika valley of Bhutan.^[18] In Bhutan, collisions with power lines have been another cause of mortality in some areas.^[1][19] Eggs may also be preyed on by ravens that may use the opportunity provided when humans disturb the parents.^[3] The drying of wetlands can cause increased accessibility of the nests leading to predation while a rise in the water level can submerge nests.^[20] Loss and degradation of habitat are the main threats facing the black-necked cranes. The problems are most serious in the wintering areas, where wetlands are extensively affected by human activity including irrigation, dam construction, draining, and grazing pressure. In Tibet, widespread changes in traditional agricultural practices have reduced the availability of waste barley and spring wheat.^[20]

Populations in Bhutan are well protected both culturally and legally although some disturbance from tourism exists.^[21]

The black-necked crane is evaluated as Near Threatened on the IUCN Red List of Threatened Species.^[1] It is listed on Appendix I of CITES.

 

See also

 

 

 

 

 Binomial name

 

 Grus nigricollis

Przhevalsky, 1876

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

THE YELLOW- RUMPED HONEYGUIDE

 

The yellow-rumped honeyguide (Indicator xanthonotus) is a sparrow-sized bird in the honeyguide family that is found in Asia, mainly in montane forests along the Himalayas. They are very finch-like but the feet are strong and zygodactyl, with two toes facing forward and two backward. They perch on honeycombs and feed on wax. Males tend to be territorial and stay near honeycombs while females and juveniles forage widely. They are brood parasites, laying their eggs in the nests of tree-hole breeders, possibly barbets.

 From Eaglenest Wildlife Sanctuary in Arunachal Pradesh, India

Description

From Pabyuk-Naitam, East Sikkim, India.

John Gould.

The yellow-rumped honeyguide is sparrow sized and has a stout finch-like bill. The plumage is largely dusky olive and the forehead and lores are orange while the upper plumage. There is a streaked appearance to the wing feathers. The rump is deep orange and extends into the back grading to sulphur yellow. The chin and throat are yellowish while the lower plumage is pale grey with dark streaks. The bill is yellow but dark towards the tip. Females have less extensive yellow on the face and the rump is yellow and lacks the orange. Allan Octavian Hume described the subspecies radcliffi (after Colonel E. Delmé-Radcliffe^[2]) based on specimens from Hazara but no specimens or information from the region have subsequently been obtained putting it in some doubt. The species was described by Blyth based on specimens from near Darjeeling. Ripley described specimens from the Naga Hills as subspecies fulvus (not always recognized), said to be smaller and darker, with the streaking on the abdomen reduced and the yellow on the forehead restricted to the anterior.^[3] This population may be identical to the nominate of the eastern Himalayas.^[4][5] They have twelve tail feathers and nine primaries. The wing is long and pointed.^[6][7]

 

Behaviour and ecology

Head

A chipping call is produced in flight and when agitated. The flight is straight (may sometimes be undulating^[5]) and direct, sometimes in flocks of 20 to 30 birds. At deserted honeycombs, the bird clings tight and presses its tail on the surface of the comb. They feed mainly on the foundation wax of Apis laboriosa that attach the comb to rocks. They feed on active beehives without disturbing the bees much.^[4] They have been observed to make use of the attacks of Vespa mandarinia on Apis laboriosa colonies.^[8]

A display of a male involved fluffing its feathers, holding the bill high and flicking wings while swaying from side to side. A female was observed flicking its tail and pressing it down with wings drooped before being mounted by a male.^[4] They are brood parasites, laying their eggs in the nest of host species. The host species for the yellow-rumped honeyguide are as yet unknown and undocumented. Young birds of honeyguide species have bill-hooks with which they destroy the eggs and chicks of the host.^[5] The male holds territories around hives and are polygynous, allowing females with whom it had mated and their young into the territories. This mating system has been termed as "resource-based non-harem polygyny".^[9]

Unlike other honeyguides, this species has not been observed to lead humans and bears to bee hives.^[5]

 

Distribution and habitat

Adult photographed in West Sikkim, India

The species has been recorded from northern Pakistan (Hazara and Murree Hills^[10]) but the population here may have been extirpated^[5] and then in the Himalayan regions of India from western Uttar Pradesh and Himachal Pradesh extending into Nepal, Sikkim, Arunachal Pradesh and Bhutan (where it is relatively common). It is also found in southeastern Tibet and northern Myanmar.^[5] It is found in coniferous and dry-deciduous forest with rocky boulders and cliffs. May make altitudinal movements seasonally.^[6]

 

 

 

 

 

 

THE LONG- BEAKED COMMON DOLPHIN

 

 The long-beaked common dolphin (Delphinus capensis) is a species of common dolphin. It has a more restricted range than the short-beaked common dolphin (D. delphis). It has a disjointed range in coastal areas in tropical and warmer temperate oceans. The range includes parts of western and southern Africa, much of western South America, central California to central Mexico, coastal Peru, areas around Japan, Korea and Taiwan, and possibly near Oman.^[1][3] Vagrants have been recorded as far north as Vancouver Island. They live in shallow, warmer temperature waters near the coast. They also live in the tropical and subtropical regions.^[4]

 

 

Physical characteristics

 

The long-beaked common dolphin is medium-sized, but smaller than the more popular bottlenose dolphin. Adults range between 1.9 and 2.5 m (6.2 and 8.2 ft), long, and can weigh between 80 and 235 kg (176 and 518 lb), although a range between 80 and 150 kg (180 and 330 lb) is more common.^[5] Males are generally longer and heavier.^[5] The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back.^[6] This species also has a rounded melon on tops of their heads used for echolocation.^[4] It has a long, thin rostrum with up to 60 small, sharp, interlocking teeth on each side of each jaw.^[7] They have more teeth than any other delphinids.^[8]

 

Taxonomy

Delphinus c. tropicalis in the Red Sea

The long-beaked common dolphin is a member of the common dolphin genus, Delphinus within the dolphin family, Delphinidae in the cetaceans order.^[4] Until the mid-1990s, the different forms within Delphinus were not recognized as separate species, but were all considered members of the species D. delphis.^[3][5] In 1994, Heyning and Perrin^[9] did research on these species and then Kingston and Rosel^[10] confirmed there were two separate species. Currently, the two recognized species of Delphinus  are the short-beaked common dolphin (D. delphis) and the long-beaked common dolphin.^[1] The long-beaked common dolphin is generally larger with a longer beak than the short-beaked common dolphin and has a longer rostrum.

The Indo-Pacific common dolphin is sometimes considered a separate species (D. tropicalis), but is more often considered a form of the long-beaked common dolphin.^[1][3]

Behavior

Delphinus capensis with whale watching vessels off Kochi, Japan

Long-beaked common dolphins can live in aggregations of hundreds or even thousands.^[3] Within these large groups, smaller subgroups of 10 to 30, related in either sex or age, typically are found.^[4] They sometimes associate with other dolphin species, such as pilot whales.^[3] They have also been observed bow riding on baleen whales, and they also bow ride on boats.^[3] Breaching behavior and aerial acrobatics are common with this species.^[5]

 

Diet

 

The long-beaked common dolphin has a varied diet consisting of small schooling fish, such as sardines, anchovies, mackerels, pilchards, mullet, drum or croaker. These dolphins may occasionally eat small cephalopods such as octopuses and squid, and more rarely eat small crustaceans like large shrimp or small crab. Since they gather in huge superpods and there is seldom enough food in one place to support all of them, smaller groups leave the main pod for a few hours to feed.^[11] They are able to dive in the water to about 900 feet (270 m) and hold their breath for up to 8 minutes to catch prey.^[4]

 

Reproduction

 

 

See also: Dolphin (Reproduction and sexuality)

The long-beaked common dolphin has a gestation period of 10 to 11 months typically during spring or autumn.^[4][5] The newborn calf has a length of between 80 and 100 cm (2.6 and 3.3 ft) and a weight of about 10 kilograms (22 lb).^[5] The young and juvenile dolphins coloration and patterns are darker than the adults.^[11] Typical interbirth interval ranges from one to three years.^[5] In captivity, this dolphin has hybridized with the common bottlenose dolphin (Tursiops truncatus).^[3][12] One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.^[12] The long-beaked common dolphin can live up to 40 years.^[4]

 

Relationship to humans and other species

 

Long-beaked common dolphins are not common in human care as they are extremely difficult to keep in captivity. In the wild, however, they have been seen travelling with bottlenose dolphins, pilot whales, and yellowfin tuna.^[13]

 

Conservation

 

Delphinus capensis is covered by the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia^[14] and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).^[15] One of the main threats to the long-beaked common dolphin is fisheries. Out of 930 dolphins observed off of Peru between 1985 and 2000, 120 of them had many lacerations on their head, skin, appendages, and teeth. Most of these injuries were from fisheries-related connection.^[16] Another threat to this species is pollution because many of them have shown signs of organochlorine residue on their blubber.^[17] On the coast of California there are only about 25,000 to 43,000 dolphins and on the coast of South Africa there are 15,000 to 20,000.^[5]

 

 

 

 Binomial name

 

 Delphinus capensis

Gray, 1828