The Gila Monster

            The Gila monster is the largest lizard in the United States, and one of the few species of venomous lizard in the world. It has a stocky body with a large head and a short, fat tail. The skin consists of many round, bony scales, a feature that was common amongst the dinosaurs but is unusual in today's reptiles. Gila monsters have a striking bright pink and black colouration and the two subspecies can be distinguished by their different patterns; the banded Gila monster (Heloderma suspectum cinctum) has a band of light markings along the back whilst in the reticulated Gila monster (Heloderma suspectum suspectum) these light marks are joined in a network. With their venomous bite and elusive nature, these lizards have inspired many myths over the centuries.

Status

            Classified as Near Threatened (NT) on the IUCN Red List.

Population

            This species is never very abundant, but its abundance varies greatly. It is represented by well over 100 collection/observation sites that are well distributed throughout the range (Campbell and Lamar 2004). The total adult population size is unknown but is probably at least several thousand; the species is fairly common in at least some parts of the range. Beck (1985) estimated that the population in Utah included 450 to 800 individuals, down from an estimated 2,000 to 5,000 before the 1930s. It is probably declining even more seriously in Mexico.

Habitat

            Occupied vegetation types include desert grassland, Mohave and Sonoran desert scrub, and thorn scrub (Sonora); less often oak or pine-oak woodland. In Mexico, it occurs on lower mountain slopes and adjacent plains and beaches, sometimes in irrigated areas. Canyon bottoms, arroyos (dry creeks), and rocky slopes may support relatively dense populations in some parts of Arizona and Sonora.

Range

            The majority of the Gila monster's range is in western and southern Arizona, south to southern Sonora in Mexico, although populations are also found in restricted areas of California, Nevada, Utah and New Mexico. Of the subspecies, the banded Gila monster occupies the northern extent of the species' range. The name 'Gila monster' is derived from the Gila River Basin in Arizona, part of this species' range.

Biology

            As an adaptation to their harsh desert environment, Gila monsters spend a large proportion of their time underground in burrows, hibernating during the winter and sheltering from the midday sun in the scorching summer months. The lizards emerge from hibernation in spring and the majority of their activity occurs in the following three-month period. Mating may take place from April to June; males 'wrestle' to assert dominance. Females then lay their clutch of up to 12 eggs in late June or August. Eggs are laid in depressions dug into the soil and unusually remain incubating underground throughout the winter, hatching the following spring.

            In springtime, Gila monsters are active during the day, although they are mainly above ground in the morning and late afternoon to avoid the midday heat. These lizards feed on eggs, young birds and rodents, as well as lizards; juveniles are able to consume over 50% of their body weight at one time. Gila monsters are able to survive for months without food as they store fat in their particularly large tail. The infamous venomous bite of the Gila monster is used as a defensive measure rather than to attack prey. If threatened, these lizards will back away hissing with their mouth open, and if provoked they attack surprisingly quickly with a bite that can be extremely painful to humans, although it is rarely life-threatening

Threat

            Populations have been exploited (illegally) by commercial and private collectors, and they have suffered from habitat destruction due to urbanization and agricultural development (New Mexico Department of Fish and Game 1985). Concrete-lined canals are barriers to movement, as are busy highways. Mortality on roads likely is increasing as traffic volume increases on established highways and new roads are built. The most important reason for the decline is habitat loss resulting from development. It is probably decreasing in southern Sonora due to expanding commercial agriculture.

Conservation

            Gila monsters are protected throughout their range, first receiving protection in 1952 in Arizona when they were the first venomous reptiles to receive such legislation. Over 300 individuals exist in captivity in the United States, and with greater understanding of these elusive lizards many of the common myths and superstitions around them have been surmounted. It is hoped that conservation measures will allow this a colourful desert-dweller to persist despite its depleted habitat.

References

            http://en.wikipedia.org/wiki/Gila_monster

            http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Gilamonster

            http://animals.nationalgeographic.com/animals/reptiles/gila-monster/

            http://www.desertusa.com/sep97/du_gilamonster.html

            http://www.desertmuseum.org/books/nhsd_gila.php

Vaquita

            The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Within this order, there are two suborders, the Mysticeti, or baleen whales, and the Odontoceti, or toothed whales. However, these terms can also be used as a way to distinguish size among species, with cetaceans longer than about 9 feet considered whales, and those less than 9 feet considered dolphins and porpoises.

The four major differences between dolphins and porpoises:

1. Dolphins have cone-shaped teeth while porpoises have flat or spade-shaped teeth.

2. Dolphins usually have a pronounced “beak,” while porpoises do not have a beak.

3. Dolphins have a very curved or hooked dorsal fin, while porpoises have a triangular dorsal fin.

4. Porpoises are generally smaller than dolphins.

            To get even more specific, the term porpoise should also refer only to the six species that are in the family Phocoenidae (harbor porpoise, vaquita, spectacled porpoise, Burmeister’s porpoise, finless porpoise and Dall’s porpoise.)

Vaquita

            The vaquita (Phocoena sinus) is a rare species of porpoise. It is endemic to the northern part of the Gulf of California. Estimates of the number of individuals alive range from 100 to 300. The word "vaquita" is Spanish for little cow. Since the baiji (Lipotes vexillifer) is believed to have gone extinct in 2006, the vaquita has taken on the title of the most endangered cetacean in the world. Other names include Cochito, Gulf of California Harbor Porpoise, Gulf of California Porpoise, Gulf Porpoise, Hafenschweinswal, and Marsouin du Golfe de Californie.

Physical Description

            The vaquita is the smallest of all cetaceans. The current known maximum length is 1.5 m, and the weight about 45 - 50kg. Females are larger than males, as is the case with most species of the porpoise family. The flippers are proportionately larger and the dorsal fin is taller and more falcate. Although it shares the typical stocky body shape of all porpoises with a girth up to 68% of its body length and a blunt beakless head, the vaquita’s appearance is quite distinct from the other five porpoise species. The vaquita has an even, dark gray tone on the back that morphs into a lighter gray on the sides ending in a whitish belly. However, by far its most distinguishing feature is its face. The vaquita sports a black ring around each eye, a stripe from chin to flipper and a definitive black lipped-smile.

Habitat and Range

            The habitat of the vaquita is thought to be restricted to the northern area of the Gulf of California. The vaquita lives in shallow, murky lagoons along the shoreline and is rarely seen in water much deeper than 30 meters; indeed, it can survive in lagoons so shallow that its back protrudes above the surface. The vaquita is most often sighted in water 11 to 50 meters deep, 11 to 25 kilometers from the coast, over silt and clay bottoms. Its habitat is characterized by turbid water with a high nutrient content.

Status

            Classified as Critically Endangered (CR) on the IUCN Red List.

Population

            Estimates of the number of individuals alive range from 100 to 300 and is still falling by 40 animals every year.

Biology

            The vaquita is an elusive marine mammal, which surfaces slowly, barely disturbing the water’s surface when it breathes and then quickly disappearing for long periods. Its cryptic behavior and rarity may be the reasons why little is known about the biology of the vaquita, except that most vaquita births occur around March, gestation is believed to last around 10 to 11 months and one individual was estimated to have lived for 21 years.

            Little is also known about the social organization of this enigmatic species. While the vaquita is most often seen in schools of one to three individuals, groups as large as eight or ten have been seen, and these small schools may form large, loose aggregations for short periods.

            The vaquita has a varied diet, comprising fish that live on or near the ocean bottom, squid and crustaceans. Like other cetaceans, the vaquita produces high-frequency clicks which are used in echolocation. This may be used to locate their prey, but several of the fish species it feeds on are known to produce sound and so it is possible that the vaquita locates them by following their sound, rather than by echolocation. In the murky waters of its habitat, echolocation may also be used to communicate with other vaquitas.

Threat

            It was estimated in 2007 that only around 150 vaquita remained in the world; a number that is declining rapidly as the species is impacted by significant threats. The upper Gulf of California is not only home to this Critically Endangered species; it is also the site of intensive commercial and artisanal fishing. Vaquitas become entangled in the gill nets and trawl nets that are used in these activities, claiming the lives of an estimated 39 to 84 vaquitas each year. This is considered the principal threat to the vaquita’s survival.

            The habitat of the vaquita has undoubtedly been changed by the damming of the Colorado River in the United States and the resulting loss of its flow into the Gulf of California; however, the Gulf remains incredibly productive and loss of river input is not believed to be an immediate threat to the vaquita.

Conservation

            Time is quickly running out for the vaquita, with a group of scientists in 2007 stating that they believed there were only two years remaining in which to find a solution to saving this species. Some measures have already been implemented; the Mexican government created the Upper Gulf of California and Colorado River Delta Biosphere Reserve in 1993 to protect the vaquita and other endangered species. In 2005, the Government also created a vaquita reserve, the area of which partially overlaps with the Biosphere Reserve. A ban on gillnet fishing is currently being enforced within the vaquita reserve, but gillnetting and shrimp trawling continues in the Biosphere Reserve and elsewhere within the range of vaquita. Whilst these are incredibly important steps in the battle to save the vaquita, if conservation efforts are not increased substantially the vaquita will become extinct.

            The Mexican government created the International Committee for the Recovery of the Vaquita (CIRVA): a group of scientists from the UK, Canada, US and Mexico. CIRVA recommends that the most critical measure for the conservation of the vaquita is to reduce by-catch to zero as soon as possible. This will need to be achieved by banning the use of all entangling fishing nets within the vaquitas range. Unfortunately, this is not an easy law to implement, as this will have a serious impact on the people whose livelihoods depend on fishing in the Gulf of California. Funds are urgently needed to buy out these net fisheries and to develop economic alternatives for those people affected. One can only hope that lessons are learnt from the tragic tale of the baiji and that necessary measures are implemented before the vaquita too is driven to extinction.

References

            http://en.wikipedia.org/wiki/Vaquita

            http://www.defenders.org/vaquita/basic-facts

            http://wwf.panda.org/what_we_do/endangered_species/cetaceans/about/vaquita/

            http://vaquita.tv/about-vaquita/

The Snow Leopard

            The Snow Leopard (Panthera uncia) is a white to Smokey-grey colour, with yellow tinged fur and patterned dark-grey to black rosettes and spots. The snow leopard has many adaptations for its cold habitat; long body hair and thick, woolly belly fur, large paws and a well-developed chest and enlarged nasal cavity that warms the cold air as it is breathed in. The long, thick tail is almost a metre in length and is used for balance and as added insulation when wrapped around the body and face at rest. The short forelimbs and long hind limbs enable this leopard to be particularly agile in its steep and rugged habitat.

Status

            The Snow Leopard is classified as Endangered (EN) on the IUCN Red List. Listed on Appendix I of CITES and Appendix II on the Convention on Migratory Species (the CMS or Bonn Convention).

Population

            The total wild population of the snow leopard was estimated at only 4,080 to 6,590 individuals by McCarthy in 2003. Many of these estimates are rough and outdated. There are also 600-700 snow leopards in zoos around the world.

Habitat and Range

            Snow leopards are generally found at elevations between 3,000 to 4,500 metres in steep terrain broken by cliffs, ridges, gullies and rocky outcrops. Extremely fragmented populations are found in the harsh, remote, mountainous areas of central Asia, with the majority of snow leopards located in the Tibetan region of China.

Biology

            Adults are solitary, although the home ranges of males and females overlap extensively. Females reach sexual maturity at two to three years and the mating season runs from early January to mid-March, when long-drawn-out wailing calls can be heard echoing amongst the cliffs. Litter size is usually two to three cubs, which are born with black spots, and become independent from their mother at over two years old.

            Most active at dawn and dusk, snow leopards are opportunistic predators capable of killing prey up to three times their own weight. Their prey consists mainly of wild sheep and goats, although livestock will also be taken, especially if wild prey has been depleted. These cats will kill an average of one large animal twice a month.

Threat

            The natural prey of the snow leopard has been systematically hunted out of many areas of the high central Asian mountains and leopard numbers have declined as a result. Big cats often turn to domestic stock as an alternative source of food and this can incite retaliation from local farmers. Snow leopard fur was once highly prized in the international fashion world and around 1,000 pelts were traded a year in the 1920’s. A further threat to this species comes from the increasing demand for bones for traditional Oriental medicine.

Conservation

            Snow leopards are protected throughout most of their range and international trade is banned by their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES). The International Snow Leopard Trust and the Snow Leopard Conservancy are the world's two leading organizations dedicated specifically to conserving this endangered cat. Both organisations have developed a multifaceted approach to the conservation of this species; involving research and data storage, educational initiatives, community-based conservation, and the protection of livestock to prevent retributive killing of snow leopards. Local people are involved in various initiatives and there are plans to link fragmented populations by habitat corridors, which may improve the chances of the long-term survival of this secretive and critically endangered cat.

References

          http://en.wikipedia.org/wiki/Snow_leopard

          http://www.snowleopard.org/

          http://www.agarman.dial.pipex.com/snowlep.htm

          http://www.biosphere-expeditions.org/altai?gclid=CPX_vcq8468CFQl66wodxD2glg

          http://www.snowleopard.org/catfactsclassroom/catfacts/population