How many frogs are there in new zealand

Calling frogs have been found to consume seven times the amount of oxygen used by resting individuals, and the oxidative capacity of trunk muscles has been found to be seven times higher than that of leg muscles. Males make most of the noise, both for attracting mates in the breeding season and for establishing territorial spacing. In other species the males have been found to remain just within auditory range of each other.

One of the basic male calls is the advertisement call, which identifies the species, sex, reproductive state and position of the caller, and it is designed to attract mates and establish a territory. In areas of the tropics where there may be dozens of species of frogs in a small area, many of them closely related, vocal divergence is a key mechanism in species recognition and speciation, in that it is a barrier to wasteful mismatings. In our three introduced species, males congregate at breeding sites—usually ponds or swamp areas—in the spring and set up loud choruses.

Each species has a different call. Calls can be heard at any time of year, but are less frequent in winter and during dry periods in summer. The two bell frogs are most vocal between September and February. In distinguishing calls, it is helpful to remember that the green and golden bell frog is found only in the North Island, north of a line from Whakatane to Awakino, and is commonest from Auckland north. The southern bell frog is found throughout the country, while the whistling frog occurs throughout the wetter areas of the South Island and in Manawatu, with the odd record from Taranaki and the King Country.

Whistlers are sold in pet shops in Auckland and can be expected to spread more widely in the north of the country. A part from the noises it helps to generate, the capacious frog mouth is notable for the tongue it contains. Glands in the roof of the mouth produce sticky secretions which coat the top of the tongue which faces down when the tongue is out.

Frogs are predatory carnivores, feeding mostly on insects, which they catch with their tongue once the prey moves within range. Good eyesight is essential for this style of feeding, and protruberant frog eyes can see in virtually all directions at once—the most extensive visual fields of any vertebrate. Unlike human eyes, in which the focus is changed by altering the shape of the lens, frog eyes are focused by muscles moving the lens towards or away from the cornea.

Prey can be captured under very low light conditions—when it is much too dark for humans to see—and feeding responses seem to be triggered by visual cues: the size, shape and speed at which an object is moving. Sometimes inappropriate objects trigger the capture impulse. Frogs have been found with stomachs full of seeds seized as they fell to the ground or floated past on the surface of a stream.

Hawaiian toads have been killed by snapping up the falling poisonous blossoms of strychnine trees. While it is likely that native New Zealand frogs have good eyesight since they feed at night in the bush , their tongues are small and rounded, not at all the elaborate fly-swats of the introduced species. More feeding undoubtedly takes place beneath the rocks where they live.

But what do the native frogs actually eat? Observing them feeding in the wild is almost impossible, so more oblique approaches must be employed. Examining stomach contents is one option, but as it involves killing individuals, it is not much favoured for protected and possibly endangered native species.

Collecting faecal pellets from frogs held in captivity and examining them for prey remains is an alternative. Another is putting a variety of prey species in with captive frogs and seeing which prey disappear. It turns out that Leiopelma frogs eat very much what they might be expected to eat: amphipods, pseudoscorpions, small spiders, insect larvae, springtails, beetles, fern spores, ants, mites and the occasional small snail. Scientists are concerned not only with what native frogs eat, but what might eat them.

In Whareorino, mice, rats and wild pigs are probable predators. Pigs frequently root among rocks, turning them over and devouring whatever is beneath.

Some birds are potential predators, too. Weka would make short work of a frog, and moreporks could take them at night. Frogs seem able to coexist at some level with rats and mustelids, but there is clear evidence from the subfossil specimens that ranges have dramatically contracted and species become extinct since kiore were introduced.

Ben Bell has seen a large galaxiid fish twice take a young frog of this species into its mouth, and twice spit it out. Like many frogs, our native species may be distasteful to predators. Habitat destruction or modification by human activities such as logging or animal depredations goats, deer and pigs also constitutes a probable threat to native frogs on the mainland.

Because frogs use their skin as well as their lungs in gaseous exchange it is thin and must be kept damp. Skin glands produce moistening secretions, and in some species toxic substances as well. Most notorious are the steroidal alkaloids produced by Central and South American poison-arrow frogs. These chemicals are much more potent than the plant poison curare, also used on poison arrows.

Other frogs produce tetrodotoxin or a closely related compound , the powerful neurotoxin found in pufferfish, the Australian blue-ringed octopus and a variety of other creatures. It is thought that tetrodotoxin is actually produced by bacteria, and reaches higher animals through the food chain. The same may be true for the alkaloids, at least some of which are now thought to originate from beetles and millipedes which frogs feed on.

Monarch butterflies and their caterpillars do something similar, retaining the toxic compounds they ingest from swan plants. Just how any of these animals accomplish this treachery is a mystery. Most of their secretions are merely disagreeable or induce the would-be predator to gag or yawn, affording the frog a chance to leap away, or, in the case of some tropical tree frogs, to glide to safety. In gliding frogs the digits are long and the webbing between them is much enlarged.

Most frogs can make jumps of between six and seven body lengths, though the record is held by a South African frog—a veritable Carl Lewis of the animal kingdom—which executed a prodigious bound of over 10 metres. Frog secretions have long attracted the interest of humans—and not just for use as poisons. Licking or kissing cane toads is against the law in Australia, and toad slime is also a restricted substance in the US.

In fact, being in possession of any one of several species of toad is a crime in some US states. A potent soup can apparently be made from the skin of these toads, or the mucus can be scraped off, dried and smoked. The magainins show potent activity against microbes ranging from the Herpes simplex virus to the parasite that infects Bluff oysters, Bonamia.

A topical magainin cream has proved effective in treating foot infections, impetigo, bed sores and more, and other products are being developed which, it is hoped, will help in the treatment of periodontal disease, cystic fibrosis and possibly even cancer.

It was an anthropologist in Brazil who brought this compound to scientific attention. On waking, they claimed they could hunt all day without getting tired or hungry, and boasted that none of their arrows would miss.

Humans must rate as major predators on larger varieties of frogs in countries like France and the United States. The French, whose renowned predilection for frogs has earned them a national nickname, seem to have cornered the market in slime. The US imports about a third as much—around a million kilograms—to meet its own culinary needs, supplemented by a sizeable local frog take.

Nowadays, the preferred method is to shine a bright light from an aluminium dinghy to spot and dazzle the frog, which is then plucked from the water by hand. Different states have different frog seasons, and there is a nightly bag limit—eight in Missouri, 18 in Arkansas, and so on. The legs of a good bullfrog can be 25 cm long, and, dipped in egg and flour, then fried, they are considered excellent tucker. Frog eating is nothing new.

Not surprisingly, hunting is making frogs scarce in parts of Asia, and, as a result, agricultural pests and malarial mosquitoes are on the increase. In fact, some countries are now having to spend far more on agricultural pesticides than they are earning from frog exports. However, human predation is not the cause of most of the decline in worldwide frog populations.

Habitat destruction can account for shrinking numbers in some regions, but frogs are disappearing even from areas where direct human activity is virtually absent. Consider as an example the Californian mountain yellow-legged frog.

The species was abundant in the mountains of the state as recently as , but by very few frogs could be found. Fifty per cent of sites where the species had been previously recorded in the Sierra Nevada were found to have no frogs at all. Further south, in the San Bernardino, San Gabriel and San Jacinto Mountains—where, again, the species had once been abundant—surveys from to uncovered just adults. The introduction of fish that prey upon the frog and its tadpoles could account for part of the decline, but the frog has vanished from many areas where there are no fish, and survives along with fish in other areas.

Two years later only five animals could be found, and not one has been seen since. Frog ID Key. Frogs and the LAW. International Frog Projects. Poraka or Pepeketua? Save the Frogs Day. Mining and Frogs. Belly-flopping frogs. Jane Goodall's visit. Archey's Breeding Success. Amphibian Extinction Crisis. About Us. Contact Us.

Herpetology Native frogs Introduced frogs Conservation How many frogs? Save the frogs Other amphibians Frog Projects. Introduced frogs: Although at least 8 species of frogs were imported into New Zealand in the mid- to late s, only three of these species established populations that still exist today. These all belong to the family of Hylid tree frogs. They are fairly easy to distinguish from the New Zealand native species as they all produce characteristic calls, unlike the mainly silent native frogs.

Click here to hear Helen Sharpe's "Frogcast" about how to identify the three species of introduced frogs. In the late s several consignments of these frogs were received from Sydney and released by the Auckland Acclimatisation Society. There have been several attempts to establish populations of this species in the South Island, but it appears that the climatic conditions are not favourable and the species is restricted to the upper half of the North Island north of Gisborne.

They occur around the same ponds as the Southern Bell Frog and may interbreed. There is a fold of skin usually cream in colour running from the eye along the side of the animal to its groin. This fold is bordered by a thin black line that continues over the head to the nostrils.

The back of their thighs and groin area are bright blue and the belly is smooth and white. The skin is very smooth and there is only webbing on their hind feet. They have suckers for climbing on all toes and fingers. Males are smaller than the females with an average length of about 60 mm, whereas females can be larger than 90 mm. The frogs prefer temporary ponds in full sunlight that are usually shallow and free of aquatic predators such as Mosquito fish.

They are quite unusual in the frog world in that they like to bask in the sun and are active during the day. Females may lay between three and ten thousand eggs in a floating gelatinous mat, which sinks after hours. The eggs hatch into black tadpoles after about two days, and metamorphosis occurs about two months later. They have been very successful in New Zealand and can now be found throughout most of the country.

They are similarly coloured to the Green and Golden Bell Frog but often have a warty back. They generally have more dark brown or black blotches on the back and there is always a pale green stripe down the middle of their back although this can change in intensity depending upon environmental conditions.

The back of their thighs and groin area are bright blue to turquoise and the belly looks granular. The cat is also a prime offender. Though they were once abundant on the mainland, about 40 percent of our lizard species are now confined to small predator-free islands see Tables 9. Both tuatara species are also confined to islands. In all, more than 40 percent of our surviving reptiles are now threatened with extinction. One tuatara species is highly endangered.

The other is still abundant but is considered threatened because the number of independent populations has declined by 25 percent this century. Among the lizards, half the skinks species and a quarter of the geckos species are threatened Daugherty et al. Debate continues about the number of geckos, skinks and tuataras that became extinct after humans arrived in New Zealand. A species of tuatara which was described in from bones on the East Coast of the North Island Sphenodon diversum has been accepted as valid and listed as extinct Daugherty et al.

It is hard to tell, without genetic analyses, whether other tuatara bones from various parts of the country belong to existing species or to unrecognised extinct ones. A firm case can be made for the recent extinction of a large skink, Cyclodina northlandi , whose bones have been found in Northland Worthy, Two other lizards, known only from museum specimens, are listed as possible extinctions.

One of these, a skink classified as Oligosoma gracilicorpus , may belong to a living species. The other, a large gecko named Hoplodactylus delcourti , was found in a French museum and assumed to have come from New Zealand, but firm evidence of its origin has not been established Towns and Daugherty, While examples of extinction are few, the evidence of drastic population declines is overwhelming.

Lizard bones found in caves, dunes and middens show that many of the species now threatened on the mainland or confined to small islands were once widespread Towns and Daugherty, Species which once had continuous populations are now absent from large areas or limited to isolated populations hundreds of kilometres apart. In the northern North Island, for example, 10 56 percent of the 18 resident lizard species have gone. Most of the remaining 8 species persist in low numbers and in scattered localities Towns and Daugherty, Human predation probably played little direct role in the decline of the lizards, though it may have affected the tuataras, first by reducing the seabird populations on whom coastal tuataras preyed, and second by reducing the tuataras themselves.

Several lizard species are also found in middens but were probably trapped there while scavenging Towns and Daugherty, They were generally avoided, though some were killed when encountered because of their evil powers, while others were called on for protection, some species more than others. European settlers had little interest in hunting lizards, but museum collectors in the late s harvested tuataras intensively and may also have put pressure on some lizard populations.

The collectors appear to have eliminated one tuatara population on East Island before legislation stopped the trade Towns and Daugherty, Habitat loss has had a significant impact on the reptiles. In recent decades, for example, two species of South Island 'giant' skinks Oligosoma grande and O. Another skink, O. Not all reptiles respond negatively to habitat modification, however.

Tuataras on some islands, for example, can reach artificially high densities when areas of forest are converted to pasture - provided predators are not present Towns and Daugherty, In such circumstances, hungry tuataras may be a threat to other endangered species confined to the islands with them, such as giant wetas and click beetles.

Predatory mammals appear to have taken the greatest toll of New Zealand's reptiles. The first predator onslaught occurred when the Pacific rat arrived. The tuatara, the Robust skink Cyclodina alani and McGregor's skink Cyclodina macgregori were among the first reptilian casualties. By the time Europeans reached New Zealand, these species had disappeared from the mainland, where they were once widespread Towns and Daugherty, The second onslaught occurred about years later when Norway rats arrived in European ships.

They were accompanied by pigs, which also eat lizards and tuataras. Norway rats are bigger and more aggressive than Pacific rats and can swim up to 1. The dense tuatara population on Whenuakura Island off the Coromandel coast was wiped out within two years of being invaded by these rodent Vikings Newman, The third onslaught came in the late s. This time even tree-dwelling skinks and geckos became victims as ship rats, stoats and cats joined the chase.

The lizards most vulnerable to the predator onslaughts were the larger ones and those which were active at twilight or at night Whitaker, Today, predator-free islands carry much greater species diversities and population densities than are found on the mainland or on islands where rats are still present. Lizard populations on islands where rats have been eradicated have shown rapid increases in numbers and habitat range Towns and Daugherty, A good example of what skink and gecko life must have been like on the mainland before human settlement can be seen on Middle Island in the Mercury Islands group where 11 reptile species co-exist in an area of just 13 hectares.

A study site in native tussockland in central Otago also shows how a relatively small area can support a dense and diverse population of lizards. Eight species live together, but they occupy very specific niches, vary considerably in size, and have slightly different tastes in food see Table 9. On island sanctuaries the tuataras, skinks and geckos are relatively safe, though their populations often remain small and, hence, vulnerable. On the mainland, however, several of our reptiles are at considerable risk, even in reserves.

Since , the number of known lizard species has more than doubled, from 29 to 61, as scientists have discovered new ones or reclassified old ones. More rare species are probably awaiting discovery but, given their small populations and the threats facing them, identification will be a race against time. In late the Department of Conservation began investigating reports from forestry workers that large lizards had been seen in the Bay of Plenty. To many people, however, one lizard looks the same as any other, a perception which herpetologists are trying to dispell.

Not only are geckos and skinks quite different from each other, the species themselves show considerable diversity. Geckos are distinguishable from skinks by their wide eyes, benign smile and slightly baggy skin. They are seen less often than skinks because few geckos inhabit urban areas.

Well camouflaged, and with excellent hearing and eyesight, they can easily avoid detection. Geckos are long-lived; some are known to live for more than 40 years. The ancestors of both the skinks and the geckos have been established in New Zealand for more than 15 million years Patterson and Daugherty, New Zealand's 29 gecko species are all unusual in the way they produce their young.

They give live birth to baby geckos, almost always twins, instead of laying eggs. Only one other gecko, a New Caledonian species, is known to bear live young. Recent research indicates that some geckos may play a significant role in plant pollination.

Pollen, which smears the lizard's chin when it sips the nectar from the flowers of flax bushes and pohutukawa trees, can stay there for up to 24 hours Higham, The most notable pollinators are the Pacific gecko Hoplodactylus pacificus and New Zealand's largest lizard, Duvaucel's gecko H. Skinks are the streamlined members of the New Zealand lizard fraternity.

The 30 known species are all endemic, and all but one give birth to live young instead of laying eggs. The one exception is known as the egg-laying skink Oligosoma suteri. Skinks are faring much worse than geckos at present, with twice as many on the threatened species list.

One of the rarest species is Whitaker's skink Cyclodina whitakeri a 20 cm lizard once found throughout lowland forest areas of the North Island. It is now reduced to one tiny mainland population, and two small island populations with a total occupied area of less than 20 hectares Towns, ; Towns and Elliott, Among the rare species is New Zealand's largest and longest skink, the Chevron skink Oligosoma homalonotum.

With its pale head and brown body bearing 'lance corporal' markings, the Chevron skink measures up to 30 cm. Their feeding habits and behaviour are still largely a mystery. Cats are thought to be the Chevron skink's main predator, but pigs, ship rats, Pacific rats, and even mice, all add to the pressure. Habitat loss and degradation through residential subdivision and tourist development, and forest browsing by feral goats and cattle, have placed added pressure on the Chevron skink's survival on Great Barrier Island Towns and McFadden, ; Close, a.

Tuatara are the oldest and best known of New Zealand's reptiles. They are also the most long-lived, with some individuals having reached their th birthday. The order to which they belong, the Sphenodontida, had species in many parts of the Earth about million years ago, but they were gradually driven to extinction as the closely related dinosaurs became more dominant.

Most were gone or on the way out by million years ago, except the tuataras which found a haven in the new-born New Zealand landmass. Once abundant throughout the North and South Islands, both in forests and among coastal seabird colonies, the tuataras became extinct on both main islands after humans arrived. Today, two species survive on about 30 rat-free islands. Gunther's tuatara Sphenodon guntheri is limited to a small island in Cook Strait where about adults and their young share a 1.

In late , 50 individuals were transferred to another island as part of an effort to extend the species' range Holmes, The common tuataras Sphenodon punctatus number about 60, and are divided into a Cook Strait sub-species and a Northern sub-species, the latter located on islands in the Bay of Plenty and the Hauraki Gulf.

Though tuataras have been fully protected since , the number of populations has fallen from 40 to 30 in the past century. Apart from rats and cats, tuataras are also threatened by international wildlife smugglers Ansley, In addition to the land-based reptiles, four species of marine turtles regularly visit with New Zealand.

One of them, the leatherback turtle, is the heaviest reptile on Earth and can reach weights of nearly a tonne the record-holder weighed kg. Two species of highly venomous sea-snakes also slip in from time to time but, as denizens of warmer waters in tropical climes, their visits are probably accidental.

Although New Zealand's birds are a well-researched group, it is not possible to say with precision how many species and sub-species have lived and died here. New genetic studies and newly discovered bones continually revise our count of existing and extinct species. Such revisions improve our knowledge of the birds' story but, unfortunately, they do not make it read any better.

Each newly identified species merely adds to the extinction list or the currently threatened list. Apart from taxonomic revisions, the statistics on New Zealand birds can be confusing for other reasons.

Many species are divided into several subspecies, or geographically isolated populations, some of which have their own distinctive characteristics. These populations are often treated as separate taxonomic units or taxa thus adding to the overall bird count. Further sources of confusion arise when whole groups of birds are excluded from the statistics, such as seabirds, or introduced birds, or non-endemic native birds i.

If all New Zealand's bird taxa species plus additional subspecies are counted, including seabirds, non-endemics and introduced species, the total number of bird taxa currently in New Zealand comes to , comprising 33 alien species, native land species and subspecies, and 72 native seabird species and subspecies. The threat of extinction is not spread evenly among them, however. The taxa most at risk are those which happen to be the most unique - the endemics. All our extinct species and nearly all our threatened species are endemic.

In contrast, the introduced and non-endemic birds tend to be mobile and adaptable. Most of the introduced birds were brought from Europe or Australia within the past years and are well-adapted to the open landscape humans have created here.

Most of the non-endemic natives are also open-space birds. Some are migratory species, for whom New Zealand is a necessary part of their international range. Others are accidental tourists that flew or blew here within the last few thousand years from Australia or the Antarctic.

They include such successful species as the harrier hawk, the pukeko and the black-backed gull. As if their success in modern New Zealand were not enough, the introduced and non-endemic species are also buffered from extinction by having secure populations overseas. In contrast, the endemic birds are on their own.

Most of the following discussion is concerned with the state of our endemic birds. Land and sea-going species are discussed separately. Where relevant, statistics are given for both species and taxa i.

The species classification generally follows the Ornithological Society's checklist Turbott, , but also includes four extinct seabirds yet to be formally described and named. Ignoring subspecies, it appears that, when humans reached New Zealand, they found at least full species of land birds that is birds whose primary habitat is on land, freshwater or the coast and 65 species of seabirds e. More than two-thirds of the land birds 93 species and one-third of the seabirds 22 species, including the four unnamed ones were endemic or unique to New Zealand see Tables 9.

Today, 43 of the endemic land species 46 percent are extinct, and 4 of the endemic seabirds 18 percent. A further 7 subspecies of land birds are also extinct. In the towns and farmland of New Zealand it is hard to imagine the scale of the country's bird losses because birds still seem plentiful.

Sparrows, starlings, blackbirds, chaffinches, song thrushes and magpies are everywhere. Asian mynas dominate the road verges in the upper North Island. Introduced pigeons form dense clusters in city centres. Rooks have become closely watched agricultural pests in Canterbury and the Wairarapa. But all these birds, 33 species in total, are interlopers brought here in the past years.

They bear little resemblance to the giants they have replaced - the great Haast's eagle, the giant swan, the pelican, the rails and, of course, the moas. By the time Europeans arrived, 34 species and 1 subspecies 35 taxa of endemic land birds had gone.

Following European settlement 9 more species and their constituent subspecies 13 taxa in all were wiped out and a further 6 subspecies were lost. This leaves 50 surviving endemic species comprising taxa , of which 37 comprising 66 taxa are now listed as threatened Department of Conservation, b.

Overall, then, 84 percent of New Zealand's endemic land bird species have become extinct or threatened since human occupation. Of today's 50 surviving species, 74 percent are threatened see Figure 9. These statistics are only likely to worsen in the foreseeable future as palaeontologists and archaeologists bring more evidence of extinct species to light, and as pests and habitat degradation push more birds onto the threatened list or into oblivion. The irony of this is that the thing which makes the endemic birds unique and globally important - their evolutionary isolation - is also what has rendered them so vulnerable Holdaway, ; Anderson and McGlone, They evolved no defences against humans and other hungry mammals see Table 9.

For the first time they faced predators that could hunt by smell at night and that could follow them into their tunnels and hollows. Many had little or no ability to fly, so they could not escape forest fires and hunters, nor emigrate to safer habitats.

In the face of such pressures and limitations, the survival to date of some species is nothing short of remarkable. Among the threatened land birds are most of our flightless species, such as the takahe see Box 9. The takahe Porphyrio mantelli is a flightless blue bird belonging to the rail family. It looks like a heavier version of its close cousin, the pukeko, or Purple Swamphen. In fact, the takahe is a descendant of stray pukekos which landed here from Australia several million years ago.

In the placid New Zealand environment they lost the power of flight, put on weight, and prospered. Now they are in danger of dying out. The takahe were already rare when Europeans arrived and, for the first half of this century, were thought to be extinct. In , however, about survivors were found in the rugged and remote Murchison Mountains in Fiordland. Several pairs have been transferred to predator-free islands and have had some breeding success.

But in the wild their plight is worsening. The Fiordland population is down to about birds. For a long time it was believed that the takahe's preferred habitat was the high tussock country where the survivors were found Mills et al.

Although takahe bones have been dug up in many parts of New Zealand, these were assumed to date from Ice Age times when tussock grasslands were more extensive. Today, however, the bones are believed to be more recent. Far from being tussock dwellers, it now seems that the takahe were most at home stepping and pecking their way along the edges of lowland streams and forests.

Chytrid Conference. Frog Week. Frog Week Photos. Year of the Frog. Conservationist of the Year. Plight of the Frogs Party. Waikato Region. Auckland Zoo. Orana Wildlife Park. Dunedin and Wellington. Frog ID Key. Frogs and the LAW. International Frog Projects. Poraka or Pepeketua? Save the Frogs Day. Mining and Frogs. Belly-flopping frogs. Jane Goodall's visit. Archey's Breeding Success. Amphibian Extinction Crisis. About Us. Contact Us. Herpetology Native frogs Introduced frogs Conservation How many frogs?

Save the frogs Other amphibians Frog Projects. In New Zealand we currently have four species of native frogs and three species of introduced frogs.