Papua New Guinea has a very rich frog fauna which is thought to number well over 200 species. Due to high mountains and thick rainforest many of these are extremely difficult to find and photograph, resulting in few examples ever being published.
This 'frog pond' in Variata National Park, situated in the mountains above Port Moresby has many resident species of frogs.( photo: Neville Coleman)
Seen from the road on the way up the mountains to Variata National Park this magnificent waterfall give some indication as to just how rugged searching for frogs can be in Papua New Guinea. ( photo: Neville Coleman)
By comparison, Australia which is a much larger land mass has around 220 species so far discovered. However, Australia has vast expanses of dry, desert-like semi-arid areas and although some Australian frogs have adapted to live in this harsh environment, species are few and far between in these areas.
Although a lot of work has been accomplished in establishing species records over the years by various biology departments in Papua New Guinea and visiting scientists, it does not appear that many Papua New Guinea people are aware of their native frogs. Most of my inquiries have only resulted in local villagers showing me introduced cane toads Bufo marinus which have become extremely common and range from the mountains of Port Moresby to the islands of Milne Bay since they were incidentally introduced from Australia over 60 years ago.
This Cane Toad Bufo marinus from Walindi, New Britian Province is not native to Papua New Guinea, being incidently introduced over 60 years ago from Australia. ( photo: Neville Coleman)
The cane toads in and around the town areas of Port Moresby are small and under-developed, while those up in the mountains (Variata National Park) are quite large and very healthy. On the Milne Bay mainland and some islands they are huge and extremely common at various localities.
It's easy to understand why many Milne Bay villagers think the toads are frogs because they grew up with them and the toads have always been there. Also the toads are large and inhabit open space areas around yards and creek outlets and sit up very straight when hunting.
Local frogs, on the other hand, have shy retiring natures and mostly hide away, only being noticed during their breeding seasons when the males call. Whereas some male Papua New Guinea frogs may call all night during the breeding season, others may only call for an hour or so at dusk and produce very soft sounds, making them extremely difficult to locate.
Found in a tree three metres above the ground at night this male Ambon Tree Frog Litoria amboinensis has a call characteristic of a 'chuckling' giggle. ( photo: Neville Coleman)
Worldwide frog decline
Over the past 20 years there has been a general decline in frogs with some common species becoming extinct in various countries. This has been attributed to global warming, fungus attacks and over-zealous collecting by scientists.
In Australia, some species only discovered 20 years ago are now believed to be extinct. At least 10 species have not been seen or heard for years despite wide-scale searches, and many others are on the endangered species lists. Interestingly enough, some of the species now rare and endangered in Australia are common in Papua New Guinea.
2008 -YEAR OF THE FROG
2008 is the year of the frog and with a world focus on frogs as environmental indicators there has been a huge interest in their natural history, behaviour, lifestyles and general knowledge. It seems quite credible that some resorts in Papua New Guinea might take advantage of this interest and take steps to find out what frogs are in their immediate vicinity, perhaps even offer 'frog watching' as part of their guest activities (as some of the more successful mountain guesthouses and resorts have done in Australia).
In Papua New Guinea, frogs live everywhere, high up in rainforest trees and right down to the ground. They live in and around streams, rivers, ponds, waterfalls, grasslands, swamps, in trees, under the ground, in gardens, high up in the mountains and right down to where creeks enter the sea.
Growing to 135 mm the White-lipped Tree Frog Litoria infrafrenata is the largest and one of the most common species and was found at Walindi plantation, Kimbe Bay in West New Britain. ( photo: Neville Coleman)
Although it is generally considered a lowland species, this juvenile Congenital Tree Frog was photographed at the Variata National Park frog pond, high in the mountains behind Port Moresby. ( photo: Neville Coleman)
One of the most common species around Port Moresby, the Congenital Tree Frog Litoria congenita is generally found in flooded grassy areas after rain. Also finds its way into some shower areas, gardens and nurserys. ( photo: Neville Coleman)
While the biology of some is well documented, many others remain a mystery. Some develop from eggs laid in the water and turn into tadpoles; others lay their eggs in nests where the males look after them until they hatch out as juvenile frogs.
Tadpoles of pond-dwelling frogs have small mouths. Those that live in fast flowing streams have a highly developed suctorial mouth, which enables them to cling into rock surfaces and avoid being swept downstream.
It is thought that most frog species feed on flying, crawling or burrowing insects though little is known if there is any preference except that they would take advantage of whatever was in season at the time.
Frogs generally have dull night time colours and brighter daytime colours. Males and females may also have different colours from each other. Frogs are able to alter their patterns of colour and also alter their skin texture. Sometimes they may appear smooth and at other times the skin may be raised in bumps, granules, ridges or wrinkles. Most alter their colours and texture to suit their surroundings.
With his throat sac fully extended, a male Graceful Tree Frog Litoria gracilenta advertises for a mate. This species has the widest geographical range of any tree frog in Papua New Guinea. ( photo: Neville Coleman)
Although some species may be active during the day, most have nocturnal natures with large well-developed eyes allowing them to "see" in the dark. The few that live underground have small eyes.
Often very difficult to find during the day, this well camouflaged male Rocket Frog Litoria nasuta was discovered at night and is the only common species of ground – dwelling tree frog in Papua New Guinea that is completely terrestrial. ( photo: Neville Coleman)
Very common in the gardens around Walindi Plantation Resort this attractive little Frog Platymantis sp. calls from tree trunks and stumps during summer. ( photo: Neville Coleman)
Females are generally larger than males. Males attract females by calling during the breeding season. The male vocal sacs extend beneath the throat and puff up as the male calls. Once a female responds, the male clasps the female from behind in a tight embrace encouraging her to lay eggs, which he then fertilises with sperm as they leave the female's body.
With such a huge number of frog species, the variants and colour variations and the many areas which are yet to be thoroughly explored, it will be many years before the Papua New Guinea frog fauna is completely recorded, if ever! Certainly, with over 200 recognised species and another 200 possibles there are enough to encourage frog enthusiasts from across the world to experience another aspect of Papua New Guinea's rich natural heritage.
Copyright Neville Coleman