PSEUDECHIS PAPUANUS

Lachesis,

I'll save some time by copying and pasting a post re this species that I put up on another forum a day or two ago ...

Currently the status of the Papuan blacksnake Pseudechis papuanus in Papua New Guinea is far from clear, and it appears that the snake is under significant threat of local extinction across much of its range.

Why is it endangered?

Put simply PNG is facing a Bufo marinus-led ecological disaster on a scale that is unprecedented. Cane toads have been in PNG almost as long as they've been in Australia, but absolutely nothing is being done to halt their invasion. They occur not only in southern PNG from Alotau to the eastern banks of the Fly river, but have also spread along the north coast to well into the Sepik, and even turn up in the PNG Highlands ... not to mention the islands of New Britain and New Ireland where they were first introduced!

Since 1992 there has not been any evidence found to suggest that Papuan blacksnakes Pseudechis papuanus still occur in either Central or Gulf provinces - locations where 30 years ago they were relatively abundant snakes. By no evidence I mean 'no evidence' - no live or dead snakes, or sloughs of blacksnakes have been found despite enormous efforts.

As far as I am aware, the only live snakes which have been caught in Papua New Guinea in the last 20 years were captured either by Mark O'Shea (who probably knows more about this snake than anyone) or myself in the South Fly district of Western province; and we are talking of only a handful of snakes in total!

Last year I was very fortunate to capture live specimens in the South Fly district of Western province - which is currently cane toad-free. These photographs were taken during that fieldtrip - which was funded by the Australian Geographic Society - and hopefully a writeup of the trip will appear in a future edition of the AGS Magazine...

Of course cane toads are not the only reason for the decline of this snake. Much of their habitat in Central and Gulf province has been irreversibly changed over the last 30-40 years, and deforestation is certainly a major contributing factor. Some of this habitat loss is due to logging operations, but in the main, most is due simply to PNG's rapidly expanding human population.

Like all blacksnakes, these guys flatten the throat horizontally when threatened ...

 

My impression is that these very snakes are extremely shy and very flighty. Getting one to sit still for photographs was an enormous challenge, especially when using an 18-35 mm wide-angle lens which necessitates being less than 20 cm from the snake - as in the 1st photograph at the top.

We are currently collecting specimens as part of my ongoing research work in PNG, and the hope is to learn something about their biology as well as the intricacies of their venom.



Interestingly, a single specimen of this species has been recorded from Saibai Island - in Australian territory in Torres Strait. Saibai lies just a few kilometres off the coast of PNG's South Fly region to the west of Daru. Whether or not it is common there remains to be determined.

The following map from our newly published book "Venomous bites and stings in Papua New Guinea" illustrates the apparently declining distribution of this species ...



As you can see, their range, which once extended right across most of southern PNG is shrinking. No specimens have been recorded from the Gulf of PNG - interesting because having been there, I know there is quite a bit of suitable habitat. We spent many months showing photographs to local people and while death adders Acanthophis laevis and small-eyed snakes Micropechis ikaheka were frequently picked out of the stack, nobody picked out any blacksnakes in the area west of Ihu and East of the Turama River mouth.

The only Gulf province specimen that I have a record for, was found east of Kerema in Kukipi village, and was involved in the death of a young man there in 1982. In Central province, two specimens were killed in Veifa'a and another in Moreguina in the early 1990's, but there have been none since.

Apart from specimens caught by either myself or Mark O'Shea in the South Fly district over the last 19 years, and the three snakes killed in Veifa'a and Moreguina in the early 1990's, the only other recent record is that of a snake involved in the death of a man at Pisi village on the Aramia River west of Balimo in the Middle Fly district last November while I was at Balimo Hospital. This is one of the areas where I hope to collect specimens early next year.

At the same time I have no yet given up on finding a surviving population in Central or Milne Bay provinces. A lot of the habitat suitable to these snakes has been destroyed close to human settlements, and while cane toads are ubiquitous, I have hopes that in some of the more remote parts of these provinces - areas with little human activity - it might still be possible to find this species. One such area is the very eastern corner of Central province, east of Magarida running along the coast to around Nube in Milne Bay province. This area is extremely remote and we get reports from people familiar with Papuan taipans Oxyuranus scutellatus canni of another type of large black snake in that area.

One of the tools we are using in our snakebite studies - the commercial CSL snake venom detection kit - an enzyme immunoassay for venom immunotype - is being used at the moment to identify the type of venom in a large series of patients, and perhaps some evidence may emerge to suggest a location where bites by blacksnakes still occur. This may enable us to identify areas of habitat in which populations still exist.

Cheers


David Williams