Yes, if you don't mind Wolfgang, that paper would be useful if you can dig it up. I know of a very interesting example here in Australia where Pseudonaja textilis have managed to recently colonize an island through such behaviour - and it has resulted in a population density on the island apparently higher than the adjacent "mainland". And this gets to one of the reasons why I am interested in this aspect of snake behaviour. The initially larger population of an invading species in itself is really quite interesting. This might be indicative of an obvious survival strategy of snakes exploiting new territory - an initial unstable swamping effect of the invading species as it in effect rapidly occupies an available niche (enhanced by alteration of the usual population regulating mechanisms on the species like say the absence of the usual predators, or an abundance or variation in food supply), before a stable lower population is achieved once the ecosystem has adjusted to the altered energy flow so created. This could also partly explain why population densities of snakes may vary so much across their ranges over large land masses (and by analogy over large water masses in the case of sea snakes). I have always considered the huge populations of Notechis scutatus that once inhabited parts of Australia, as only temporary phenomena that followed environmental changes impacting on habitat. Periodic flooding of much of inland Australia may also explain some of the peculiar distributional patterns of Cannia australis and some of the Pseudonaja nuchalis complex, and ipso facto their variable abundances at sites over time. Major population crashes are believed by some observors to have occured as numbers of snakes in Australia appear to be greatly reduced. So there is a belief that snakes are dying out in Australia, and indeed this may be the case for habitat has been lost here on a massive scale, feral predators are in huge numbers, and motor vehicles have likely never had a greater presence, etc etc. But where habitat is still relatively undisturbed, snakes (Elapids) are usually in numbers more in keeping with their trophic position as high order predators - they are actually rather rare in stable systems I think. It is how snakes disperse and respond to new areas of range that may provide clues as to their adaptability and ultimately perhaps their survivability under human-induced environmental perturbations. From what I have seen, the impact of human population expansion means a pretty bleak future for snakes in the medium to long term. I think it's going to be initially a mixed bag though - with most glowing brightly before the candle goes out say like Boiga on Guam, or Pseudonaja textilis in urbanised western Sydney. Some may indeed appear to even "adapt" to human settlements say like your Cobra mates in Asia or Pseudonaja in altered agricultural landscapes of inland Australia at least for a while...higher numbers in perturbed environments...but ultimately I think even these will crash to lower more vulnerable population levels...and then its probably all-over red-rover if your a snake wanting a place in the near future I'm afraid. But here's hoping humanity will start to like snakes being around...



Regards



Richard Wells

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