It's a well known fact that different reptile species are often active at different temperatures. Within a given area different nocturnal species of reptile will as a general rule be active on nights of different temperature, although because of their ectothermy reptiles have a tendancy to be most active on warm summer nights. Within the Sydney (Australia) area the above is certainly true. Nocturnal reptiles are most active on above average temperature nights during the summer months.

It is very hard to actually specify a preferred air temperature for activity of a reptile species due to the importance of other factors such as time of year, warmness or coolness in general that year, cloud cover, air pressure movements, humidity, moon position, etc. Over the past four years I have done well over 100 night hunts (usually by driving down deserted bush roads) in the Sydney area. The table (below) though not based on any hard data is based on my experience. The air temperatures given for each reptile species are those at which most specimens are found active at night. Most species will (on occasions) be found active at air temperatures up to 6'C lower and more than 10'C warmer than those preferred although in general as temperatures move further from those preferred, less individuals of the given species are likely to be found active. Most activity by nocturnal reptiles around Sydney at air temperatures widely deviant to those preferred tends to occur in association with the arrival in Sydney of cold Fronts and the hot then cold temperatures on either side of them. The temperature of an active nocturnal reptile is also invariably higher than that of the air around it. Another interesting fact is that species of reptile directly dependant on one another for food are active in similar weather (e.g. Typhlopids and Vermicella annulata).

Air temp. 'C Species

26 Acanthophis antarcticus (Death Adder)

25.5 Pygopus lepidopodus (Common scaly-foot)

25 Diplodactytus vittatus (Stone Gecko)

24.5 -----------

24 Notechis scutatus (Tiger snake),Hemiaspis signata (Swamp snake), Lialis burtonis (Burton's legless lizard), Underwoodisaurus mili (Barking gecko), Cacophis squamulosus (Golden crowned snake), Morelia spilotes (Diamond snake)

23.5 Cryptophis nigrescens (Small-eyed snake)

23 Furina diadema (Red naped snake), Boiga irregularis (Brown tree snake)

22 . 5 Oedura lesueuri (Lesueur's gecko), Phyllurus platurus (Leaf-tailed gecko)

22 Typhlina nigrescens and T. proximixa (Worm snakes), Vermicella annulata (Bandy bandy)

21.5 ------------

(Photographs of all above named species and the habitat where they are found at West Head is depicted in the book Australian Reptiles and Frogs by the same author).

Raymond Hoser has been an active herpetologist for about 30 years and published over 100 papers in journals worldwide. He has written five books including the definitive works " Australian Reptiles and Frogs ", "Endangered Animals of Australia" and the controversial best seller "Smuggled - The Underground Trade in Australia's Wildlife". Click on the text below for details about his latest book that is of major interest to herpetologists everywhere.