29 June 2008

Reptiles - An Overview

Markings and coloration of reptiles can vary considerably and these visual features can at times be misleading. So please bear that in mind (particularly with skinks) when trying to identify them. I have noted the most consistent features of each photographed species, so rely on these rather than overall appearance. Habitat type is also usually important, so try to take that into consideration too.

Some reptiles can be very difficult to find as they live amongst leaf litter and seldom venture out to be seen. These need to be either trapped or raked out and in my opinion this would interfere with other flora and fauna, so I do not do it. Instead I rely on accidental encounters, but naturally this has severe limitations and many species are missed altogether.

The reptiles in the Esperance region are faring (with a few exceptions) reasonably well. However I suggest without feral cats and foxes they would be better, even if the reptiles that fall victim to them were ignored. The problem as I see it is the lack of suitable habitat where these animals can hide and overwinter, this exposes several species, particularly the larger lizards, to higher predation. The lack of retreat habitat I believe, also interferes with population levels of species not targeted by cats and foxes, such as the larger snakes.

So what has changed over the last 100 years to cause this habitat scarcity. Well for one, many reptiles would have had less need to find a safe retreat, as the then native predators would not have been so relentless. The reptiles would have been able to be more active without falling prey to these numerous, determined and persistent introduced predators.

Also of concern is the loss of suitable reptile and bird habitat to other introduced animals like the feral honeybee. Introduced bees are a serious problem for native species that require hollows in order to live and reproduce. These hollows exist on granite and limestone outcrops, in trees including grasstrees and burrows dug by other animals. Any current occupiers are evicted and the hollow taken over by the bees. Once this takeover occurs the hollow is rarely available for native species again, so another scarce retreat or nesting site is permanently lost to native species.

Probably of greatest concern is the drastic reduction of newly created habitat that reptiles can use. These were made largely by the mammals that have been lost or greatly reduced by cat and fox predation. Mammals such as the Bush Rat is a good example. These rats build extensive burrows that are ideal for the larger reptiles to use and overwinter. Although bush rats still survive in the area, their numbers are relatively small and are kept that way because of the predation by these introduced predators. Even when the now locally extinct mammals did not dig burrows, they did other things like restricting weedy growth, ate insect pests and generally scratched around that in turn encouraged regrowth of certain species, which then encouraged greater flora and fauna diversity for the prey of reptiles to eat and prosper. So the environmental conditions have changed, which means not only less habitat for reptiles, but also less food for them to eat. This results in smaller and more vulnerable animal populations all round.

Below is a list of retiles that I have not encountered or photographed. It must be borne in mind that I regard the Esperance region, as between 150 and 200 km radius of Esperance, so a very large area with many habitats and consequently the possibility of sheltering a very wide range of reptiles that are not necessarily spread throughout the district. Most of these are relatively small animals that can also easily remain hidden. Most of the common names are quite descriptive, so if you have seen a reptile that does not match the photos in the blog, check out the common name features to narrow the search.

Crenadactylus ocellatus ocellatus - Clawless Gecko.
Diplodactylus granariensis granariensis - Western Stone Gecko.
Underwoodisaurus milii - Barking Gecko.

Aprasia repens - Sand-plain Worm-lizard.
Aprasia striolata - Striated Worm-lizard (seen in coastal alkaline regions).

Delma australis - Marble-faced Delma (Legless Lizard).
Liatis burtonis - Burton's Legless Lizard.

Cryptoblepharus virgatus clarus - Cream-striped Fence Skink.

Ctenotus catenifer - Chain-striped Heath Cenotus (Skink).
Ctenotus impar - Odd-striped Ctenotus (Skink).
Ctenotus schomburgkii - Barred Wedge-snout Ctenotus (Skink).

Egernia napoleonis - Southwestern Crevice Skink.
Egernia multiscutata - Bull-headed Skink.
Egernia richardi - Woodland Crevice Skink.

Hemiergis initialis initialis - Southern Five-toed Mulch Skink.

Lerista dorsalis - Southern Four-toed Lerista (Sandswimming Skink).
Lerista microtis intermedia - South Coast Five-toed Lerista (Sandswimming Skink).
Lerista microtis microtis - Southwestern Five-toed Lerista (Sandswimming Skink).

Menetia greyii - Common Dwarf Skink.

Morethia butleri - Woodland Dark-flecked Morethia (Flecked Skink).
Morethia obscura - Shrubland Pale-flecked Morethia (Flecked Skink).

Amphibolurus norrisi - Mallee Lashtail Dragon.
Ctenophorus maculatus griseus - Wheatbelt Spotted Sand Dragon.
Ctenophorus ornatus - Ornate Crevice Dragon.
Ctenophorus salinarum - Saltpan Ground Dragon.
Rankinia adelaidensis chapmani - Eastern Heath Dragon.

Ramphotyphlops australis - Southern Blind Snake.
Ramphotyphlops bicolor - Dark-spined Blind Snake.
Ramphotyphlops bituberculatus - Prong-snouted Blind Snake.

Acanthophis antarcticus - Southern Death Adder.

Drysdalia mastersii - Master's Snake.

Parasuta nigriceps - Black-backed Hooded Snake.
Parasuta spectabilis bushi - Esperance Hooded Snake (confined to the Scaddan area).

Rhinoplocephalus bicolor - Square-nosed Snake.