Copperhead Snake

Introduction

Copperheads have managed to eke out an existence in some of the coldest high rainfall regions of Australia, where most other snakes would perish. And one species at least appears to have benefitted from European settlement, with the conversion of forest to open agricultural country creating more favorable habitat for this moisture-loving serpent.

Identification

All species of copperheads are fairly similar in general form and colouration. They are moderately robust and muscular in build. The scales of the back and upper sides are semi-glossy and uniformly blackish to grey brown in colour, with a brownish or orange flush in some individuals of Lowland and Highland Copperheads. The lowermost rows of lateral scales are enlarged and these are usually a paler colour, particularly on the neck and forebody. There are no markings except for an obscure neck band and/or a dark vertebral line in some individuals (more obvious in juveniles). Belly colour is cream to grey. The head is relatively narrow and barely distinct from the neck. The upper labials are characteristically “barred” with a whitish anterior edge. The eyes are moderately large, pale coloured with a brown to reddish-brown rim, and the pupil is round.

The common name Copperhead refers to the coppery-brown coloration of the head and particularly the snout of some individuals (most often seen in Lowland Copperheads).

Midbody scales in 15 (rarely 17) rows, ventrals 140-165, anal and subcaudal scales single.

Habitat

Pygmy Copperhead - in the Mount Lofty Ranges, the species occurs almost exclusively in high altitude forest. However, on Kangaroo Island it can be found in a wide variety of habitats, including coastal dunes, samphire flats, open grassland, closed woodland and in agricultural areas. It shelters in deep matted vegetation such as tussock grasses, under flat stones and in or under fallen timber.

Highland Copperhead – this species occurs in woodland and open forest, usually near water (especially still water such as in wetlands and small creeks). It also inhabits disturbed areas such as grazing lands and cleared areas. The snake shelters under fallen timber in deep matted vegetation such as tussock grasses, in abandoned burrows and under large flat stones.

Lowland Copperhead - inhabits grassland, heathland, woodlands and open scrub. It is often found in habitats next to water, such as marshes, lagoons, swamps, lakes, creeks, streams and rivers. This species is able to live in areas heavily disturbed, even those that have been under agriculture for over 100 years. Here they occur around dams, soaks, canals and drainage ditches, and along the verges of roads. The snakes shelter under boulders, logs, stumps and sheets of roofing iron, in clumps of dense vegetation such as buttongrass, cutting grass, gorse and Juncus and in yabbie burrows, muttonbird burrows and disused rabbit and rodent burrows. Lowland Copperheads have been recorded overwintering in shallow shelters such as under large rocks, logs, roofing iron and tractor tires and in piles of hay bales. Overwintering sites are usually near water.

Distribution

Copperheads are restricted to relatively cool and cold environments in southeastern parts of Australia, including Kangaroo Island, Tasmania and the Bass Strait Islands.

• Pygmy Copperhead (Austrelaps labialis) - only found in the Mount Lofty Ranges east of Adelaide and on Kangaroo Island.

• Highland Copperhead (A. ramsayi - highlands of New South Wales and eastern Victoria.

• Lowland Copperhead (A. superbus) - lowland areas of southeastern South Australia, southern Victoria, Tasmania, and the islands of Bass Strait (including Flinders, King, Hunter, Preservation, and Great Dog Islands).

Feeding and diet

In the wild, the snake eats mostly ectothermic prey such as insects, frogs, lizards (and lizard eggs), and snakes. They will also occasionally take warm-blooded prey such as birds and mammals. Skinks are by far the most common prey item consumed.

Copperheads are also reported to be cannibalistic.

Breeding behaviours

All 3 species are ovoviviparous (live-bearing). There is evidence to suggest wild females do not breed every year. Watch a video of copperheads mating in March 2021, filmed by Peter Roland in South Warrnambool, Victoria.

Male copperheads engage in combat at the onset of the breeding season. In contrast to male combat in many other elapids in which the males use their head and forebody to try and press down the head and forebody of their opponent, males of Austrelapsseem to keep their heads apart and only intertwine their bodies.

Austrelaps labialis - Males are mature at a snout-vent length of at least 305mm and females are mature at a snout-vent length of at least 304mm. Perceived combat between males has been observed in early to mid-autumn on Kangaroo Island. Gravid females can be found from mid-spring to late summer (November-March), and wild caught snakes have given birth in mid-summer. Litter sizes range 2-10 (average of 7). It is interesting to note that the new-born young are of a similar size to those from the much larger species of copperhead (166-170mm).

A. ramsayi - Snout-vent length at maturity in males is about 446 mm in New South Wales and 588 mm in Victoria and in females is about 463 mm in New South Wales and 545 mm in Victoria. Females with large yolking follicles can be found in early spring (October) and gravid females from early spring to early summer (October to January). In the highlands of eastern Victoria, females emerging from winter quiescence in mid-spring (November) have large follicles. Average litter size is 15 (ranges from 9-31).

A. superbus - Mating has been reported to occur in late summer (March), however it is not clear whether this observation occurred in the wild or in captivity. Maturity is reached at a snout-vent length of at least about 477 mm in males and 436 mm in females in the southeastern part of mainland Australia and at about 527 mm in males and 617 mm in females in Tasmania. Females with large ovarian follicles can be found in early spring (end of September) and females with oviducal young occur in early spring to mid-summer (October to February). On King Island, in Bass Strait, females have given birth by late February. Between 9-45 young are born (average 15) between January and March, with larger females giving birth to correspondingly larger litters.

Seasonality

Highland Copperheads have been recorded emerging from winter quiescence in November and re-entering quiescence in late April - early May. The snakes appeared to be active significantly earlier in the day in autumn than in spring and summer.

Lowland Copperheads – in a study done at two localities in southern Victoria, one lowland (near sea level) and the other highland (650-750 m), the snakes at the lowland locality emerged from winter quiescence earlier in the season than those at the highland locality (August vs September in one warm year and September vs October in a one cool year). Conversely, the snakes from the lowland locality entered their winter shelters later in the season than the snakes at the highland locality (late April or early May vs March).

Other behaviours and adaptations

Copperheads are primarily ground-dwelling however, they will climb occasionally, for example, in order to bask. They are mostly diurnal although they may be active on warm evenings.

Danger to humans

Copperheads tend to be secretive and prefer to avoid encounters with humans. If cornered a copperhead will hiss loudly, flatten its body and thrash or flick about, but usually without biting. Further provocation will cause the snake to lash out and bite. The venom is powerfully neurotoxic, haemolytic and cytotoxic, and a bite from an adult of any of the species may be potentially fatal without medical assistance.

Conservation status

The Pygmy Copperhead Austrelaps labialis is listed as Vulnerable (IUCN Red List).

Predators

The Mount Lofty Ranges population of Pygmy Copperheads is threatened by predation by both domestic and feral cats.

Copperheads may be parasitized by ticks, with one Lowland Copperhead reported harbouring as many as 60 ticks. Known endoparasites include certain protozoans, cestodes (tape worms), nematodes (round worms), pentastomids (flukes or tongue worms) and trematodes (flukes).