The first ever reported cross-genus matings in Australian
elapid snakes (Serpentes:Elapidae).
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Originally Published in Crocodilian 7(3)(November 2007):21-24.
This paper documents for the first time cross-genus mating in Australian elapid snakes. The taxa in question were a 14 month old male Northern Hill Death Adder (Acanthophis bottomi) with parentage from Litchfield National Park, NT, and a four-year old Copperhead (Austrelaps superbus) with parentage from Healesville Victoria. The mating was observed on several occasions, including 18 October 2004, when it was photographed. The mating is also reconciled with what is known about an apparent hierarchy between different genera (see Hoser 2005) and also in terms of predicting other likely cross-genus matings of Australian elapids.
Australian elapid species are not known to hybridise in the wild. The only possible exceptions to this are in terms of some of the Death Adders, genus Acanthophis (see Hoser 2002 and sources cited therein). Two more recent known hybridisations in that genus is a case of A. hawkei and A. woolfi (both Barkly Tableland (NT/Qld) Taxa), and another of A. cummingi and A. bottomi (both specimens in this instance being from the Northern Territory). In both cases young were produced in early 2007.
In the period Jan-Oct 2004 (and beyond), I held numerous elapids of various genera for the purposes of doing live reptile shows.
Included were snakes of the genera Pseudechis (Red-bellied Black, P. prophyriacus), Panacedechis (colletti), Notechis (Tiger, N. scutatus), Pseudonaja (Brown, P. textilis), Acanthophis (various species, including A. antarcticus and A. bottomi) and Austrelaps (Lowlands Copperhead, A. superbus).
All relevant snakes had their venom glands surgically removed using the method detailed in Hoser 2004. All recovered from the operation without complication and acted and behaved perfectly normal immediately post-operation.
Other than being rendered non-venomous, these snakes were unaffected by the operation (including retaining their fangs in tact) and all aspects of their behavior in terms of feeding, aggression, conduct to one another and so on remained perfectly normal.
Contrary to deliberately false and misleading inferences by F. Schillings in Crocodilian and elsewhere, no snakes were “frozen” and none died painful deaths from ice crystals forming in their blood. Snakes were cooled to several degrees above zero and Schillings would be well aware that the freezing point for distilled water is zero (not higher) and for most other fluids, including biological ones the freezing point is actually marginally below this point.
While the initial reason for the operation was safety in terms of handler (myself) and other persons in the vicinity of the snakes, the overriding reason for later operations was for the snake's own welfare.
Venomoid snakes as they have become known could be handled without risk in the same manner as normally harmless pythons. This removed the stress to the snakes usually encountered when handled with hooks, tongs, "necking", tailing and the like.
As a result the snakes remained less stressed and it became easier to observe snake to snake reactions without the additional factor of fear of the handler.
Because venomoid snakes had no venom, it also became possible to place different taxa with one another without fear of one killing another due to adverse bite.
Hence it became routine to ship and transport all the above-named genera together in a single container and without barrier. The limiting factor was size of snakes in that they all had to be of similar size in a given container, so that big ones did not squash smaller ones.
On rare occasions that one snake bit another no adverse reaction would occur due to the lack of venom.
The mixing of venomous snakes of different taxa also allowed me to observe first-hand the reactions of these snakes to one another without actually placing any individual snakes at risk and/or minimizing it.
This point is notable as in 2004, I had a non-venomoid Copperhead (Austrelaps superbus) bite it's similarly non-venmo0moid brother and kill it through envenomation, which was unexpected due to the fact they were siblings.
Snakes are very conscious of one another and as rule prefer not to have contact with others. This includes their own species.
This fear is probably based on a real instinctive fear and nervousness of being attacked and/or eaten.
While snakes that are grouped continually lose this fear to some extent, it remains at all times and is readily evidenced when doing live shows with the snakes.
The snakes don't appear to mind being picked up and moved by the handler (myself), but when placed near other snakes or a head moves near another (as in when several snakes are held at once) it is usual for one or both snakes to jump away in apparent fear.
In terms of most aspects of their lifestyles, the snakes seem to ignore one another and run their own show. Their movements are dictated in the main by their own preferences (for heat and food) and not those of other snakes. When snakes tend to group in cages, it is mainly due to a convergence of aims (seeking heat and the like).
Notwithstanding this, there appears to be a definite hierarchy that forms and within a species it runs as follows, large to small and females over males, although when mating the males literally rape the females by mounting them and attempting to copulate.
Between species the hierarchy in terms of Victorian taxa ran as follows: Brown then Tiger, then Black then Copperhead. This hierarchy reflected in terms of specimens getting right of way, best hiding spots in cages (usually one only in my cages, even when snakes are grouped) and even positions when shipped in a cramped container, like a small plastic tub.
In terms of the latter this reflected in which snakes would end up on top and when eight of the above taxa were jumbled together in a small container the positions would reflect the above hierarchy. That is the Brown snake/s would be on the top and Copperhead/s on the bottom.
These positions were trend differences and not the case all the time.
Based on the fact that in the wild state all four (above-named) taxa would rarely if ever come across one another (although in some cases they clearly would), it is reasonable to assume that the hierarchy that forms in the captive situation is based on the instincts of the snakes and is literally wired into them.
As to why different genera take a higher position over one another, this isn't known.
However the hierarchy is important as in terms of wild snakes in some areas, it's been assumed to date that habitat preferences is the main determinant of where snakes are found.
The hierarchy may in fact have a greater importance than hitherto realized especially where the different taxa both occur in the same general area. The hierarchy may in fact be the reason why one of two taxa is forced from one area or habitat to another adjacent one.
The hierarchy and not habitat choice may be a major determinant in some (but not all ) cases.
In terms of mating between snakes, snakes would not generally attempt to mate one another when transported. The main reason for this was the near impossibility of this most of the time.
For a given snake to try to mount and mate another when in a tangled mass of eight or more snakes, would be very hard.
To further prevent unwanted mating's I tended to ship males with males and females separately. This sex differentiation was regardless of taxa, the result being it'd be common to ship female Blacks, Tigers and Copperheads in one box as a tangled mass and males of the same taxa in another box as a bundle.
Death Adders were generally shipped on their own due to their particularly strong dislike for other snakes and tendency to bite them, sometimes merely if crawled over. Their venomoid state made no difference to this behavior.
Two male one-year-old Hill Death Adders (Acanthophis bottomi) were frequently shipped as a pair. However it soon became apparent that one male would attempt to mate the other male and so they were generally split up.
On different occasions both were placed with an adult female Copperhead (Austrelaps superbus) and both mounted and mated with her.
On 18 October 2004 this was photographed and this is the first known occasion of cross-genus mating in Australian elapids.
For the record, the male Northern Hill Death Adders had parents from Litchfield National Park (NT). The female Copperhead was four years old at the time and from Healesville, Victoria.
This was the first time cross-genus mating has been observed in Australian elapids and based on other observations by myself would presumably be rare indeed.
Note that the Death Adder that mated had been heated non-stop 24 hours a day until a month prior. It is known from over 20 years of involvement with this genus of snakes including in terms of captive breeding, that males heated this way do not produce viable sperm.
If held on a 12 hours heating on, 12 hours off (with the "off" dropping to below 20 degrees Celsius), then after 10-12 weeks viable sperm will be produced.
Hence it was expected that there would be no young produced from the above union.
OTHER CASES OF CROSS-GENUS MATING ACTIVITY
On another occasion in September 2004 a large male Tiger Snake (Notechis scutatus) from Eltham, Victoria was placed with a large female Death Adder (Acanthophis antarcticus cliffrosswellingtoni) from Ardrossan South Australia. The Tiger Snake appeared to be interested in mating the female Death Adder, but she was not interested in him. The female Death Adder spent the next 12 hours running away from the Tiger Snake in the same cage and no copulation was possible. Days later the same Death Adder willingly mated with another Death Adder (Acanthophis antarcticus antarcticus) from near West Head, NSW.
On another occasion a male Red-bellied Black Snake (Pseudechis porphyriacus) from Campbelltown, NSW was placed with a large female Tiger Snake (Notechis scutatus) from Sorrento or nearby in Victoria. No mating occurred. In the first instance the two snakes shared an upturned pot, merely to rest in, but within hours the Red-bellied Black Snake had vacated the hide and merely moped near the water bowl.
There was no other hide in the cage and it was clear that the Tiger Snake had somehow pulled rank and somehow forced the expulsion of the Black Snake, (or the Black Snake had been intimidated enough to leave).
That the hierarchy was in play was evidenced by this situation remaining for some days. When the Black Snake was returned to it's own identical cage on it's own, it immediately went to it's own upturned pot hide (that didn't have a Tiger Snake resting in it).
When snakes are grouped including the taxa named above (excluding Acanthophis) it is typical for the higher ranked ones to occupy the only hide in the cage (as in the Brown Snakes), while others are forced to mope in the open areas of the cage.
The failure of the Tiger Snake to mate the Death Adder and of the Black to mate the Tiger, in contrast to the success of the Death Adder to mate the Copperhead may not be surprising if one reconciles this with the above-mentioned hierarchy.
The Death Adder mating Copperhead was a case of a higher ranked snake mating with a lower ranked one. In both the other cases the snakes trying to mate were lower ranking than their females.
While it'd be theoretically possible for lower ranked male snakes to mate with higher ranked females, it is probably reasonable to expect such to be rarer than the reverse.
Finally, in terms of potential offspring, no one to date has cross-bred Australian elapid snakes of different genera. However it is clearly possible to cross-breed different species within a genus.
In early 2004, I obtained (still-born) young from a mating of a male Acanthophis antarcticus from Sydney, NSW, with a female A. cummingi from near Darwin, NT. That the young were still-born is believed to have been due to the age of the female (about 12 or more years old) and more importantly the Baytril used to treat a reovirus and it's symptoms during a critical period in the year prior to giving birth (see Hoser 2003a, Hoser 2003b).
Baytril is known to cause deformities in other animals, due to it's impact on cartilage formation. The reovirus and Baytril treatment was also blamed for two other Acanthophis antarcticus females giving birth to litters of stillborn young at the same time.
They had been mated by males of the same species.
Acanthophis males do not appear to have strong preferences for their own species if exposed to other Acanthophis species, in some cases actually preferring to mount other taxa.
The preferences trend towards larger females, hence meaning it is more likely for a male A. pyrrhus to mate with a female A. antarcticus, than the other way around.
There are reports that Rob Bredl in Queensland cross-bred a captive Collett's Snake (Panacedechius colletti) with a Blue-bellied Black Snake (Panacedechis guttatus) with live young hatching. These species are similar and at one time the former was regarded as a subspecies of the latter. Tests on the mitochondrial DNA (cytochome B) of the two taxa, indicate a recent separation of the taxa (3% separation).
More recently another cross between the two taxa (Blue-bellied Black Snake) and Collett’s occurred, with four fertile eggs out of a larger clutch actually hatching. Two of the four young lived for about a year until they were killed in an accident, while it is understood that the other two lived for to maturity.
Hoser, R. T. 2002. Death Adders (Genus Acanthophis): An updated overview, including descriptions of 3 new island species and 2 new Australian subspecies. Crocodilian - Journal of the Victorian Association of Amateur Herpetologists 4(1):5-11,16-22,24-30, front and back covers.
Hoser, R. T. 2003a An epidemic of OPMV. Macarthur Herpetological Society Newsletter. July 2003.
Hoser R. TR. 2003b. Reovirus - Successful treatment of small elapids. Crocodilian 4(3):23-27.
Hoser, R. T. 2004. Surgical Removal of Venom Glands in Australian Elapid Snakes ... The creation of venomoids. Herptile 29(1) March: 36-52.
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