WILD SNAKES WITH PROBLEMS OF CAPTIVE SNAKES
488 Park Road
Park Orchards, Victoria, 3114, Australia.
E-mail:changed (see foot of page)
Originally Published in hard copy in the Bulletin of the Chicago Herpetological Society, 43(8): (August 2008):132-3.
A study of wild caught snakes within a 60 km radius of the CBD in Melbourne, Australia from 2001-2003 showed that more than 50% of adult Tiger Snakes (Notechis scutatus), Copperheads (Austrelaps superbus) and Brown Snakes (Pseudonaja textilis) carried parasitic mites (of unknown species).
In most snakes these mites were only detected after the reptiles were placed in a white plastic container with a segment of Shelltox Pest-strip with Dichlorvos as the active ingredient, whereupon the mites fell off the snakes and died.
Noticed in three snakes were constrictions of the tail that were consistent with failure to properly slough as seen in emaciated captive snakes that are infested with mites.
For some years, I have held a permit from the Victorian Wildlife Authority to trap and release reptiles that are deemed nuisances or a threat to safety of persons or their domestic pets.
Essentially, the operation of the permit is as follows. A person, who is usually in a state of fear, phones myself directly or by referral from another party such as a government authority, wildlife refuge or similar seeking the removal of a snake or other reptile. I then go to the address and attempt to capture the reptile, assuming it can still be found by the time I arrive at the address.
In most cases the 'offending reptile' is found and caught.
By law the reptile is then released in suitable habitat nearby. A typical example is a large wildlife reserve such as Westerfolds Park in Melbourne's north-east.
Due to long-standing misgivings in terms of re-releasing species in new areas (see Hoser 1995) and the fear of transmitting parasites and diseases to other populations of snakes, or for that matter to my own captive collection of snakes (many of which are Victorian native species), all caught snakes were placed in a container with a Dichlorvos-based section of pest strip for at least 30 minutes after capture.
This is sufficient to kill all the mites on the snake and also small ticks.
There is no detectable affect on the snakes.
For the record a typical dosage is a 2 cm X 3cm section of (fresh) pest strip in a 30 cm long X 19.5 cm wide X 10.5 cm high enclosed plastic container (known as a click-clack), with ventilation holes in the lid. Used pest strip segments are stored in foil and plastic to retain potency, which will over time fade.
Large ticks which are sometimes seen on snakes are either manually removed, or in some circumstances left on the snake overnight. In those cases the snakes are also left with a section of pest-strip, which usually results in the large ticks dying by morning.
Sometimes snakes would be injected with ivermectin as an effective means to kill the ticks.
Rarely, a spray would be used to kill the mites, but due to the slower death time of the mites from the spray, the pest strips were generally used on “wild caught” snakes.
While mites are rarely seen on snakes (or large lizards) when removed from properties, except in unusual and heavy infestations, the fact is that following treatment as described, more than half are found to have mites on them.
In the period from 17 October 2001 to 22 November 2003, the following reptiles were removed by myself from properties in the Melbourne area. All were treated with pest strips.
· 5 Brown Snakes (Pseudonaja textilis)
· 28 Tiger Snakes (Notechis scutatus)
· 9 Copperheads (Austrelaps superbus)
· 3 Eastern Bluetonged Skinks (Tiliqua scincoides)
· 1 Blotched Bluetongued Skink (Tiliqua nigrolutea)
Two of the Brown Snakes had mites, most of the Tiger Snakes had mites and all of the other reptiles had mites.
In most cases between 10 and 30 were observed dead in the containers with the reptiles after treatment.
For the copperheads, none showed signs of mite infestation until treated with the pest strip sections.
In conversations with herpetologists, the general perception has been that problems with mites are a feature of captivity. It's been asserted that population explosions of mites that lead to severe blood loss and emaciation in confined and constrained reptiles is a unique feature of captive reptiles.
It's been asserted that wild reptiles are able to wander away from mites that fall off them, whereas in the captive situation, mites that are scraped off or fall off the reptile can then re-climb onto them.
Hence it's also been generally asserted that wild reptiles do not suffer as a result of the usually lower level mite infestations seen.
Some snakes retrieved by myself did appear emaciated, in particular a large Tiger Snake found at 200 Nepean Highway Seaford on 7 November 2002, which had a severe tick and mite infestation.
These parasites are common to Mornington Peninsula reptiles (see Hoser and Valentic 1996 for another example).
Whether the emaciation occurred as a result of the parasites or the parasites took advantage of weakness in the reptile to gain a foothold on it, or a combination of both is not known.
However this paper seeks to demonstrate emphatically and for the first time ever that parasitic mites can adversely affect reptiles in the wild state.
TAIL DEFECTS IN SNAKES
Observed in a number of snakes were missing ends of tails and signs of injury, including the Seaford Tiger Snake mentioned above. Bearing in mind that as a rule the snakes caught were set to be released more-or-less immediately, there was no real motive to pay much attention to so-called 'battle scars' and other physical defects unless they really stood out.
Hence the inspection of most snakes, including the Seaford one was cursory and nothing more of relevance can be recalled.
On 11 March 2003, I retrieved a (small) 40 cm male Tiger Snake from 3 Edward Court, Ivanhoe in inner suburban Melbourne. This area is adjacent to the Yarra River and in spite of it's proximity to the Melbourne CBD has lots of Tiger Snakes.
This snake was found to be somewhat emaciated and to have mites, with about 60 falling off when the snake was treated.
This is very a high number of mites based on the small size of the snake.
The snake was noticed to have sections of unsloughed skin on the anterior neck region and also a constriction of unsloughed skin towards the end of the tail.
The constriction was so severe as to have left the end part of the tail dried and shrivelled and it appeared that without intervention it would simply fall off over time as all that appeared to be left was bone.
This was the last 2.5 cm of tail.
Mites are known to cause severe emaciation in snakes and in the captive state shedding problems and mites seem to go hand in hand.
The pattern of shedding problems in this wild snake fitted the profile of what I have observed in countless captive snakes affected by mites.
Based on the lack of other alternatives, it appears that in this wild snake, it's shedding problems were directly attributable to the mites.
Subsequent to this a large Tiger Snake was caught on a property at 89 Banyule Road, Rosanna, which had a constriction about 3 cm from the end of it's tail.
At a glance it appeared to be a wound from an attack by an animal, but further inspection revealed that the section of tail had a constriction around the affected section with normal scales beyond that.
This feature did not appear to be a battle wound or birth defect and hence I could only attribute it to a sloughing problem at some stage past.
This snake did carry mites, but only about 10 fell off it when treated.
As the snake was over a metre long, it'd be likely that the few mites on it at the time of capture were not causing it discernable harm then.
On 21 November 2003 I retrieved a large 1.2 metre Copperhead from the Bayside Christian College at Robinsons Road, Baxter.
This snake, while in immediate pre-slough (eyes cleared after clouding), it appeared to be in optimal condition. When treated with pest strip about 20 mites fell off it, which for a wild snake of that size is a negligible infection. The snake also carried at least two large ticks.
As mentioned already, both parasites are common on wild-caught snakes in the Mornington Peninsula region (which includes Baxter).
This snake also had a moderate constriction evident about 2 cm from the end of the tail tip, although the scales beyond the constriction were perfectly normal and healthy.
The constriction again indicated a sloughing problem as opposed to other cause.
Diseases, ailments and husbandry issues thought to be manifestations of captivity, may also occur in wild snakes. It is likely that some of these issues, including mite infestations and mite-related problems are more prevalent than previously thought and have been merely overlooked by field workers in the past.
Numerous private keepers and field collectors who have shared their experiences with myself and given me unfettered access to collections and data.
The Victorian Wildlife Department (called Department of Sustainability and Environment (DSE) this week) provided the relevant permit (number CC2027519) and this is gratefully acknowledged.
Hoser, R. T. 1995. Release into Hell. Monitor 7(2):77-88.
Hoser, R. T. and Valentic, R. 1996. Notes on a herpetological field trip in the Australian State of Victoria. Monitor 7(2):24-34.
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