WILD SNAKES WITH PROBLEMS OF
CAPTIVE SNAKES
Raymond Hoser
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.
ABSTRACT
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.
GENERAL
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.
CONCLUSION
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.
ACKNOWLEDGEMENTS
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.
REFERENCES
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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