Extreme Feeding Methods For Snakes From Australia
Raymond Hoser
488 Park Road
Park Orchards, Victoria, 3114, Australia.
E-mail: adder@smuggled.com
Originally published
in the bulletin of the chicago herpetological society, 42(4)(April
2007):62-65.
Abstract
Experiments in the period 2002-2006 with various food
types showed that Australian elapid snakes and Australian pythons are capable
of feeding on a far greater variety of food types than the literature or
previous anecdotal reports have indicated.
Experiments
with totally unnatural food items showed that in the captive situation,
non-natural food types sometimes have distinct advantages over the snake's
usual diet in terms of ease for the owner to source and sometimes even in terms
of nutritional benefit for the snakes.
As
a result of this study, the repertoire of feeding methods for keeping elapids
(pythons and no doubt other snakes as well) is greatly increased.
Potential
foodstuffs include the following, lizards, rodents and other mammals, fish
(most types), amphibians, birds, and parts of all the preceding, including
(although not necessarily recommended) filleted fish, meat pieces (of most
types), bones, meat balls, sausages, stir fry, whole steaks and even prawns and
calamari.
Introduction AND
MATERIALS AND METHODS
It's
sometimes said that necessity often breeds the most radical or useful
innovations.
Within
the bounds of Australian snake keeping, all species are thought to live
exclusively on vertebrates. The only
exception being Typhlopids, which generally live on ants.
Some
of the small fossorial species (e.g. Simoselaps),
that are rarely kept by hobbyists are known to eat reptile eggs in the wild
when they are available, but in line with most other small elapid snakes, they
also feed on small lizards, which appear to dominate the dietary intake.
Hence,
until now the foods used by keepers for their snakes have generally been small
skink lizards for small and neonate snakes, graduating to rodents for the larger
snakes.
Due
to legal restrictions in some states, small lizards cannot be used as
food. Thus there's been a strong shift
away from species of snake that require such food for any or part of their life
cycle.
Exceptions
to all this have been generally in large snakes, which have also been fed
birds, rabbits and other large items.
For medium sized (usually about 1 metre) snakes, day old chickens from
hatcheries have also been used as food when rodents have been unavailable, but
are not regarded as being as good a food source, due to their lower nutritional
value per body weight (or feed).
The
use of day-old chickens is less now than in the 1980's, as the hatcheries that
used to offload surplus males for free are now able to sell them to zoos and
wildlife parks for food for birds of prey and hence there is no longer an unmet
demand.
Because
the price of these chickens is similar to rodents, snake keepers have tended to
stick to the rodents instead, due to their higher food value.
Some
keepers experimented with fish some years ago and published their results, most
notably, Brian Barnett and later Simon Kortlang (see Barnett 1981 and Kortlang
2001) and also myself (Hoser 2004).
However
in the case of the first two above named keepers, their experiments were limited
to live fish and only in as much as to see if snakes would eat them. They did not rely on fish as a major part of
their snake's diets.
However,
before and since those papers were published, the use of fish for food by
keepers has been essentially nil, until 2002/3 when I started using dead and
frozen fish as a primary food source for the purposes of raising young Death
Adders and later other species of snake.
The
result is a finding that almost all Australian snake can in fact be fed fish of
almost any species (fresh or saltwater) and kept indefinitely on them (Hoser
2004).
Obviously
species known to be poisonous or with spines should be excluded.
However
in terms of the latter, chopping off the spines may be possible in some cases
and if this is, then those fish can be fed to snakes in the usual way.
To
catch fish in local ponds is easy using so-called "bait traps" as
sold in most fishing shops, or perhaps even more easily, bought by the kilo in
fish markets.
One
kilo of "whitebait" (Galaxias
spp.) a smallish sized fish, is enough to raise a about four litters of a dozen
snakes from say 15 cm to triple that length, whereupon they can then be
switched to large mice.
A
kilo of whitebait in Australia is about $10, (five pounds or five Euros), which
makes them a far better buy than any rodents.
Small
eels (elvers) are also another useful food alternative for snakes in Australia,
but they tend to come on the market only erratically. This is because they generally come from Tasmania and their use
outside the herpetological market is limited.
They are also regarded as an inferior bait to the more commonly
available (and cheaper) whitebait.
Excessive
use of fish as a diet for snakes is known to lead to a thiamin deficiency, but
this is averted by use of wiping Vegemite yeast extract on the fish before they
are fed to the snakes.
The
snakes don't seem to mind the taste of Vegemite, which is amazing, as I can't
stand the stuff.
(Humans
put it on slices of bread)
It
is sold in shops here in Australia, the equivalent in the USA and UK is
“Marmite”.
Another
safeguard used by myself when raising snakes on fish is to alternate with other
food items occasionally (say every third or fourth feed).
Typical
of the alternatives are rodent limbs (to shoulder or hip) or tails as culled
from adult rodents that are fed to larger snakes.
The
larger snakes are quite happy to eat rodents minus body parts and in fact may
even find the feeding process easier (due to a lack of protrusions) and then
digest the food quicker as the skin is broken at several points.
(Obviously
limb culling is for already dead rodents, not while they are still alive).
In
anticipation of getting young snakes, rodents are culled for limbs and tails
routinely.
This
saves the expense of buying "pink" mice or rat-pups and reduces the
overall food bill.
Fish
feeding in Australian snakes and the use of rodent parts is covered by myself
in another paper (Hoser 2004) and so the detail is not repeated here.
Another
feeding technique used, and briefly mentioned is that of slashing or cutting
food items such as skink lizards.
This
allows for more rapid digestion of food, again due to the added entry points of
digestive juices.
This
allows for young snakes raised on skinks to be able to digest more food, more
rapidly and hence grow faster. This is
an important consideration if skinks are being used to raise snakes as their
nutritional value is generally low.
Without slashing or cutting skinks (already dead of course) and feeding
more often, snakes raised on skinks tend to grow more slowly than their
counterparts fed on other foods.
(Dead
and frozen skinks are used, not live, so as to remove as many parasites as
possible before the snake eats the skink).
Fish
as a food source is good, rapidly digested and so on, but as already mentioned,
is not a good staple for snakes.
Rodents
are generally the food of choice, but when one has a large collection of snakes
and does not breed rodents, it is a constant struggle to buy in food rodents
(frozen) at a reasonable price.
By
purchasing rodents in bulk at times of general surplus, it's possible to obtain
rodent food for less money than it'd cost to breed them yourself in terms of
food, and that's before labor is factored in, and hence my practice of using
frozen rodents as a primary food for my snakes.
Within
these constraints I experimented on alternative foods, such as meat, in order
to see:
A/ Whether or not snakes would eat it and
B/ The nutritional value of such foods and whether or
not they represented a cost effective alternative to the more traditional foods
used for Australian snakes.
MEAT FEEDING IN AUSTRALIAN SNAKES
There
have been anecdotal reports of Tiger Snakes (Notechis scutatus) feeding on strips of meat when in
captivity. Such reports have been
believable on the basis that Tiger Snakes are particularly voracious eaters in
captivity and are known to strike and bite at unusual objects for food,
including their keepers hands.
So-called
"food bites" are the most common kind of bite that keepers get from
their Tiger Snakes.
On
the basis of the various unconfirmed reports of Tiger Snakes eating meat, I
decided to see how far I could test the meat eating habits of snakes without
adversely affecting the health of them.
These
feeding "experiments" as detailed in this paper occurred in
2003-2004.
Before
going further, I should mention that in the first instance, the experiments
were done on well adjusted captive snakes.
Later when it became evident that not only was meat eating not harming
the snakes, but actually of measurable benefit, the experimentation broadened
to include newly captive reptiles and numerous species.
First
off, I offered two subadult Tiger Snakes (one of each sex), strips of cooked
Silverside meat. The meat was laced
with vinegar and garlic.
The
first snake was offered Silverside as a follow-on from a mouse it was eating.
The
snake did just that and ate the Silverside.
The
second snake was offered a scented piece which was waved in front of the snake
after a mouse was dangled in front of the snake. It struck at and ate the meat.
Subsequent
to this (and during the same feeding session) one snake ate another piece of
silverside waved in front of it and unscented.
The
fact the other snake didn't eat this meat on second offer probably had as much
to do with the fact it was no longer hungry rather than the properties of the
meat itself.
The
theory was tested by offering the snake a mouse and it too was refused.
Why
Silverside?
Well
my wife had cooked up some for a dinner and we had some left overs.
That
the snakes ate the meat wasn't too startling a fact in hindsight, particularly
as most keepers are aware that snakes are not high in the intelligence stakes
and can be induced to eat all manner of objects (for example refer to Hoser
1981, 1989, Hoser 2003c and Stopford 1980).
However
of greater interest was the nutritional benefits of the food eaten.
Firstly
the meat was held down and digested.
That was a good start.
Furthermore
the high protein content of the meat and lack of bones, hair and so on, meant
that the snakes put on exceptional condition in terms of the amount of meat
eaten.
In
other words the meat had high food value.
That
the meat wasn't regurgitated also put it in good stead as a food source.
Put
another way, the digestive systems of the snakes had absolutely no trouble
dealing with the protein intake.
As
to what the effects of a long-term high protein diet has on snakes are, that is
largely speculative as no studies have been published on this.
It's
been thought that snakes that eat low protein food in the natural state, that
get exposed to a high protein diet in captivity may succumb to diseases unknown
in the wild situation.
This
theory has been postulated as an explanation for difficulty breeding pythons of
the genus Aspidites and granuloma
that form within the lower intestines.
In
terms of these latter ideas, I am far from convinced, but notwithstanding this,
do accept that a high protein diet may not be good as a permanent feature of
the diet of captive snakes.
Over
the next three months, the same two Tiger Snakes were then taken on a tour of
the local supermarket freezer, being offered all manner of meats that are sold
over the shelf. Included were pork,
salted ham, steak (lamb and beef), sausages, calamari rings (squid), prawns,
chicken wings (plucked for human consumption), kangaroo meat, (and also
road-killed possum meat fillets) and so on.
All
were eaten and digested without incident.
Similar
feeding experiments were done on several other species of elapid, including
Death Adders (Acanthophis antarcticus,
A. bottomi and A. cummingi), Copperheads (Austrelaps
superbus), Small-eyed Snake (Rhinoplocephalus
nigrescens), Eastern Brown Snake (Pseudonaja
textilis) and Red-bellied Black Snakes (Pseudechis
porphyriacus). All ate and digested
meat as purchased from a butcher or a supermarket.
The
meat was usually served up to the snakes as filleted strips as a "follow
on" from rodent food.
In
all cases the meat was digested without incident, except the two (exceptional)
instances detailed shortly, and in all cases was credited with obvious gains in
condition in the relevant snakes.
Newly
acquired, newborn and otherwise non-feeding snakes (as in snakes that wouldn't
take any food voluntarily) were as a matter of course force-fed meat strips and
all made rapid gains in condition.
Three
newly acquired Red-bellied Black Snakes (Pseudechis
porphyriacus) which had a host of ailments, including internal parasites,
general emaciation and carrying a reovirus (see Hoser 2003a and Hoser 2003b)
were force-fed strips of steak for their first three feeds (at weekly
intervals) and all gained condition as much as could have been hoped under the
circumstances.
Other
snakes from the same source, similarly affected, in other collections and not
force-fed, died.
While
it's likely that rodent or fish based food items would have also enabled the
said Black Snakes to gain condition, it is doubtful if the same degree of gains
would have been seen in such a short period.
Noticeable
with the meat diet is that due to the high density of the food eaten, digestion
time is slightly increased as compared to most food items of the same size and
shape.
However
this is only of note in that a delay of an extra day or two between feeds is
needed.
The
only adverse case involving meats being fed to snakes was one of five snakes
being force-fed some salted ham, cut into strips. The two smallest Death Adders regurgitated it within an hour of
eating it. The three other snakes
(including another slightly larger Death Adder) held it down and all gained condition
as a result.
(The
two regurgitating Death Adders were force-fed rodent parts the next day and
digested this without incident).
Both
snakes remain alive and well, many months later and also after further feeds of
fish, rodent parts or small rodents and meat.
There
is no doubt that the extreme saltiness of the (ham) meat is what precipitated
the regurgitation in the two snakes least able to cope with salty food.
Similar
regurgitation has also sometimes been seen in small snakes that are fed
excessively salty marine fish (including whitebait), (including snakes affected
by the reovirus as documented by Hoser 2003a and 2003b)
Notwithstanding
the single adverse incident just given, meat has been shown to be useful and
digestible by (what appears to include) most Australian species of snake.
From
a cost-effectiveness view, chicken necks as sold for dogs (at about AUS $2 a
kilo) are the cheapest and most nutritious alternative to rodents for most
larger snakes (as in 1 metre or over), being easily digested and providing high
nutritional value.
In
other words, meat in strips of basic kinds such as pork, beef and lamb can be
used as a food source for most Australian elapids which will eat it without
incident. The use of such alternatives
may be useful during times when rodent availability is down.
FURTHER FEEDINGS OF NOTE AND OTHER FACTS
OF RELEVANCE
The
eating and digestion of Calamari by Tiger Snakes was expected, but is still
very unusual. There are of course no
previous records of the land-dwelling species feeding on deep sea squid, nor
would any be expected.
A
Tiger Snake also ate and digested a prawn without incident.
Due
to the high cost of prawns in shops, they would not generally be regarded as a
food alternative for snakes and the case given here was merely the result of a
test just to see if the snake would actually eat and digest the prawn.
However
this does show that Australian snakes may in fact feed on food way outside that
which they would encounter in the wild.
In
other words what snakes can eat in captivity should be dictated by their
stomach's ability to digest food and not necessarily what they encounter in the
wild.
Death
Adders would also eat meat without incident, but generally as a follow-on from
rodents as did Copperheads (Austrelaps
superbus).
Red-bellied
Black Snakes were able to be assist-fed meat strips. In other words, the food was placed in their mouths and the food
would be eaten.
Tiger
Snakes were in the first instance the experimental subject of choice. This was because it was assumed (perhaps
wrongly) that they would be the most likely snakes to eat almost anything on
offer.
To
that end, they were on occasion offered strips of cooked meat, cooked fat, raw
fat and on one occasion two ate lamb riblets (sold as dog bones) that were
dropped at the bottom of their cage.
The
two snakes both had trouble getting the hard and rectangular items down and
after getting them down took about a week to digest the items sufficiently to
stop the ends of the bone sticking out of the snake's sides (as in showing up
as squared ended spikes under the scales).
Notwithstanding
this, the bones were digested without incident.
Noting
that there was no adverse affects from meat eating by snakes, and that several
of several species in my care would eat such foods without inducement, it was
decided to test wild-caught snakes with such food items.
As
a rule, it is illegal to catch and keep wild snakes, but as part of a
capture/release permit, I sometimes found myself with snakes at my address for
a short period.
Among
these were a Tiger Snake that had eaten a ratsack infected mouse and in the
first instance was evidently ill and an Eastern Brown Snake that had injured
itself on it's head, neck and mid-body by getting caught up in netting.
Both
were held for about five days until A/ The snakes were evidently healthy and
B/ I had time to drive to a suitable
release location.
To
my surprise both snakes ate unscented meat strips when offered to them. These were both wild-caught snakes that had
never been held in captivity, or offered any other food such as rodents.
As
already stated, both were subsequently released as per licence requirements.
Eastern
Brown Snakes in particular seem to have a fancy for red meat (beef, lamb,
etc,), even more so than Tiger Snakes and two in my care both ate unscented
lumps of red meat that was simply thrown into their cages.
I
can only guess that this is so due to the known dietary preferences of the wild
snakes. In the wild state, Brown Snakes
prefer rodents, while Tiger Snakes prefer frogs and birds (although rodents
also feature prominently in their diet).
To
get an idea of what I mean, it is easy to pull the legs of a rodent free from
the socket (shoulder or hip) and at the same time leave the fur on the body in
terms of the upper part of the limb.
The
muscles (meat) looks similar in texture and colour to red meat such as steaks.
(Those
familiar with Eastern Brown Snakes would understand why I just opened the cage
lid, threw in the food and shut the lid again).
A
small-eyed snake (Rhinoplocephalus
nigrescens) caught as a so-called "snake rescue" was assist fed a
strip of beef. It was digested without
incident. The snake was then
photographed and released.
This
species is typical of the small elapid snakes that account for the majority of
Australia's serpent fauna. Their diet
is generally thought of as small lizards and save for the occasional specimen
that is "taught" to eat young rodents, they have until now been fed
skinks by most keeper.
Experiments
by myself on small elapids has shown them to thrive on fish such as whitebait
and comparable freshwater species. Meat
strips can also be added to their dietary repertoire, although as with fish,
they should (if used) only be a part of the snake's diet, not all.
Pythons
(Diamond and Carpet, Genus Morelia)
were also offered whole steaks and parts thereof and all were eaten and
digested without incident.
In
another series of feedings a Carpet Snake ate cooked and raw sausages. The same snake also ate chicken wings as
sold in a supermarket deli department.
At
our facility in the period post 2004, most larger snakes are fed a diet that
dominates in chicken necks due to their high nutritional value, the eagerness
in which the snakes eat them (as for mice in most cases) and the low cost.
THE FECES
Another
point of note is the sort of feces passed by snakes that eat lots of meat (such
as beef, lamb, ham, etc). Unlike the
rodent-based feces that typically have a white part (uric acid) and then a
brownish black part consisting of the rest, including undigested fur and hair,
a meat-based feces is radically different.
It tends to be a pasty white colour throughout and well bound. I assume that this has something to do with
the general lack of "roughage" and the high protein nature of the
food eaten.
CONCLUSIONS
As
no long term experiments or studies have been done on snakes kept exclusively
on high-protein meat diets, I am not in position to detail the long term
effects or to say whether or not such a diet is of positive or negative
long-term benefit, although certainly several years in, snakes fed diets
dominating in things like chicken necks have remained in good health and even
bred (Hoser 2007).
However
I can say that as a short-term proposition the use of high-protein meats
appears to be beneficial as an alternative to the (usually) preferred food of
rodents.
High-protein
meats are also substantially cheaper than rodents (per kilo or in terms of food
value per dollar) and hence may form a useful adjunct to the dietary armory of
a snake keeper, including when rodents are in short supply and/or if a keeper
has a large number of snakes to feed.
REFERENCES
Barnett, B. F.
1981. Observations of fish feeding in Reptiles. Herpetofauna 13(1):11-13.
Hoser, R. T.
1981. Note on an unsuitable food item taken by a Death Adder (Acanthophis antarcticus)(Shaw). Herpetofauna 13 (1):31.
Hoser, R. T.
1989. Australian Reptiles and Frogs.
Pierson and Co., Sydney, NSW, Australia:238 pp.
Hoser, R. T.
2003a. OPMV in Australian Reptile Collections. Macarthur Herpetological Society Newsletter, Issue 38:2-8.
Hoser, R. T.
2003b. Reovirus - Successful treatment of small elapids. Crocodilian 4(3):23-27.
Hoser, R. T.
2003c. Notes on feeding captive death adders (Acanthophis antarcticus), including posturing behaviour in response
to large food items. Herpetofauna
33(1):16-17. H
Hoser, R. T.
2004. Feeding innovations for snakes. Litteratura Serpentium (March) 24(1):33-47.
Hoser, R. T.
2007. Australia’s Tiger Snakes. Reptiles March 2007, (also published on
the internet at: http://www.animalnetwork.com/reptiles/detail.aspx?aid=28279&cid=3702&search=
).
Kortlang, S.
2001. An alternative food for reptiles - Fish. Monitor - Journal of the Victorian Herpetological Society
11(3):14-16.
Stopford, J.
1980. Unusual Food Intake of a Diamond Python. Herpetofauna 12(1):35.
