Extreme Feeding Methods For Snakes From Australia
488 Park Road
Park Orchards, Victoria, 3114, Australia.
Originally published in the bulletin of the chicago herpetological society, 42(4)(April 2007):62-65.
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.
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.
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.
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.
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.
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