[Ed]

I believe I will take Mr. Yeager up on his invite to continue this discussion.

When referring to mixed enclosuresi the use of the word mixed is an inapt description as this indicates that the animals are together in a homogenized fashion. Because this is not what typically happens multispecies is a better description of the properly set-up enclosure.
Multispecies enclosures are becoming more and more common with the larger and better Zoos (including some of those at the forefront of dendrobatid breeding such as NAIB) and Aquaria. Many of the multispecies enclosures at these institutions have been present for years (some for more than a decade) with little to no problems and in some occasions house multiplegenerations of the animals on exhibit.

There are a lot of issues that are thrown when ever multispecies enclosures are brought up on various forums (not just this one) these include (and I am sure I missed a few),

1) the spatial requirements of the animals are violated
2) pathogens
3) stress

Spatial needs of the animals, this is a issue where some hard and fast numbers have become set in stone in the hobby. Usually, people speak about 5 gallons per frog. To make this simple, I am using the assumption that the 5.5 gallon tank is the standard for the 5 gallons that is the commonly used reference.
Within the 5.5 gallons of space, the space used by the frog (I am going to use a tinct as a standard for the larger dart frogs) is typically very different than the space "alloted". In a typically planted set-up the frog will only use the bottom of the tank most of the time so the actual used total space can be calculated by the surface area of the bottom of the tank (8 inches by 12 inches) and say 3 inches of head room for the frogs to hop. A 5.5 gallon tank contains 960 cubic inches so the frogs only really use 30% (288/960 = 0.3) of the available space or about 1.65 gallons.
What this means is that people have to pay attention to how the tank is portioned out for the frogs. With the set-up described above (5.5 gallon tank) there may be between 4 to 5 inches (substracting for bottom of the tank) of height in the tank that is not used by the dart frog. This would indicate that another species could inhabit that niche if the owner of the enclosure was so inclined. In a manner similar to aquariums, people can look at the enclosure as having an upper portions, a middle portion and a lower portion. In most of the smaller enclosures, this will only be two levels. The other space designates a niche that can potentially be used for a different species. This is where multispecies enclosure planning begins. The person needs to be aware of how much space is really being utilized in the enclosure by the animals. This will give you the first step on the path to the next choice if you wish to keep multispecies enclosures.

After comments (if any), next topic pathogens (last will be criteria to help make the correct choice).

Ed

 

[Ed]

I would wait until the next series before you consider mixing from different regions.

Ed

 

[Ed]

Actually folks I chose the Beginners forum for the point that this is where people tend to inquire about mixed species exhibits so this is the appropriate venue for the topic. I am breaking this into parts as otherwise the single post would be huge running the risk of losing some of the important points.

Hi Chuck,
There are few basic items that are best illustrated with a simple set-up as opposed to a complex set-up. I intend to get to the potential arboreal part soon (and will include ideas such as visual barriers, refugia etc). (I intend to address some of the hybridization issues but anura is a large genera with some possibilities that preclude hybridization problems).
The whole point to this discussion is to hopefully provide some guidelines for the people who may be considering this venture.

On to the second part of spatial needs. The following paragraph is based on the absolute minum supplied by a simple set up. The most important point is that amount of space provided by the 5 gallon/frog rule begins to break down pretty quickly.

In enclosures larger than the 5.5 gallon tank used in the example, the space not used by a frog like a tinct can be much more dramatically different as in many tanks, the height increases faster than the length and width of the tank(although there are often tanks such as 20 longs that are not as problematic.
For example a ten gallon tank is 20 long x 10 wide x 12 high giving a total of 2400 cubic inches. However if we then calculate the usable volume of the tank using the same criteria used in the 5.5 gallon tank (in the first post) we get 3 inches high x 10 inches wide x 20 inches long we get 600 cubic inches or 25% of the total volume of the tank (and only a 50% increase of the usable space of a 5.5 gallon tank).
If we then go up to a 20 gallon high tank 16.5 high x 12 wide x 24 long we get 4752 total cubic inches with a usable area of 3 x 12 x 24 = 864 cubic inches. In a 20 gallon high tank the amount of usable space drops to a low of 18% of the tank (or a total of 3.6 gallons) yet the 5 gallon/frog rule has us then placing four dart frogs in the tank. In a 20 gallon long (approximate external dimensions of 30x13x12 gets 4680 cubic inches with a usable space of 1080 cubic inches a use rate of 23% or a total of 4.6 gallons).
When looking at even larger standard enclosures such as 55 gallon aquaria (48 x 12 x 20 = 11520 total cubic inches) with a usable space of 1728 cubic inches or a total of 15% of the tank space or a total of 8.25 gallons. (Or based on the 1frog/5 gallon rule 11 frogs which would each have 157 cubic inches each or a total volume of .68 gallons each)
So the usable space indicates that there is something wrong with this method of determing density of frogs as the actual density of multifrog enclosures exceeds the 5/gallons frog limit commonly recommended by the masses as the size of the tank increases (each frog has 300 cubic inches of space/frog (using the 5 gallon/frog rule) in a ten gallon, and 270 cubic inches in a 20 long as opposed to 157 cubic inches of space in a 55 gallon). (Using ten gallons per frog is slightly better but still suffers the same drawbacks).
This then raises the question, then why are we able to keep these frogs at these densities in larger enclosures?

Part of the reason why is because the large enclosures lack floor space, they provide vertical room for decorations that allow the frogs to use more of the volume of the enclosure (but still not an equivalent volume per frog). These decorations provide visual barriers allowing the frogs to escape one another much as they would on the forest floor.

Additionally, in the larger enclosures the minimal amount of floor space decreases but the total amount of space increases. It is this other space that needs to be considered for other species.

Any further questions/comments? If not, I hope to address some of the complex enclosures items.

Ed

 

[Ed]

Your calculations make no sense what so ever, as many of us don't jsut have a ground level and backgrounds. We have hiding areas, branches protruding formt he background, the glass itself, etc. so the frog truly does use the full 5 gallons that given to it."


Actually Derek this is physically impossible as this would require the entire volume of the 5-gallons to be filled with the mass of the frog and/or the structures leaving out any space for air.

Ed

 

[Ed]

Hi Tad,

Where do you see the math being flawed? How are the calculations inaccurate given that there is no background in the examples given so far and no significant plant cover to climb into? The examples to date are to show that a simple enclosure stocked with the 1 frog/5 gallon rule has some flaws in the logic as the size of the enclosure increases.

So you have a simple enclosure without a background or other items planted above the surface of the soil? The frogs are climbing on and spending a significant portion of the time only on the bare glass?


Did you read all the way through to where I said

"Part of the reason why is because the large enclosures lack floor space, they provide vertical room for decorations that allow the frogs to use more of the volume of the enclosure (but still not an equivalent volume per frog). These decorations provide visual barriers allowing the frogs to escape one another much as they would on the forest floor.

Additionally, in the larger enclosures the minimal amount of floor space decreases but the total amount of space increases. It is this other space that needs to be considered for other species."

Ed

 

[Ed]

Hi Tad (and for everyone else, this will be a long response so I will make a second post after this one).

snip "I meant to say the math is accurate just didn't think you conclusion was/is logical... but I guess in all honesty I'm not entirely sure what you are trying to say. At one point you seem to be stating that the only important factor in tank size as far as the frog is concerned is floor space. Then you go on to say that the rest of the space can be used to house other species? As if this space will be ignored by dendrobates and used by ?xxx species?"

I am building up to a couple of concepts that are very counterintuitive and I guess I am taking the long road to them. The simplistic set-up is to get people thinking about all of the unused space in some of the tanks, that may or may not be utilizable by the dendrobates. There is a lot of volume in the tank that can be utilized by other species. I think I make this clearer in the next installment.

Snip "Honestly I don't think anyone has ever meant 5 gallons per frog to be a hard and fast absolute. Obviously common sense comes into play. But considering the typical landscaping and layout of most tanks, I would think its a decent figure. I do think that both a 20 high and a 20 long can house the same number of frogs. When all is said and done if they're landscaped/stocked with plants properly you end up with a fairly similiar amount of useable living space. I think this would hold true up to your larger size tanks (120-280). Though this will depend on how dense the vegitation happens to be."

This is not what I have had said to me in some recent pms. There is a strong belief in the 5 gallons/frog as an absolute minimum and I think that when people are considering multispecies enclosures this can be a problem (heck I think as an absolute its a problem anyway). Its a good starting point but for planning but its taken (in my opinion) way too seriously. I have more to say on this in the next installment.

in the larger enclosures the minimal amount of floor space decreases but the total amount of space increases. It is this other space that needs to be considered for other species."

snip "I'm thinking you mean the ratio of floorspace to volume decreases and that the frogs are primarily concerned with floor space? And that much of the newly available volume is inaccessible to the frogs (being that its space near the ceiling? or in the emptiness between the top and bottom?)."

(The main point to remember I am only discussing the minimal amount (and only the minimal) per frog available). Not that they are primarily concerned with floor space (even though my experience with a lot of tincts had this to be the most common pattern) but in a simple set-up you are pretty much restricting the frogs to the floor space (by limiting the available cover and habitat). But again it was partly to get people to consider that a simplistic set-up does not give the frogs as much space as you might believe.

Snip "I think the "wasted" empty space between the top and bottom can be used if the tank is planted in a lush manner (think about the difference between a gymnasium and a 3 story apartment building that share the same dimension."

This is where I am slowly going. I make some assumptions on this in the next post that increase the amount of space in the calculations. However, this still does not provide a 100% usage of the space.


snip "But that doesn't seem to be typical or even atypical but maybe limited to something a frog would travel in and most certainly not a display tank."

I have bred tincts, auratus, azureus, E. tricolor and P. terriblis in those types of set-ups. They are the sort of setups you see in areas that are looking to breed frogs and need to be able to individually account for the frogs on a daily basis (Cincinnati's entire off exhibit breeding set-up was kept this way). This may not be the most common in many private hands but it is not that uncommon either.

snip "But once again I'm not entirely sure what your getting at, if the volume/space of the tank is not accessible to by the frog I don't see it being used by species "X" either. Unless were talking about humming birds? or some other flying/hovering species. I have what I would consider to be somewhat moderatlely planted 29 gallon tank with 3 tincs and I would say the tincs spend more than half of their time *not* on the ground."

There are other options than hummingbirds (whose density is limited not by space but the number and location of nectuaries but are still one mean bird).

Snip "I think you could talk about different "zones" of the tank being utilized by different species if your talking about tanks that are more than 6ft high. I would assume that any dendrobate would be willing and able to use/climb the vertical space of any tank that was shorter than 4ft."

Doesn't have to be that big depending on the choices. But then I am talking about more than dendrobates here.

Ed

 

[Ed]

Okay here is the next installment. (the top and part of the middle is just covering the minimal amount of space available in more complex enclosures).

To repeat this again I am looking at (conservatively) minimal spatial
availability not the maximum the frogs can/will use (this is an important
distinction). (I used a 20 H and a 55 as these are right outside my office and as such are easily measureable)
So even looking at the minimal space available to the frogs in a more
complex set-up such as those that include drip walls and plants, the ratio of habitable space still decreases as the volume of the tank increases as more and more of the volume of the tank is represented by glass and air volume (but it is this change that creates the changes in the moisture levels, humidity, air flow patterns and light patterns that create different microhabitats allowing the multispecies options).
If we assume that we lose 2 inches of height due to a false bottom set
up and include a tree fern fiber drip wall (as this is thicker than a cocos panel) which is about 1 inch deep. As plantings in tanks tend to be an admixture of tall and short plants as well as open spaces to permit viewing, an assumption that the frogs can use 100% of the first 6 inches in height will give a base line estimate of usable space (instead of estimating usable space in a varied planting). The drip wall is kept to a depth of three inches out from the surface of the drip wall and is assumed to be 100% usable by the frogs.
So for a 20 high tank 24 long x 16.5 high x 12 deep. Deducting for the
substrate and drip wall changes the numbers to the following
14.5 inches high x 11 deep x 24 inches long. So we do not calculate out
the same overlapping volume twice, the three inches from the drip wall are excluded from the bottom area calculations. So then the minimal usable area ends up being (6 inches (height) x 8 deep x 24 long) + (14.4 height x 3 inches deep x 24 inches long)= (1152 ) + (1036.8) = 2188.8 as the conservative minimal estimate for usable space. Yet this is still significantly less than the total volume of the tank (4752 cubic inches so when the total minimal usable estimate is applied you get only 46% of the tank (or 9.2 gallons or 2.3 gallons per frog) as estimated usable space. In a 55 you get (6 inches height x 8 deep x 48 long) + ( 18 height x 3
inches deep x 48 inches long) = (2304) + (2592) = 4896 cubic inches or 42.3% of the volume of the tank (or 23 gallons total or 2.1 gallon/frog) the general trend of the increasing volume decreasing minimal usable space. So once again the idea that each frog gets a minimum of 5 gallons of space breaks down as the enclosures get larger (This is counter intuitive but true unless the enclosure's floor area increases as the height increases (some breeder tanks are an example of this). (However for territorial/aggressive species it is still a place to start planning.) .

There are significant differences between the minimal amount of
available space in a simple enclosure as opposed to a complex enclosure (which is why I needed to demonstrate out the differences via the cubic inches). When considering larger tanks, the 5 gallon rule may be a place to start (although in my personal experience, it is easily possible to keep and breed some darts and many hylids in higher densities for long periods (years to a decade or so )).
The reason the density works in the larger enclosures is not because each frog necessarily has more space but has the illusion of more space. (And this is where I was going the entire time with the previous discussion). This is where having an idea of the minimal usable/available space comes into play with a species that is territorial and/or aggressive as it gives you an idea as to how many visual barriers, hide areas or other refugia may be necessary to accommodate the individuals in that cage. In simple cages, multiple hide areas (often one per animal) as well as visual barriers are needed, in complex enclosures fewer visual barriers are needed as the multiple available height levels available as well as the leaf and stem structure of the plants perform this function while hide areas may also be totally supplied by the plants.

Visual barriers consist of anything that blocks the sight path from one
animal to another. This prevents excess aggression as well as allowing an animal to flee from an interaction (as well as potentially increasing the density the at which the animals can be kept). Visual barriers are not important to nonterritorial/nonaggressive species such as some hylids (except by providing more surface area for perching). When considering multispecies enclosures (and I am actually not talking about more than one dart frog species per enclosure), the complexity of the enclosure provides multiple niches for other species to inhabit. Species that would not do well together in a simple enclosure may do very well together in complex enclosures due to the advantages of the multiple niches provided. The additions of some thin branches to the upper areas of the tank can create an entirely new habitation zone for a different species. In general for most multispecies enclosures there needs to be some gradient in the enclosure to be able to support more than one species. This is more easily and visibly accomplished in the very large enclosures but there are also options available in smaller enclosures that are complexly set up.

Now on to the real heresy. The space taken up by the dart frogs is not
used to determine the spatial needs of the other potential inhabitants (as long as they are not dart frogs or a species that looks/acts like a dart frog). The needs of the other specie(s) such as visual barriers and
hide spots for territorial species all applies and consideration must be given to be prevent these requirements from making a habitat that is detrimental to the dart frogs. (such as overperching, basking lights increasing the temperatures too high, etc). The reason that the space occupied by the dart frogs is not counted against the spatial needs of the other animal is that unless the species chosen to live in the same enclosure behaves/looks like a dart frog it will be ignored by the dart frogs (there are some other guide rules which I will bring up later). For example, if one of the sympatric Gonatodes or Sphaerodactyline geckos are chosen as the second target species, the dart frogs will ignore the lizards. However as these are territorial to each other in their
own right, the limits required by spatial needs of these lizards will curtail
the number of lizards in the enclosures. Now this does not mean that there is an unending number of animals that can be placed in the enclosure. There is a finite number but the number is not directly determined by the amount of space available but by the availability and amount of suitable habitat(s) that the volume can contain. (Obviously the smaller the tank, the fewer the habitats).
The number of niches then determines the number of species (while the territorial needs of the animal will determine the density or number of animals per enclosure predicated on some comments to follow). In addition it is also partially dependent on the target species chosen, the size and complexity of the enclosure, the ease of cleaning of the enclosure and the ease of feeding the animals. In general the smaller the cage, the fewer the species, depending on the species in question. Multiple species are still possible in a small enclosure and are often set-up unintentionally as many people do not count the various invertebrate populations that are established in the enclosures (most of which are not native to the frogs areas to begin with) for janitorial and/or frog food purposes. I tend to use one species to a niche as a basic rule of thumb which has been very workable for me.

So to sum it up just to begin to consider if multiple species enclosure is an option the following must be determined (this is before we get to parasites/disease and stress)
1) Is there more than one niche available?
2) will the conditions available to the animals (both frogs and others) be suitable for those animals?
3) If the animal(s) are territorial, do I have enough visual barriers and hiding spots?
4) Can I easily feed, clean and maintain the enclosure in the chosen configuation? If not, will any changes made to make the enclosure easier to maintain change the animal(s) requirements? and if so can I then meet those requirements?
5) Will the shape or behavior of one animal affect the territoriality of another animal in the enclosure?

So in other words, a lot of issues need to be considered for the set-up before placing multiple species together. It is possible but it takes a lot of planning and thought to do it properly and this still does not take into account the other two items.


Ed

 

[Ed]

It might be best to wait until I finished all of the issues then they can be summed up.

Ed

 

[Ed]

Hi Derek,
The numbers were made to calculate out a conservative minimal area available and the assumption that the frogs could use 100% of the six inches of height was an assumption to make the calculation easier. (If you want to figure out the exact amount, map out your total tank, calculate out the available volume provided by each item (hint calculate plants as solid cones or columns for ease) and subtract the volume of solid objects. Next spend the next two weeks or so mapping out the exact areas used by the frogs every 15-20 minutes. )

Actually, when using solid objects, (if I remember correctly) the surface area squares while the volume cubes. So the bigger and thicker the branch or piece of wood used in the tank, the less usable area is available as the volume of the branch takes up more than it provides. In addition, horizontally oriented branches can have as little as 1/3 of the branch usable (unless the frog can cling totally upside down). Plants provide more surface area and space for the animals than branches do by virtue that the multiple leaves and that they do not occupy a total volume.

Ed

 

[Ed]

Okay here is the next installment.

The subject of cross infection by parasites and diseases is often given as
reasons to avoid multiple species enclosures but the details of the reason(s)
are frequently lacking. When examined in a somewhat global manner, the reasons
are more clear cut. As our knowledge of exotic pathogens becomes more extensive
more and more examples of cross infection and mortality from exotic sources
becomes apparent. Some examples of this are chytridmycosis in many species of
amphibians (possibly the result of the world wide transport of African clawed
frogs (Xenopus)), mycoplasma infections in tortoises of the genus Gopherus
(possibly from exposure to infected South American tortoises) (which has now
also been isolated from box turtles (Terrepene), monkey pox in Prairie Dogs
exposed to giant pouched rats (and humans exposed to the infected prairie dogs)
and Herpes B infections in humans from infected primates (mainly Macaques if I
remember correctly). Because of this, animals should only be mixed with animals
that are from the same regions to minimize the risk of cross infection with
novel pathogens and parasites. There is a risk of infection regardless of the
closeness of the origins of the animals (there are some examples of ranavirus
infections between nearby vernal pools that were the result of researchers
failing to clean boots and collecting gear but nothing on the huge scale of the
examples listed above) but the risk of a novel pathogen getting loose in a
collection are minimized when zoogeographically correct animals are kept
together. This is because there is a good chance that the disease is not novel
to animals from the same regions possibly permitting the infected animals to
resist an infection and/or clear it.
Simply observing the condition of the animal may not give any warning if the
animal is a carrier of the disease/parasite as the animal can be asymptomatic
(such as Xenopus and chytrid), some rodent carriers of hemorrhagic fevers, and
Old World Primates infected with Herpes B. The mixing of carriers and novel
hosts allows the disease the chance to jump to a new host potentially resulting
in significant mortality of the new host species.

So the points from this topic are as follows (rephrased to cover all of the
possible issues I can think of )
1) the multispecies enclosure should be as close to zoogeographically correct as
possible with respect to at least the vertebral inhabitants (given the
restrictions on importation of soil and invertebrates into the USA, this is may
not be possible with many invertebrate species native to the animal's habitat).
2) If possible the animals should be sympatric
3) Ideally species that do not naturally have overlapping distribution ranges
should not be mixed ( for example even though green anoles (Anolis carolinensis)
are found on Guam does not mean they should be kept with Oceanic geckos (Gehyra
ssp).)
4) points 1, 2 and 3 should be followed as closely as possible regardless of the
person's belief in the suitability of the inhabitants. For example, even
through squirrel tree frogs (Hyla squirrella) will quite happily live in a
terraria set up for dendrobates, this is not a suitable animal as it is not
zoogeographically correct. If the person wishes to keep a small hylid with
Dendrobates, then they should consider Hyla leucophyllata or Hyla ebraccata as
possible options.
5) Aquatic and semiaquatic chelonians are not suitable to be kept with any
animal that is at risk to ameobiasis.

 

[Ed]

Actually they will feed on D. hydei and ten day old crickets are readily accepted by them as well as tincts, auratus, leucs......


Ed

 

[Ed]

Crickets only predate on other items if food and/or water is lacking.

Both H. leucophyllata and H. ebraccatta mass a little less than or about the same as a large tinct. As the weights and temperatures are about the same the metabolic rates are about the same. This would make the caloric requirements about the same. This would then mean that the number of food items needed to be consumed are about the same. So it would not require hundreds and hundreds of ffs in the cage to feed the frogs. (If you want an explination of the caloric needs based on body size and temperature I refer you to Amphibian Medicine and Captive Husbandry for the explination).

The size of both their mouth and the size of the dendrobates mouth prevents frogs from trying to eat frogs.

Ed

 

[Ed]

Actually what I should have said is that a very large H. ebraccata or H. leucophylatta masses about the same as a large tinct and most of these are hylids are actually smaller.

Prey items in anurans.....
1) In most anurans, the prey item needs to fit a certain size and shape profile. There are species where this is not the case such as Bombina (but Bombina do just fine with larger sympatric species of Cynops such as C. cyanureus without injury to either party) and Certophrys (which probably should not be kept with anything else)for example. (In addition, many of the freshly imported C. orientalis suffer limb loss within a month or two of importation due to bacterial infections and damage during importation. Many of the sightings of lost limbs in pet stores or after purchase are due to this and not damage from the toads). Both Bombina and Ceratophrys are generalists, that will attempt to consume prey items as large as they are or larger. In addition, Bombina can enter into a "feeding frenzy" during which they will grab and attempt to consume anything. Dendrobates and the Hylids referenced above will not. In addition, with the Bombina reference provided by Derek, there is a significant difference in the mass of the two animals (at least 5 to 1) unlike the Hylids I suggested.
2) Some anurans exposed to the higher prey ratio in captivity can become "trained" to attempt to capture items that touch them as a feeding reaction. This is not common or usual. I have seen it in two species to date that were both blind, Leptodactylus pentadactylus and Osteopilus septentrionalis. However even if that was the case with the two species I suggested, neither species would be able to injure even a small Dendrobatid frog. The jaw strength just is not there. I believe that this is what Derek observed with the P. sauvagi.
3) While in captivity there may not be a "set" time for feeding, there are preferential times for feedings. These follow the frogs normal activity schedule. It is only the addition of food items at specific intervels that causes the disruption in the normal behavior of the frogs.

Toxicity:
This is another subject that gets tossed around a lot. One of the points to remember that with some notable exceptions (such as Rana palustris) the amphibians are not running around leaking skin toxins. This only occurs when the amphibian is under severe stress. Synthesizing (in those that make their own), storing, excreting skin toxins are all energetically expensive and to leak these all of the time is counter productive to the animal as a general rule. If you see an amphibian reacting in a manner that shows the production of skin toxins, there is some major crisis occuring in the terraria (and the release of the toxins is usually only a symptom and not the primary event).

 

[Ed]

Hi Dave,
I have done my first round draft on the subject of stress and need to sit down and refine it a couple of times.

The highest density I have kept at work, let me think on it, I have kept several species at very high densities, probably the highest density at the moment is either a breeding group of RETFs in a 20 H (13 animals) or the group of A. zeteki on exhibit (I'll need to figure out the space in that exhibit as it has several tiers).

Ed

 

[Ed]

Derek,
If that is your opinion please state it as such. Otherwise please supply a citation that the density listed is excessive.

Dave, If I understand your answer correctly

The breeding colony is off exhibit. With regards to RETFs,
1) they are non-territorial and easily cohabitat.
2) the chances of reproductive success is increased as the density of the animals is increased.
3) Post cycling and reproduction they will be moved to a larger enclosure. The question was asked, what was the highest density I have kept anurans and as adults that is the answer.

However the ability to keep them at these densities is true of many hylids, spring peepers (Pseudacris crucifer), green tree frogs (H. cinerea), and other small hylids do well at these densities. However you need to be aware of the animal's behavioral requirements as I would not suggest keeping Hyla boans this way or any of the genus Centronella.

The zeteki cage is larger but to be sure of the space I have to measure it out.

What you say about Zoo enclosures and the public is true in many places (and the visitors behave this way at work). This is why many of the enclosures I try to set-up has a noncryptic species and other animals that may or may not be obvious. For example there are Flat-tailed tortoises (Pyxis planicauda) in a large enclosure with Standing's Day Geckos (Phelsuma standingi), Ornate Plated Lizards (Zonosaurus ornata) and panther chameleons (which have all reproduced in this enclosure). Hardly anyone sees the geckos or the plated lizards as they tend to be very cryptic but everyone sees the tortoises. I would rather set up enclosures in this manner which allows for more diversity than to try and place one or maybe two large animals in an enclosure (or to try and place a larger number in an enclosure than I am comfortable with to try and make them visible).

The once was a study performed to see which exhibit in a Zoo people spent the most time watching the animals. The exhibit that won out was a large burmese python in a sterile concrete cage.......

Ed

 

[Ed]

Hi All,
I've finally gotten some time to get back to this thread..

Here are the thoughts on "stress"
This is not as complete as I would have liked to make it but I fear I will not have the time to make it more complete as my schedule has suddenly become very tight.

The third and hopefully last installment.

Stress is the third item often used as a reason to justify why multispecies
enclosures do not work. For this to be discussed appropriately, the definition of stress needs to be outlined before any meaningful discussion can take place. Stress is best defined as anything that disrupts the homeostasis of the animal. However not all of the items that cause stress (called stressors) has a negative impact on the animal involved. Thus there are both negative and positive stressors (I am only going to consider negative stressors for this article as these are the only ones that have a negative impact on the animal). Some examples of negative stressors include improper temperatures, lack of hide areas, and lack of nutrition. One of the points to remember with stressors is that unless they are extreme enough to cause rapid death and do not vary in intensity then the animals will become adapted to the stressor (with the exception of nutritional stressors) and should return to "normal" behaviors after an acclimation period. However if the stressor is not constant then the resultant stress may be sufficient to cause the death of the animal (some times referred to maladaption syndrome or failure to thrive). This adaptive process only works as long as the stressor is constant, as soon as it begins to vary in intensity, the adaption is lost.

One of the most common types of stress seen in anurans (and in fact many herps) is the animal displaying constant escape behaviors, often to the point of self mutilation (nose rubs). This is best avoided by having sufficient hiding areas (see the discussion on complex and simple enclosures from above) available to the frogs to allow them to feel secure in the enclosure thus eliminating the problem (If there are sufficient hide areas and this sort of escape behavior continues then one should immediately suspect heat stress and/or exposure to a chemical agent such as toxic fumes (paints or other solvents for example). While this sort of escape behavior can be the result of territorial displacement in many species this is typically only seen when more than one species of
dendrobatid is kept in the enclosure as the frogs do not recognize frogs that do not behave or look like other dendrobatid frogs. (While it is possible to mix multiple dendrobatid species together, this is not recommended due to the issues mentioned above as well as others such as potential hybridization). As mentioned previously, if the inhabitants are properly chosen (in other words not other dendrobates), the dendrobatids will not be stressed by the other species as the dendrobates will not respond to the other species in a territorial response. This is why other occupants are often treated as so much cage furniture (I used to have a picture of an auratus perched on the head of an eyelash viper feeding on fruitflies).

Another comment regarding stress that is often tossed around is that animals kept in multispecies enclosures will not breed due to the stress of the multispecies enclosures. This is typically due to improperly set up enclosures which lack suitable habitat for reproduction. If the parameters are correct the animals will breed regardless of the number of species in the enclosure (however see the previous discussion on spatial requirements on limits for the number of possible species in an enclosure).

Stress of an animal in the multispecies enclosure will be the same as that in a single species enclosure as long as the animals are chosen under the guidelines provide previously and suitable micoclimates, and refuges are present

 

[Ed]

Hi Brent,
I left out the whole discussion of why a person would want to create a multispecies enclosure as this is a personal decision that needs to be made by each person when comes to their enclosures. With the exception of educational institutions, I doubt that most people at this time set-up multispecies enclosures at home as they are content to concentrate on one species at a time. However, my personal opinion is that if someone does try it they should at least be given the best information available so they may potentially succeed at the attempt.

With regard to your point about hard to breed species and elbow room, this may not be the reason (or the whole reason) as the sucess that results in keeping them in single species enclosures may be due to the maximization of suitable habitat as the mistake often made in multiple species enclosures is not in attempting to pick suitable cage mates but in attempting to maximize the available niches to maximize the number of species that can be placed together. If this is the way in which the enclusure is prepared then most of the time the attempt is doomed to failure.

A properly setup and stocked multispecies exhibit does not mean that it will be action packed or even that you will see all of the animals all the time. It doesn't even mean that anything has to be visible (unless one of the species is very visible (such as emerald tree boas or tortoises).
As Brent commented, if you make simplistic enclosures then the animals may have less interesting behaviors which the average member of the public may never see, but may get lucky and see it (I remember a faimily about 5 years ago watching a RETF lay eggs on exhibit, they stayed for the entire time, watching that one act.


By the way has anyone else seen the article in the 2004 summer issue of the Herpetological Bulletin on D. truncatus? The author indicates that this species coexists just fine with arboreal species such as D. ventrimalculatus.


Ed

 

[Ed]

Hi,
I was checking my dendroboard messages and I accidently deleted one from someone asking me some questions.
If you are waiting for a response please send me the message again.

Sorry about that
Ed

 

[Ed]

Hi Brent,

snip " One bone I will pick though is that I'm uncomfortable defining stress as simply something that interferes with homeostasis. That certainly covers the physiological response to stress but I don't think it adequately covers behavioral components. Stress can create a shift in behavior. The shift is not always negative. For example drought stress can prime an animal for breeding behavior when moisture returns. But stress can also interfere with desired behaviors. The stress of too many competitors could interfere with breeding behaviors even though the animal is able to "maintain homeostasis". I'd just like to see the definition broadened a bit is all. "


But isn't the behavioral modification an attempt to deal with the physiological effect of the stress and return the animal to a homeostasis? It is only (in general to repeat what I said (not so much for you but for some who may be surfing the thread)) when these behavioral shifts cannot accomedate the physiological effects of the stress that the animal cannot adapt to the situatuon and may die. Which has been documented (although I am only aware of anecdotal documentations) with respect to constant aggressive interactions over the limited reproductive resources (such as we see in tincts on occasion). As this should not be a constant stressor (as for example the females are not constantly receptive and the males can only tend a limited number of clutches of eggs) for the animals, the keeper is required to recognize and correct the situation by supplying more reproductive resources (such as oviposition sites) and/or reducing the density of the animals. (I am of course assuming you are referring to same species/genus reproductive interference and not across genera. In cross genera reproductive interference such as call interference, anurans adapt their calling to prevent overlap and interference (as is seen in multispecies choruses)).

(Some partly coherent thoughts).
Ed

 

[Ed]

Hi Brent,
I think I understand the issue.

Does this sound right?

All of an animal's available behaviors are not the result of an animal's attempts to return to or maintain homeostasis due to stress(es) but behavioral changes in response to stressor(s) are the result of animals attempting to return to homeostasis. (getting back to your play example). (Just for a comment here, as a joke some dice were placed in with Atelopus zeteki at the Baltimore Zoo and the Atelopus were noted to be wrestling the dice around the cage. Was this play behavior, or were the frogs acting on some other stimuli is unknown but I thought it was interesting).

(That said, I have a hard time picturing behaviors that are in response to a stress that does not affect the physiological homeostasis of the animal as even changes in hormones affect the homeostasis of the animal. There may be a resetting of the homeostasis such as when males may be calling but this is usually a drain on resources the animal has and can result in death or abandonment of eggs/tadpoles if the energetic outlay is excessive)

However, the animal's ability to have or use some of those behaviors may also be directly affected by the status of the animal with respect to homeostasis. For example, I would be surprised to see play behavior in an animal that is heat stressed, starved, or injured. (I know I'm taking it to extremes here for simplicity).

Ed