mixing/multispecies exhibits.

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

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?

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.

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."

Click to expand...

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?).

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.

Of course if your limiting to what your talking about to:

iven that there is no background in the examples given so far and no significant plant cover to climb into?

Click to expand...

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.

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.

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.

-tad

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."

Click to expand...

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

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

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

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.