Single Large, or Several Small?

With the onslaught of human expansion around the globe, finding patches of habitat for animals to remain in the wild (such as it is) is proving to be increasingly difficult.  Conservationists are scrambling to preserve what little habitat remains, which in some cases requires buying it outright.  In these situations, they are often faced with the challenge of answering the question of SLOSS - Single Large?  Or Several Small?  Is it better to establish one large new reserve, which could hold larger, more sustainable populations of different species?  Or is it best to go for several smaller ones, opting not to put all of your eggs in one basket and protect several disparate patches of habitat.

Think about it like this - if you were in charge of planning protected areas for the United States of America, would it be best to have a small park in each of the fifty states?  Or to say, "Okay, Montana is off limits" and sacrifice the rest?

I've often encountered a different version of the SLOSS question, this one pertaining to zoos.

Most zoos - and virtually all aquariums - are landlocked.  This is especially true of the older, urban zoos, typically built in the hearts of the cities.  The chance to expand outward is often limited or nil - that's a major reason behind the establishment of the Conservation Centers for Species Survival program.  But what to do with the land inside the zoo itself?  Is it best to do a small number of very large enclosures, or to do as many small ones as you can fit?  The first option can provide picturesque, spacious enclosures that visitors will love (size = welfare in the eyes of many zoo visitors).  The second can allow for a tremendous amount of diversity.  On a small scale, imagine that you were given responsibility for a new reptile house construction project.  Should you try to incorporate as many diverse animals as possible in separate enclosures, which would be of tremendous value to conservation programs?  Or, you could say "This half of the building is for Komodo dragons, this half is for crocodiles, and we're done."

Large exhibits have their advantages.  They give you room to house more individuals of a species - instead of three zebras, you can have an actual herd.  That gives you more benefits in the form of social interaction, mate choice, and the expression of natural behavior.  It makes it easier to introduce mixed-species occupants to an enclosure.   Animals have the option of getting further away from the public, enjoying some privacy.  Visitors feel better seeing animals with more space.

Having many smaller enclosures, on the other hand, can also give you a lot more flexibility.  Suppose you have an animal or a species that's not getting along or doing well with its exhibit-mates, say a bird that's getting beaten up by other birds in the aviary (and even in a massive free-flight aviary, bully birds will always be able to find that one bird they want to pick on).  It would be nice to have the option of having a separate enclosure that this bird/species can be relocated to for its own good and comfort.  Likewise, you can have more flexibility with separating animals for breeding, introductions, raising of young, and medical purposes.  Many zoo breeding programs are also limited by the amount of space that is available for the next generation of animals.  Having more enclosures means more animals can be housed in a zoo or aquarium.

Perhaps the best - if most complicated - version is to go with some variation of both.  It would be great to have the largest enclosures that are practical/possible (not always the same thing) that could be segregated as needed into separate components.  For example, an African exhibit that could consist of yards of zebra, antelope, ostrich, and giraffe, which could be opened up into one large habitat when the opportunity is available, but separated as needs be.  If the antelope, for example, are having calves, they could be isolated in their enclosure - comfortable and spacious enough for them - but kept protected from the zebras, the males of which sometimes have a homicidal fascination with baby antelope.  If a new giraffe arrived at the zoo, it could be introduced to the other species one at a time instead of being flung into a whole mess of other animals in one go.

There are constant new ideas and innovations that go into the design of optimal habitats for zoo and aquarium animals, and members of the field are constantly striving to create new ones.  It's a far cry from the earliest days of modern zookeeping, where the only considerations that an enclosure had to satisfy were could people see the animal and could the animal escape.  We've certainly come a long way, but there's much further still to go...