True, dividing it by the animal would be simpler (but since I don't have to do the work is irrelevant) however, please look at the work through the eyes of those whom are not yet familiar with all the names.

Picture a list of the animals on earth alphabetized by their Greek or Latin scientific names, and then contemplate how you would find out what is native to the present environment.

Present usage it seems is to use whatever earth animal might fit the present need be it prey for lunch, or viscous beast to survive, rather than take full advantage of a colorful and much more fantastic bestiary.

I have read through all of the present entries and remember a few that will come in quite useful someday, however I can not remember them individually by name so will either use something else or be force to go through the entire list again to find the one I seek.

The first division should be geographical (state sized) and then by environment, for when in a desert all I am interested in are the inhabitants of this particular desert.  Both the prey and the predators.  Dividing by animal means I still have to go through all of the divisions to acquire a mental picture of my location.

Reality is irrelevant
Perception is all

Of particular aid (especially for the curious and less informed) would be a list categorized by environment.  Then subcategorized by function.

ARCTIC
sub             mammalian
sub/sub            vegetarian/prey
sub/sub            predator


sub             avian
sub/sub            vegetarian/prey
sub/sub            predator


sub             fish (waterborne)
sub/sub            vegetarian/prey
sub/sub            predator

WOODLANDS - TEMPERATE


sub             mammalian
sub/sub            vegetarian/prey
sub/sub            predator


sub             avian
sub/sub            vegetarian/prey
sub/sub            predator


sub             fish (waterborne)
sub/sub            vegetarian/prey
sub/sub            predator

and so forth through categories such as light woods, mountains, alpine mountains, swamp equatorial, swamp frigid, desert, scrub desert, salt water oceans, etc. etc.

This would allow those of us less knowledgeable to study the bestiary in organized groups rather than to be forced to bring up EVERY entry on a long list (which soon will cover most creatures) to find out what lives in an area and where they lie in the food chain.

Finding that there are so far no predators in the icelands and tundra thus far, was time consuming and draining --- but interesting.

Also more detailed maps color coded to mach the chosen category list would allow quick and easy research on what is in the general area of the town you decide to be in at any given time.  As well as a hint of the difficulties to be encountered in travel to some other distant destination.  

Plants should then be sorted similarly.

Individual entries can then limit that creatures range to certain geographical areas with the given terrain type.  Some may need to be linked to more than one terrain.

If I'm in deep woods it would be nice to know what might be encountered and those (not being listed) which I need not fear meeting.

Question??????
May we assume that most earth animals would exist in their natural habitats as well.   ie- Are there polar bears on the ice shelves fishing for seals?

Reality is irrelevant
Perception is all

As i was making my character in this context, I made a few assumptions which may prove usefull.


Given no real facts about the tribe I ASSUMED (ooooops) that they would be partially migratory as is usually required of peoples living in a hostile environment. Living the summer in their clan's ice castle near the coast and living richly on the migration patterns of elk, moose, caribou et. and the seals, fish etc. in the sea. In the fall as the edge of the ice sheet moves away and the herd animals migrate south they have to abandon the castle and spread out along the coast to stay in range of the sea. Building strings of family houses out till the turn of the seasons when they must retreat house by house back toward the castle. In late spring when the family groups (20 to 30 strong) have returned, the clan (1,000 or so) is again in contact with the other clans and trade, spouse seeking and celebrations are in order.
I do think that I have overassumed a little.