As others have remarked (see this excellent write-up by Wayne Rossi for example http://initiativeone.blogspot.com/2013/05/od-setting-posts-in-pdf.html ) the wilderness given by the rules in OD&D is a wild, fantastic place crawling with nightmarish creatures and punctuated by tiny struggling beacons of civilization. Generating the monstrous population of this “upper world” wilderland is done through a series of tables. What distinguishes these tables most from later versions of D&D is that each table is given a creature type category and each type is generated on a separate table first. For example, one one might roll “flyers” on the first table and then roll giant eagles on the Flyers table.
But why go through this extra, seemingly superfluous step? No doubt the reason is to allow a referee to create custom lists of creatures for their wilderness while maintaining the same encounter type frequencies called for in the rules.
The creature types given in the rules are:
All the monsters and characters of D&D fall into one or other of these categories, (possibly more than one) and all these categories have a pretty wide variety of creatures – except for Lycanthropes. Lycanthropes are the most specific of the categories, having the least members – only 4 in the 3lbbs. Why aren’t lycanthropes simply folded into the “men” category or some other? Perhaps the answer is simply a result of Gygax and Arneson’s conceptualization of the category types. In the entry on vampires, Lycanthropes are stressed as a separate type not to be confused with undead. I suppose the logic was that if they are neither undead nor normal men they must be a separate type, more or less by default. The upshot is that using the OD&D wilderness tables as is will give a much higher occurrence of the four kinds of lycans than any other monster.
Perhaps though, there’s a little more to the story than simply a fluke of classification. The wilderness encounter tables of OD&D appear to be derived and expanded from Dave Arneson’s “Encounter Matrix I”, a copy of which can be found at the start of the “Into The Great Outdoors” section of First Fantasy Campaign. Encounter Matrix I is a d20 table Dave Arneson came up with in the very early days of Blackmoor to generate random monster encounters when the Blackmoor players first began to leave the dungeons and explore the countryside. The derivation of the D&D wilderness encounter table from Encounter Matrix I is fairly obvious in that both have exactly the same location categories except that D&D adds one new terrain category “cities”. An important distinction however is that the FFC list has only individual monsters taken from the CHAINMAIL miniatures rules – Ogres, trolls goblins, air elementals etc., instead of the creature type categories of D&D. Both lists however share the category “Lycanthropes” in common. Perhaps even more interesting, Lycanthropes occur most frequently in woods on both lists, at very nearly the same frequency 21.4% (FFC) to 25% (D&D). So the curios abundance of lycans in the D&D wilderness appears to be as much a carryover from the early Blackmoor wilderness as anything else.
Now I don’t want to get carried away with this. Undead for example appear more often in Arnesons’ lists than in the OD&D list. There are ghouls and “wrights” in the Mountains in the Blackmoor wilderness where as no undead are listed in D&Ds mountains, but the general character of the Blackmoor wilderness does seem to have set the stage from which the D&D wilderness was crafted and the predominance of Lycanthropes appears to be an artifact of this relationship going to the earliest milieus of the game.