No CR's in 1e. Max weight equal to a black bear. reptile, bird or mammal.
Thanks, squeen, I had no idea that CR was not used in 1e. *sarcasm*
I mean that all those 1e creatures I listed are more or less equivalent in power, in comparison to a 1e fighter of a given level, as a 5e CR1 creature in comparison to a 5e fighter of that same level. They present the same level of threat.
All those creatures are "legal" to choose by any reading of the entry, being birds, reptiles or mammals no larger than a black bear. Animals in that group ranging from an average XP of 106 (for a cheetah), to an XP value of 212 (for a leopard) all translate to being CR 1 in 5e.
Now, if we include animals like a jaguar, which averages slightly smaller than a black bear but averages 300 XP in 1e, on account of having more hit dice and more special attacks/defences, that is equivalent to a CR 2 creature in 5e. So if you were looking only at that power, the 1e druid is actually more powerful than the 5e druid.
How do I know this? I spent years crafting a 1e to 4e conversion table, based on the XP on 1e monsters, the level of 4e monsters, and how dangerous those monsters were to characters of a given level. I did something similar with 3e to 4e and 5e to 4e, so I can make conversions from one edition to another.
And this might have all been conjecture, expect that it has turned out that my tables ended up having a pretty decent shot at predicting the actual level or CR assignments of monsters in the later editions (ironically excepting 4e, which has a different philosophy of monster power). So, for instance, if I was converting a 1e gnoll worth 46 XP to 3e I would give it a CR of 1, and if I was converting it to 5e I would make it a CR 1/2 monster. And in fact, the 3e version of a gnoll is a CR 1 monster, and the 5e version of a gnoll is a CR 1/2 monster. Plus when I run a converted monster it performs pretty much like I would have predicted, and when I convert a module the appropriate level ranges end up being comparable to the original.