[Sam Baughn]

Terrain and lighting can make a big difference. A goat isn't much threat until you encounter an aggressive one while half way up a slope you need to hold on to with both hands and one good hit will send you tumbling down to the bottom. A fat-tail scorpion isn't a problem in the open, but it's very bad news if you stick your hand into its hiding place. A venomous snake lurking in long grass at night means you had better be wearing good boots or you are getting a dose. Almost anything is a threat when you're swimming. Even straight-forward desperate carnivores will usually try and attack at night, when humans are at a serious disadvantage but they get little or no penalties.

Swarms are also very nasty unless the party are prepared for them with magic, birdshot, etc. Sheer numbers work well for other creatures too; being outnumbered by highly manoeuvrable opponents is always bad news in GURPS.