To what degree can Air Pistols and Air Rifles fend off wild dangerous animals, such as coyotes, wolves, bears and snakes?
Are pistols less effective than rifles? My family lacks any firearms license or training!
Whilst leaf peeping in Canada this past month, multiple cougars came up too close to us! Fortunately, we never hike on our own. Our power in numbers and air horn scared these coywolfs away!
Air guns are effective against small animals such as rodents. The more powerful air weapons can take down larger animals such as deer, but these are hunting weapons.
Never use any weapon (or even carry it unboxed) unless you have been trained. A licence may be required, and their use may also be subject to the landowner's restrictions, and of course to state and national laws.
To stand any chance of being effective, the gun will need to be deployed and ready. The closest and easiest targets to hit are your companions, so there may be a higher chance of accidentally wounding or killing one of your own party than a threatening animal. Besides, carrying a weapon will put you in entirely the wrong 'mind set' to be enjoying the Great Outdoors.
There have been previous questions on the stack. About wolves:
Should a hiker be concerned about wolves in the back-country?
About bears:
If I cross paths with a bear, what should I do?
And here is advice about bears from the US park service:
Staying Safe in Bear Country: Bear Spray & Firearms.
Your biggest defence is being in a group, and making enough noise not to startle any wildlife you encounter. Most will avoid contact with humans.
Not at all, Canadian regulations define any air gun with a bullet energy greater than 6J(oules) to be a firearm.
For comparison a .22 Short bullet, which is the least powerful mass-produced caliber and considered underpowered for anything larger than a rat, starts at 60J. The .30-06, the most popular hunting round and the smallest thing you'd want to use on a bear, is around 4000J and more powerful rounds well suitable to stopping bears can easily top 6000J. So the most powerful unrestricted air-gun you can buy without a license is literally 500 - 1000X less powerful than what's needed.
Just get a can of bear spray. You can get it at any outdoor store in Canada, it's convenient to carry on a belt and is more than enough for a Coyote or a Cougar. Just make sure you try it at least once (there's more than enough in them for a quick test spray), to remember how far the droplets go(and how wind affects it! Spraying upwind is a great way to use it on yourself!)
Technically crossbows don't require a license, but you won't hit anything without a lot of practice, they are way less convenient to carry loaded than guns and if you kill e.g. a cougar with a crossbow because you say you felt threatened, good luck proving you're not a poacher if someone noticed, so just stick to the bear spray.
P.S. I just remembered that technically, flintlocks, including modern replicas, are legally antique firearms and don't require a license E.G. a blunderbuss(flintlock shotgun) on sale online in Canada with no restrictions: https://www.thingsmilitary.com/long-arms/blunderbuss/ But quite frankly, that's even worse than a modern crossbow, aside from the noise factor, since flintlocks have an inherent chance to misfire. Putting it here for completeness.
Frame Challenge:
Coyotes, wolves, bears, snakes and cougars are all very different animals. Some of them can, in some special circumstances, pose different dangers to you.
But none of these dangers are best addressed (or even addressed at all!) by bringing guns into the equation, be they air-powered or traditional firearms.
If you are interested in how to avoid the dangers potentially posed by a specific animal then I suggest you ask a follow up questions.
