They don’t have to outrun the tiger, just the slowest jungle fowl.
And the tigers will really be in trouble when man has hunted tigers well in Asia 
Chickens don’t have to outrun tigers. They can fly, remember?. They don’t have to fly far, just 15-20 feet up into a tree. Even lazy domestic chickens are capable of flying this far.
There are KFC outlets all over Asia and still the chickens survive. I suppose that is because normal chickens are too big for KFC.
Basically, small birds can go where tigers can’t, fitting between tangled trees and crossing soft swampy terrain. When the going gets tough on the ground, they can hop up into the trees, which is about all they need to do.
my nominee for weakest land animal would be the rabbit. not just to predation but starvation due to over-grazing and diseases. their reproduction is such that they can trump all those by a wide margin so they can still proliferate. their other big enemy would be loss of habitat. it’ll probably take several generations of bankrupt realtors before rabbits are wiped out.
a bird roosting up a tree would be near-last in my list of endangered animals.
A year or two ago there was something on a local news broadcast about some chicken that had gotten loose; for whatever reason this chicken meant something to someone. That’s the kind of chicken it was. But I digress. The surprising thing was that anytime anyone got anywhere near that bird, which several people had attempted to catch, it shot up like a rocket to a high branch or a second-story window or something along those lines. I had no idea they could fly that well, but I did know that escaping danger is usually the reason a chicken flying.
Come to think of it, when domesticated hens ruffle their feathers isn’t that really an instinctive but futile attempt to fly to safety?
Now that the OP has been answered, I can show you this photo I took in Kuala Lumpur, capital city of Malaysia, of an entire KFC SKYSCRAPER!
http://www.imgplace.com/img266/5511/37kfcskyscrapermalaysia.th.jpg
Sorry, wrong picture size.
The Malaysia KFC skyscraper should be more visiible here:
http://www.imgplace.com/viewimg266/5511/37kfcskyscrapermalaysia.jpg
–Upside the head!
–Down the other side!
I love this place!
As stated upthread, even domesticated, modern chickens can fly some. My chickens ruffle their feathers when they are annoyed or when they get wet. When they ruffle their feathers, they fluff up their whole bodies at once, all the way up onto their heads. When they spread their wings to fly, it’s just their wings. Flight ability varies from breed to breed. But even the heavy, lumbering ones can fly a little.
Okay, it’s been said before but judging by the followup questions, it needs to be repeated:
Chickens CAN FLY. Wild chickens CAN FLY. Domesticated chickens CAN FLY. They don’t soar gracefully on the lightest breeze, but they CAN FLY. There’s no “futile attempt” involved.
Of course, the same question can be asked about any fowl that nests on the ground - how the heck do they survive being all eaten up before the little chicks/ducks/geese/partridges/etc. get big enough to fly? They answer is, most of them manage to survive - between hiding, environment too tough/tangled for the predator to get through, etc.
So…since chickens can’t fly, how do they survive?
Not only can a jungle fowl fly, he can do so while defeating a cat in mortal combat. (Read “Tale the third” in the linked post.)
I’ve seen one or two in the Cuc Phuong national park in northern Viet Nam. They’re (more-or-less) protected from people there, and there aren’t any tigers left in that area. I’m not sure what their normal predators were, but they hide well and can run pretty quickly over short distances. I sure wouldn’t be able to catch one.
Good LORD, that third link has got to be the worst-proofread article I’ve ever seen on Cracked.
I thought domestic chickens usually have their wings clipped, which would prevent them from flying. That’s why I said futile.