I mean it varies from area to area, but foxes killing hens is a stereotype for a reason. Cats will try too as will many other predators depending on area.
You leave that door open one night and expect to return to a garden of feathers...
I love eggs, and have often thought about having my own chicken... although with my current urban living situation, it would be quite hard :)
In terms of diseases, there are some nasty ones like red mites that can suck their blood, but disinfecting the coop takes care of that (and I've never seen any evidence of it). The only thing my chickens have really suffered from is scaley leg, but you can get ointment for that.
I also find they decide to pluck their own feathers out at odd times due to moulting or broodiness.
//edit//Also, for urban chicken keepers: http://www.omlet.co.uk/
http://www.backyardchickens.com/a/raccoon-chicken-predators-...
Racoons are very sharp creatures and can open cages and pens that aren't designed well. If your wire mesh is too large and your chickens stay close to they edge they will lay wait and grab them thru the cage.
http://ag.ansc.purdue.edu/sheep/ansc442/semprojs/2002/predat...
- Being that dogs and coyotes are among the greatest predators of sheep, a llama can be very effective in alerting and protecting a flock of sheep against such predators. A good guard llama is very cautious and curious of these predators and will usually charge them, and if the predator does not retreat, kick and stomp them.
- One llama is capable of guarding up to 2,000 sheep in up to 300 acres, and can decrease the amount of predation in a flock up to 100%.
- Also, llamas ... often will protect birthing sheep and will alert producers to sick or hurt sheep.
http://en.wikipedia.org/wiki/Guard_llama
- Some llamas may herd the animals they are guarding into a tight group or lead them away from danger and to the spot where they may feel the safest.
Quite impressive, what llamas can do.
On my dads farm one of our goats had babies (kids?), after a few weeks we allowed them to roam the pastures. For some reason the donkey had something against one of the kids and stomped it to death, then proceeded to throw its dead body around like a ragdoll for hours.
I never trusted that donkey again.
* Snakes (sometimes, having a snooze still full of young chickens),
* Eagles,
* water rats,
* wild dogs,
* foxes,
* feral cats,
* neighbour's dogs,
* pigs,
* kids,
* and others I have probably forgotten.
Did not have any issues with snakes or water rats (Sweden), but we did have a issue with flooding. With water just a hand deep, one or two would sometimes drown (the rest would either sit on the sitting sticks, or roosting).
On a more positive side, I never had any issues with cats (even feral ones from what I remember) or dogs. there are no wild dogs where I lived, but we did operative a store right next to the hen house, and customers dogs (and kids) were often running around.
Our cat did try and stalk the hens for fun when we first got them, but never attacked them and he was a decent mouser.
In general, to a cat, "runs away" == "prey" and "comes right up to me" == "equal and/or potential threat"
Partly aggression - chickens are/can be nasty and will attack other animals with sharp beaks. Combine this with the fact that they're flock animals, one cat isn't going up against multiple flying, aggressive, pointy ended foes.