I believe that MOST of Tony's problems were from domestic dogs.........
However, when we lived up on the ranch in eastern Oregon, the coyotes were leary of people, but would come in at night and kill calves as the cow was literally giving birth.
They will grab anything they can get by with quickly- cats, small dogs, chickens, whatever, however there have been attacks in our area by the packs that have taken down ROTTIES and other large and healthy dogs!!!! They have lost their fear of people and dont even run when we go outside, they stand and look and the slowly go about their business!
I would follow as much of Miniv's advice- put up hot wire, shoot at least AT them if you dont want to kill them, at least a shotgun in their general direction and doing something every time you see them to let them know they are not wanted will help keep them leary of your place, but certainly not totally away. They are VERY smart and VERY fast- and yes, can carry diseases including rabies!!!!
I would do whatever you can to discourage them, but if they are 'paired up', they probably already have a den somewhere. The female looks like she is still pg. to me, no pups yet.
We call cats and small dogs, etc.. here 'Coyote Candy'.