What could kill and eat 30 chickens in 1 night and not leave a single body.

[Welshies]

Foxes mate for life. It was probably a couple of foxes.
Disclaimer- Coyotes do not travel in packs. They are not pack animals, excluding the "Eastern" coyote which is actually a coyote-wolf cross. Those howls from "packs" are actually just coyote families yipping in a special way to make them sound bigger (so they are less likely to be threatened). Wolves are pack animals... coyotes are not. Coyotes do mate for life, however. And if this may have been a pack of coyotes they would not have attacked your birds, but a deer.
It is a fox. They are known for this trademark attack.
Sources- 10+ years of being in the bush, tracking, hunting, photographing wild animals

 

[Welshies]

Weasels, I'm just learning about those things. Teeny and cute, but crazy vicious. Not capable, I don't think, of carrying off anything larger than maybe another weasel?

ETA: I think coyotes probably do "operate" from within a pack. I hear them howling for each other all the time, and I especially love hearing coyote packs with howling puppies. But since I only ever see them along, except for once, it's my guess that they travel throughout the day, on their own in search of food, and then maybe they have a coyote meet up at the town hall?

Weasels can carry off a full grown snowshoe hare. 5 pounds or so.
Coyotes aren't pack animals. They are familial units, but not pack animals... those 'coyote packs' you are hearing are parents with pups.

 

[Welshies]

It looks a bit like the bobcat scat we found around our property, but for the seeds. Although if a bobcat ate a rodent that had recently consumed seeds, wouldn't the seeds get into the bobcat scat?

No, only the hair would show up.

 

[Sunshine Flock]

Weasels can carry off a full grown snowshoe hare. 5 pounds or so.
Coyotes aren't pack animals. They are familial units, but not pack animals... those 'coyote packs' you are hearing are parents with pups.

People say weasels can fit through an opening that's just an inch wide. Aren't they really small? But they can carry off a rabbit?

 

[KettermanHillCoop]

To the @EggWalrus ... if you can put a ruler next to the scat, that would be rather helpful. Also, split it length-wise to get a good pic of the inside of the scat.

I'm trying to get a visual on the girth of the scat using the leaves...but it's rather difficult. Right now I'm thinking the girth is too big for a fox...but without any measurements...it's tough. So I will hold my opinion until I have something better to go on.

Just a side note...although scat particles can help with knowing what the animal ate...it is not a sole conclusive variable to identifying the animal.

Edited to add: Are there any scrape marks near the scat?

 

[Welshies]

People say weasels can fit through an opening that's just an inch wide. Aren't they really small? But they can carry off a rabbit?

Yes they are tiny. Even half an inch. They are 8 inches long but evil little predators- they've even attacked people.

 

[Sunshine Flock]

Foxes mate for life. It was probably a couple of foxes.
Disclaimer- Coyotes do not travel in packs. They are not pack animals, excluding the "Eastern" coyote which is actually a coyote-wolf cross. Those howls from "packs" are actually just coyote families yipping in a special way to make them sound bigger (so they are less likely to be threatened). Wolves are pack animals... coyotes are not. Coyotes do mate for life, however. And if this may have been a pack of coyotes they would not have attacked your birds, but a deer.
It is a fox. They are known for this trademark attack.
Sources- 10+ years of being in the bush, tracking, hunting, photographing wild animals

Very informative, Welshies. Keep posting. I'm learning a lot.

 

[Sunshine Flock]

Yes they are tiny. Even half an inch. They are 8 inches long but evil little predators- they've even attacked people.

Great, now I even need to fear the adorable little Disney type characters in the woods.

 

[Sunshine Flock]

No, only the hair would show up.

To clarify based on your experience, bobcat and cougar scat should always have fur, right?

But from my experience coyote scat is often dark and packed with berries, no fur that I could see. So furless scat could be a coyote, but definitely not a cougar?

 

[Welshies]

To clarify based on your experience, bobcat and cougar cat should always have fur, right?

But from my experience coyote scat is often dark and packed with berries, no fur that I could see. So furless scat could be a coyote, but definitely not a cougar?

Yes. Cougars are strictly carnivores, because like the domestic cat they don't have the ability to properly digest plant matter. Whereas the domestic dog, like coyotes, foxes, and wolves, is an omnivore- they can digest plant matter. Foxes and coyotes are very oppurtunistic, even raiding gardens or crops. http://vetmed.illinois.edu/wildlife/fun-facts/foxes-and-coyotes/