A - There's a food shortage. With drought, and, in some areas, encroaching building, food is not as available as it needs to be.
B - Learned behavior. Animals that were solitary, found more success in numbers for hunting/survival. All my life we saw single animals, or pairs, or mom's with pups. Now, in the same area, and others, packs of up to 16 individual are traveling and hunting together.
C - Crossing. I've noticed a change in the look of some coyotes in the past few years. I believe that there's far more crossing of them with domestic dogs as more come in close. That would change their behavior, I believe.
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