Black vultures most certainly will kill cattle, primarily calves, first by blinding them. It is a terrible thing to see.
https://www.farmprogress.com/livestock/black-vultures-become-threat-livestock Turkey vultures tend not to kill larger livestock, but have been documented killing chicks and such.
We actually had this discussion in a mammalogy class back in the early 90s. There were some very adamant people on both sides of the argument. Definitions are a problem when defining behaviors because few behaviors are absolutes within species. People always find exceptions to the rule.
They are pack animals if you define a pack as being a group, but for some sticklers, they aren't pack animals and that has more to do with the definition of pack being exclusive or inclusive including non-family members.
What most people call packs of coyotes are just family units called 'bands' before the offspring have departed the group. From a technical standpoint for some, a family (nuclear or extended) unit isn't a pack, but from a pragmatic standpoint, we call them packs. I am not saying you are in error, only that there are published sources that make the distinction between family units and groups comprised of multiple non-related and related individuals packs. Without doing genetic testing, however, you can't know the relatedness of the members of the group.
https://www.nps.gov/articles/000/coyote-info.htm
So depending on the definition, one might say that they are not pack animals, but nobody can argue that they don't live in groups for at least part of the year. Older offspring tend to break off from the 'pack' as the parents make new pups, but they don't necessarily leave the first year.