http://en.m.wikipedia.org/wiki/Collective_animal_behavior has a nice summary of some of the research. Clearly there has been quite a lot.
While some of it is in the form of decision rules, these seem to be too simple for the kind of decision making we have been discussing. Our view is that animals do complex reasoning using instinctive expert knowledge.
There is nothing anthropomorphic about this, except that we are forced to use our own concepts in order to try to understand the concepts that the animals are using. But we are not attributing these human concepts to the animals. If anything, our concepts are something of an impediment.
On the other hand some of the conjectures regarding animal behavior seem to be too complex. For example, the Wikipedia article suggests that group decision making may be based on the Condorcet method of voting, but this seems entirely too anthropomorphic. See http://en.m.wikipedia.org/wiki/Condorcet_method This method involves not merely voting but a ranking of alternatives by each voter. These ranking votes are then tallied by someone. It is an extremely complex procedure.
Horses grazing in motion are not repeatedly voting on the direction they will move. I suspect that something very different from voting is going on. For example, something that has degrees of importance, which voting does not have. Invoking the human concept of voting makes it harder to see this, not easier.