One of our islands has a beach on it known as cow wreck beach because a boat laden with cattle crashed there in the mists of time and it is littered with cattle bones as a result. The bar is decorated with weird looking cow skulls and the island now has a couple of herds of these running around:
Legend dictates that these are the descendants of the lucky refugees of that shipwreck who swam or floated better than those decorating the bar although there's no evidence of that to my knowledge and they could have come in on another boat just as easily. They persist in what is best described as a semi-wild state and I thought they were far enough away from your average domestic cattle to be of interest. I think we might have a bull on the left and cow on the right in the above photo btw (if you are wondering about the different horn shapes).
Of interest here I guess is the zebu-style hump on the back and the dewlap looking neck development which would probably tell someone more versed in cattle domestication something about these guys. I just love the horn shape on these.
Less so on the big guy above. In terms of ecological impact these are a competitor with our native Iguana for food in that they eat the same things and/or alter the botanical composition a little bit by selective grazing but I don't think they are the most serious threat to those guys and if we could deal with some of the other issues I think the iguanas and cattle should both do ok. In terms of ownership, the local joke is that if you want to know who owns a cow the only way to find out is to shoot and grill it, whereupon the agrieved owner will immediately show up (a load of cows were impounded recently on another island after wandering around on the road and no-one has claimed them yet). I suspect in the case of these guys they are pretty much a communal resource that occasionally gets culled by those with the interest and inclination to take part but I may be wrong and these may be someone's pride and joy). Human care or no, they were doing OK though and the next generation was nestled safely in the bushes.