We are aware that there are many farmers who raise their livestock in an organic manner, thus providing “free range” products. 

Such Free Range animals are not brought into shelters to be dosed or dipped or vaccinated. 

Such animals may be counted in the same way as game or wildlife by flying a grid pattern and taking photographs at regular intervals.

These photographs can be normal digital images or Infra Red images or simultaneous Dual images for greater accuracy.

Even with such technology, it may be difficult to differentiate between different  breeds of sheep or even between sheep and goats. That is where timing with respect to ambient light and the use of varying photographic angles make a difference.