I'm betting that is some sort of research project for a student somewhere. There are some things going on that are likely being used to test human responses.
It appears, but I'm not sure, that the sheep on the bottom move out quicker, but that may be because those bushes tend to obscure them slightly.
It appears the sheep on the top are eaiser to catch quickly, maybe because they are at the top.
And as others have stated, the sheep that moves around but NEVER runs, causes you to "jump the gun", but also causes you to be slow in response to real runners from that area.
I'd bet all of the activity is recorded somewhere and there's a study of some sort involved.
I stayed mostly around .220, but I had some good runs where I was in the 0.17 zone. I had one run where I got a sheep at the top at 0.125, and one that was just below him at 0.000, but then they ran two out of the shrubs close together and I was in the 0.260 zone getting them.