Probably because it's a nicely done modpack and that it's different from other modpacks in the form of worldgen. I personally enjoy it, and I also enjoy Tekkit. I do tend to lean more towards Big Dig though.
It's a feature. Once it has enough animals in it's range, it stops feeding them and vaporizes any extras. When you go and kill some, it will start producing them again until it gets back to amount that was there before you started killing them.
Do you have any useful skills or talents (web design, programming, 3D modelling, texturing)? Are you good at finding bugs in programs? Can you do voice overs? Are you intelligent and capable of dealing with idiots?
Yes, yes, go away now. You said you'd solve it, and by staying here you'll be classified as an 'untrained monkey who has just been released from the zoo' by none other than yourself.
Once again, I hope you get bent sir/madam!