There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
Body dimensions will have nothing to do with prey availability, no doubt a cat that has more prey will be larger, why wouldn't they be, but body length and shoulder height are not dictated by prey availability, when both had/have abundant prey, their body dimensions still show significant overlap in the wild.
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So even if we were to throw out the body mass advantage for the bengal, the body dimensions show no advantage towards the Amur of being a bigger cat. So assuming they could put on more weight than a bengal with equal prey seems a bit of a stretch, since I don't know where exactly you could distribute the extra poundage.