This is the short story "EpilogueEpilogue" by Poul Anderson. First published in Analog Science Fact/Science Fiction in March 1962. The story opens as follows:
His name was a set of radio pulses. Converted into equivalent sound waves, it would have been an ugly squawk so because he, like any consciousness, was the center of his own coordinate system, let him be called Zero. He was out hunting that day. Energy reserves were low in the cave. That other who may be called One, being the most important dweller in Zero's universe, had not complained. But there was no need to. He also felt a dwindling potential. Accumulators grew abundantly in the neighbourhood, but an undue amount of such cells must be processed to recharge One while she was creating. Motiles had more concentrated energy. And of course, they were more highly organized. Entire parts could be taken from the body of a motile, needing little or no reshaping for One to use.