Darwin noticed that birds that were good at finding scarce food in the winter had a better chance of survivng and producing offspring. What did he call his struggle for existence?

The correct answer is known as "Natural Selection".

Natural selection is best described as is the differential survival and reproduction of individuals due to differences in phenotype. it's miles a key mechanism of evolution, the alternate in the heritable developments feature of a population over generations. Charles Darwin made famous the words "natural selection", contrasting it with synthetic selection, that's intentional, while natural selection isn't always.