European breeders, which have to compete with the larger great crested grebe for fish, eat a greater proportion of invertebrates than the longer-billed American subspecies, although both races eat mainly fish in winter. Birds of the nominate subspecies from the northernmost breeding populations in Finland and Russia, beyond the range of great crested grebe, have a longer and more slender bill than those further south, reflecting a greater proportion of fish in the diet where their main competitor is absent. If food is scarce, parents may desert unhatched eggs, or allow the smallest chicks to starve, although the latter strategy appears not to be particularly efficient in protecting the older chicks.