Mészáros won the mention for his photograph of an ant drinking from a raindrop on a flower petal. The image, entitled Raindrop Refresher, won in the category for animals other than mammals and birds in their natural habitat.
This year's contest, which is supported by BBC Wildlife magazine, drew a record 43,000 submissions from 94 countries.
An exhibition of the contest winners opened at the Natural History Museum on Friday.
