Small farms with natural landscape features such as shade trees, hedgerows and tracts of intact forest provide a refuge for some tropical bird populations, according to an 18-year study in Costa Rica.

For almost two decades, ornithologist James Zook has been collecting detailed records on nearly 430 tropical bird species found on small farms, plantations and undisturbed forests in the country.

While birds thrive the most in undisturbed rainforests, Zook said some species usually found in forests can establish populations in “diversified farms” that partially mimic a natural forest environment.

“How you farm matters,” said Nicholas Hendershot, a Stanford University ecologist and co-author of the study published Monday in the journal Proceedings of the National Academy of Sciences.