Despite a high mortality rate for whooping crane chicks, wildlife specialists have hope for the endangered bird’s population in Wisconsin after a nearly 15-year effort to reintroduce the species.

Since the reintroduction program began in 2001 at the Necedah National Wildlife Refuge, pests and inexperience have caused whooping cranes to struggle with successfully reproducing in the wild.

A record 24 cranes hatched from 37 nests in Wisconsin this year, but only three chicks have survived so far. If those chicks survive to the fledging stage, the count will tie with a previous record of three surviving fledglings from 2010.

“It’s a year that shows us progress and even more hope for the success of this reintroduction,” said Julie Langenberg, head of the North American programs for the International Crane Foundation.

A hybrid “whoophill” chick, the product of a sandhill and whooping crane pair, also hatched at the Horicon National Wildlife Refuge. The chick, which likely is sterile and doesn’t contribute to the whooping crane population, was captured on Wednesday.

Biologists have been working to combat swarms of black flies, which have caused cranes to abandon their eggs in years past.

This year, a forced re-nesting experiment was successful, with each pair re-nesting and eight new eggs hatching. However, the success at least was partly due to black fly numbers reaching only a fraction of last year’s peak population, which likely was caused by cooler weather and may not happen again in the future.

Researchers also hope the mortality rate will decrease and the hatching rate will continue to climb as younger whooping cranes become more experienced with nesting and rearing chicks.