Rescuers are trying to save about 100 bright yellow finches after they were found stuffed in cages with no food or water in a bus near Peru's border with Bolivia.

Authorities originally recovered 581 birds but said Thursday that less than one-fifth are still alive.

Investigators say the saffron finches were discovered Tuesday during a routine inspection and were being illegally transported in 16 small cages in order to be sold in Bolivia.

A suspect has been detained and could face up to three years in prison for wildlife trafficking.

Jessica Galvez with the National Forest and Wildlife Service says many of the birds became stressed by the poor cage conditions, cold temperature and high altitude.

Officials plan to return the survivors to their native habitat in northern Peru.