Frequent fliers often find themselves with hefty phone bills, and global travelers can drain their roaming data allowance. But eagles?

Russian ornithologists tracking the migration routes of 13 endangered steppe eagles carrying SMS transmitters ran out of money when one of the birds, Min, drained the researchers’ phone credit for the project.

He suddenly sent hundreds of backlogged text messages at once as he flew from Kazakhstan, where rates are cheaper, to Iran, where they are more expensive, a researcher said.

The researchers, from the independent R.R.R. Conservation Network, have been tracking eagles’ migration routes since 2015 in an effort to focus conservation efforts on specific areas. The birds can come into contact with power lines, poison traps and a veterinary drug that killed millions of vultures in the 1990s.