It happens. An animal is captured for study, is released, but dies soon after. A certain percentage of fatalities is expected in any study where animals are handled. In Chile recently, five fur seal pups died after being captured, AAAS’s ScienceShot reports. There had been no previous fatalities in the four years of the study.

Veterinarians studying the dead pups found they all had a hookworm infection. The infection sent the seals’ adrenal glands into over-drive, stressing their hearts. The researchers say that fieldworkers should not try to capture seals that show signs of chronic infection, which is probably good advice when working with other animals as well.

Read the ScienceShot article here. It includes links to the paper and other information.