Tracking devices such as video cameras, GPS tags and other research instruments can disrupt the natural behavior of the animals they are attached to by increasing drag as much as 100 percent, according to new research, which for the first time quantifies the energy cost to animals the devices are attached to.
The research benefits and insights gained by affixing recording devices to animals are unparallelled. Famously, the National Geographic Society's "Crittercam," which provides a view of the world through the eyes of a variety of creatures, including humpback whales and bull sharks, has generated some never-before-seen footage from unique points of view.
But a new study published in the journal Methods in Ecology and Evolution, suggests there is a cost to the acquisition of the data.
"Many marine animals make yearlong breeding migrations crossing entire oceans, while others may rely on high speeds and acceleration -- enabling them to catch prey or to escape predators," said T. Todd Jones, a scientist with the NOAA Pacific Islands Fisheries Science Center in Hawaii, who led the study while a doctoral fellow at the University of British Columbia.
"If the drag costs from carrying tags disrupts their natural behavior, they may miss out on breeding and foraging seasons, be unable to catch enough food, or even end up becoming someone else's meal."
For the research, Jones and his colleagues created fiberglass casts of sea turtles and placed them in a wind tunnel.
The team found that most commercially available tags increased drag by less than 5 percent in fully grown adults, but the same devices increased drag up to 100 percent when used on smaller juveniles.
"In addition to the animal welfare and conservation implications, excessive drag may also impede the collection of research data in the wild," Jones said.
"The guidelines we've developed can help ensure that the data collected accurately reflect the animals' natural behaviors in the wild, so we can devise conservation strategies accordingly."
As part of the research, the team developed a universal formula that will allow others to calculate drag for a wide range of marine species, including turtles, mammals, fish and diving birds.