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For Stress-Free Penguins, Use a Rover

By Elizabeth Preston
Nov 3, 2014 5:31 PMNov 20, 2019 1:44 AM


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The first time a colony of Antarctic penguins sees a towering human striding toward them, it must be like First Contact. They've never seen a species our size on land before, or anything that moves like we do. Even after penguins have interacted with researchers, the approach of a human is a physiologically stressful experience. To avoid stressing out their subjects so much, some researchers are experimenting with remote-control rovers. They're hardly natural, but it turns out penguins don't mind a motorized, four-wheeled intruder nearly as much as they mind us. Stressing out penguins is bad for researchers, not just for birds. A panicked penguin can alter the data scientists are gathering, and may disturb its neighbors in the process. One way scientists are trying to bother animals less is by using tiny, under-the-skin transponders rather than the usual tags. These transponders are similar to the chip that a vet might implant in your dog. The only trouble is that the tag has to be read from close range: if you can't hide a scanner where the animals are likely to walk past it, someone has to walk around and scan each bird like a box of cereal at the grocery store checkout. Yvon Le Maho of the University of Strasbourg and his colleagues are trying to solve this problem with a rover. Weighing about 1.3 kilograms and bearing RFID antennas, the remote-control vehicle can scan three penguins per second—as long as they let it get close enough. The scientists tested their rover on penguins in Antarctica to see how much it bothered them, compared to humans. First they outfitted 34 king penguins with heart-rate monitors. The territorial penguins were in their breeding season, some balancing eggs or chicks on their feet and ready to defend their space from intruders. When the rover or a human approached penguins as if to scan them, the birds' heart rates went up. But no matter how near or far the intruder was, the penguins' heart rates were higher around humans. The penguins did attack the rover—and the human. ("The rover has indeed to be quite strong with such a territorial bird, which is defending its territory with its beak and flippers," Le Maho says. "It should also [be] designed without any bump which could hurt the bird when it is fighting." He doesn't comment on how human experimenters should protect themselves.) But a penguin's maximum heart rate when facing a rover intruder was always lower that when facing a human. And if the rover stopped moving, the birds quickly relaxed again. They stayed on edge for longer when a human was standing there. The scientists also tested out their rover on emperor penguins. These are "shy," non-territorial birds, so the researchers tried a different approach: they decked out their rover with a fake penguin chick on top. With a plain rover, 28 percent of emperor penguins acted wary. But with the fake chick on top, every bird let the rover get close enough for a scan. They even called to it like a fellow penguin, apparently not put off by its wheels and motor noise. Finally, the authors did a pilot test of their rover with elephant seals. These are multi-ton animals it's also best not to bother. When humans approach they "generally react strongly," but the seals let a rover get close enough for scanning. Why didn't the scientists decorate the rover with an adorable fake animal every time? Le Maho says they took a different tactic with the king penguins. They covered the whole rover with either a white or black cap that disguised its wheels, thinking that the white version might look like a small local bird called a lesser sheathbill that the penguins are used to seeing. Yet the king penguins didn't react to a white rover any differently than a black one. "My view today is that the rover should have instead been covered by a very well designed [model] sheathbill," Le Maho says. On the other hand, he thinks that to infiltrate the colony of the timid emperor penguins, a rover needs to be disguised as a penguin. Whether it's dressed up or not, the rover is still an alien intruder to a penguin colony. Yet they seem to tolerate it much better than they tolerate a human. "I think that the large size of humans compared to the small rover is a key element," Le Maho says. No matter the reason, rovers may be a good way for us to keep our big, creepy selves away from our research subjects. Image: Le Maho et al.

Maho, Y., Whittington, J., Hanuise, N., Pereira, L., Boureau, M., Brucker, M., Chatelain, N., Courtecuisse, J., Crenner, F., Friess, B., Grosbellet, E., Kernaléguen, L., Olivier, F., Saraux, C., Vetter, N., Viblanc, V., Thierry, B., Tremblay, P., Groscolas, R., & Le Bohec, C. (2014). Rovers minimize human disturbance in research on wild animals Nature Methods DOI: 10.1038/nmeth.3173

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