Researchers Successfully Using 3D Printing to Study Complex Animal Behaviors

While we’ve seen the effects that 3D printing can have on human mating rituals, the technology can also be used to help with animal breeding research. 3D technologies are often put to work in studying animal behavior, and the American Association for the Advancement of Science (AAAS) Science magazine recently discussed several recent examples of this.

Husband and wife team Daniel Mennill and Stéphanie Doucet, both behavioral ecologists at Canada’s University of Windsor, have been researching the yellow toads that make their home in the forests of northwest Costa Rica for ten years. Every year when the rains come, hundreds of the toads gather for a quick, intense breeding season of about one day.

The scientists discovered years ago that during this season, the male toads will change their color from brown to bright yellow so they can more easily identify females, which stay the same color. But, how do the females choose which male to mate with?

Mennill said, “3D printing is really advancing the questions that we’re able to ask as field biologists.”

Doucet and Mennill originally used handmade clay models to figure out why the male toads changed color, but needed a more sophisticated method for determining how the females find their mate among hundreds of male toads of similar color. That’s where the 3D printed RoboToad comes into play.

Lincoln Savi, a Master’s student at the university, created the 3D printed amphibian replicas, using software and scanned photos to sculpt them into precisely the right texture and shape. Then, Savi painted several of the 3D printed RoboToads, which are motorized in order to move randomly and appear alive, to look like their male toad counterparts.

Some of the 3D printed RoboToads were painted a dull chartreuse color, while others are bright yellow. Pairs of these toad models, one of each color, will be set up in outdoor arenas once the rains come, so the researchers can see which color the wild female toads are more interested in. According to Mennill, the team is already set up in Costa Rica, “sitting there staring up at the sky [and] waiting for the first rains to arrive,” so they won’t be too late to learn the secrets of the toads’ unique, one-day mating ritual.

Grégory Bulté, a biologist at Carleton University in Ottawa, is using 3D printing to study a different kind of wild animal – the northern map turtle. 3D printing has been used to protect and help turtles in the past, but Bulté is using the technology for a different purpose. The female of the species can grow to twice the length of the male, and Bulté has wondered for years whether the males took size into account during mating and were attracted to the largest females. Unfortunately, due to the fact that the turtles are skittish, and also mate at the bottom of the lake, it was difficult to observe them.

So his team 3D printed two identical models of female northern map turtles, with one noticeable difference – their size. Both the larger and small 3D printed turtle models were placed together on the lakebed, along with rigged cameras that would record what the wild male turtles’ preference was. According to the research report published in Animal Behavior, Bulté’s hypothesis was proven correct, as the wild males tried to mate with the larger 3D printed turtle model more often.

Bulté said that it would have been difficult to use live animals in this study, as they “would introduce a host of other variables that would be difficult to control,” such as one female turtle being related to the male, which could potentially affect his choice of mate. Bulté calls 3D printing “almost an ideal system,” especially because several models can be manufactured without great cost.

But 3D printing, according to ornithologist Mark Hauber, also lets scientists develop animal models on a fine scale – like eggs. Hauber studies brood parasitism, where birds will lay eggs in the nests of other species so they can raise the chicks instead. In the past, researchers studied birds’ reactions to this behavior by putting models of parasitic eggs, made of wood and plaster, in their nests.

But, 3D printing has allowed Hauber’s team to create cowbird egg replicas that look much more realistic than wooden models. Then, the researchers were able to study if a robin’s decision to throw parasitic eggs from their nests was influenced at all by size variations of only a few millimeters.

Hauber, who has made the digital models for his 3D printable eggs available for free on Shapeways, said that these models can assist other scientists and resesarchers in replicating similar experiments.

However, the number of research groups taking advantage of 3D printing is still fairly small – perhaps because, as Temple University biologist Jocelyn Behm suggests, beginners are intimidated by the technology. Behm, who studies how predators respond to invasive lizards, is using 3D printed models in her experiment rather than introducing a live exotic species into an ecosystem.

Behm said, “I really thought 3D printing was difficult … but then once I got into it, I realized it’s not that hard.”

In order to help other researchers, Behm posted a preprint on bioRxiv about her own 3D printing experience, along with reviews about other recent papers that have used the technology. According to Bulté, collaboration is key when it comes to successfully using 3D printing to study animal behavior.

“If people don’t talk to each other, then [they] might think it’s less accessible than it really is,” Bulté said.

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