The Voyage of La Pirata

Hayward, working with his wife Shandelle Henson, professor of mathematics, has long been interested in the habitat selection by animals and finding ways to predict their behavior. Hayward and Henson have had success with mathematical modeling of seal and gull habitat occupancy behavior in the past. After observing marine iguanas during a vacation to the Galapágos Islands in 2006, they wondered if they could apply similar techniques to understand and predict the behavior of these animals, which are members of an entirely different taxon than those they’d previously studied.

The marine iguana (Amblyrhynchus cristatus) leads a pretty predictable life. The only lizard in the world that feeds in the sea, the iguana spends most of its day sunning on the beach, warming itself. When it’s sufficiently warm, the iguana swims out into the water, dives, and eats algae. It’s not in the water very long; because the waters around the Galapágos stay relatively cool, thanks to the Humboldt Current. After about 30 minutes of meals-onthe- go, the now-chilled iguana crawls back onto the beach and plops down. “Sometimes they’ll stay there all night until the sun comes up the next morning, and as soon as they’re warm again, they turn around again and go back into the water,” says Hayward. They seemed like good subjects for testing the theories of mathematical behavior modeling.

The entire Galapágos archipelago is a national park, and much of it is open for research. The Ecuadorian government requires that at least one member of the research team speak Spanish, as all proposals and communications are conducted in that language, and Hayward does not. However, Brianna Payne, a biology graduate student who had worked on the Seabird team in the past had been a Spanish major and “was casting about for a project,” says Hayward. “She went to work and she was the one that got this project off the ground in terms of logistics.”

As the resident Spanish speaker, Payne wrote the project proposals and corresponded with personnel at the Charles Darwin Research Station and the Galapágos National Park. “In all of our meetings, they wanted to talk to me and have me sign all the papers. They insisted, ‘No, you’re the principal investigator; he’s your research assistant.’ I got some fun out of that—my major professor was my research assistant,” Payne smiles. 

With approval from the Ecuadorian government and an AU Faculty Research Grant in hand, Hayward, Payne and Megna “took off a little early from school” and landed in Quito, Ecuador where they met Chávez. From Quito the team flew to Puerto Ayorta, Galapágos. Before leaving for Isla Fernandina, however, the group had to go through extensive quarantine to avoid introducing foreign particles or bacteria to the pristine environment of that island. Then followed a 22-hour sail to the island on a 42-foot boat called La Pirata, helmed by a cheerful Ecuadorian named Lenin. “As in John, the Beatle?” Hayward asked. “No, like the Russian!” exclaimed the driver proudly. “I knew I liked him immediately,” chuckles Hayward. 

Early the next morning, La Pirata dropped the four researchers off on the jagged shores of the volcanic island with food and 125 gallons of water, “and we were there for three weeks.” The island is completely uninhabited and without modern conveniences, so it was just the researchers and the animals they were observing. The researchers gathered the majority of their data from continual observations of the marine iguana population. In a rotation of four shifts, the iguana observer on duty counted the animals on the beach and recorded every time an iguana left or came back from the beach.

Simultaneously, using an automated portable weather station, a tide-height pole and a solarimeter, Hayward and his team collected a wealth of environmental data including changes in temperature, relative humidity, tide level and solar radiation. “Essentially, we were counting animals entering and leaving the water and monitoring environmental data for Brianna and Shandelle to model,” says Hayward. As the researchers got accustomed to living on the island, Payne noticed their behavior changed as well: “We were studying these creatures to see how the environment affected their behavior, and the more time we spent there, our lives changed too. We started behaving in ways that meshed with the environment.”

“So it turns out that animal behavior, and even people behavior, is very deterministic,” says Henson. “You can’t predict what an individual is going to do, but you can predict with very high probability what a group is going to do.” The model Henson and Payne created predicts about 80 percent of the variability in the data, and shows that four factors affect iguana haulout times: solar elevation, tide height, heat index, and cloud cover. So if it happens to be a colder and cloudier day, iguanas will spend longer on the beach to warm up and will enter the water later. 

With so much of the iguanas’ behavior dependent on environmental factors, it is not surprising that drastic changes in the environment can have devastating effects on the rare Galapágos populations. Henson gives the example of El Niño events, which occur every four to 10 years and make the surface temperature of the ocean higher than normal, as a good analog for the effects of warming and climate change. “In the Galapágos, the effect of El Niño is huge,” she says. “You might have only 500 of a certain type of organism in the world. During an El Niño event, they might drop down to just 20.” During El Niño events, “you get massive die-offs every time,” says Hayward. “The algae go and then the lizards, and then the cormorants, even the sea lions. The whole food web collapses during these times, and there just aren’t enough calories to go around.” The Galapágos is at a huge risk from long-term climate change, and “it’s scary, because it’s probably the most important biological laboratory on the planet, this little cluster of islands.”

The Galapágos Islands are the perfect field laboratory to study biogeography and processes of adaptation, says Hayward. “We have in the Galapágos fascinating cases of adaptive radiation. The islands are a lab where we can actually see change in the plants and animals happening.” In addition to their uniqueness, the species on Isla Fernandina are completely fearless due to a lack of predators and human contact. “It’s not that anyone has tamed them,” says Henson, “they’re just not afraidof you. You have to walk around the bluefooted boobies because they won’t get out of your way, and the sea lions will swim up to you and look at you.” Although the researchers aren’t allowed to touch any of the animals it’s possible to sit right next to a giant tortoise and not disturb him in the least.

“For that reason alone, the place is special,” Hayward says. Its distinctive and relatively untouched ecology make it worth preserving. “If we want to protect an organism or an ecosystem, we have to learn as much about it as possible,” agrees Henson. “Anything we can learn to minimize the interactions between humans and animals in environments like that will help preserve them.”

Photos from Top: La Pirata just offshore Isla Fernandina; The research team of Libby Megna, Jim Hayward, Brianna Payne and Susana Velastegui Chávez pose for a last photo before leaving Isla Fernandina; The researchers were awed by the beauty of La Cumbra reflecting the light of the sunset. La Cumbra, still volcanically active, continues to shape Isla Fernandina; The researcher’s camp was located within a flightless cormorant colony. Flightless cormorants are among the world’s rarest seabirds—only about 1,000 pairs exist; The Galapágos hawks, like many of the other animals there, are extremely tame; A baby Galapágos fur seal peers curiously at the camera.