On the Backs of Tortoises by Elizabeth Hennessy

On the Backs of Tortoises by Elizabeth Hennessy

Author:Elizabeth Hennessy
Language: eng
Format: epub
ISBN: 9780300249156
Publisher: Yale University Press


Figure 6.1 José Villa, one of the first two guards of the Galápagos National Park Service, marks a tortoise on Pinzón, late 1960s. Photo taken by Miguel Castro. (Used with permission from the Charles Darwin Foundation Archives)

With funding from the National Geographic Society, the MacFarlands spent months camping among the giants, observing their behavior. The animals would arise at dawn, spend most of the day grazing, and settle in for the night about 4 p.m., as the sun began to wane (on the equator, sunrise and sunset vary little from 6 a.m. to 6 p.m. throughout the year). They often rested in muddy pools that helped regulate their temperature and protect them from mosquitoes that lined up to feed on the tissue between the scutes of their carapaces. Yellow warblers, vermilion flycatchers, and lava lizards would also gather around the tortoises, feeding on flies that constantly buzzed in their eyes. But most impressive was watching ground finches approach a tortoise, “hopping and chirping” until the tortoise stretched out her legs and neck. She stood still while the finches hopped on her legs, neck, and head, pecking at her skin. They were removing ticks, the MacFarlands realized. “The tortoise didn’t even blink when the finches pulled ticks from the corners of her eyes and from her nostrils. Throughout the 51/2 minute cleaning session, the animal stayed stock still” until the birds had flown away.22 The MacFarlands had observed one of the wonders of cross-species mutualism in the islands.

Both the MacFarlands and Castro’s team spent considerable time observing tortoise reproductive behavior, which MacFarland described for National Geographic readers: “The rutting male tortoise stalks about looking for mates and sniffing the air for their scent. Spotting a female, he chases her down and usually begins courtship with intimidation, ramming her with the front of his shell and nipping at her exposed legs until she draws them in, immobilizing her.”23 During nesting season, early in the year, they followed female tortoises as they migrated to dry lowlands near the coast. MacFarland spent ten days following one tortoise as she attempted to dig a nest but was repeatedly thwarted by the rocky ground. Finally, about four o’clock one afternoon Jan called Craig over for what seemed like a promising attempt. Using her “tremendous strength and agility,” the tortoise “excavated [a nest hole], using only her hind legs—probing, shaping, measuring. Her forelegs held the front half of her 150-pound body raised above the ground in an unchanging position.”24 She dug for five hours; when her labored breathing increased pace, she wriggled and waved her tail and then dropped her eggs ten inches to the bottom of the nest. Using her foot, delicately not to crack the eggs, she spread the pile into a single layer and then urinated on the surrounding dirt to make a thick mud cap for the nest. By the time she finished, it was 3:30 a.m. For anywhere from three to eight months, the eggs would incubate in the nest, warmed by sunlight, until hatchlings would dig their way out.



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