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but unlike most turtles and lizards. Indeed, the twenty-three species of crocodiles, allig-
ators, caimans, and gharials, plus more than nine thousand living bird species, derive
from a Mesozoic archosaur radiation that included other dinosaurs, winged pterosaurs,
and diverse extinct crocodilians. 14 Today the alligators look lazy, but I know their be-
havioral repertoire includes a high walk, a gallop, and leaping straight up out of wa-
ter; I know how those jaws that can crush a deer also gently transport their babies
from nest to the water's edge. I've seen the Bronx Zoo's captive crocodilians respond
to training with the alacrity of my dog Riley, and all this reminds me that we've been
mattering to each other for a long time. 15 Almost two million years ago an aptly named
Nile crocodile relative, Crocodylus anthrophagus, consumed early hominids, 16 while
less than two thousand years ago, two Pacific island species, distantly related to extant
crocodiles, went extinct likely because of human depredation. 17
Natural history provides facts about organisms, including the ones Linnaeus and
Darwin found so loathsome, and thereby expands our background for using and appre-
ciating nature. 18 From the standpoint of ecology and aesthetics, of appreciating giant
reptiles in a broader context, no other vertebrates preempt the crocodilian role of gi-
ant freshwater meat-eater. In terms of evolutionary history, crocodilians are the closest
living relatives of birds and our best surviving icons for a world once ruled by ponder-
ous herbivores and huge flesh-eating reptiles, one that predated the rise of mammals.
Because someone had discovered these things and I'd learned them, that big American
crocodile casting an eye my way was the epitome of a biologically sublime experience,
one that otherwise would have been less compelling. Later, I did wonder what was go-
ing on in its walnut-size brain, thought to myself probably quite a lot, and felt lucky to
stand by Nine Mile Pond at such a provocative moment.
Gordon Burghardt, my Ph.D. advisor, has pursued diverse research over his forty-year
career, ranging from serpent feeding behavior to behavioral development in hand-
reared black bears and free-living green iguanas. In teaching and writings he's often
stressed Jacob von Uexkühl's Umwelt— literally, “surrounding world,” but defined by
von Uexkühl as that perceived by particular animals—and two projects sharpened Gor-
don's parallel concerns for their inner worlds. Together we showed that hatchling east-
ern hog-nosed snakes responded to danger by body-flattening, hissing, and striking, fol-
lowed by death-feigning, in which they writhed about, then lay belly up and still. Most
importantly, we discovered that these innate behaviors were influenced by experience
and context: snakes rapidly switched back and forth between death-feigning and crawl-
ing away depending on whether a threat (Gordon or a stuffed owl) faced them or faced
away. 19 About that same time, he began studying a two-headed black ratsnake, nick-
named “IM” for instinct and mind. IM's heads often struggled over food, and domin-
ance shifted repeatedly over the years; one head consistently preferred smaller prey,
although each consumed roughly the same overall amount of food. 20
Now let's revisit Niko Tinbergen's four research aims for ethology, the questions
that inspired my graduate research: How is behavior controlled, how does it develop
within an individual, what's its ecological significance, and how did it evolve? In
1997, Gordon, having earlier spent a sabbatical with Rockefeller University's Donald
Griffin—the discoverer of bat echolocation and pioneering advocate for understanding
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