This, he explains, “results in an integrated response to the ongoing situation.” Information about landmarks, distances, spatial relations, memories, sights, sounds, and smells must all funnel into a core of important brain regions and then fan out between them. To achieve it, a certain pattern of connectivity in the brain is required. True navigation is a triumph of cognitive integration, says Shanahan. “Humans excel at cognitive integration,” says Murray Shanahan, a computational neuroscientist at Imperial College London-although he admits that failures are commonplace, “as when I remove the Ubend of my sink,” and then “pour its dirty contents back into the plughole, causing an unwelcome deluge.” (Or the equivalent sink lore of my family: When, minutes before our big annual Christmas party, my mother stood at the sink in dismay, having just poured a cauldron of mulled wine for fifty through a mesh strainer directly into the drain, leaving only a clump of damp cloves, peppercorns, and bay leaves to serve to her guests.) So does the human brain, with its 100 billion neurons. The brain of a bee, with only a million neurons, does it. The problem in a brain, then, is how to pull together all those distributed resources-the totality of what an animal knows-to meet a challenge (such as navigation) or respond to unpredictable circumstances (like a storm). In the lingo of neuroscience, brains are known as “massively parallel, distributed control systems.” Roughly speaking, that means that they contain a colossal number of little “processors”-neurons-that operate in parallel but are distributed all over. This notion seems to dovetail (if you’ll excuse the expression) with a new theory about the overall organization of bird brains-and our own. Her spatial grid may not be bicoordinate at all, but multicoordinate, layered with a still mysterious mix of sun, star, and geomagnetic cues, sound waves, and swirling signboards of smell, all thoroughly integrated. She may use multiple and redundant cues to find her way, and mental maps unlike anything we’ve ever encountered. Like an executive who enjoys having two cell phones and a laptop tuned to the Weather Channel, a pigeon may rely on all kinds of available information for guidance. Related Segment Read ‘The Genius Of Birds’ With The SciFri Book Club! In this arena, as in all aspects of bird (and human) life, idiosyncrasy and opportunism may prevail. Another pigeon was a champion distance navigator, but once he got within six miles of his loft, says Walcott, he just kind of gave up and landed in a garden somewhere. When released at an unfamiliar site, he always flew to the nearest mountain before flying home-unlike any of the other birds raised in his loft. Walcott tells the story of one pigeon raised near a prominent hill in Massachusetts. Individual birds are also just eccentric and seem to use their orientation cues according to their own styles. Likewise, sibling pigeons raised in different lofts have different responses to magnetic anomalies: One finds its way despite the weird magnetic pattern the other is bewildered by it and loses its sense of direction. A pigeon raised in a loft without ambient odors orients using other cues and isn’t affected when deprived of its sense of smell, according to Charles Walcott. A lot depends on how a pigeon grows up-and where. ![]() In Blaser’s study of homing pigeons, she found that the pigeons never beelined to their target each time, they took a slightly different route-“a compromise between their chosen compass direction, topographic factors, and their own individual flight strategies,” she says. ![]() ![]() ![]() Which cues a particular bird uses on any particular journey may depend on the scale of the trip, or what’s handy, or the environmental conditions (like a kayaker in fog, it may resort to lesser ones when the chief ones aren’t at hand), or simply its own individual predilections.įor instance, which cues a pigeon uses to home in on its loft may depend on its life experience and its own quirky choosing. There’s no clear evidence that any one sensory cue is the whole story. I find it oddly thrilling that the mental maps of birds remain… well… unmapped.
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