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Avian Astronomy – Mapping Migrations in the StarLab

Research in the Planetarium
Humanity is not the only species with an astronomical inclination. In studying the strategies by which different bird species navigate their migratory paths, it was discovered that some bird species are also keen observers of the starry night sky. The first experiment to shed light on this amazing capacity actually took place under the simulated night-sky of a planetarium, just like the Milky Way Starfield in our own StarLab! With this in mind, our Mapping Migrations lesson will begin under this same simulated night sky, to familiarize ourselves with the lights which guide so many amazing migratory flights.
Birds and the Stars
In the pioneering 1967 experiment, a Cornell ornithologist took a group of Indigo Buntings into a planetarium to test the hypothesis of whether the stars were the species’ primary means of finding their way along their biannual migratory excursions. With the Buntings in specially designed cages from which the planetarium ‘sky’ was clearly visible, the research team monitored whether the stars displayed had any influence on where the birds would position themselves. To track their positioning, the experimenters designed the special cage with an ink-coated flooring, and white paper-coated wall – so as to track the footsteps of the Indigo Buntings as they shuffled inside their individual cages.

John Blair, Nat-Geo Creative
What they found was that when the starfield of the Milky Way was projected onto the planetarium ceiling, the footprints left on the cage floor were concentrated to the side opposite of the North Star, Polaris. This observation was consistent no matter how the starfield was rotated, no matter which side of the planetarium Polaris was projected onto. As a control, the researchers placed these encaged birds in a dark planetarium, devoid of stars on the ceiling – resulting in random footprints distributed evenly across the tracking paper. These observations led the researchers to conclude that the Indigo Buntings were explicitly aware of specific stars in the sky, and were able to consistently orient themselves in relation to these specific stars. 

Entomo-Logic on iNaturalist
Navigation in the Animal Kingdom
And birds are far from the only animals to have been observed navigating this way. Of the many non-bird animals that rely on the stars to find their way, perhaps most exceptional is the humble Dung Beetle. Even this silly beetle keeps track of its location relative to its home burrow by careful observation of the night sky, the Milky Way in particular.  But how do these different animals fare on a cloudy night? 

When the starry sky is cloaked in clouds, Dung Beetles can be found aimlessly pushing their balls of ‘food,’ often simply in circles. These beetles navigate almost entirely by following their celestial cues – and when these guiding lights are occluded, they are helpless in finding their ways home. Perhaps luckily for them, birds possess significantly more sophisticated navigational capacities than the humble scarab – not so helpless when the stars are hidden from view. But how possibly could a bird distinguish its cardinal directions without the visual aid? Can any of the seven senses that we humans know help these birds to find their way?

Geography of Migrations – One Obstacle After Another
In our Mapping Migrations lesson, students will see far more than the epic distances that these birds can navigate.  Projecting a detailed world map onto the StarLab sky, our discussion will progressively zoom in – firstly, to study the individual routes that species follow. Students will explore in-depth the epic journeys that these navigational assets facilitate. We will examine the adaptations facilitating such feats of flight, as well as the variations that allow some species to stay year-round in wintry regions while others must fly for food. Geography is integral to this lesson as we explore why these birds migrate in the first place, and the obstacles the birds must contend with along their migratory routes.
We will learn about the prominent obstacles along different flight paths, in the sequence by which they are encountered – constructing a sort of “memory palace” along these many long tracks of natural geography, as students imagine themselves climbing over peaks and then traversing featureless sandy (or sea-foamy) expanses. Birds of different shapes and sizes choose drastically different migratory paths, encountering distinctly different obstacles along the way. These obstacles take many forms – high mountain ranges, barren deserts, swathes of open ocean, etcetera. Mapping Migrations illuminates these many features by closely following the different species along their treks.  We’ll identify which birds prefer which routes, and why.
Overcoming Obstacles – Strategies for Making the Trip
​So why do bar-headed geese insist on climbing over the Himalayas? Why (and how) do some ruby-throated hummingbirds fly over the Gulf of Mexico? Our focus – already magnified onto the geography of different migratory routes – will then zoom in even further, to study variations among the birds themselves. The behavioral and physiological adaptations that facilitate these feats can each be explored: how broad-winged birds exploit thermals; how prevailing winds offer free carriage – even calculating the total number of wing-beats a hummingbird needs to get from Canada to Costa Rica can serve as an awe-inspiring entry point for budding ornithologists. Live animal encounters and teaching artifacts are also available for this presentation – allowing first-hand observation of some of these famous fliers – to help us all begin to wrap our heads around their otherwise unimaginable abilities.

Allen R. Biggs on iNaturalist
Composed by Ben Fletcher.

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