New Yorkers can catch a fleeting glimpse of Nature’s royalty if they hurry. On Saturday I observed dozens of migrating monarch butterflies – glorious kings of the insect world – quivering atop goldenrods on the coast lining Dead Horse Bay in Brooklyn. Other naturalists in the city have reported monarch sightings in Park Slope in Brooklyn and at Robert Moses State Park in Long Island, where a citizen scientist says she spotted about 1,000 monarchs.
You don’t need to understand science in order to appreciate these majestic, orange-and-black patterned beauties gracing our dirty streets, but the biology permitting their voyage is pretty neat.
The stop in New York will be one of many along their approximately 4000 kilometer (or 2485 mile) journey from the eastern United States and southeastern Canada to central Mexico, where they will winter atop mountains in groves of sacred fir trees. The migration is unique among insects, and it piques the curiosity of scientists who try to understand how the creatures find their path without prior experience. Each monarch I spotted in Brooklyn is taking this trip for the first time, and is at least two generations removed from the previous generation of North-South migrants (pdf).
Monarchs orient themselves by the light of the sun, and keep track of time with a circadian clock located in their antennae (pdf). This clock helps them navigate by interacting with the sun-compass, so that the sun’s movement across the daytime sky doesn’t throw them from their course. When biologists removed monarchs antennae, or painted them black to block light input, the butterflies could no longer find their way (pdf).
Like sea turtles and birds, monarchs might also take cues from Earth’s magnetic field. And the fact that each incredible voyage is a monarch’s first and last suggests a genetic basis. Towards this end, Steven Reppert, a neurobiologist at the University of Massachusetts Medical School in Worcester and his colleagues are sequencing the monarch genome. Buried among the credible scientific reasons he lists for sequencing this delicate creature, is “Butterflies enrich our lives.”
So if you inhabit the Big Apple, enrich your life by doing what the Russian novelist and lepidopterist Vladimir Nabokov would do, and head out to the coast or one of the city’s parks. Right now.
Images of Monarch butterflies at Dead Horse Bay in Brooklyn by Amy Maxmen.