A Real Sign of Spring - Mourning Cloak Butterflies

​The final few weeks of February have been anything but winter around New York Harbor. South winds and above normal temperatures have made many people thinking of spring.
 
But it’s not just people who believe change is in the air. The first fluttering butterfly of the year was seen on Saturday, February 25, near Sandy Hook Bay.
 
A single mourning cloak (Nymphalis antiopa) was silently flapping its wings among dreary bare tree branches in February. While I’m sure there were additional sightings of mourning cloaks around the harbor over the last few days, as the mourning cloak is normally the first butterfly seen in spring, this was my first sighting of the year.
 
It was one of earliest sighting too. Normally the butterflies emerge from hibernation on warm, sunny days during March or April depending on temperatures and snow cover.
 
The mourning cloak is a common butterfly around New York Harbor, but one with unique properties. It has the ability to hibernate as an adult throughout a cold winter. It uses a special form of hibernation known as “cryo-preservation,” which allows molecules of glycerol to enter cells and act as anti-freeze to prevent dehydration and the formation of ice crystals within cells, which can cause death and destruction of internal organs. It’s an amazing way to live through extreme cold, so much so that some scientists are studying cryopreservation as a way to freeze people with present-day incurable diseases so they may be cured in the future.
 
While it sounds like science fiction, cryopreservation is just business as usual for mourning cloaks. The butterflies are literally frozen like popsicles all winter long, so they can emerge early in the year to feed and mate before the peak of spring bird migration or before other predators, such as dragonflies and spiders, really get hungry.
 
Around this time of year, the butterflies will wake up inside a small tree hole or under loose bark or inside the cracks of buildings when warm temperatures and the warm rays of the sun reach their frozen bodies. The butterflies will then bask by opening their wings and angling their bodies toward the sun, to increase body temperature prior to flight. It wakes from inactivity to live once again.
 
But not for long! Unfortunately its nearly 10 month adult life (a long life for a butterfly) nears its end every spring. The butterfly quickly has to find food; one of its favorites is oak tree sap. Then the little critter has to find a mate and start the next generation of mourning cloaks before it passes away.
 
A male will usually select a sunny perch to warm its body and wait for a mate. A brief aerial courtship will take place with a fertilized female subsequently laying 30 to 50 eggs on small branches of aspen, birch or willow trees.
 
The eggs laid in early spring will hatch into small, black caterpillars that are marked with white speckles and two large red spots. The caterpillars will eventually pupate and emerge as adults by June or July, thus continuing the cycle of life.
 
Mourning cloaks get their unique name from the burgundy or purple and gold colors that adorn the edges of their wings. These colors were traditional found on cloaks worn by English royalty “in mourning.”
 
On the next sunny, warm day keep your eyes open in forested parks and preserves and you might just catch sight of the first butterfly of spring around New York Harbor - the mourning cloak.