Author Archives: Kristin S.

The Myth-Busting Mourning Cloak

Posted on April 2, 2013 by Kristin S.

Mourning cloak copyright Frank ModelEvery year I wait eagerly to see my first butterfly of spring. Most likely, it will be a mourning cloak (Nymphalis antiopa), a large butterfly with velvety brown wings and yellowish white wing edges. This beautiful “harbinger of spring” emerges on the first warm days, often before all the snow has melted.

How does the mourning cloak appear so early in the season? Hold onto your hats because this gorgeous insect contradicts everything we tend to believe about butterflies:

Myth 1: Butterflies die or head south for the winter.
Mourning cloak adults hibernate through the New England winter. Relying on “antifreeze” chemicals in their blood, mourning cloaks spend the winter in a sheltered place, such as in rock crevices, under bark, or in a woodpile. They emerge on warm days, sometimes as early as February, and treat us to visions of spring with their graceful flight. Other overwintering butterflies in New England to watch for include eastern commas, question marks, and compton tortoiseshells.

Myth 2: Adult butterflies only live for a few days.
Due to their overwintering strategy, mourning cloaks can have a lifespan of over 10 months. One of our longest-lived butterflies, mourning cloaks have been seen in flight in Massachusetts during every month of the year.

Myth 3: Butterflies nectar on flowers.
There are no blooming flowers in early spring when mourning cloaks emerge, so how do they feed? Mostly on tree sap, particularly from oaks. Mourning cloaks will also feed—brace yourself—on animal droppings and decaying things. Occasionally, if I have been hiking hard, a mourning cloak will land on my hand or head, attracted by the minerals in human sweat.

So, on the first warm day head toward a sun-dappled opening in the woods, preferably with storm-damaged trees and broken branches dripping sap, and wait for this resilient insect to make its appearance. Like you, it has managed to survive another New England winter.

To learn more about the mourning cloak and other butterflies of Massachusetts, check out Mass Audubon’s Butterfly Atlas.

Photo © Frank Model

The Science of Snowflakes

Posted on February 7, 2013 by Kristin S.

Ever wonder just why no two snowflakes are alike? Read on!

The Makings of a Snowflake

A snowflake is simply a bunch of ice crystals stuck together. Each crystal started as a speck, perhaps a particle of volcanic ash or evaporated ocean salt or even a grain of pollen. As the speck cooled high up in the atmosphere, water vapor stuck to it. Tossed about in the cold air, the speck collects more water vapor, grows bigger and heavier, and begins to fall to earth.

The shape of a snow crystal depends on how wet and cold the air is where the crystal forms. As the crystal falls through the air, its shape and size may change as conditions change. Crystals may collide, clump together, and break apart. Breathe on that snow crystal on your mitten and it will change again, melt, and disappear.

The journey each snowflake takes, falling through rapidly changing conditions, makes it unlikely that any two snowflakes will be exactly alike.

Types of Snowflakes

Each snowflake may be unique, but in 1951 scientists classified types of snowflakes into an international snow classification system. Since then, the system has been revised and new systems have been created, but they all enable us to organize and talk about snow crystals. (Montana State University even offers an undergraduate degree in snow science.)

What types of snow crystals are you likely to see? Crystals shaped like columns, needles, and hexagonal plates generally form under low temperatures, little moisture, and grow slowly. Complex crystals—the beautiful star-shaped crystals we think of as the traditional snowflake—form under higher temperatures and humidity. The type of snow crystal that falls will often determine whether a snowfall is sticky, slippery, powdery, or good for snow building.

Seeing Snowflakes

Wilson Bentley, born in 1865 in Jericho, Vermont, devoted his entire life to studying and photographing snowflakes. His gorgeous photos, first published in 1931, are still studied by scientists and available to the public in Snow Crystals reprinted by Dover Publications. Bentley’s contributions are immortalized in a museum and monument in Jericho and in a lovely children’s book, Snowflake Bentley,  by Jacqueline Briggs Martin.

So when it starts to snow and it’s safe to go outside, channel your inner Bentley and go snowflake watching. Here’s how:

  • First, locate a dark surface. Simple household objects—a black scarf, a piece of black construction paper, or a dark baking tray—work fine.
  • Next, take your dark surface outside, cool it to air temperature, and then hold it out flat to catch some falling snowflakes.
  • Take a look at what you capture, but be careful not to breathe on the flakes or they will melt and disappear. A magnifier will bring out the details.

Enjoy and learn more about snow during a Mass Audubon program this winter. And please stay safe during the storm!

Photo: Wilson Bentley Snowflake via snowflakebentley.com