Some animal species look very similar to each other. Here are some tips for distinguishing a few of the trickier lookalikes you’ll find at our wildlife sanctuaries.

Monarch vs Viceroy

Everybody’s on the lookout for monarchs lately, but don’t be fooled by the viceroy. This black and orange butterfly looks so much like a monarch that it’s hard to believe they’re not closely related.

Scientists have long known that monarchs are poisonous to predators. They used to believe that viceroy butterflies copied the monarchs’ patterns to trick predators into leaving them alone as well. However, we now know that birds find viceroys distasteful, too. In fact, these butterflies share a similar appearance so that if a predator has a bad experience eating one, it’ll leave both species alone.

There are several subtle differences between the two species, but the simplest way to tell the difference is to look for the extra black band on the hind wings of the viceroy.

Monarch                                    Viceroy

Green Frog vs Bullfrog

These greenish-brown frogs live in permanent wetlands like ponds and marshes. Green frogs typically grow up to about 4 inches, whereas bullfrogs can grow up to about 6 inches. But how do you know if you’ve found a green frog or a young bullfrog?

Green frogs have two ridges—one on either side of the body—that start behind the eye and run down the back. Bullfrogs have much shorter ridges; these also start behind the eye, but stop after curving around the circular hearing organ (called a tympanum).

The two species also have very different calls. The green frog makes a sound like a banjo string being plucked—“gunk.” The bullfrog makes a deep sound like “gr-rum.”

Green Frog                               American Bullfrog

Downy Woodpecker vs Hairy Woodpecker

These two woodpeckers share similar black and white patterns, and in both species, males have a dot of red on the head. To tell these two apart, look at the beak.

The downy’s beak is very small—about a third the length of the rest of the head. The hairy’s beak is as long as the rest of the head. Also, the white outer tail feathers on a hairy woodpecker are typically white, whereas on a downy, they’re patterned with black and white.

Also, you’re more likely to see downy woodpeckers in urban areas; hairy woodpeckers prefer spaces with less human activity.

Downy Woodpecker                     Hairy Woodpecker

Tell us about the similar-looking species that you find most challenging, and we’ll keep them in mind for future articles about lookalikes.

Woodpecker photos via USFWS

You may have seen the story in the Boston Globe on August 13 about how monarch butterflies have been hard to find at Mass Audubon’s Boston Nature Center. Monarchs may be our most popular and well-known insects, and this is the time of year when we should be seeing their familiar orange and black wings over gardens. But observers all across the state say they’re spotting very few of them.

Is this a sign that monarchs everywhere are in trouble? And if so, why? The answers to these questions aren’t as simple as you may think.

A Closer Look at Monarch Numbers
The number of monarch butterflies in Massachusetts fluctuates from year to year, and when the insects are scant here, they may be numerous elsewhere. We have to be careful about using our local sightings to talk about the overall health of the species.

However, we do know that observers in nearby areas, such as eastern Canada, Vermont, and New Jersey, are also reporting low monarch numbers this year—what we’re observing here may be part of a larger pattern.

Perhaps most alarmingly, the monarch population hit a record low at its overwintering sites in Mexico, down 59 percent from the previous year’s December count—and researchers have documented declines there in six out of the past seven years.

Threats to Monarchs
There are many reasons why monarch numbers may be dropping. Because they travel over such a wide area and spend time in different habitats, they’re vulnerable to environmental change all along their route. Here are some issues:

1. Habitat destruction in Mexico, where monarchs winter, has historically represented a major threat.
2. They’re sensitive to extreme weather; they don’t do well if it’s too hot or too cold, too dry or too wet.
3. Monarchs are very specialized—they only lay eggs on milkweed. These plants have declined in the central and mid-western states’ expansive corn and soybean fields due to changes in farming practices, such as new developments in herbicides.

Learn More
Consider participating in one of our upcoming programs about monarchs and other butterflies. We’ve got butterfly walks for both kids and adults, where you’ll learn about their life histories and favorite plants, and hopefully glimpse some monarchs.

You can also participate in research programs at Ipswich River Wildlife Sanctuary in Topsfield, Allens Pond Wildlife Sanctuary in South Dartmouth, and Wachusett Meadow Wildlife Sanctuary in Princeton. You’ll learn how to “tag” monarch butterflies, applying tiny stickers to their wings as part of a continent-wide research effort to track their travels.

Have you seen any monarch butterflies this year? If so, tell us where and when in the comments.