Blog Home Vermont Center for Ecostudies
Serviceberries flowering in the spring. K.P. McFarland

Field Guide to May

By Vermont Center for Ecostudies May 4, 2020

The month of May is a show-off. Grass glows green under blue skies. Woodland wildflowers break out of the ground and demand attention. Trees flower and leaves burst from long-dormant buds. Songbirds arrive on southern night winds and liven the dawn with a chorus of song. May shouts of life and rejuvenation. Here’s a few bits of natural history for your May days.

10030, , ribbon-snake_580x400_acf_cropped, , , image/jpeg,, 580, 400, Array, Array © Nathaniel Sharp
Eastern Ribbon Snake © Nathaniel Sharp
10032, , watersnake-3_580x400_acf_cropped, , , image/jpeg,, 580, 400, Array, Array © Roy Pilcher
Northern Watersnake © Roy Pilcher

Snakes of Spring

By Nathaniel Sharp

Amphibians like Wood Frogs and Spotted Salamanders run the show in April as they migrate to their vernal breeding pools, but as temperatures rise and the sun sticks around for a little longer each day, Vermont’s snakes begin to slither onto the stage. Of the 12 species of snakes in Vermont, 9 have been documented on the Vermont Atlas of Life on iNaturalist during the month of May.

By far the most numerous and familiar is the Common Garter Snake, which overwinters in underground dens, sometimes gathering in surprisingly large numbers. For the first few warm days of spring, these large groups of green, black, and yellow-striped snakes will hang out and soak up the sun near their den, searching for mates and occasionally creating ‘mating balls’ of multiple males competing for the attention of a single female. There is another similarly-striped snake to be on the lookout for in Vermont, the Eastern Ribbon Snake, a much rarer species in the state often found in fields or open areas near water. This sleek, handsomely patterned snake is striped with black and yellow much like a Common Garter Snake, but sports white markings on the face and a deep chestnut stripe running along its side.

Two species of snakes that are often mistaken for their venomous counterparts are the Northern Watersnake and the Eastern Milksnake. Boldly patterned with contrasting bands, both these species are nonvenomous and rather common throughout Vermont, with the Eastern Milksnake especially often turning up near human habitations. Some of Vermont’s smallest snakes are also making their first appearances in May, including the Dekay’s Brownsnake, Ringneck Snake, and the Redbelly Snake, the latter of which is occasionally encountered crossing roads on warm wet nights along with migrating amphibians.

If you’d like to provide a safe haven for these gorgeous hunters of garden pests such as slugs, snails, insects, and rodents, consider setting up a ‘snake hotel’ or a few simple cover boards. Stacking sheets of plywood or flat rocks with some space in between can provide a covered, warm spot for snakes to spend their days and nights. Laying a single sheet of plywood on the ground in a sunny spot, with enough room for snakes to slip underneath, can also provide much-needed shelter.

To learn more about Vermont’s snake species, visit the Vermont Reptile & Amphibian Atlas. If you encounter any of these snakes out in the fields and forests of Vermont this May, don’t forget to snap a photo and upload to the Vermont Atlas of Life on iNaturalist!

Bobolink © Susan Elliott
Bobolink © Susan Elliott

A Song on the Wing

By Liza Morse

With the first week of May upon us, the vanguard has arrived. Using stellar and magnetic cues to guide them along their 6,000-mile journey, the first male Bobolinks have arrived in Vermont’s pastures and hayfields. Their bold backward tuxedos and yellow caps add to the explosion of color appearing across the spring landscape, as ephemeral wildflowers dot our forest floors and maples glow red in a dusting of tiny blooms.

Having arrived, these males will begin to establish their territories, singing from perches overlooking fields as well as in flight. In addition to establishing territory, these song flights — a common behavior among grassland bird species — also serve to attract females. Within a week of the first male Bobolinks’ arrival, the first females will start arriving as well. These females will then select their paramours, in part, based on their song flights. Longer song flights indicate to the female that a male has larger fat reserves and the potential to fledge more young. Thus, a longer song flight means more mates for a male Bobolink.

So keep an eye out in fields across Vermont, this month, for what look like flying wind-up toys and sound like R2-D2. With any luck, while catching your eye, these little guys will catch the eye of a female Bobolink, too boot.

Egg masses with and without algae.  © K.P. McFarland
Egg masses with and without algae. © K.P. McFarland

Eggs and Algae

By Kent McFarland

Peer into a woodland vernal pool in New England right now and you’re liable to find masses of developing Spotted Salamander eggs. Many of them have a green hue visible throughout the gelatinous mass. Most things lying in water eventually get coated in algae. But in 1927 Lambert Printz realized this was a special green algae only found on these eggs and formally named named it Oophilia, meaning egg loving, amblystomatis, from the genus name for spotted salamanders.

In the 1980’s biologists wondered if perhaps there was more to the relationship between algae and animal. They found that spotted salamander embryos grown without green algae didn’t develop as quickly. It was thought that the algae perhaps provided more oxygen for eggs in potentially oxygen-poor waters.

However, biologists recently reported in the Proceedings of the National Academy of Science that they discovered green algae actually living inside the cells of developing spotted salamander embryos. In an Indiana University press release biologist Roger Hangarter said, “With the ability to use gene-specific probes, it is now possible to determine the presence of organisms that may not be easily visible by standard light microscopy. In the past, researchers looking with simpler light microscopy techniques than are available today failed to see any algae in the salamanders.”

This special symbiotic relationship is termed endosymbiosis, in which two species not only share living space with each other, but one actually lives inside the cells of another. They found evidence of green algae in salamander oviducts suggesting that transmission may occur from one salamander generation to the next via transmission through eggs.

Learn more about vernal pools on the VCE web site.

Tricolored Bumble Bee K.P. McFarland
Tricolored Bumble Bee K.P. McFarland

Bumble Bee Basics

By Spencer Hardy

There is so much happening outside this time of year that it’s easy to get overwhelmed by flashy warblers and adorable ducklings. But this May might be a great time to slow down and focus on the slightly smaller critters close to home. Checking the nearest rhododendron, blueberry, or even dandelion patch should be all it takes to find a critter as fluffy as a duckling AND as colorful as a warbler – Bumble Bees of course!

Vermont currently has 13 different bumble bees species (with 3 extirpated species) and any yard or small park is likely to have at least a couple species. May is an ideal time to start exploring this genus since only the queens are active and they are larger and easier to identify than the workers and males that come later. Unlike honeybees, only the queens survive the winter, tucked away in the leaf litter or a rodent burrow, having mated in the late summer or fall.

Identifying some bumble bees can be challenging, but luckily there are few species that are distinctive and widespread. The Tricolored Bumble Bee (Bombus ternarius) is the most colorful species with bright red on the abdomen and large black shield on the thorax. There is currently only one other species that has red on it, the Red-belted Bumble Bee (B. rufocinctus) which is limited to the Champlain Valley and won’t be active until later in May. Many people may have heard of the Rusty-patched Bumble Bee (B. affinis), which was once common in Vermont, but has not been seen in Vermont since 1999 and is currently only found in a few places in the midwest.

Another distinctive species is the Yellow-banded Bumble Bee (B. terricola) which has declined significantly in parts of its range, but has rebounded nicely in Vermont and is now found statewide in small numbers. It can be recognized by a yellow-black-yellow pattern with the middle portion of the abdomen yellow. If you live near a field with abundant Red Clover flowers, you may also encounter the Northern Amber Bumble Bee (B. borealis), a very large species covered in amber hairs.

Unfortunately 3 or 4 of the most abundant species are less distinctive, but if you are interested and want to study up, species profiles and an identification guide can be found here. As always, take lots of pictures and submit them to the Vermont Atlas of Life on iNaturalist.

Lake Sturgeon © dwalc400
Lake Sturgeon © dwalc400

Our Living Fossil

By Emily Anderson

If you see a long, shark-like form in the water below your kayak as you paddle along Lake Champlain’s shores, do not panic—you may have caught a glimpse of a Lake Sturgeon. Although they may look a bit like sharks, you do not need to worry about them taking a bite out of you. Lake Sturgeon feed primarily on bottom-dwelling creatures, such as insect larvae, mollusks (including invasive zebra mussels), crayfish, and smaller fish. Given their choice of prey, these fish prefer shallow water where the depth does not exceed 30 feet.

From mid-April to mid-June, Lake Champlain’s Lake Sturgeon migrate into tributaries to spawn. First, it is the males making their way upstream, then the females follow. For Lake Sturgeon, spawning is not a yearly occurrence—males will usually spawn every 2 to 3 years, while females will typically only spawn every 4 to 9 years. While these may seem like long intervals, they stay in step with the sturgeon’s slow rhythm of life. Lake Sturgeon have been known to live up to 150 years. They also take a while to reach adulthood—males often mature at 12 to 15 years old and females mature even later at 20 to 25 years old.

This combination of maturing late and having long intervals between spawning events has proved troublesome for this species’ recovery and it is currently listed on Vermont’s endangered species list. Although Lake Sturgeon populations have stabilized and reports of accidental catches have increased in recent years, state biologists estimate that it will be another 25 to 50 years before they can consider the population successfully restored.

To learn more about how scientists are monitoring Lake Sturgeon, listen to this episode of Outdoor Radio.

West Virginia White butterflies mating on fresh spring leaves. K.P. McFarland
West Virginia White butterflies mating on fresh spring leaves. K.P. McFarland

Spring is Fleeting for a Butterfly and Its Wildflower Host

By Kent McFarland

It’s not a gaudy butterfly. It isn’t the biggest or the smallest. In fact, it’s mostly just white. But this butterfly is unusual—it only flies in forests. To see this butterfly you need to visit a rich, mature hardwood forest carpeted with spring wildflowers. West Virginia Whites fly slowly and close to the forest floor. Follow a woodland stream until you find the host plant—and the butterfly.

The West Virginia White is almost completely white above with some gray scaling on the forewing. Below, the wings are whitish with veins outlined in pale gray scales. It is often confused with the Mustard White, which by contrast shows distinct, dark green-black veins on the underside of the hindwing during its spring flight.

Spring form Mustard White butterfly.  K.P. McFarland
Spring form Mustard White butterfly. K.P. McFarland

Adult butterflies sip nectar from spring ephemeral wildflowers like Toothwort (Cardamine), Spring Beauty (Claytonia virginica), Violets (Viola), and others, perhaps pollinating some of them along the way. Their caterpillars only feed on Toothwort and Rock Cress (Boechera). Like the flowers they feed on, West Virginia Whites also are spring ephemerals.

10007, , Two-leaved Toothwort Cardamine diphylla, , , image/jpeg,, 1666, 2500, Array, Array K.P. McFarland
Two-leaved Toothwort (Cardamine diphylla) K.P. McFarland
10009, , Cutleaf Toothwort (Cardamine concatenata), , , image/jpeg,, 1666, 2500, Array, Array K.P. McFarland
Cutleaf Toothwort (Cardamine concatenata) K.P. McFarland

Spring ephemeral wildflowers are perennial woodland plants that sprout from the ground early, bloom fast, and then go to seed—all before the canopy trees overhead leaf out. This allows plants to take advantage of full sunlight reaching the forest floor during a short time in early spring. Once the forest floor is deep in shade, the plant’s leaves wither away.

Closely tied to healthy hardwood forests, some West Virginia White populations are declining or have disappeared through loss of forest habitat, high populations of deer overbrowsing understory plants, climate change, and the spread of an introduced weed called Garlic Mustard (Alliaria petiolata).

10004, , Garlic Mustard (Alliaria petiolata), , , image/jpeg,, 2500, 1667, Array, Array K.P. McFarland
Garlic Mustard patch. K.P. McFarland
10005, , Garlic Mustard (Alliaria petiolata), , , image/jpeg,, 2500, 1667, Array, Array K.P. McFarland
Closeup of Garlic Mustard flower and leaves. K.P. McFarland

Garlic Mustard was first found in the United States around 1868 on Long Island, New York and spread throughout the butterfly’s range. Adult butterflies are fooled by Garlic Mustard. The chemistry of the plant makes it inviting for females to lay eggs on the leaves, but once they hatch, the caterpillars quickly die from ingesting alliarinoside, a compound unique to Garlic Mustard. When it is present, the butterflies place nearly two-thirds of their eggs on Garlic Mustard rather than a native host plant.

You have to hurry to see this butterfly. As soon as the canopy leaves burst and shade the forest floor, the adults are gone until the next year, when if all goes well, a new generation flies again.

Help us track butterfly populations by adding your surveys and sightings on our new and expanded eButterfly project by recording the presence or absence of species as well as abundance through checklist data. A checklist is one or more observers like you going out for a known amount of time over a known distance and recording all species and individuals encountered. This is the most valuable information for understanding butterfly ranges, abundance, seasonality. Grab your camera and start recording butterflies for fun, for science, and for conservation.

Black-throated Blue Warbler © deandsusan (from iNaturalist)
Black-throated Blue Warbler © deandsusan (from iNaturalist)

The Dawn Chorus Begins

By Kent McFarland

From the seemingly simple trill of a Swamp Sparrow to the mimicry of the Northern Mockingbird, a songbird’s ability to learn is music to our ears. As Miss Maudie said in To Kill a Mockingbird, “Mockingbirds don’t do one thing but make music for us to enjoy. They don’t eat up people’s gardens, don’t nest in corncribs, they don’t do one thing but sing their hearts out for us.” The choir begins to warm up in early May and by the end of the month a full concert is conducted each morning.

This is when birders are most delighted. They can’t help themselves. They’re calling out each species as they hear the song, sometimes to themselves just to acknowledge the wonder, other times to people around them that might not be noticing the fine vocals. Bird watching by ear is a craft that takes years of practice.

Here are six tips to help you learn to bird by ear:

Comments (2)

  1. D.moss. says:

    You guys are the best
    As a green mtn.gardner
    I really appreciate your sunlight!

  2. Betsy Bahrenburg says:

    Is it ok yet to remove dead stems from my garden? I know they are places for insects to overwinter, etc. BUT I AM REALLY SICK OF SEEING THEM!
    Tell me it is time! Please!

Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.