A skein of Canada Geese head south across a September sunset.
© Nathaniel Sharp
It can happen almost anywhere. On a cool, foggy morning, for example, when fall warblers drop from their nocturnal, migratory flights into your backyard, and clusters of Common Green Darners congregate on a nearby riverbank. Or along a mudflat some afternoon when you notice a Spotted Sandpiper teetering and then darting after prey. Or on some wooded trail when you spot the first ruby red leaves among late-summer's faded green. Here is your field guide to life slowing down and on the move in September.
By Kent McFarland
Back in mid‑July, Boxelder Bugs (Boisea trivittata) started laying eggs on the trunks, branches, and leaves of seed-bearing (female) Boxelder Trees. Since then, they’ve been leaving the trees in search of spots to overwinter. You may see them massed together on warm exterior walls, rocks, and tree trunks. Although you can find nymphs during fall, only fully grown adults survive the winter. They are most abundant during hot, dry summers followed by warm springs. As the weather cools, they find cracks and spaces around homes, outbuildings, rocks, and trees. Sometimes, they end up inside buildings, where they are often seen around windows. Please share your sightings of Boxelder Bug clusters to the Vermont Atlas of Life on iNaturalist!
By Kent McFarland
Bright red leaves under a clear blue sky make for a spectacular sight, but what strikes us as simple beauty could mean survival for a tree. As green chlorophyll breaks down without replacement, we begin to see the underlying orange and yellow carotenoids characteristic of our region’s birch, beech, and maple leaves. These pigments help capture light energy during the growing season, unlike the red anthocyanins made in maple leaves during fall leaf senescence. They are manufactured from sugars found in the leaf and produced in greater amounts as the nights cool and days shorten. When a hard freeze comes along, production ends. Why would a tree use energy to make a pigment in a leaf that is about to die and fall off? Find the answer on the VCE blog or read more from the US Forest Service.
By Ryan Rebozo
As the Vermont summer comes to an end, we want to spend a little more time thinking about beaches. Our minds might drift on warm afternoons from the state’s famous green mountains to distant, sandy shores. Yet while there is no coastline in Vermont, sandy beaches and even dunes can be found here, supporting an interesting suite of disturbance-adapted plants.
Beaches and dunes are dynamic habitats that remain open through natural disturbances, such as ice scour, wind energy, and wave action. As you may imagine, these open habitats, subject to wind and wave energy with dry sandy soils, are difficult places for plants to survive. As a result, beach plants have evolved various strategies to help them persist in these environments. These strategies include prostrate growth forms (low, creeping plants) that keep them out of the wind, hairy or succulent leaves to limit desiccation, long-term seed banking for optimal germinating conditions, and floating seeds to aid dispersal on nearby water.
Still, these habitats are rare in Vermont, with sand dunes limited to Lake Champlain and sand beaches found primarily along Lake Champlain and bordering parts of only a handful of other large lakes in the state. Because these habitats are so limited, beach-dependent plant species are rare. A few examples are Champlain Beach Grass (Ammophila breviligulata ssp. champlainensis), Beach Wormwood (Artemisia campestris ssp. caudata), Wright’s Spikerush (Eleocharis diandra), Beach Heather (Hudsonia tomentosa), Beach Pea (Lathyrus japonicus var. maritimus), Beach Pineweed (Lechea maritima var. maritima), and Seabeach Dock (Rumex pallidus), which is only known from historical records.
The state-endangered Lake Champlain Beach Grass can only be found along the shores of Lake Champlain, Lake Ontario, and the St. Lawrence River. It is an earlier-blooming subspecies with smaller inflorescences than the widespread Beach Grass (Ammophila breviligulata ssp. breviligulata). Our local subspecies resulted from the westward expansion of breviligulata along the ancient Champlain Sea followed by isolation from other populations when land rebounded and separated Lake Champlain from the Atlantic Ocean.
Next time you visit beach habitat on one of our larger lakes, take a minute to observe some of the plants in the sand and consider the strategies they need to grow, reproduce, and disperse seeds in these difficult conditions. Make sure to share your observations to iNaturalist to help biologists monitor these species!
By Kent McFarland
When weather radar was first deployed, operators called them “ghosts”—mysterious blips moving across the screen on clear nights. It turns out that these were often detections of migrating birds, insects, or bats. In addition to sensing and depicting meteorological phenomena, radar networks can be used to watch and track birds’ movements. Since the first units were placed along the Gulf Coast in the 1950s, ornithologists and birders have become increasingly aware of the power of using radar to study bird migration. And it’s available at your fingertips!
The consortium of researchers who turn weather radar data into information about the size and direction of migratory flights is called BirdCast. Their tools incorporate eBird data collected on the ground into a platform that’s greatly expanding our understanding of migratory bird movement. See tonight’s migration forecast and live migration maps. Or visit BirdCast’s migration data dashboard, which shows what has already migrated overhead or is passing during the night on a live data feed beginning each night after sunset. You might find that 300,000 birds passed through Vermont last night—probably warblers, pewees, and sandpipers among others! Tune in to the night sky and discover what’s passing you by.
By Michael T. Hallworth
Right now, many Common Green Darners (Anax junius) are stretching their wings for the first time and are about to make the most important flight of their lives. Some lucky nymphs developed quickly this summer, but many have spent over a year in the cool waters of northern New England. As the temperatures dropped last fall, many nymphs entered diapause, a state of suspended development under the ice, and waited for their time to shine. Any day now, they will start a flight that could take several weeks to complete.
Each September, droves of Common Green Darners embark on a migratory journey south and start the transition into the next phase of their annual cycle, which requires at least three generations to complete. Common Green Darners aggregate along coastlines and rivers while they migrate. It’s spectacular to see. If you catch a glimpse of adults on the move, upload your observations to iNaturalist.org or OdonataCentral to help us track their movements. The cooler temperatures signal it’s time for them to head south on a journey that’s likely not easy. Their migration coincides with those of two avid predators—the American Kestrel (Falco sparverius) and the Merlin (Falco columbarius). Each of these small falcons frequently hunt and eat dragonflies while aloft. If and when the darners arrive in the southern reaches of the United States, or possibly even the Caribbean, they will lay eggs, starting a new generation that will not migrate. In early March and April, the entire cycle begins anew when the first generation of the year will migrate north and dazzle us once again when they arrive in May.
By Spencer Hardy
If fall is mild, the season’s very last bees may hang on until early November; however, bee activity will certainly decline this month. But there are a couple of species just getting started. Aster Cellophane Bees (Colletes compactus) are beginning to emerge for the first time since last October and are frantically collecting enough pollen to support their offspring underground for the next 10–11 months. As their name suggests, they prefer asters but will also visit goldenrods and other late-summer composites.
Also emerging around this time, from the same nests, is the Autumnal Cellophane-Cuckoo (Epeolus autumnalis). Females of this species won’t be collecting pollen though—they’re focused on finding nests of Aster Cellophane Bees and sneaking an egg into the larder of their host. Vermont has more than 75 species of cleptoparasitic “cuckoo bees” and many of them specialize in just a few host bees. These cuckoos are generally active for a shorter period than their hosts and are much rarer. For example, the Autumnal Cellophane-Cuckoo was first collected in Vermont in 2019, while biologists have collected its host sporadically since at least the 1960s. However, it’s likely both have been in Vermont for centuries.
Explore all of Vermont’s bees and find out how you can help us learn more about these species through our Online Bee Guide.
By Nathaniel Sharp
Autumn bird migration in Vermont often brings to mind graceful flocks of Common Nighthawks and Canada Geese wheeling their way south, or perhaps the famously ‘confusing’ fall warblers that move through the state in huge numbers. In this land-locked state, one would be forgiven for overlooking the migration of shorebirds often associated with brackish mudflats and the seacoast. Still, they can be some of the most exciting and interesting birds found in Vermont this time of year.
A group that includes sandpipers, plovers, godwits, dowitchers, and others, shorebirds have a tiny window to successfully breed—many of them in northern tundra—before making their globe-spanning migratory journeys to places as far away as South America’s tip. With such a short breeding season bookended by massive trans-oceanic migrations, “fall” migration for some shorebirds can actually start as early as July! However, September is when we can expect to see the greatest diversity and numbers of shorebirds anywhere there are mudflats (or their equivalents) in the state.
Many of the major shorebird hotspots are in the Champlain Valley. Places like Delta Park IBA and Dead Creek WMA can be magnets for these birds, especially during years when lake water levels are low and vast mudflats are exposed. Away from Lake Champlain, look for shorebirds anywhere there might be wet, exposed mud to poke around in search of food. In some cases, manure pits and muddy river edges can provide just enough habitat for a migrating shorebird or two to stop for some much-needed refueling on their long journey south.
Be sure to report any shorebirds (or any birds) you see this September to Vermont eBird!
Thanks so much for this early fall gift of beauty and wonder.