Fresh Pond Almanac

April at the Meadow

While April in Massachusetts often still has a few cold, wintry days, spring has undeniably arrived when the fourth month of the year rolls around. No matter what fickle weather the month may throw our way, the accumulation of warmer temperatures means that Fresh Pond’s many plants are kicking into full swing, vying to occupy valuable photosynthetic real estate. With this change comes the awakening of the pond’s many insects as well, with Lusitania Meadow seeing its first influx of pollinating bees and flower flies in April. While summer of course won’t be in full swing by the end of the month, we’ll be well on our way. By the end of April, the herring are running in the mystic river, the area’s many bird chicks are growing up, and the air is abuzz with insect activity.

EwA citizen scientists and interns survey the Lusitania meadow 📍 for arthropods every single week during the warm seasons. During the colder months, we explore the general biodiversity of the reservation in more detail. This gives us the opportunity to get to know the meadow and its surroundings intimately. Each week highlights different relationships between the plants and their visitors—fascinating stories unfold. This almanac is a wonderful means to share with our communities what we observe and record at Lusitania over the course of the year.

Once a month, we open our nature documentation sessions to the public. Check us out on Eventbrite and come experience with us the magic of EwA’s study sites—oases in the middle of a very urban area.

The many trees in the Boston area will be flowering and leafing out during the month of April. Throughout the month, Boston sees an average daily high of 13.1ºC (55.6ºF), and it is the first month of the year to see an average daily low above freezing, at 4.8ºC (40.6ºF). On average, April’s lowest overnight temperature is -0.7ºC (30.7ºF), just barely below freezing. Just like March, though, April can bring a fluke snowstorm—many of our readers will remember the April Fool’s Day Blizzard of 1997, which brought up to three feet of snow to the region. Other than that, April is a rainy month, with an average precipitation of 99 mm. But we all know what they say about those showers.

April Showers Bring … April Flowers?

While the many wildflowers around Fresh Pond are unfurling their leaves throughout April, most of them won’t flower until later. There are a few exceptions, though; both violets (genus Viola) and marsh marigolds (Caltha palustris) produce beautiful flowers that can be seen at Lusitania Meadow in the latter half of the month. 

Marsh marigold | iNaturalist record © Claire O’Neill

Marsh marigolds, which actually belong to the buttercup family (Ranunculaceae) and are not closely related to any “true” marigolds, thrive in wet, marshy soil. As such, they grow near the swampy center of Lusitania Meadow (which should not be entered without authorization) and around the culvert near the southwest corner of the meadow. While this might render them a bit hard to approach closely, their attractive yellow flowers should be easy to observe from the path. 

Despite their warm yellow color, marsh marigold flowers do not, in fact, have true petals, morphologically speaking. What appears to be the flower’s petals are actually sepals, the part of a flower that usually appears green and supports the actual petals. In marsh marigolds, these sepals replace the petals instead of supporting them and are covered in a vibrant yellow layer which gives the flower its pleasant appearance. Marsh marigold flowers are most often pollinated by hoverflies belonging to the family Syrphidae.

Violets, on the other hand, are perhaps best known for their petals. Violets worldwide come in a variety of different flower colors, from deep purple to mauve, white, pink, and yellow. Violets readily hybridize with each other as well, which can make the identification of individual species a little more of an art than a science. A study even suggests that evolutionary pressures cause certain violets to change color schemes in subtle ways to suit the needs of their pollinators. A certain two-colored variety offered a warmer flower for visiting bees and was theorized to help attract them in cooler, forested environments, while in a typical environment, the bees preferred the lighter, one-colored variety.

The mature seed pods of both violets and marsh marigolds often look similar, but the two plants use different methods of seed dispersal. A more familiar seed dispersal method, which many violets employ, is the ballistic expulsion of seeds from a bursting, mature seed pod. These seeds are then further dispersed by foraging ants, increasing the potential of these seeds to find new suitable habitats. Some violets even rely exclusively on foraging ants to spread their seeds. Marsh marigolds, on the other hand, rely on water to disperse their seeds in two different ways. First, falling raindrops striking an open marsh marigold seed pod will cause the seeds to be forcibly expelled from the pod. Second, marsh marigold seeds easily float, so when their habitat floods, or if a flying seed finds water, it can float along until it lands on the water’s edge somewhere—often a great place for it to grow!

Flowering plants and their associates are the focus of much of EwA’s citizen science work, and of our summer almanacs, so visiting these early flowers is a nice way to get in the mood for summer.

Spring Syrphids

Frequent visitors to marsh marigold flowers and some of the first insects you’ll see around Lusitania Meadow in April are hoverflies of the family Syrphidae. Syrphidae is a diverse family of flies that contains over 6,000 currently identified species across over 200 genera. Sometimes called flower flies, these insects are prolific pollinators and one of the most commonly observed families of insects in EwA’s arthropod surveys. Flies such as these are the reason that flies are second only to bees in terms of general pollination productivity.

A globetail (a kind of hoverfly) © Claire O’Neill [ Record > ]

Narrow-headed Marsh Fly © Daniel Onea [ Record >

One of the more noticeable types of syrphid fly you might see in the Lusitania meadow in April is the drone fly (genus Eristalis). These flies are quite effective mimics of stinging bees, and their mimicry goes deeper than just aesthetics. While drone flies have a yellow, hairy appearance much like that of the honey bee, there’s evidence to suggest these flies also mimic bee behavior. A 2000 study found that when foraging, drone flies tend to spend an amount of time at each flower that more closely correlates to the habits of bees than to those of other flies. Thus, the mimicry is deepened, and a potential predator would have a hard time distinguishing between the two even after observing behavior. 

When observing one of these flies on a cold April morning, a question will come to mind: how did these seemingly delicate creatures survive the winter? The answer is relatively complex: depending somewhat on the species, syrphid flies might overwinter in Massachusetts at any different life stage. Some, such as drone flies, often overwinter as mature adults, the females, even after mating, wait to lay fertilized eggs in the spring. Some overwinter as larvae or pupae safely tucked away in whatever relatively safe microclimate they can find. What all of them have in common, though, is diapause, a state of developmental stasis in which an arthropod’s metabolism slows to an almost imperceptible crawl.

Speaking of syrphid fly larvae, some of these seemingly innocent and beautiful hoverflies, like calligraphers (genus Toxomerus) and globetails (genus Sphaerophoria), are brutal predators in their earlier life stages. The eyeless larvae of these flies feed largely on sessile, soft-bodied insects such as aphids, feeling their way around infested plant stems and leaves until they happen upon their helpless prey. Upon apprehending an aphid or the like, one of these larvae will pierce its exoskeleton, lift it from its place on the plant stem, and suck out its innards. It might seem amazing that a completely blind predator could have such an easy time of it, but it’s happening all around us throughout the later months of the summer when aphids are plentiful.

The larvae of drone flies have some similarly fascinating adaptations. Called “rat-tailed maggots”, these larvae usually live in stagnant, oxygen-deficient bodies of water, scavenging organic matter. The larvae get their name from the long siphon tube at the end of their abdomen, which they use as a sort of snorkel as they search for food at various levels in the water.

Mourning Cloak (Nymphalis antiopa) | iNaturalist record © Daniel Onea

While in April, we haven’t quite reached the late-spring boom of insects that Lusitania Meadow will see, there are already lots of insects to observe and ponder. Be on the lookout for Marsh flies. Besides flies, you might also see honey bees, ants, or Morning Cloak butterflies on a visit to Fresh Pond in April.

Bird Migrant Arrivals

Female red-winged blackbird (Agelaius phoenicus) | iNaturalist record © Claire O’Neill

April also brings with it the true beginning of migration season for New England’s many migratory birds. Female red-winged blackbirds have arrived at the meadow by April, joining the males who arrived a few weeks earlier in March. A large diversity of warblers, such as pine warblers, palm warblers, yellow-rumped warblers, and yellow-throated warblers, can begin to be seen in the greater Mystic River watershed throughout April. In April, the area also sees larger passers-through, such as common loons. The end of the month also sees the beginning of the Mystic River herring run, which brings many larger fish-eating birds to the area, such as bald eagles, ospreys, and double-crested cormorants. Finally, a pair of great horned owls have returned to nest in the woods at the southern edge of Fresh Pond this year, and while they cannot be approached closely and trails near their nest have been closed, you can certainly keep an eye out for them. Whether you’re coming to look for these majestic birds or delight in the tiny, beautiful world of spring flowers and flower flies, Fresh Pond offers a lot to see for the eager naturalist in April.

Of course, there is so much more to enjoy in March at Lusitania! Go check for yourself and enjoy your visit. 📅Join an EwA walk next month. Share your findings with us (you can comment below)! We will be back next month with a new slice of life in the meadow.

EwA Useful Links

📸 EwA at Fresh Pond biodiversity occurrence observations in April

🦆 Birds of Lake, P, and Marsh: Water and Wetland Birds of Eastern North America (1999) by John Andrew Eastman.

🌿 The Book of Field and Roadside: Open-country Weeds, Trees, and Wildflowers of Eastern North America (2003) by John Andrew Eastman.

by Mike McGlathery | Updated April, 1st 2024

First published on April 8th, 2020. Editing & layout by Claire O’Neill. Banner picture © Joe MacIndewar. All the photos in this article are visual records that the EwA team collects at our various study sites, including at Fresh Pond. Click on any picture to land on the record and its owner. Photos are licensed under Attribution-NonCommercial (CC BY-NC). See EwA’s biodiversity occurrence records specific to this place in the EwA at Fresh Pond iNaturalist project.

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