This account is of my second Naturalist Certification Series field trip and is quite long, but hopefully of interest for the variety of plants, animals and interactions they retell. There's more I should be doing to fully develop this entry, but I'm eager to finally get it posted, since it has already been more than a month.
17 May 2014
Burrows Run Preserve Hockessin, DE
8 a.m. Sunny
We gathered in the parking area just off Ashland Clinton Schoolhouse Road, surrounded by the tree swallows (Tachycineta bicolor) being studied by a University of Delaware graduate student for response to stress. Their comfort around people and their acrobatics above and around us immediately drew my attention, but being just a bit late, I hurried over to Joe who was starting to explain the day. We would be hiking through five distinct terrestrial ecosystems this morning, discovering what we could and learning about how the plants and animals in each interact.
Meadow
To start, Joe pointed us towards surveying flags he had planted just into the tall grass around the parking area. In groups of two or three, we explored the area immediately surrounding the flags, seeing what we could find in this meadow ecosystem. Other than the charismatic tree swallows, my knowledge was rather limited to start; I recognized the work of spittle bugs (Philaenus spumarius) , but even with them, it didn’t occur to me to disturb them and discover what the insects actually look like. When Joe came over to check on our progress and identify things for us, he swept a mass of spittle off a stalk of grass with his fingers and cleared it off to reveal a small, light green animal with a large abdomen and black eyes, what I learned is a larval form of the insect. It was an utterly ridiculous moment of joy for me - I had never thought to uncover one before, the ethic of leaving plants and animals alone as much as possible so ingrained in me I sometimes don’t even realize how it is influencing me
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| bed straw |
In addition to the spittle bugs, we identified various meadow plants: bed straw (Cruciata pedemontana), blackberry, dandelion, Persian speedwell, Queen Anne’s Lace, and warm- and cool-season grasses, including bluestem. Digging below the matted dead grass at the base of the plants, we found moss and very small flowering plants in a miniature ecosystem of their own.
We regrouped and shared what we had found, with a number of plants, an insect and a spider added to the list by other groups. Joe then handed out the sweep nets and peanut butter jars familiar to many of us from teaching various programs with kids and sent us back out to the tall grass. The wonderful thing about the sweep nets is that it is fun to do, and the boy who attends these field trips with his dad, who is in the course, had a great time brushing the net along the grass. Between the three of us, we captured a number of plant bugs - the most common catch for everyone it turned out - a jumping spider, a crab spider, and numerous gnats and other insects that would remain anonymous to me. While the sweep nets are fun, they still make me anxious with a group, because they pull in so many animals I can’t identify.
Once again, the large group shared what they found, adding leaf hoppers, aphids, a praying mantis, a weevil, a caterpillar and a small black beetle to the list. Someone found a goldenrod stem with a gall, and we learned that a certain wasp larva will mature in the gall, feeding off the plant before emerging as a flying insect, unless it is eaten itself by either a different kind of wasp, as this one had been, or a downy woodpecker, which will drill into the galls.
To wrap up the meadow exploration, Joe took a soil core, showing how the meadow soil had some sand and some clay but mostly silt, and that it was colorful, with warm browns and rust colors, evidence that air has gotten into the soil to allow oxidation of minerals. This is characteristic of mesic soils, the majority of the soil in the Piedmont, well-drained and neither arid nor wet.
Thicket
Setting off down the hill from the parking area, we immediately began our focus on a thicket ecosystem. The hike allowed us to observe a linear thicket - the hedgerow around the field - and a larger thicket that had grown up after the nature society stopped mowing another field 20 or 25 years ago. As we walked along the hedgerow, Joe explained how some birds use both the thicket and the meadow, which helps explain the diversity and importance of ecotone, the transitional habitat between ecosystems. As an example, he noted that bluebirds perch in thickets but drop to the ground to catch insects. Red-winged blackbirds (Agelaius phoeniceus) perch towards the tops of trees to sing, but nest on the ground in the field.
We would find what seemed to be an impressive number of birds to an inexperienced birder like myself (more than 40 by the end of the hike), but our first discussions along the thicket dealt with the plants. After the obligatory highlighting of poison ivy, the next two plants that grabbed our attention (Autumn olive and Oriental bittersweet) were invasive exotics, which do particularly well in thickets - growing up and outcompeting natives in disturbed areas allowed to go to seed, which characterizes most thickets. The first native tree we saw, an ash, was afflicted with a native fungus, ash rust, which will kill the affected twig, though the tree should resprout and survive. The fungus can kill small ash trees, however, and is somewhat unusual in the Piedmont, since its other host is spartina grass, a salt marsh plant. Some theorize the amount of salt we use in the winter has allowed spartina grass to grow alongside our roads, providing hosts for the rust.
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| black cherry, flowering |
The first we saw was an orchard oriole, a maroon or rust-colored bird that favors thickets. Soon after, a yellow warbler caught everyone’s attention. This one sang for us and flew down to check out a call played on a smartphone - birds can sometimes be drawn close because the singing is done by males who will defend territory if they hear others. Lucky as we all were to see this warbler well, even more was in store. Just a bit further into our walk, we saw three yellow warblers chasing one another up and down the thicket, bright colors against and through the tangle of green. It may have been two males competing over a female, but it was hard to follow.
We heard and saw a red-winged blackbird, catbird, mourning dove, flicker and a common yellow-throat without moving far, but the next highlight was an indigo bunting. He was singing high in a tree, as they usually do, but he flew from above us to a tree across the corner of the field from us to another tree where we could see him through binoculars. Indigo buntings are actually common songbirds in eastern North America, but they are usually heard but not seen.
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| Dame's Rocket (Hesperis matronalis) |
Continuing on the path along the thicket we walked past common mullen and stopped at another patch of invasives. This was where we saw the mile-a-minute vine, but we spent more time discussing Dame’s rocket and garlic mustard, two invasive mustards. In addition to identifying the plants, which have four petals and upright seed pockets, we learned all mustards are edible and can be used in pesto.
One of our fellow classmates is learning to forage, I learned later in the day, adding a plant or two a season, and a bit of the appeal started to sink in for me during this trip, perhaps as the idea of confidently recognizing and identifying plants in the wild started to seem possible.
Continuing on we came across our first, and only, visible decomposer of the meadow, a mushroom of some kind growing in the trail. As the hike focused on terrestrial ecosystems, we were trying to find representatives or each of the main classes in an ecosystem: producers, consumers and decomposers. Producers and consumers were proving no problem, even to the point of finding primary and secondary consumers (those that eat plants and those that eat those that eat plants), but decomposers were not as apparent. Still, that didn’t mean they weren’t present, and much of the decomposition necessary is no doubt handled by bacteria.
As we crossed the thicket to another field we heard two more birds, one of whom had even the birders debating what it could be before Joe explained it. The more common one we heard was a field sparrow, whose call was brilliantly described as like “ a ping pong ball dropping on a table.” The bird who had stumped the group, although it’s call was distinctive and noticeable as we approached, was the inaptly named prairie warbler, an indicator species for a thicket. The call of the prairie warbler is in rising notes with a buzzy quality.
From the break in the hedgerow we crossed a second field, one maintained by fire rather than mowing. In our region, land tends towards forest, with succession moving from meadow to thicket to young forest and finally mature forest. Meadows that persist do so almost universally through human intervention, both historically and today. Most of the eastern woodlands were cut during European colonization of North America, but after agriculture moved into the Midwest, fallow fields in New England and the Mid-Atlantic began to return to forest. Some fields at Burrows Run are being maintained because they now serve important ecological functions, providing habitat for animals whose historical homes in Midwestern prairies have been converted to agriculture.
The meadow we were crossing from the hedgerow had been burned about a month before, which I found surprising, because you can see in the photo that the area looks green and alive. Fire not only maintains meadows by killing plants that would convert it to thicket and eventually forest, it also feeds the soil. This particular field is burned every two or three years, when conditions (moisture, lack of wind, time of year) are just right for a controlled burn, which still involves many trained staff and the fire department on hand.
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| The Burrows Run meadow burned a month before |
Once inside the thicket allowed to cover an entire old field rather than a hedgerow, we almost immediately spread out to find a plant we didn’t know to sketch, giving us a chance to observe it closely and time for Joe to come around to tell us all one-by-one a bit about what we had chosen. I realized I was going to have my pick of things I didn’t know, so I settled on something early, a vine with opposing leaves that looked like it could be interesting to draw. A bit embarassingly, it turned out to be Japanese honeysuckle; I had not realized how much I relied on the flowers to identify honeysuckle. Likewise, yarrow fooled another student, who has much more robust versions of the non-native plant, used for herbal remedies, growing in his yard at home.
The exercise turned up some more surprising finds as well, including two species of cinquefoil, which best guesses had as common cinquefoil (five leaves, serrated at the ends) and rough (six, serrated all the way around). Another student picked sensitive fern, which provided an opening to talk about how to distinguish the various plants; in the immediate surroundings we also found the very common Christmas fern and the Lady’s fern. One final striking but not necessarily appealing find was cedar apple rust on an eastern red cedar; the fungus was very noticeable in the boughs of the tree, orange balls throughout the plant. It is a particularly bad problem for apple growers, and as we saw, attacks cedars as well.Floodplain Forest
Leaving the drawing exercise, which we would repeat later in a mature forest, we headed into the floodplain forest, our third ecosystem of the morning. The first plant we discussed on this part of the hike was wild geranium, one of a relatively small number of native wildflowers that bloom in the spring. These ephemeral flowers have adapted to bloom quickly early in the year, before the trees of the forests where they live have fully leafed out, and then live much more subdued lives the rest of the summer into fall and winter. We also found a native mustard - spring cress - which we had a chance to taste; the leaves had no distinctive taste at first, like grass, perhaps, but at the end and certainly the aftertaste had the tang of mustard. The taste, slow to start, actually lingered for quite a while into the hike.
The floodplain forest was not immune to invasives. This was where we found Japanese stiltgrass, a hardy and persistent weed that chokes out other plants by spreading in dense mats, and lesser celandine, which will also take over large areas. But most of what we found in the floodplain forest were good examples of native plants that thrive in wet soils: jewelweed, pin oak, sycamore, and ash-leafed maple, commonly called box elders for their association with the insect and the tree with the widest range of any in North America. We also came across large patches of horsetail, a plant early settlers used to scrub out pots.
We continued to find some interesting plants, like Greek Valeria, Lady’s thumb and the native wood nettle, which Austin voluntarily rubbed on his arm to describe to the group how it differed from the imported stinging nettle with which we are all more familiar. But the floodplain forest also brought forth a number of birds, completely different species than we had seen so far. Two kinds of flycatchers appeared, the Acadia and the pewee, which was very helpful for a beginning birder thanks to its eponymous call and its habit of returning to the same perch repeatedly to eat after catching flying insects.
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| The flycatchers were hunting over Burrows Run |
There was a red-eyed vireo I heard but did not see, though others may have; like the indigo bunting, red-eyed vireos are actually common in the area during the summer but rarely seen because they stick to the canopy. And we saw a Baltimore oriole, which is another charismatic bird with its bright orange coloring and distinct, five-note call. The section of floodplain forest in which we found the Baltimore orioles was an ideal illustration of their preferred habitat, with scattered tall trees in a relatively open canopy.
Another indicator species we found in the riverine forest was the slippery elm, the only native elm in the area, which seemed to be a theme for the trees - that one species was the lone native representative - the slippery elm, the black cherry, the eastern red cedar standing in for not just cedars but all conifers. I don’t know if this is because of the Mid-Atlantic’s location as the northern-most portion of some southern species’ range and the southern-most area in which to find northern species, like the cedars, but it seems possible.
Mature Forest
We crossed a bridge over Burrows Run and were immediately in the mature forest ecosystem for the trip. We found a new fern - the New York fern, which is tapered both where it grows from the plant and where it terminates in the air, as if it were a candle being burned from both ends - and the region’s only native azalea, called the pinxter flower or pinxter bloom. After highlighting the oak-hickory-beech forest’s closed canopy, semi-closed understory and herb layer and open shrub layer, Joe sent us out to find unfamiliar plants to draw again. 
As with the last time, I found one quickly, and managed a decent sketch, although my scale got a little tripped up when I switched from leaf to leaf. It was a short green plant with broad leaves, and it was clearly an eye-catcher - after Joe told me it was a native wildflower (not blooming at the time) called Lion’s Paw, I heard him give the same answer to at least two other students further down the trail. Other highlighted plants included the maple-leafed viburnum, which is a common shrub in mature forests, and bloodroot, which grows its seeds with sugary appendages attractive to ants, which disperse and plant the seeds by carrying them off to anthills.
The forest grew uphill from the creek, which provided us with a couple of additional opportunities. One was to see mesic soil. As in the meadow, Joe took a soil core from a wetland area between the forest and the creek, but this time the soil was dark, black, filled with clay, although a few rust-colored patches suggested the wetland may dry out in the summers. Defining a wetland involves finding the right soil, indicative plants (skunk cabbage was prevalent throughout the area) and, perhaps obviously, having water present.
The other opportunity was to hear a Louisiana water thrush, which given the time of year, was likely nesting in the area. (Like the prairie warbler, the Louisiana water thrush is misnamed, since it’s actually a warbler as well). Louisiana water thrushes only live in high-quality forests with high-quality streams running through them. Like the stonefly and mayfly larvae shows Ashland’s creeks have high water quality, the Louisiana water thrush was telling us this forest around the Burrows Run was in good shape.
As you might expect in the mature forest, in addition to the flowers, shrubs and birds, we spent a good deal of time focused on the trees. The predominantly oak-hickory-beech composition of the forest indicates the forest is older; tuliptrees dominate early successional forests, as we would see firsthand in our final ecosystem on the hike. The trees grow in different ways, which leads to their association with certain stages of forest succession. The tuliptrees seed and grow fast in the sun, stretching up early in areas becoming forests. But oaks, hickories and beeches better tolerate shade and can survive more shaded forests, thereby replacing the tuliptrees as they die.
The forests are not completely one or the other, of course, and as part of our exploration of the mature forest, one of the first trees we measured was a tuliptree. Joe had a special tape measure that converted a tree’s circumference at 4.5 feet up the trunk to its corresponding diameter, allowing you to then multiply by a species-specific growth factor to find its age. The tuliptree was about 92, a nearby beech around 86. Another tree chosen for its size was about 180. Old-growth forest is exceedingly rare in the Eastern United States, though not completely missing, but these were ages that fit with a mature forest having moved through succession and into a climax stage.
Turning up the hill of the forest, we continued to find a number of interesting plants, like low-bush blueberry and silvery spleen wort, which had to have been the most intriguingly named fern of the day. We found a couple more decomposers - shelf fungus and puffball fungus. And I stopped to admire some really happy, healthy mayapples, taller than I’ve seen at Ashland and in full flower. The mayapples were something, but I paid for loping along at the back of the group when the leaders saw a great horned owl fly by with a snake in its talons. Of course, you can’t see everything, but it hurt to miss that. Great horned owls are apex predators, hunting just about any animal they can catch up to and including foxes. Their favorite food, however, is skunk, a fact guaranteed to get a good reaction from kids.
As we emerged from the mature forest we heard green frogs and bullfrogs calling from a man-made pond separating the older growth from the early successional forest. Also between the two was Delaware’s record Black Gum or Sour Gum tree. As I’ve found with big trees in the past, such a thing is impossible to show properly with a photograph.
Early Successional Forest
Our first activity in the young forest was a second method of discovering tree age. The group took cores from three trees, which allows you to count the rings in a tree’s trunk without felling it. The tree is not harmed by the process, or at least not irretrievably so. The three cores confirmed the ecosystem as a young forest: 47, 69 and about 80. This part of the property was bought by a family in the 1930s that then allowed the field to grow up in the area, so the ages tracked to what was known of the property’s history.
While the tree coring was underway I took the time to look at a catbird through binoculars, not having had a real clear look earlier, which probably amused some of the birders in the group. Catbirds are quite common and rather dull in appearance, completely gray, though the hue varies on different parts of the bird. Still, I haven’t seen many of them in the cities where I live and work, so it was novel to me.
We heard an ovenbird, a warbler that nests on the ground in woods, but after that most of the rest of the hike consisted of class members being stationed by plants along the trail to share a bit of information about them. On the walk through this section of forest we saw both Solomon’s Seal and false Solomon’s Seal, also known as Solomon’s plume, which made it easy to learn how they differ.
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| showy orchis |
We saw two new ferns - rattlesnake fern and interrupted fern - and a rare flower from the orchid family, showy orchis, that appeared to be establishing itself, spreading from a few plants that had been re-introduced by people.
We saw a native vine called wild yam and very near the end of the trail I was given sweet cicely or aniseroot to show, adding two more edibles to our finds for the day.
Species list
Meadow
Plants
bed straw
blackberry
little bluestem
orchard grass
dandelion
Persian speedwell
Queen Anne’s Lace
goldenrod
clover
common mullen
dame’s rocket
garlic mustard
Animals
spittle bugs
jumping spider
crab spider
tree swallow
leaf hopper
plant bug
great blue heron (flying over)
black vulture
turkey vulture
Fungi
mushroom
Thicket
Plants
poison ivy
autumn olive
oriental bittersweet
ash tree
black cherry
prunus avium
sassafras
bush honeysuckle
blackberry
eastern red cedar
black walnut
common cinquefoil
another cinquefoil
Japanese honeysuckle
sensitive fern
Christmas fern
Lady fern
golden ragwort
crabapple
yarrow
Animals
orchard oriole
yellow warbler
red-winged blackbird
catbird
mourning dove
flicker
indigo bunting
common yellow throat
prairie warbler
field sparrow
mile-a-minute weevil
Fungi
Ash rust
cedar apple rust
Floodplain Forest
Plants
wild geranium
ironwood
Japanese stiltgrass
spring cress
jewelweed
ash-leafed maple
horsetail
wood nettle
black cherry
lady’s thumb (polyganum)
Greek valeria
lesser celandine
slippery elm
mayapple
Animals
blue jay (flying over)
pewee flycatcher
Acadia flycatcher
Baltimore oriole
leaf-footed bug
red-eyed vireo
acrea moth
wood thrush
tent caterpillar
Mature Forest
Plants
New York fern
pinxterbloom azalea
beech
oak
hickory
lion’s paw
ironwood
blackgum
maple-leafed viburnum
arrowwood
dilettatum
Northern red oak
tuliptree
bloodroot
false Solomon’s seal
low-bush blueberry
mayapple
silvery spleen wort
black how viburnum
spice bush
Animals
leaf-footed bug
red-bellied woodpecker
Fungi
shelf fungus
puffball fungus
Early Successional Forest
Plants
tuliptree
privet
burning bush (winged euonymus)
wild yam
showy orchis
rattlesnake fern
Solomon’s seal
Japanese barberry
interrupted fern
poison ivy
Solomon’s plume
wineberry
jetbead
aniseroot
hackberry tree
Animals
ovenbird
catbird
cyanide millipede
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