Wednesday, September 30, 2020

Algae Impersonators at Smoyer Park Pond

For most, perhaps all of the summer, open water was only a memory at Smoyer Park's pond. In its place was a layer of green, molded into static swirls that blotted out what in previous years had been a play of light and wind on water. It's like closing the curtain on a stage.

Though I'd seen a pond in North Carolina similarly coated shore to shore, the disappearance of open water in Smoyer Park came as a surprise. What was it, and had it happened before? One regular walker in the park said it had never been as bad as this year. 

An older photo from early September, 2014 shows just a little algae or algae-like growth accumulated along the shore, offering more evidence that this year is different. 

I mention "algae-like" because not all accumulations of green growth on ponds are algae, as became more evident as we took a closer look at this year's green growth in Smoyer Park's pond.

The closer look was prompted by a link in a Sustainable Princeton email to an NJ Spotlight article about the increasing number of lakes in NJ beset by harmful algal growth, and the likely link to nutrient pollution flowing into waterways from fertilized lawns, farm fields, and pavement. We tend to think of nutrients like nitrogen and phosphorus as beneficial, but excess nutrients in nature tend to cause harmful chain reactions. In a waterway, they can lead to blooms of algae, which then die and decompose, sucking up the dissolved oxygen needed by fish. Some species of algae produce toxins, such as those alleged to have recently killed hundreds of elephants in Africa.

I contacted Jenny Ludmer, who lives near the park and takes a great interest in local nature, and suggested the possibility that a new algae might be causing the excessive coverage in Smoyer Park. As an example of recent changes, a strange algae has shown up in early spring in one of my backyard miniponds the past couple years. I also looked up the once pristine lake of my childhood, Lake Geneva in Wisconsin, and found that algal growth stimulated by rising temperatures and nutrient pollution, plus an invasive plant named starry stonewort, are now interfering with boating and swimming.

Jenny and I discussed whether the green was duckweed or algae. She took another look and sent this photo that made it look like the duckweed had been coated in a layer of green goo. Concerned about the potential for toxins, she also sent some photos to the state DEP, which promptly dispatched someone to take a sample. It sure looked like algae, and yet the state report showed "HAB not present," meaning no harmful algal bloom. They found a little Cylindrospermopsis--a cylinder-shaped blue-green algae--and not much more.

Finally, I returned to the coated waters of Smoyer Park for a closer look. Was it algae that was cheating us of any reflection of the sweetgums now turning glorious colors on the far shore?
A closeup of the surface showed scattered duckweed, but something else as well, much smaller and much more numerous. 
The small green particles were gritty to the touch. The internet, as usual, offered an instant answer: watermeal, in the genus Wolffia, which includes what wikipedia calls "the smallest flowers on earth."

It's a native species, but can be expansionist in its behavior. Warming waters and runoff from chemical fertilizer used on lawns in the small watershed that feeds the pond are some potential causes of this year's "over the top" growth. 

Smoyer Park's is not the only pond having this problem. Brooklyn Botanic Garden included a small pond in a stream corridor they carved into their grounds a few years ago. Their pond's first two years of existence were marred by rampant algal growth, but this year, its watermeal that has moved in. They are hoping that over time, nature's checks and balances will take hold. But the example of an older pond like Smoyer Park's suggests that time is no longer the mender it once was.

For anyone wanting to report potentially toxic algae outbreaks, there's a form at this link.

Tuesday, September 22, 2020

Autumn Clematis and the Really Big Show

Even now, as the flowers begin to fade, 

autumn clematis makes this lamppost look like it's wearing a voluminous fur coat. 
It's been a good year for autumn clematis, whose big floristic show revved up in these parts nearly a month ago, caught in a photo where a cascade of flowers-to-be was piggybacking on a neighbor's fenceline. 

There is great appeal in the blooms, and yet this vine should come with a warning sign.

In my mind, though not in the garden, I pair the nonnative Autumn clematis (Clematis terniflora) with the native virgin's bower (Clematis virginiana), which also has white flowers and a sprawling habit. An easy way to tell the two apart is the leaves, which are toothed in the native, rounded in the nonnative. The native's flowering comes earlier in the summer and lasts a week rather than a month.

Together they tell a familiar story, in which the native has become comparatively rare. Years back, I took this rarity to mean that the native was less aggressive, but in fact the native when planted in the garden has proven just as hard to control as the introduced species. While sending up vines that grow over other plants, as you'd expect of a vine, both also spread underground, popping up in all sorts of places where you had other plans. 

Why is it the nonnative that can be seen covering a whole side of an abandoned parking lot in Montgomery north of Princeton? 
or lining the road to Cape May Point State Park? 

There are books that claim that nonnative invasive species are somehow superior to the natives, and that we should embrace these "winners" rather than counter them. Hopefully that dubious premise has faded into obscurity, unlike so many other dubious premises that now strut their stuff on the national stage.

More likely, the autumn clematis's capacity to grow unhindered is due to its unpalatability to deer and other wildlife. That would explain why the native virgin's bower is rare in local nature preserves while it runs rampant in my garden in town, where deer seldom venture. 

Periodically, I head down the great eastern piedmont from Princeton to North Carolina, where I've been involved with saving some rare habitat known as piedmont prairie. This small remnant on the outskirts of Durham, NC contains a clematis that will seem odd to anyone accustomed to clematis being a vine. This one, called curly top, Clematis ochroleuca, grows a foot or two tall in full sun and special soils formed from the underlying diabase rock. Princeton has lots of diabase rock along its ridge, which also hosts rare species, though not the same ones as in NC. 

The name "curly top" might come from the way the flowers curl downward, or from the curly seedheads that are also characteristic of the more common kinds of clematis. 
Another clematis in the piedmont prairies of NC is leatherflower, Clematis viorna, a small vine whose flower also points downward. 

Witness a high quality piedmont prairie, and you'll see how rich and diverse an intact native habitat can be. Though cheated of the periodic fires that used to sustain them, prairie remnants have persisted here and there, mostly under roadside powerlines where trees were not allowed to shade them out. I've rescued plants from a few that were being lost to development, and marveled at how each shovelful would contain four or five species. Nature was demonstrating how co-evolution moves towards a rich coexistence. Presumably, each species is limited in some way, most likely by herbivory, from running roughshod over the others. 

Witness that, and a monoculture of autumn clematis will look both showy and disturbing. 

Friday, September 04, 2020

A Monarch Butterfly Status Report

Around mid-summer, I begin wondering how the monarchs are doing. Last summer, in 2019, they were more numerous than usual in the Princeton area, and as I googled for news of their numbers in 2020, it was with the expectation that their population was on the upswing. Surprisingly, their overwintering numbers in the mountains west of Mexico City were down dramatically. The count comes out in March, just before they begin their journey north, and was down by half compared to the winter of 2018/19. 

The low count this past winter was due in part to less than favorable migration weather last fall. Warm weather in the north delayed migration southward, and a drought in Texas left little nectar for the monarchs as they funneled through Texas on their way to Mexico. From Princeton, that flight is about 2500 miles, powered by the liquid sunlight of nectar.

This summer, I saw one every few days. Here's a male visiting Joe Pye Weed in our backyard. 

You can tell it's a male by those two spots on the back wings. 

The monarch has a delicate look, but a powerful flight. A single beating of the wings sends it rocketing forward at unexpected speed. 

One of summer's finest moments can be spent watching a monarch navigate a garden. In our backyard, masses of variously sized wildflowers form a kind of mountain range with peaks and valleys that the monarch masterfully navigates just above. Turning on a dime, coasting, darting this way and that, the monarch's flight can seem like whimsy, or an incredibly efficient and complete survey of a garden. 

Sometimes a monarch visits every section of our garden without landing, then heads off. What was it looking for? A mate? A milkweed to lay eggs on? Clearly not nectar that other more predictable insects are busy feasting upon. Oftentimes, the monarch's motivations are an enigma.

One time this summer, I witnessed a monarch whose intent was very clear. In the "Veblen Circle" of wildflowers at the botanical garden we're creating next to the parking lot at Herrontown Woods, there's a mix of purple and common milkweeds in sufficient numbers to satisfy a monarch caterpillar's voracious appetite. Yet until this summer, I had never seen a female monarch land on one.

August 7, however, a monarch came along and perched on the side of a leaf, then bent its abdomen around and under to lay an egg on the underside. All I had was an iPhone to record the moment, and didn't dare get close enough for a good photo, lest the monarch be distracted from its mission.

Though we can witness, appreciate, and take small steps to support any monarchs that come along, our capacity to influence their destiny is limited. As Monarch Watch Director Chip Taylor explains on his highly detailed blog, "High numbers in the northeast do not translate to high overwintering numbers." In other words, we can support monarchs by planting milkweed and other wildflowers, but their fate is largely being determined by weather and land management playing out elsewhere.

A 2019 New Yorker article with a less than auspicious title, "The Vanishing Flights of the Monarch Butterfly," quotes Chip Taylor describing how a banner year in 2018 was largely due to the favorable weather the monarchs experienced at various stages in their migration. With humanity still on its climate-radicalizing fossil fuel treadmill, and massive misuse of herbicides killing milkweed in farm country, the cards are increasingly stacked against monarchs getting lucky with the weather. The "inland hurricane" that swept through Iowa in August seemed an example of the increasing extremes the monarchs face.

Still, there is the delicate, improbable power of their flight, and the promise of an egg. Nature is incredibly resilient if given a chance. There are raingardens to plant and milkweed to propagate. Common and purple milkweeds spread underground, making it easy to dig one up and start a new planting that will soon expand on its own. So much tears at the foundations of our world. Let the odds be what they may, to care and to act defines who we are. 

The best source I've found thus far for updates on monarch status, and potential for participating in a larger effort, is the Journey North website:

Thursday, August 20, 2020

Video Tour: An Intro To Steve's Garden

A video tour to help you gain acquaintance with the classic native wildflowers of mid-summer in Princeton. The video is a good companion to the previous post, Wildflowers of August. 

Wildflowers of August

Sound the trumpets! The main course of summer's feast of flowers is underway. Time to gather them into one big blogpost bouquet.  This collection is gathered from my backyard and from the botanical garden at Herrontown Woods.

Rose mallow hibiscus (Hibiscus moscheutos)

Wild senna (Senna hebecarpa)
Cup Plant (Silphium perfoliatum)
Joe Pye Weed (Eupatorium sp) in the background, boneset (Eupatorium perfoliatum) in the foreground.

Cutleaf coneflower (Ratibida laciniata)
Jewelweed (Impatiens capensis)
Ironweed (Vernonia novaboracensis)
Purple coneflower (Echinacea purpurea), with some bottlebrush grass on the left.
Woolgrass (Scirpus cyperinus) -- a sedge that grows taller and matures later than most native sedges
 Groundnut (Apios americana)

Thursday, August 13, 2020

A Native Praying Mantis Finally Seen

Hard to believe it's taken this long in my life to see a native praying mantis. Most of the ones we see are native to China--a realization not unlike learning that honey bees were brought here from Europe. 

As with the spider that frightened Miss Muffet away, this praying mantis dropped from above, from the low-hanging branch of a red oak that I had disturbed while shifting a board into position for cutting. The board was destined to become part of a new stairway into the basement at Veblen house--a project that was now delayed while I took photos of the praying mantis. It stood firmly planted on the board, its four back legs forming a quadripod while it rocked left, then right, holding its poses like a Balinese dancer.

There are other examples of native species that go unseen, having been so thoroughly displaced by an introduced species that you wonder if the native still exists. Native bittersweet and native Phragmitis come to mind. 

If there were any lingering doubt about this native praying mantis's existence, I could take heart in the thought that shadows don't lie. Come to think of it, the tradition of shadow puppets is Balinese as well.

An internet search shows that there are three types of praying mantis most likely to be found in our area, the Chinese species being the most common. There's a European species as well, and then the native, the Carolina mantis.

Five days prior, while rejoicing in all the pollinating insects attracted to flowers at our botanical garden at Herrontown Woods, I took a closer look at a wildflower and noticed another creature similarly drawn to the scene, but with a motive different from my own. 


This was likely the Chinese species, waiting patiently atop a Joe Pye Weed bloom. 

There are two contradictory beliefs that people hold in their heads, well separated lest they collide. One is that praying mantises are good because they eat harmful insects. That's was certainly true when a praying mantis visited my desk to snare an annoying housefly. The other belief is that pollinating insects are important for ecological health and agricultural abundance. The reality is that praying mantises chow down on pollinators, including butterflies. Whether the relatively abundant Chinese mantis is doing more harm than good is hard to say, but worth asking.

Cannibalism in praying mantises: 
Female praying mantises are known to sometimes eat males during and after mating. For instance, they may pluck the male's head off while in the act--it being a body part the male really isn't using at that particularly moment--then polish off their partner in the afterglow of the tryst. What male, motivated by a desire to see its genes passed along to the next generation, would not give its body gladly to nourish the female's manufacture of eggs? More on this noteworthy behavior in a Univeristy of Michigan post about the native mantis, Stagmomantis carolina, and a NatureNotes post on mating mantids in a Princeton meadow.

Wednesday, August 05, 2020

Spotted Lanternfly in Princeton

Most people by now have heard of the spotted lanternfly, an insect native to China, Vietnam and parts of India that somehow showed up in eastern Pennsylvania in 2014. A leaf hopper with distinctive markings and colorful wings, it spread rapidly as it sucked the juices out of grape vines, orchards, and trees like Ailanthus, black walnut, maple and red oak.

Two years ago, local papers reported a sighting of spotted lanternfly in northeastern Princeton. Last year, the summer of 2019, a couple friends reported seeing it in Princeton--Mimi found a few in her backyard in western Princeton; Scott saw some in Herrontown Woods near the parking lot. 

For me, it didn't become real until I encountered this curiously tilted nymph on a butternut tree leaf near Veblen House in Herrontown Woods in early July. A Penn State Extension post describes the insect's colorful development from egg to nymph to the winged adults that emerge in late July.

For some reason, I had avoided writing about the spotted lanternfly. Maybe I was maxed out on the world's problems, and didn't really want to delve into the prospect of yet another introduced insect wreaking environmental havoc. 

Unlike the Emerald ash borer, which has gone largely unseen as it skeletonizes our vistas, quietly killing every untreated ash tree in Princeton, 

the spotted lanternfly sounded poised to make a highly visible and messy invasion. The PA Dept. of Agriculture published a pdf with graphic photos showing mildewed foliage and tree trunks covered with the adult insects. And because plant juice is very dilute, the sucking insects need to move a lot of juice through their bodies to get the nutrition they need. That means that both nymphs and adults expel large amounts of "honeydew", which drops down from the trees and vines, and coats foliage on the ground with sugary liquid, promoting the growth of mold. Their egg cases look like mud, affixed to trees or cars or most anything. It sounded like our habitat restorations and garden beautifications would be reduced to a tattered, moldy mess.

Below are compiled some research and experiences with spotted lanternfly this past weekend at Herrontown Woods. 

Ailanthus--the Spotted Lanternfly's favorite food

Turns out that the spotted lanternfly has a strong preference for sucking the juices of Tree of Heaven (Ailanthus altissima). Native to China, Ailanthus is fairly common in Princeton and can be invasive, forming clones and sprouting aggressively from its roots if cut down. A stand of Ailanthus can be used for trapping the spotted lanternfly. Penn State extension offers tips for homeowners on this. 

At the Herrontown Woods botanical garden, next to the parking lot, we have an Ailanthus growing, and sure enough, some adult lanternflies were found clinging to its bark.

Looking up, the Ailanthus leaves appear to be getting eaten, though the lanternflies are said only to suck from the trunk and the stems, not the thinner tissue of the leaves themselves. 

In a sense, the preference for Ailanthus is good news. An invasive tree is being attacked by a newly introduced insect from a similar region of the world. But the tree is also helping the insect expand its numbers through the summer, and toxic compounds in Ailanthus, when ingested by the lanternfly, may confer some protection from predators.

The lanternfly's honeydew is causing sooty mold to grow on the plants underneath the tree.  The NJ Dept. of Agriculture info sheet reports that the sap dripping from "weeping wounds" on tree trunks can attract stinging insects. 

Probably the best thing to do is to take down the Ailanthus, using techniques described here.

More advice for homeowners

There's an enjoyable and clever article on various tactics on the MercerMe site. For instance, the adults are very quick to jump if you try to squash them. The article says their reflexes slow down with persistent efforts, however. Will test that next time. 

Utilizing more finesse is a trap a Pennsylvania teenager came up with after watching the lanternflies climbing the trunks of trees. She ringed the tree with tin foil to channel the ascending insects into a bag, where they would die within 24 hours. Another thorough read for homeowners is at this link, including a test to see if chickens would eat them. They didn't,

but something is clearly eating them, as these wings at Herrontown Woods show. 

Longterm prognosis

Will the spotted lanternfly prove to be a longterm calamity, like the Emerald ash borer, or fade into the background as a passing problem? Will it be a lasting plague for vineyards and apple orchards? An article reports that few lanternflies were seen this year in the area of Pennsylvania where it was first discovered five years prior.  Local Princeton arborist Bob Wells is quoted in the Town Topics as saying that though vineyards and apple growers have reason for concern, for homeowners the insect "won't be much of a threat at all." I inquired on a listserve that includes land managers in Pennsylvania who have had the insect around for several years now, and got mixed responses. One observed reduced numbers one year, then a rebound the next. 

It can be hard to know if you have spotted lanternfly in your trees. My friend LisaB, who lives near Herrontown Woods, had a couple black oaks fall near her property in late July, and was surprised to find numerous SLF nymphs on the leaves that until then had been elevated 70 feet above the ground. She had seen none in her yard up to that point. Her photos show the last nymph stage (red), 

and a beautifully captured example of what a newly formed adult looks like. Documented in past posts on this blog, insects like cicadasbutterflies, and apparently spotted lanternflies as well, must hang down as they unfurl their new wings. If the wings brush up against any obstruction, they can easily become misshapened. 

Update, Aug. 6: Walking through Quarry Park, closer to downtown, I noticed some Ailanthus trees near Spruce Circle,  looked up at the leaves above, and saw them there as well, a few scattered adults sucking juice from the rachis of the compound leaves. Will the spotted lanternfly be background or foreground, a quiet addition or serious pest? Time will tell. 

In the meantime, it looks like removing Ailanthus trees would be the most straightforward way to limit this new arrival's numbers and impact.

Reporting: I tried reporting the Herrontown Woods and Quarry Park sightings. The email address bounced, and the telephone number is always busy. It may be that the state doesn't want to hear about sightings in counties where the insect is already present, or maybe it's so widespread by now that the information isn't helpful.

Does milkweed kill lanternflies?

On the leaves of common milkweed growing near our Ailanthus tree, I found several lanternflies belly up or immobilized, leading to speculation that the insects sucked juices from the milkweed and died from the toxins therein. Apparently, as an introduced species, they have yet to evolve an aversion to the plant.

Sunday, August 02, 2020

Lisa's Salamander Rescue

This spring in late April, I received a surprising email from my friend LisaB who lives out next to Autumn Hill Reservation, across from Herrontown Woods. An amphibian had mistaken the water sitting on top of her swimming pool cover for a vernal pool, and laid a cluster of eggs there. My somewhat informed guess? Spotted salamander eggs. 

What to do with this unexpected gift? The salamander was not completely off-track in having laid its eggs in a puddle suspended over a swimming pool. Through uncanny luck, the swimming pool's owner happens to care deeply about the amphibians that inhabit the woods behind her house.

Lisa had contacted me back in March--March 15 to be exact--to report that the frogs in the neighborhood had been on the move the night before. "This was definitely Herrontown frog migration night," she reported. "Dozens on the road at 5:30a, all headed" towards Herrontown Woods to mate and lay eggs. "I only saw them in a relatively narrow band of ~a half mile, from the entry to Autumn Hill to the curve at Stone Hill Church. They were mostly moving in the dark early this morning--by 7am they were gone. Hope that protects them to some extent. Traffic picks up after 7." She suggested we organize next spring to serve as crossing guards for amphibians needing to cross Herrontown Road to get to their mating grounds, as is done elsewhere in the state.

On May 25, Lisa sent me a report on what she had decided to do with the salamander eggs, which otherwise would have been lost when the maintenance crew came to service the swimming pool. Since it's inappropriate to remove salamander eggs from a nature preserve, Lisa took this backyard gift as a rare opportunity to see salamander development up close.

"I put some in a deep vernal pool in Herrontown Woods and hung on to a few. They live outside in a tank so they get all the usual temperature variations, plus bonus mosquito larvae to eat. They seem to really like live blackworms, which I am now growing in my fridge (uh, don't tell my kid). I'd love to see one develop spots, which takes a few weeks after transformation. They already have puny little front legs!"

On June 24, another update:
"Salamander larvae are starting to transform! Losing their gills and showing their spots. Voracious carnivores!"

And on July 7, more detailed reports begin about the salamanders' metamorphosis, mixing affection with the close observation honed in her career as a scientist: "The two that transformed first flew the coop. For now I put lids on the tanks, so the next three to transform are still here. Some cool things I didn't know:"

1) "As they start to transform, their GILLS start to develop bright yellow spots just before they regress."

2) "Each one has a unique spot pattern that coalesces and intensifies as they transform, which makes them easy to tell apart. Not sure what nucleates the spots."

"This sequence of photos, taken two days apart, shows the development of spots on a transformed salamander."

"They become very shy once they transform. The larvae are just hanging out in the water column. I know they're about to transform when I look in the tank and I can't find them. The ones that have transformed are always burrowed under the moss. Interesting, for a stage with what looks like aposematic coloring ("don't eat me! I'm brightly colored and probably toxic!"). Probably they aren't actually toxic, and so the bright yellow spots pretty strongly select against anyone who is ever out in the open."

3) "The darkness of the larval stage seems influenced by substrate--ones raised on light rocks are lighter in color than ones raised in a pile of leaf litter. Not sure if it's a developmental camouflage or they're just dark because they're eating/covered in leaf gunk. "

"Man, do they eat a lot of blackworms! 1/8 lb so far."

Here are spots developing on a "new guy." Photos taken on days 1,2,3, 6, and 7.

By mid-July, thoughts turned to what to do with the salamanders once they've grown. "Technically I think I'm not supposed to release them, given there is some risk of introducing new pathogens into the local population (e.g., from the worms I feed them, which came from afar). Two did escape, though, so that ship may have sailed."

The Watershed Institute didn't have room. Salamanders apparently, and fortunately, given the potential danger to wild populations posed by poaching, don't make very good pets. They prefer to remain hidden, and can live up to 20 years. Many have toxins in their skin, and can easily absorb harmful oils and chemicals on our skin if we touch them. 

Finally, Lisa reached out to the Mercer County wildlife center, which then reached out to the senior biologist from the New Jersey Division of Fish and Wildlife Endangered and Nongame Species Program, who gave the following advice:

"From what I’ve read below I consider this to be a pretty low risk release and would recommend her to release them as near as she can to reasonable habitat by her property and best case would be to release them during the late morning when there’s some rain or release them an hour or so after sunset during a rain." 

One thing I've learned while putting this post together is that spotted salamanders (Ambystoma maculatum) have a longer incubation period than most species. Most vernal pools dry up once the trees leaf out. Only a few stay wet enough long enough to sustain the larvae until they metamorphose into juveniles.

Lisa sent a link describing how spotted salamander eggs incorporate algae into the body of the embryo. They become solar salamanders. The algae symbiotically provides energy and eats the salamander's waste. The algae fades away during the larval stage of the salamander.
Thanks to LisaB for all these photos and information. One more thing she shared speaks to why this was such a meaningful experience for her:
"I've been turning over stones looking for salamanders since I was a kid, and have seen hundreds of Eastern Redbacks. Once, when I was <10, one of the other kids found what I now know was probably a spotted salamander, and came running to tell the others (we thought they were lying about a salamander the size of a hotdog). That was the closest I've come to seeing one, despite the fact that they are all over here, until 40+ years later one decided to lay eggs on our pool cover."