Training Deer to Eat MORE Japanese Knotweed

This post represents a first for PrincetonNatureNotes.org, in that it is written by someone other than me. Mark Nowotarski lives in Stamford, CT, and contacted me more than a year ago after discovering a 2014 post I had written entitled Training Deer to Eat Invasives. Independently, he had begun foraging the Japanese knotweed growing in his backyard (young shoots are edible) and noticed that deer began browsing it as well. Released from any co-evolved limits on its growth, Japanese knotweed has spread across the US and globally, displacing native species and overwhelming any human efforts to counter it. Unlike people, deer are 24/7 land managers. Their appetites decide what can and cannot grow in our yards and woodlands. Training deer to eat a relatively edible species like Japanese knotweed could conceivably, in some situations, relieve browsing pressure on the native plant species deer tend to prefer. As the deer in Mark's backyard continued to consume young sprouts of Japanese knotweed, he sent me photos and text that I incorporated into a post a year ago.

This past growing season, Mark expanded his experiments and observations, exploring how a willingness to browse Japanese knotweed could pass from one generation of deer to another. It's still unclear how much of an impact deer browsing could have on the spread of Japanese knotweed, but it's an interesting inquiry. Along the way, we learn about deer family dynamics, the potential grazability of another uber-invasive, porcelainberry, and even the possibility that deer saliva affects the chemistry of plants. Thanks to Mark for sharing his work with us.

Training Deer to Eat MORE Japanese Knotweed

By Mark Nowotarski

In our post last year, “Training Deer to Eat Invasive Plants – Japanese Knotweed”, I shared observations of white tailed deer (Odocoileus virginianus) browsing a patch of Japanese knotweed (Reynoutria japonica) in my backyard in Stamford CT. The local deer had learned to browse the knotweed continuously from spring to fall resulting in drastically stunted canes. This had allowed numerous native plants to recolonize what had previously been an invasive monoculture. Steve and I speculated that perhaps if we cut the fully mature canes in other nearby patches of knotweed (i.e., coppicing), new shoots would grow and the deer local to those patches might browse the new shoots as well. I’m happy to report that that strategy at least partially worked.

Deer Raising Fawns on Knotweed

Before we talk about manual coppicing, let’s talk about how it’s occurring naturally. This first video, shot in May in my backyard, shows you what deer browsing spring knotweed shoots looks like.

A buck with new antlers approaches several knotweed shoots (Fig. 1). He gives a quick sniff, bites the top portions off, and eats them. The cut stems that are left behind are about 2 feet tall.

This particular buck may well be one of the fawns raised on knotweed in my backyard in the prior summer of 2024. Does and fawns form a family group when the fawns are born in late spring. They normally stay together and browse in the doe’s home range for a full year before dispersing shortly before the doe, if she’s pregnant, gives birth to the next year’s fawns. This is how last year’s fawns learn to eat the new shoots of knotweed that sprout in the early spring. The early spring browsing by last year’s fawns coppices the knotweed so that when it sends out new shoots at a convenient two foot height, the new shoots will be available for the new fawns born in late spring.

This year, our doe was, in fact, pregnant and sometime in June, she gave birth to triplets. Triplets are relatively rare (1 in 10 pregnancies) and indicate that the doe is well fed. By July, the doe and the new set of fawns were out browsing the knotweed previously coppiced by last year’s fawns before they dispersed.

In the foreground of Fig. 2 you can also see several native plants growing up through the coppiced knotweed. On the left is Canadian goldenrod (Solidago canadensis). On the right is Northern lady fern (Athyrium angustum) and sensitive fern (Onoclea sensibilis). The deer would occasionally take a nibble of the natives, but they concentrated primarily on the knotweed. 

This suggests that some of the native species less appealing to deer could begin to coexist with browsed stands of knotweed. I plan on trying this strategy next summer and will keep you posted.

I had set up a motion activated trail-cam to monitor how often, and for how long, the doe and fawns browsed the knotweed over the summer. They returned 4-5 times a week and browsed 5-15 minutes for each visit. This lasted from when I set the camera up in July all the way through late October when the knotweed senesced (i.e., dropped leaves and turned brown). So far this winter, the doe and fawns are still stopping by several times a week. In late October an 8-point buck also stopped by in the middle of the night. After a bit of hide-and-seek with the doe in the knotweed, they mated. We can now hopefully look forward to new fawns this spring.

The cycle of fawns being raised on knotweed and then dispersing in the late spring to new territories may be an important mechanism for the spread of knotweed browsing by deer. The question then becomes, can we spread it even further by coppicing canes ourselves.

Expanding Knotweed Browse with Manual Coppicing

At the same time I was monitoring the deer in my backyard I also set out this past year to explore the knotweed stands in our local parks and land trust sites to see if I could find additional evidence of deer browse. About half of the stands I inspected showed signs of early spring browsing. About half of the spring-browsed sites also showed continued summer browsing. Several of the summer-browsed sites showed a significant expansion of the browsed area versus last year. This was evidenced by areas with tall old canes from last year but only shortened canes this year. The deer hadn’t eaten the knotweed last year and it grew to full height. This year, however, they started in the spring and continued through the summer and fall keeping it short.

To try out the manual coppicing experiment, I selected four sites where there was either no early spring browsing or where there was some spring browsing but no rebrowsing of the new shoots emerging from the coppiced canes. Two of the sites did not show any rebrowsing of the coppiced canes. These sites either had no spring browsing or very scattered spring browsing. The knotweed threw out new shoots which grew to full height despite clear evidence (e.g. footprints) of deer wandering by. Apparently, the deer near those stands had not been sufficiently acclimated to knotweed as a source of food.

In the other two sites, however, the deer did resume browsing the new shoots thrown out by the coppiced canes. These sites had heavy spring browsing and well-worn deer trails right next to the knotweed stands.

The next set of figures shows the history of my coppicing experiment at one of the sites where the deer resumed browsing. 

Fig. 3 is a photo taken in April. It shows what an early spring browsed knotweed shoot looks like. It also shows a new shoot emerging from the cane a few weeks after the initial browse.

Unlike my backyard, however, these new shoots were not rebrowsed. By July they had grown to full height. This, along with the well worn deer trail right next to the knotweed stand, made it an ideal location for the coppicing experiment.

The next photo (Fig. 4) shows a section of the knotweed stand where I cut a 6 foot wide by 12 foot long section of the full grown knotweed canes to about 2 feet off of the ground. 

I cut the canes at a bias so that when I inspected them later on, I could tell whether a cut cane was my doing (angle cut) or a deer browse (horizontal cut). Cuttings were placed where they could not resprout or be washed downstream.

A few weeks later I went back to inspect and, much to my delight, the deer were browsing the new shoots emerging from the manually coppiced canes (Fig. 5). 

Where I had cut the canes, the ends were frayed and the canes turned black down to the next joint. Where the deer browsed the canes, however, the ends appeared to be sealed off and even flared out as if from accumulated water pressure coming up through the knotweed. The canes below the deer browse remained green. It makes me wonder if there is something in the deer saliva that causes a deer browse wound to heal quickly. Perhaps knotweed has evolved this way from browsing by sika deer (Cervus nippon) in their home range in Japan.

Once I confirmed rebrowsing of the new knotweed shoots at this particular site, I set up another trail cam to see what sort of deer were coming by. I half expected another family of a doe teaching fawns to eat knotweed.

 

Imagine my surprise when this magnificent 14-point buck showed up (Fig. 6). It wasn’t a family group. It was a bachelor group with up to four bucks coming through at various times.

This buck and several others came by 4-5 times a week to browse not only the knotweed, but the invasive porcelain berry (Ampelopsis glandulosa) growing over the area in the foreground and hanging off of the uncoppiced knotweed canes in the background. In fact, I suspect that the porcelain berry is the primary reason the deer were there. The knotweed was just an additional food source.

The bucks suddenly disappeared in mid-September after they shed their velvet, no doubt to pursue does during the rutting season. I have not seen them since except for one poor fellow with a missing antler. Given how well-worn the deer trail is, however, I expect to see at least some of them again in the early spring.

Deer in a given area learning to eat Japanese knotweed appears to be a multi-year process. It starts with initial occasional browsing of early spring shoots. The spring shoots are then browsed more intensely in the ensuing years. Eventually the deer start browsing the new shoots growing from the spring browsed canes. If the knotweed is in a doe’s home range, then she starts to raise her young on knotweed and then the process spreads as the fawns raised on knotweed go on to establish their own home ranges.

If you try your own coppicing experiments, please let us know how they work out. I’ve joined a project on iNaturalist called “North American Knotweed Ecology Project” where we can share our observations. iNaturalist is a great tool for finding knotweed stands in your area. If you look carefully in the knotweed photos, particularly those taken in April and May, you can often see a deer-browsed shoot here and there. Sites with browsed shoots would be a likely candidates for coppicing experiments.

In the future I hope to learn more about the general phenomenon of deer adjusting their diets to consume invasive plants; how this affects browsing pressure on native plants; and what impact it might have on the deer themselves. The deer won’t solve all of the problems with invasives, but they may very well be an important part of the solutions.

- Mark Nowotarski

Editor's note: A related initiative is the effort to train cattle to eat invasive species. A woman named Kathy Voth appears to be a leader of this approach. 

Lesser Celandine Alert!

It's time for the annual call to action to prevent lesser celandine from taking over all of Princeton. Also called fig buttercup, it's a highly invasive nonnative plant that is spreading rapidly, yard to yard and into parks and nature preserves, where it degrades habitat for wildlife. It thrives on homeowners' indifference and inaction, so I've been doing what I can, urging town officials to defend our parks and preserves, urging homeowners to take action in their own yards, explaining that herbicides are not anti-nature if they are used selectively and medicinally. My letter to the Town Topics and other local publications starts like this:

Blooming in many people’s yards right now is a small yellow flower that, upon closer inspection, proves not to be a dandelion. Variously called lesser celandine or fig buttercup, its radical invasiveness triggers a predictable progression of emotions in the homeowner. Delight at its pretty flower soon turns to alarm as year by year it takes over the yard, spreading through flower beds, across lawns and into neighboring properties. What may start as a few scattered, harmless-seeming clumps quickly becomes the equivalent of a rash upon the landscape. Unlike the dandelion, lesser celandine also spreads into nature preserves. Poisonous to wildlife, it forms thick stands reminiscent of pavement. Over time, our nature preserves become less and less edible to the wildlife they were meant to support. Native diversity shifts towards non-native monoculture.

Below are some photos to help with identification, and here is a link that includes suggested means of stopping it from taking over your yard. Though the link says only to spray through early April, I'd suggest that spraying is helpful for as long as its leaves are green. Lesser celandine is a spring ephemeral, meaning that it comes up early, then dies back in June, going dormant until the next spring. Gardeners who like to dig up plants of this or that to give to friends should be aware that, if their yards have been invaded by lesser celandine, some of it may hitchhike in whatever plants they dig up later in the season to give away. They may unwittingly be giving a fellow gardener the beginnings of a major headache.

Lesser celandine is poisonous, and yet some websites declare it edible and offer recipes. Why the contradiction? Apparently, lesser celandine accumulates toxins later in the spring. The toxins break down during cooking or after drying. Still, one takes one's chances trying to eat it, and, alas, wildlife don't cook.

I've seen bees collecting pollen and nectar from the flowers, which is all fine and good, but this doesn't compensate for the inedibility of the leaves. The invasion of our lands by nonnative plants that wildlife don't eat essentially shrinks the acreage of functional habitat in Princeton, even though a great deal of open space has been preserved. Thus the need for management.

Given that some areas of Princeton have been overrun by lesser celandine, it's important to defend those areas that have not, by closely monitoring and spot spraying where the plant is just starting to move in. Invasions begin with just a few plants here and there. An absolute minimum of herbicide is needed to easily defend these areas. Lesser celandine can easily be distinguished from dandelion. Walk the grounds before the grass gets mowed in the spring and while the plant is blooming. For lawns, a product like Weed B Gone works. For other areas, a 2% solution of glyphosate does the trick. Since glyphosate can take a week to show visible effect on the plant, it's best to spray early in the spring so that there's time to see results and spray any areas missed. For those near wetlands, wetland-safe formulations of glyphosate are available, so Roundup is not the only option.

In terms of aesthetics, lesser celandine's dense, exclusionary growth does to the landscape what people badly afflicted with narcissism do to social situations. A woodland that once hosted a diversity of native wildflowers becomes, when overwhelmed by lesser celandine, one species' declaration of Me! Me! Me! 

Here's what it looks like up close.

Here's an example of the blotchy appearance an early invasion creates on a lawn. These blotches expand until the whole yard is coated.

The closest lookalike in the lawn is the violet, whose leaves are darker, more curled, and more toothed along the edges. 

What to Think of Black Vultures?

The other day, I was thinking about how much I love chipmunks, and how much my sister hates them. How do we reach opposite opinions about the same animal? Are the chipmunks that now run amok in her vegetable garden the same chipmunks I fondly remember from childhood, scampering over rocks, their cheeks puffed out with their latest gleaning of nuts? 

Vultures also tend to get mixed reviews. Some find them creepy; others laud their soaring skills and their ecological role of cleanup crew. There are two types in Princeton--the common turkey vultures and the less common black vultures that have been expanding their range to the north over time. Many people look up, see a bird soaring, and think it must be a hawk. More often it's a vulture, usually a turkey vulture, which is black with a feint streak of silver along the back of the underside of its wing. Black vultures' wings from below appear to be tipped with silver.

For years, black vultures have perched on the chimneys of the Veblen Cottage at Herrontown Woods. At first we considered them a bad omen, but then as we learned more about them we gained respect and began to appreciate their presence. The photo is by Julie Tennant, a neighbor to the preserve who has taken an interest in the birds. The vulture still has a ring of fluffy immature feathers around its neck.

Each spring a pair of black vultures raises its young in the corncrib next to the cottage. People of course want to take a peek inside to see the chicks, but we worry that loose dogs and too many visitors could ultimately scare the vultures away.

It looked like that had come to pass this summer when the vultures disappeared for awhile, but then we saw a chick out for a walk on the cottage grounds, its plumage very much in transition.

Four years ago, one of the two chicks was slow to mature, causing the family to linger far longer than usual, often perching on the chimneys of the Veblen Cottage. We were won over by the patience the parents showed as they waited for the second chick to mature.
 

It was odd, then, having learned to care about the vulture family, to encounter an article in the NY Times entitled 

"Black Vulture Attacks on Animals May Be Increasing." Ranchers out in the midwest are claiming they are losing newborn livestock to black vultures that have been moving north into new territory. 

It's not clear from the article whether the ranchers are losing healthy livestock, or if the vultures are moving in on calves that were stillborn or dying. 

We're used to thinking of animals as occupying distinct categories. Predators kill, scavengers do not. But it would be interesting to explore how much overlap there is between the two roles. I've been struck by how black vultures's bodies look more raptor-like than the bodies of turkey vultures. And there's a bird we'd see along roadsides in Patagonia called the Chimango caracara. By its appearance it looks like a hawk, and yet it more often plays the role of a scavenger.

American black vultures are also expanding their range in Patagonia, potentially competing with Andean condors for food. Articles like these could work against the trend of our feelings about black vultures, which in Herrontown Woods have evolved towards affection. For us, they are fascinating birds, wild and yet drawn to live on the edge of our world, raising their young, and perching on the roof of nearby All Saints Church. (photo by Peter Thompson)

Be On Guard for Lesser Celandine

(This post is from 2021. Click here for more recent posts about nature.)

From backyards to front yards to curbsides to parks and nature preserves, a small invasive flower is on the march. Dominating the landscape in early spring with its yellow blooms, it turns March into LOOK AT ME, ME, ME!, because that's all you will see when lesser celandine coats the ground. Just to hoodwink homeowners, the name "lesser celandine" has sometimes been supplanted by the name "fig buttercup," but it's all the same plant, whose latin name is Ficaria verna. 

My posts about the plant date back to 2007, when I heard people mistakenly calling it "marsh marigold," which it most emphatically is not. Back then, lesser celandine was most entrenched at Pettoranello Gardens and rapidly spreading downstream into Mountain Lakes. Hopefully, when Princeton hires an open space manager, a more coordinated effort can be launched to reduce the plant's spread and protect areas not yet infested. Homeowners tend to like the plant at first, then become appalled as it begins taking over the yard and spreading to the neighbors'. 

Use herbicides on lesser celandine? The nature of good and evil.

Those who care enough about their yards and the local ecology to want to stop the plant's spread may also feel qualms about using herbicides, which are the only practical means of control. Removal by digging is cumbersome, time-consuming, and adds unnecessary weight and bulk to your trash can. I encourage people to think of herbicides for nature the same way we think of medicines for people. We know all medicines have some level of toxicity, but we use them in a minimal and targeted way to protect our health. Doesn't nature deserve the same sort of intelligent intervention? It's important to make a distinction between spot spraying for lesser celandine and the blanket application of pesticides and chemical fertilizers on lawns. If treating lesser celandine that has invaded lawns, use an herbicide that is selective for broadleaf plants so that the grass survives. If there's just one plant here and there, spot spraying each plant with glyphosate, the active ingredient in Roundup, should kill the plant without harming surrounding grass. 

Update, April 2025: If you're dealing with low ground near water, there are so-called "wetland-safe" formulations of herbicide, usually obtained online. AquaNeat is an example of wetland-safe glyphosate, which needs to be diluted to 2% to spray on the leaves. A Penn State webpage recommends Aquasweep for treating lesser celandine in lawns. Though I have no experience with dealing with a lawn that has been completely taken over by lesser celandine, one option could be to have a landscaper treat the lawn with Aquasweep or similar. Any approach will require some followup, but each year will get easier. Though spraying may be more effective earlier in the spring, it should be possible to have an impact as long as the leaves remain green. Check back in a week to catch any that were missed.

While avoiding blanket condemnations of herbicides, I also like to avoid thinking of invasive species as "bad plants." Like so many of the problems that plague us, they are "too much of a good thing." Unfortunately, though it might be tempting to keep a few lesser celandines in the yard, its super aggressive behavior makes that very risky. Best to eliminate it altogether. Winter aconite, on the other hand, is a nonnative that has a flower very similar to that of lesser celandine but has not to my knowledge spread into natural areas.

Selected past posts:

2019: Fig Buttercup--Little Flower, Big Problem - Photos of fig buttercup's (lesser celandine's) spread, along with a discussion of why this invasive species creates more problems than other common invasives.

2018: A World Paved With Fig Buttercup? - Lesser celandine's other common name is fig buttercup. This post documents in photos and text the astonishing spread of this plant in the Mountain Avenue neighborhood.

2017: Winter Aconite and Fig Buttercup--Related Flowers, Contrasting Behaviors - These two early blooming yellow flowers look very similar, but behave very differently.

2016: Letter On Lesser Celandine Strikes a Nerve - a letter in the Town Topics that got quite a response

2016: Alert, Monitoring for Lesser Celandine - This post includes links to treatment options.

2015: Marsh Marigold vs. Lesser Celandine - Lesser celandine is frequently mistaken for the native marsh marigold, which is a larger plant and very, very rarely seen.

2013: Will the Real Marsh Marigold Please Stand Up--a Confusion of Yellows - Some photos help distinguish lesser celandine from marsh marigold, dandelion, and celandine poppy.

2007: Pretty, but... - My earliest post on lesser celandine.

Princeton's Fuel Tank Raingarden Wannabe

Why would a plant lover be drawn to this desolate scene of concrete and asphalt? Because there's a raingarden behind that fence, or at least a raingarden wannabe, and that means I'm seeing not what is, which is pretty drab, but what could be, which is a dynamic, jubilant planting of native wildflowers, grasses and shrubs filling that skinny raingarden squeezed between the sidewalk and the town's fuel tank. The fuel tank was for awhile serving double duty, fueling town vehicles while its appearance fueled controversy in the neighborhood. A fine rain garden planting could go a long way towards healing the discontent, in my humble, totally plant-biased opinion.

The first good news is that the fresh layer of asphalt there appears to be appropriately tilted to shed its runoff towards the raingarden. What is a raingarden, after all, if the rain that falls on the surrounding topography doesn't flow towards it?

For some reason the raingarden hasn't been planted yet, so the plants have gone ahead and started planting themselves. It's looking a little sparse thus far. Or you could say that the plants are social distancing.

Whenever I see plants trying to colonize bare dirt, I think of people who live in an emotionally impoverished situation. Back when I was in that predicament, I was drawn to places like this. Weeds trying to grow in parched ground were my friends and fellow travelers. Maybe that's why I can remember plant names when most people struggle, because the plants aren't just variations on green. They touch something deeper in me.

This late-flowering thoroughwort is a keeper--a native wildflower whose name is unlikely to flow smoothly from many tongues. It grows like a weed, and often in weedy places, like abandoned fields or roadsides, but can sometimes achieve great elegance of form when it becomes covered with plates of white flowers in late summer. It shows up early, but blooms late. Thus the name.

Here are the leaves of mugwort, which adds no color and spreads aggressively underground, taking over neglected raingardens over time. It's a force for monoculture and monotony that must be countered early and often.

Smaller scale weeds are clustered here, close to the ground, with dandelion on the lower right, a mock strawberry in the middle, and one 3-seeded mercury on the left. When I see one or two mock strawberries like this, I'm also seeing five years hence when it will have spread to coat the ground in an unattractive and inedible way. That increases the motivation to be proactive and pull it out now, before the task becomes overwhelming. This ability to imagine the future, learned in a garden, is directly translatable to global issues like climate change, where the job only becomes harder the longer one waits. 

Lots of homeowners puzzle over what to do with hundreds of oak seedlings in their yards, when everyone is telling them we need to plant more trees. Most tree species don't need help. They plant themselves, often in inconvenient places, like this raingarden.

Playing the editor, I'd say this nonnative red clover is a keeper as well, but pull the tall sweet clover at the other end of the raingarden. Sweet clover can be kind of pretty in a gangly way, but it is one of those midwestern and western weeds that appear to be expanding eastward, like teasel, Queen Anne's Lace, knapweed, and wooly mullein. Having lived in the midwest, I've seen how they can start to take over.

Leaping into the void in plants and action a couple months ago, I pushed some "live stakes" of buttonbush into the bottom of the raingarden. Despite the poor, hardened soil, they have sprouted. Here again, I'm seeing not so much the less than impressive seedling but instead the 8 foot high shrub it could become if it's allowed to get well established.

Just up Witherspoon Street, at the Princeton Recreation Dept. headquarters next to the community pool, is a demonstration of how gardens can look if there's someone knowledgeable taking care of them year after year. There's some serious tending going on here. Even the scarily aggressive variegated goutweed (whitish leaves on the left), which tends to take over gardens, is neatly contained in a discreet clump. These gardens owe their existence and beauty

to Vikki, whose job description in the Recreation Department probably has nothing to do with plants. From what I've seen over the years, it's clear that Vikki is one of the few people in town who is hard-wired to have a soft spot for public gardening, like Polly Burlingham with her hanging baskets downtown, and the various school gardeners, and like Dorothy Mullen was until she left our world earlier this year. I'd say that all it takes is love, and from that all things follow--vision, knowledge, persistence, strategic timing.

Maybe the sad, forsaken raingarden wannabe just a block away will somehow become loved ground. It's got "good bones"--sun, inputs of moisture. Good things could happen.

Opposing Views on Chipmunks

Though I can talk to someone for an hour and not notice what they are wearing, I do notice things in nature. Take this rock for instance, which was sitting unassumingly next to the sidewalk near the back entrance of the local supermarket. I noticed the rock, and then noticed that it wasn't a rock, really, but instead was made of plastic and just happened to be the size of those electronic rat traps you might see in NY alleyways. Sure enough, a closer look revealed round entry points of the appropriate size cut in the plastic.

Then a few days later, a supermarket employee was outside near the "rock", and I mentioned it to him. That was enough to get him talking about a chipmunk that lives in the bushes there. He obviously was fond of this chipmunk, showed me the hole in the ground into which he'd seen it disappear. He hoped it was smart enough to avoid the trap. "Rats may be smarter than chipmunks," I said, realizing I wasn't exactly feeding the wellsprings of hope.

He also told me that he'd seen the chipmunk duck into the store when the doors first open, snatch whatever it could find on the floor behind a counter, and then make it's escape to enjoy its gleanings back in its own private chipmunk preserve in the courtyard. It was a darling story of a cute and enterprising rodent, but might also explain the presence of the "rock."

On my next visit, I noticed pieces of bread scattered in the small plaza near the trap, too numerous to be accidental. In the photo, the bread crumbs are in the foreground, while the trap is a tiny speck across the sidewalk in the background.

The photo nicely captures the opposite views of chipmunks that can be found in my own family. Though I don't remember ever feeding them, I grew up loving chipmunks--their striped good looks, their perky manner and upbeat chirp, the comic but highly utilitarian way they'd stuff nuts into their cheeks. All through the intervening years, I have yet to be wronged by a chipmunk, and have cheered their periodic arrival in the yard--though a vulnerability to local predators may explain why they never seem to sustain a presence.

So it was a surprise to hear my sister in Cleveland describe them as the bane of her vegetable garden. Have Cleveland chipmunks gone rogue? Or might it be that her low opinion of chipmunks is due to a lack of sufficient predators to keep their numbers in check? Interesting to contemplate a predator being the guardian of a prey's reputation.

When it comes to liking or not liking, whether in nature or society, both the judge and the judged can easily get trapped. One positive trait can make people ignore all the negatives, and one negative trait can overshadow all the positives. Emotion seeks purity--a definitive judgement up or down--even as good and evil become increasingly intermixed. When it comes to chipmunks, for now I'm content to, as F. Scott Fitzgerald wrote, "hold two opposed ideas in mind at the same time and still retain the ability to function." I'll carry opposing ideas like a chipmunk carries nuts bulging in its cheeks, to be stored as future food for thought.

Are Foxes Poised for a Cyclical Decline?

Walking back towards the parking lot at Herrontown Woods the other day, I was surprised to see a fox up ahead, trotting in my direction. It turned down a side path before it reached me, seemingly unaware of my presence. The fox was showing the classic symptoms of mange, more specifically sarcoptic mange, having lost much of its fur, and you have to wonder what it's prospects are for the winter.

 
That sad, raggedly fox moving on down the trail, seemingly resigned to its fate, brought back memories of this photo sent to me years back by Christy and Brian Nann, taken at Greenway Meadows. The Mercer County Wildlife Center confirmed for me that it was a red fox stripped of fur by mange, with little chance of survival.

Typing "mange" into the search box for this blog, I was not surprised to find that the photo was taken in late 2008, roughly ten years ago.

That eleven year gap in sightings of mange may not be a matter of chance. Somewhere along the way, growing up in small town Wisconsin or reading wildlife magazines, I learned that foxes and their prey go through a ten year population cycle. There's a boom and then there's a bust.

In recent years, we've been witnessing the boom. Foxes have been flourishing in Princeton, moving up stream corridors into new urban areas. Certainly they've been making their presence known in our neighborhood. My wakeup call came two years ago, when a fox ambushed two of our last three chickens, consuming one and leaving the other stashed under a neighbor's bush for a future meal. Clearly, the local predators were upping their game. Earlier this year, during dogwalks at dusk, I would occasionally see a fox trotting confidently down the middle of the street before ducking behind a house. Late at night, I'd hear their baleful bark in our driveway. A few blocks away, a fox family had a large litter under a neighbor's porch, causing some controversy as to what if anything should be done. The most impressive sighting came last winter, when I was standing in the Herrontown Woods parking lot. Across the stream, a beautiful specimen was moving stealthily through the woods. It paused and went into a crouch, then pounced, penetrating through the few inches of snow with uncanny precision, then trotted off with a rodent in its mouth.

There's logic to the boom, and logic to the bust that may now be underway. When predators are few, rabbits and rodents increase, providing foxes with an abundant food source. Then, as the fox numbers increase, their skillful predation continues taking a toll on their food supply until the foxes find themselves with little to eat. The too numerous foxes begin to starve, and their weakening immune systems make them vulnerable to the burrowing mites that cause mange. The fox population crashes, the rabbits and rodents rebound, and the cycle begins anew. The internet is full of stories of this boom and bust, from Colorado to one out of Vermont that gives an especially detailed description of the biology behind the afflicted fox's misery. The Vermont post suggests that mange can be an isolated event, but also tells of how mange once precipitated a 95% drop in the fox population in a city in the UK.

There are lots of questions to ask. Has the boom cycle in foxes reduced Princeton's population of rats? Might it explain why there seem to be fewer squirrels around than in past years? Might predation of mice be expected to reduce the prevalence of ticks and lyme disease? Is there a ten year ebb and flow to fox raids on chicken coops?

Though rodents can survive a boom in the red fox population, less certain is the resilience of ground-nesting birds on the Jersey shore, like the endangered plover. Red foxes, it turns out, were introduced from Europe. The native gray foxes tend to stay deeper in the forest, and so the red foxes may pose a threat in more open habitat that the shorebirds have not evolved to defend themselves against.

To protect the birds, the state Division of Fish and Wildlife has been culling the red fox population along the shore. Residents outraged by the intentional killing of such beautiful animals managed to get 80,000 signatures on a petition demanding the state's trapping program end. If the petitioners were successful, however, the results might not be exactly humane. When an unfettered population of foxes ran out of endangered shorebirds and other prey to eat, it could succumb to mange--a painful and deadly condition that makes the government's trapping program look highly humane by comparison.

Of course, no enlightened fox is going to rise up and warn its brethren to have smaller litters in order to sustain adequate prey and avoid the epidemic of mange. It is humans who have that gift of foresight and sophisticated communication that can forestall calamity, and yet our special gifts are being spent not to limit our own boom and bust cycle--played out over centuries rather than decades--but to create the conditions for a bust of such global proportions that no life form will remain untouched. Whether it's CO2 or foxes, we live in an era when superficial views of nature predominate, when the misplaced sympathies of 80,000 people can be manipulated to oppose the one government action that could protect both the endangered birds and the foxes from calamity.

This is the journey of thought, back to my youth and forward to a shared future, that can spring from a chance sighting of a forlorn fox along a wooded trail.

Some useful links: 
Princeton's Animal Control officer
Mercer County Wildlife Center

From what I've read, mange in foxes poses little risk to people or pets. 

Leaves -- A Love Story

Leaves are easiest to love during their "fifteen days of fame" in the fall. But though a true love of leaves may first take hold in the fall, maybe in a particularly colorful leaf picked up by a child on the way to school, it ultimately deepens and matures to include the less showy times that leaves go through, from an obscurity of green up above to an obscurity of brown underfoot, to a slow return to the air and ground from which they came. A love of leaves is so richly rewarded, by the oxygen they give in abundance, the shade, the transpirational, transformational cooling in the summer, the remembered exhilaration of raking and leaping into leafpiles, and the fabulous pulse of surface area and food leaves give to the ground each fall to insulate and feed the life of the soil that in turn sustains all life. Such abundant gratitude they show for the ongoing gift we give without even thinking, "a breath to build a leaf on." Leaves, after all, are built to a great extent from the carbon that we and other animals exhale.

Here are some photos collected this fall:

A sweetgum tree on Princeton University campus across from McCarter Theater. Of course, you expect leaves in such a setting to be above average,

but even the wild ones can put on something of a show, as in this field of sweetgum seedlings in a field next to Snowden Lane,

and even rival the cultivateds. This photo was taken only with the intent of showing variation in size of leaves that fell near Veblen House. The car's hatchback windshield was the closest horizontal surface. Only when looking at the photo later on did I see that nature, ever the artist, was composing the photo as much as I.

This photo of a native witchhazel planted next to a house on Linden Lane led to the unceremonious end of a phone conversation, as my cellphone battery died moments later.

In Herrontown Woods, witch hazels were more the color of these backyard pawpaw leaves. Shade can mute the brilliance of color, and sometimes alter the color itself.

The leaves of mapleleaf Viburnum vary year to year and place to place along the Princeton Ridge.

Wasn't expecting a musclewood to be so colorful. This is a lovely understory tree of Princeton's forests, but my neighbor has one flourishing in her front yard, close to a busy street. (Carpinus caroliniana)

Virginia creeper hanging from a blackhaw Viburnum. Lots of sun, lots of color.

The oakleaf hydrangia and stonecrop "autumn joy" can be a fine combo, their colors slowly shifting through the fall. The stonecrop isn't native, but stays where it's planted, and gives pollinators a fine late-summer dinner plate of nectar.

And lastly, another form of autumn joy--my older daughter when she was discovering the pleasure of leaves while growing up in Durham, NC. The child within us can make that love and delight last a lifetime.

Two Snakes Embrace in a Preserved Princeton Farm Field

I recently met with DR Greenway's Cindy Taylor to discuss management of 4.5 acres of farmland preserved by Mercer County. The land is strategically located next to Veblen House and Herrontown Woods, near the corner of Snowden Lane and Herrontown Road. It seemed destined to be added to Herrontown Woods, but was not included in last year's transfer of Herrontown Woods from county to town ownership.

While walking the property we nearly stepped on a couple snakes out mating in their field. From what I've heard and read, there are venemous snakes in northern and southern New Jersey, but not here in the central region. This one, or two, look like something a botanist would call a garter snake. I hope they didn't mind too much our human curiosity.

Up until a couple years ago the land was owned by John Powell, who was manager of the Weller farm before it became Smoyer Park. Each year on his six remaining acres of pasture, John would grow a couple head of cattle, a picturesque reminder of when Jac Weller had a real farm across the road, with bulls that would occasionally escape, prompting a surprised neighbor to call the farm to report that there was a bull in the backyard.

The preserved land includes a small pond that's filled in spring with spring peepers.

The 4.5 preserved acres are as close to a clean slate as we get in Princeton. Do we keep it as pasture with mostly nonnative grasses? Or do we shift it to native prairie grasses and wet meadow wildflowers? Periodic mowing would be needed in either case. Letting it grow up in trees would reduce even further the places where shade-intolerant plant species can grow. Or can it still perform some farm-like function? I showed NOFA-NJ (Northeast Organic Farmers' Association) the site years ago, including the adjacent farmhouse, without success.

Meanwhile, we continue our travel through the 21st century. Ash trees on the neighbor's property succumb to Emerald Ash Borer,

while garter snakes know what to do with a field, even if we do not.

Fig Buttercup Alert--Little Flower, Big Problem

Yes, spring can be lovely, with some cheery displays of daffodils, and magnolia trees in their glory. But it's also an all too good time of year to witness with dismay and alarm the ongoing and accelerating invasion of the Princeton area by fig buttercup. Also known as lesser celandine, it's a small spring ephemeral that seduces with its pretty flower, then takes over your yard and garden.

It has already radically changed the spring landscape over in the Pettoranello Gardens and Mountain Avenue area, and I've watched it spreading from yard to yard over the past five years in my neighborhood near Hamilton Ave and Harrison Street.

These photos are from Maple Street just down from Nassau Street, where a still localized infestation is radiating out from one of the yards. A yard will have one or two plants the first year, dozens the next, quickly multiplying to hundreds and thousands. It's pretty easy to see whose yard was first by the density and extent of the invasion.

Across the street, the fig buttercup is taking over the lawn and flower beds.

The next door neighbor has an invasion in its earlier stages.

Why be concerned? There are many degrees and styles of invasiveness. I'll compare fig buttercup with other aggressive plants below, but here are the essentials: Fig buttercup is an introduced species that has escaped any limiting factors that may have been present where it evolved. It's poisonous, so nothing eats it. The seeds and the abundant underground tubers allow it to spread rapidly. It can grow in the sun or shade, garden or nature preserve.

Some gardeners may feel relief that, like other spring ephemerals, it will fade back into the ground after a couple months. But that seems small consolation as it increasingly displaces other plants that might otherwise grow.

By comparison, myrtle is a groundcover that people plant and may later regret as it takes over flower beds. But it doesn't spread down the street to ultimately pave the local watershed. It merely vexes the gardener who planted it.

By the same token, wisteria vine poses a much smaller threat than porcelainberry. Though an abandoned wisteria vine can spread over an acre or more, weakening trees and suppressing all other growth, it doesn't spread by seed, so remains localized. Porcelainberry is a vine that not only smothers all other vegetation, including trees, but also spreads to new locales by seed.

Most pesky weeds of the lawn--wild garlic, dandelion, false strawberry, ground ivy, etc--have not become problems in nature preserves because they are either edible to wildlife or intolerant of shade.

That's what makes invasives like fig buttercup and stiltgrass stand out as major threats. They spread rapidly, tolerate shade and a variety of soils, and nothing eats them. Since fig buttercup dominates in spring, and stiltgrass dominates in summer and fall, they represent a one-two punch that dominates the landscape visually, and leaves little chance for other herbaceous species to prosper. Since both are not eaten, yards and preserves become increasingly inedible for wildlife.

Fig buttercup can be confused with winter aconite, which also blooms early with a similar flower, but the leaves are much different. Though nonnative, I've never seen winter aconite spread beyond the limits of a yard.

This photo shows the native marsh marigold in the foreground, with leaves much larger than fig buttercup's, which is in the background. (For a closeup comparison of the two species, click on this link.) The marsh marigold, by the way, is very rare. I've seen it only a couple times in the wild. I planted the one in the photo, over at Pettoranello Gardens, purchased from Pinelands Nursery many years ago.

Click here for past posts about fig buttercup (lesser celandine), including a letter I wrote to the Town Topics two years ago that struck a nerve.

What to do? If there are just a few plants, you can dig them up and put them in the trash (not the compost), being careful not to leave any small underground tubers behind. But though I've had organic sympathies all my life, and don't like to use herbicides, the easiest way is to use a squirt of 2% glyphosate on the leaves (Roundup is the most common brand, but more generic forms are available), or else some herbicide more specific to broadleaf plants. We take medicines, and when used responsibly in a targeted manner, herbicide can play a similar role in nature.

Environmentalism has been too caught up in good vs. bad, when the biggest threat to nature and ultimately ourselves, whether it be carbon dioxide or a pretty little flower, is too much of a good thing.