Update on Dam Restoration at Mountain Lakes

I haven't heard anything official, but it looks like the lower dam at Mountain Lakes Preserve is nearly complete. The wooden posts in the foreground mark where a ramp once was located for hauling chunks of ice out of the pond and hoisting them into the 3-story ice barns that used to rise behind the dam to the right.

The ice operation closed down around 1930, as refrigerators became more widely available. The stone wall extending the length of the dam is completely new, designed to mimic the original wall that now lies buried under the expanded earthen portion of the dam. For safety reasons, the dam is now broader and several feet higher than previously.

At the other end of the dam stands the newly restored spillway. As far as I know, the informative signs that were there prior to restoration will be reinstalled, describing the decades during which Mountain Lakes supplied Princeton with ice for its iceboxes.

Meanwhile, upstream of the two Mountain Lakes is another dam that was added onto the project, funded by the same anonymous donor. I had long argued in favor of restoring this "upper settling pond", also known as North Pond--an argument that was going nowhere until funding became available. It's located on one of the two tributaries feeding the lakes, and was built in the 1950s by the Clarks, who also built Mountain Lakes House around the same time.

The pond is called a catchment basin for good reason. Water rushing downstream from Witherspoon Woods drops its sediment in this pond, thereby greatly reducing the amount of sediment that would otherwise have continued into the Mountain Lakes. It played this role very effectively, completely filling up over the past 50 years. There must be 8 feet of very rich sediment here, which this week is being trucked away, perhaps to a topsoil business.

With the catchment basin trapping sediment, at least on that one tributary, the upper Mountain Lake will last much longer before it once again will require dredging.

This is my favorite vista, standing at the northwest, upstream end of the lakes, looking down.

Invasive Plant Threatens Albatrosses

Strange how learning happens. Here's an unlikely string of events: 28,800 rubber duckies are lost overboard in the northern Pacific in 1992. A high school english teacher named Donovan Hohn eventually hears word of this and leaves his job to find out where the drifting duckies drifted to. He writes a book called Moby-Duck and travels to Princeton to make a presentation at the public library's 2011 Princeton Environmental Film Festival.

One of the images he showed is of a baby albatross that died, apparently due to a stomach full of the notorious plastic bits that currents concentrate in that part of the Pacific. But he explains afterward that the photo of the 200+ bits of plastic in the albatross's gut tells only part of the story. Also making life difficult for the albatross is global warming, which he says is making its nesting grounds too warm, and an exotic plant called Golden Crownbeard.

Native to the U.S., Golden Crownbeard is, according to my internet research, the most invasive of hundreds of exotic plants on the Midway Islands. Chances are, it hitchhiked to the islands in topsoil--a notorious means by which plants travel to new locales. The plant displaces low-growing native vegetation, making tall dense stands unsuitable for building nests, sometimes growing so fast that the adult birds lose track of their young. Managers of the refuge are hoping to eradicate the plant from the islands.

A rubber ducky spill in the north Pacific, then, ended up bringing to Princeton a very familiar story of the impact of plant invasions on native wildlife, and the human efforts going on around the world to restore ecological balance.

Woodpile Slumber Party

Sometimes, bringing firewood in can get complicated. Nature has taken what was intended as a simple backyard woodpile and turned it into sleeping quarters and storage barn. This wooly bear caterpillar, having a fine winter's snooze amongst the squirrels' stored acorns, must not have been pleased when I inadvertently liberated its roof to heat our home. Hopefully it liked the alternative accommodations I hastily prepared for it.

The next log removed exposed this tent village of spiders. They too were relocated, log and all, so as not to suffer any further disturbance to their slumbers.

Woodpiles are the highrise apartments of backyard habitat, packed with nooks and crannies to serve a diverse clientele. Looks like the best compromise is to have more woodpiles than one will use in a given winter, so that at least some of the backyard residents will have their sleeping quarters left undisturbed.

Owl Programming Tonight at Howell History Farm

Very interesting program tonight from 7:30-9pm, for kids and adults, about wildlife that help farmers. Led by the county naturalist. Great description here.

Note: I got reports that this event was magical. A schedule of Howell History Farm programming, some of which is led by Mercer County naturalist, Jenn Rogers, can be found  here. 

Raingarden Installed at Mountain Lakes House

 One project I was able to get implemented at Mountain Lakes House in Princeton is the construction of a raingarden. I designed and located it so that it would capture runoff from the lawn, driveway and a portion of the roof. Township staff did the contouring, and planting was done by Polly Burlingham of Sigmund Garden fame, financed by a private donor.

It was particularly important to redirect runoff from the driveway down this contoured swale to the raingarden. Before, water flowed towards the foundation, which led to flooding in the basement.

Now, the runoff will have a positive effect, helping to keep the raingarden wet. A typical raingarden is designed to collect about 6 inches of water, which then infiltrates into the soil over a day or two, creating an underground reservoir of water that the wildflowers, sedges and shrubs can tap into during droughts.

Since it was installed last fall, it's still awaiting its first growing season. Plants have been labeled (cardinal flower, joe-pye-weed, winterberry, buttonbush, etc). You can reach this site by parking at the Community Park North parking lot off of Mountain Ave at 206, and walking down the long driveway through the woods to Mountain Lakes House. In the distance in the photo is the recently restored upper Mountain Lake.

Integrating Leaves Into the Landscape

There, can't you see it, the massive pile of leaves? One of my cause celebres, in case it wasn't obvious from all the previous leaf-related posts, is to get people to keep their leaves in their yards. Nutrients, reduced runoff, habitat, less dependence on municipal services--what's not to like? Obviously something, since so many people dump their leaves in the street regardless of yard size.

This residence, located out towards Terhune Orchards at the intersection with Cold Soil Road, shows how leaves can easily be integrated into a neatly maintained yard.

Rather than blow the leaves out to where they'll be a hazard next to the road, the owners have a nice cluster of trees halfway between road and house where they pile the leaves. Despite the adding of leaves to the same pile year after year, the pile won't get very high due to decomposition and raiding of nutrients by the tree roots. And anytime the owners want rich compost for the garden, they need only dig into the interior of this pile to find it waiting.

Princeton University Stream Restoration--Part 2

Down in the valley, between Faculty Drive and Carnegie Lake, near Washington Road, the geese graze peacefully in the meadow, like a flock of pygmy long-neck dinosaurs.

Just across Faculty Drive, a new landscape has been hewn out of what I vaguely remember being a dense patch of scrub near the road. Not sure what the solar panel's for, but it's a nice modern touch.

This is the bottom reach added to the stream restoration since a previous post. The relatively steep slope allows a nice series of "cross-vein" structures (boulders assembled into the shape of a "v" pointed upstream, designed to focus flow inwards towards the center of the channel.) In the background, through the woods, are Jadwin Gym on the right and the new chemistry building back to the left.

On either side of the narrow channel are floodplains designed to allow floodwaters to spread out, slow down and thereby dissipate their energy, as would happen in a natural stream. Less energy means less erosion, which means less sediment flowing into Lake Carnegie, which in turn theoretically means the lake needs to be dredged less often.

Urban streams tend to get badly eroded over the years by the powerful blasts of flashy runoff coming from hardened surfaces in town. A stream restoration such as this attempts to mend the stream, designing in the right amount of meander, floodplain and well-placed rock formations so that it will resist deformation by the erosive force of all that heavy water coming down the hill.

Assisting in this goal to some extent are some absorbent green roofs and rain gardens installed in new buildings upstream. The tree trunks scattered in the floodplain probably play some role in slowing or redirecting floodwater.

The sewer (or maybe water) line looks like it will have a bridge mounted on it, so that athletes can cut through the woods to get to the playing fields.

Looking back down the slope towards Faculty Drive, with geese and Carnegie Lake in the distance. The matting spread over the floodplain should prevent erosion of the freshly contoured soil until grass seed can sprout through it.

FOPOS Trails Committee Receives Award

If you've noticed that many of Princeton's open space trails have markedly improved in recent years, you can largely thank the remarkable efforts of the Friends of Princeton Open Space trails committee. Many a muddy stretch has been made passable with stepping stones and boardwalks, and many a mile has been cleared of wayward growth and fallen trees.

Last Wednesday, at a ceremony hosted by the Princeton Public Library, the volunteer group received a Leadership Award from Sustainable Princeton for their work. Left to right are Tim Patrick-Miller, Eric Tazelaar, Andrew Thornton, Clark Lennon and fearless leader, Ted Thomas.

 

Eric described the many locations where weekend workdays have made a difference.

Among other award recipients was another trail-related group, the Princeton Joint Pedestrian and Bicycle Advisory Committee, led by Janet Heroux, partly in recognition of their "sharrows" initiative.

Sunrise Over Chores Undone

A couple early mornings ago, I noticed that the white translucent window shade had turned pink. Could this mean there was an inspirational sunrise-over-suburbia going on? I grabbed my camera and dashed outside in time to capture this ode to backyard neglect with the working title "Sunrise Over A Pile of Woodchips I Haven't Gotten Around To Spreading Yet." Note that reality is nicely framed by the optimistic words "Sunrise" and "Yet".

Hummingbird Notes

The Princeton Environmental Film Festival is concentrated this year into three 4-day weekends, of which this is the first. Saturday afternoon included a showing of "Hummingbirds: Magic in the Air", which uses cameras with 500 frames per second to show their singular hovering skills in slow motion. After the movie came a fascinating lecture by Charles Leck, a retired Rutgers professor. Here are some notes:

• New Jersey's Ruby-Throated hummingbirds enter NJ each spring at the southern tip, returning from winter habitat in Central America. They migrate across the Gulf, flying about 8 feet above the water at 50 mph. Charles described sitting on the beach at the right time of year, watching as they'd come flying in off the ocean at the rate of about one every couple minutes. 
• For the 500 mile non-stop flight across the water, they first build up their body weight, then may lose a third of it during the flight. They store nectar in their bodies as a fat that, when metabolized for energy, becomes water that in turn keeps them sufficiently hydrated during the flight.
• During the day they maintain a body temperature around 105 degrees. Any higher and proteins would start to denature. At night, they ramp their supercharged metabolism down to 55 degrees. (The movie shows this transformation by using infrared cameras that register heat as read and coolness as blue.)
• Charles mentioned the marsh at Rogers Refuge in Princeton as the best place to see the male hummingbird mating flight, on May 7 or 8. Stop by on those dates and there will likely be other birders to show you where to look.
• Since hummingbirds cannot live on nectar alone, they have to catch insects with their skinny beaks to get protein.  Sometimes it's easier for them to rob spider webs.
• The Lecks often lead walks sponsored by Washington Crossing Audubon or the Trenton Marsh.

There's much more information at hummingbirds.net.

The Second Snow

Snow finally arrived last night, having been loathe to return ever since its much criticized, heavy footed miscue back in October. My daughter, deciding the snow was insufficient for sledding, chose instead to send her little people on an exhilarating slide off the rooftop, aided by a broom handle.

Later on, some paddleboating in snow? What were they thinking? At least it got them outdoors.

This seemed much more sensible--some restful cloudbathing after their brief but exciting sledding venture, and a bit of stretching. Many a time have I thought there should be a designated "Conspicuous Stretching Zone" in the park, where parents wishing to spend their time more productively could feel permitted to assume various self-improving poses, free of any sense of awkwardness.

I didn't see how this contraption fit into the narrative. There was no enemy castle in sight, into which to hurl plague-infested pigs. Perhaps they thought it would be a good way to get back to the second floor.

As the day's light faded, a couple hardy northerners, dreaming of winters past, looked longingly out across the lake, wondering when the ice will be thick enough to skate on.

Nature Stereotype Listing Badly

In part to lure an audience, television tends to emphasize the violent side of nature. Preferential exposure is given to storms, wildfires and animals with big teeth. When nature is consistently portrayed as an adversary, people may forget that its primary role is as an ally, and that it's up to us whether we want to work with its forces or against them.

The latest contribution to the stereotype of nature as adversary is an ad seen last week immediately following the Miss America contest. We had finally strayed from Ingrid Bergman's improbable romance with Anthony Perkins in "Goodbye, Again" just in time to see Miss Wisconsin crowned the new Miss America, which closed with an ad for Carnival Cruises. They've launched a new ad campaign that compares land-based and sea-based vacations.

In the ad, a couple gazing serenely out at the ocean, drinks in hand, flash back to last year's camping vacation, when they were trapped in a car out in the woods by an enormous grizzly bear and mountain lion, pawing at the car, trying to get at the occupants. "Never again.", the woman says. Obviously, it's best to avoid the dangers of nature in favor of a safe, clean vacation on a massive cruise ship.

The ad segued immediately, improbably, into ABC evening news' lead story about the cruise ship that ran aground off the coast of Italy. Eleven found dead thus far, at least 24 missing. The ship is owned by a subsidiary of Carnival Corporation. April 15 will be the 100th anniversary of the Titanic's demise. Not a great time to be touting cruises as safer than a camping trip.

Backyard Bird Numbers Down?

I'm hearing reports from friends that their backyard birdfeeders are not needing as frequent refills as in past years, meaning there are fewer birds around. Though we don't have a birdfeeder, I noticed a flurry of bird activity in the backyard in early to mid-December, with mixed groups of birds visiting and then moving on, but have seen almost none since then.

This from Bill Sachs of Princeton:

In winters past, we have had to replenish the seed in our backyard birdfeeder at least twice a week.  This winter, the birds seem  noticeable by their absence and the interval between needed refills has exceeded two weeks!  Oh, we have birds visiting the feeder from time-to-time, especially mourning doves and blue jays, but visits by chickadees, titmice, nuthatches and wood peckers seem much reduced.  I am curious because there was a review article in a recent edition of Science magazine on “Globalization, Land Use, and the Invasion of West Nile Virus” (A. M. Kilpatrick, Science, 334: 323-327) in which the author writes,

“The impacts of WNV on wildlife have been yet more severe than those on humans.  Millions of birds have died from WNV infection, and regional-scale population declines of >50% have been observed for several species (11).  The range of taxa that have suffered declines is surprisingly large and includes corvids, chickadees and titmice, wrens, and thrushes (Fig. 1) and probably others.  Some populations have recovered after initial declines, whereas others have not.”

And this from an avid birder in town:

We too have had fewer birds at our feeder. Don't know why. Maybe mild weather, more berries, more insects? We've had a lot of Red-Tailed Hawks in the neighborhood, too. Declines of migratory birds, e.g., thrushes, have been occurring over a few decades, and that's due to multiple factors, including loss of winter habitat in the tropics. Among the year-round residents, or short distance migrants, disease could be a factor. Blue Jays were victims a while back, but seem to have recovered. House Finches, on the other hand, were decimated by disease a few years ago and have not come back.


Note: Ran into Henry Horn, professor emeritus at the PU Dept. of Ecology and Evolutionary Biology, who agrees that birds are very scarce. Closer to usual numbers are bluejays, crows and Carolina wrens. 


Note #2: Data from the Princeton Christmas Bird Count, and also from the national Cornell Backyard Feeder Watch, will be available soon. I'll post that when it comes in.

Puerto Rico and Princeton--Parallels in a Rainforest

Even in a tropical rainforest, witnessed during a hike up El Yunque, it's possible to find parallels to Princeton's nature. El Yunque rises into the clouds 40 minutes southeast of San Juan, its slopes populated by a mix of palms and hardwoods. The Puerto Rican coqui frogs sing "ko-kee" along the path to the top.

With only the diminutive ferns of temperate forests as a reference, one has to get used to the concept of looking upward at a 30 foot high tree fern reaching into the clouds.

As in Princeton, nettles are found near streams,

Since jewel weed (Impatiens capensis) is a frequent companion of nettle in Princeton's floodplains, it wasn't surprising to find an Impatiens species growing along the trails in a Puerto Rican rainforest,

doing a good imitation of the Impatiens planted as annuals in northern gardens.

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The Impatiens in El Yunque have the same spring-loaded mechanism for distributing seeds as our jewelweed.

The mountain, with its opulent vegetation providing abundant surface area for water to cling to, acts like a sponge to capture rainfall and slowly release it into the surrounding lands below. Though it was recommended to take rain gear, we found that weather changed constantly during the day. If a light rain started, we needed only wait five minutes for some other weather to come along. I speculated, purely for the sake of speculation, that such mild, free-flowing, constantly transitioning weather would influence people to hold less tightly to moods.

It was a surprise, in such an exotic world, to find information about two familiar birds. This sign tells of spectacular mating flights to be seen above the rainforest cainopy by redtailed and broadwinged hawks.

When I travel to other parts of America, I look for parallels to two species shot to extinction in the early 1900s in North America--the Carolina parakeet and the passenger pigeon. Puerto Rico's one remaining native parrot, which may share little relation to the Carolina parakeet other than family and color, still survives in small numbers in El Yunque National Forest.

Puerto Rico: Stalking the Elusive Baby Pigeon

While visiting Old San Juan, the question may come up: What to do while the next generation is feeding pigeons in the park? Break into a rendition of Mary Poppins' Feed the Birds in espanol?

Or take a photo of a hibiscus tree,

or a colorful caterpillar feasting on a favored plant?

Finally, my mission of the moment came into focus. I remembered a segment from a radio program years back called "Ask Dr. Science (He Knows More Than You Do!)", in which Dr. Science explained why we never see baby pigeons. I forget what the answer was--something about the species' deeply engrained embarrassment over the appearance of its young. This wall of nests seemed the perfect opportunity to finally get a glimpse. Yet even here, the babies were kept so well hidden that the enigma remains, at least until you google "baby pigeons" and click on images.

Puerto Rico: Skinless Trees and People

On the way to the historic fort El Morro, in Old San Juan, we encountered something that looked less like a tree than a sculpture built of rebar.

This branch is reminiscent of a man's arm without the skin, or an exagerated version of one of Princeton's musclewood trees (Carpinus caroliniana).

This sort of growth is common in more tropical climes, particularly among species of fig (Ficus). If you google images for strangler fig, you'll see all sorts of extravagant examples.

As explained in a Wikipedia entry, a strangler fig can actually begin its life above ground, sprouting on the limb of another tree, then extend its roots down towards the ground while also sending branches and trunk upward. Over time, the original tree dies off and the strangler fig completely usurps the space.

Some of our invasive vine species in New Jersey, such as English ivy, can weaken their host tree, but they don't develop the sturdy infrastructure to continue to stand if the original tree dies.

By chance, there was an exhibition called Body Worlds just down the street in San Juan,

featuring skinless renderings of people. As a friend once said after seeing pictures of her vocal cords, there's a good reason why people have skin.

And at a local museum, a similarly fibrous merging of tree and human. It's tempting to think the painting was inspired by the local strangler figs.

Puerto Rico and Princeton--Buttress Roots

One of the pleasures of an acquaintance with plants is being able to see similarities and differences in distant plant worlds. Some of our potted plants, such as the pothos vine and various kinds of fig trees that show little ambition while standing neglected in a dimly lit corner, grow to enormous size outdoors in tropical climes.

The roots of fig trees can be as impressive as their canopies.

Here's one, growing next to dormitories at the University of Puerto Rico, that brings back memories of flying buttresses on European cathedrals.

If this tree were to ever blow over, which is looking very unlikely, it would take the wall with it.

Princeton offers a few examples of root buttressing. This white oak grows on a lower slope of the Princeton Ridge, in Herrontown Woods, where the soil is often wet for long periods.