Living in the Fall Zone

by Rosemary Jann

Although we may not be aware of it, we live in a region of borderlands. Of course, our area is politically shaped by the explicit borders of the District, Maryland, and Virginia. But the diversity of our plant and animal life derives in part from the fact that the southern limit for many northern species overlaps here with the northern limit for many southern species [https://www.dcr.virginia.gov/natural-heritage/natural-communities/document/ncoverviewphys-veg.pdf, p.23]. We also straddle a third significant geographic borderland, which is responsible for some of the most dramatic features of our region, like the Great Falls of the Potomac depicted below.

Photo of Great Falls
Great Falls of the Potomac, photo from Inspired Vision blogspot, https://ceceliafutch.wordpress.com/2011/06/29/the-magnificent-and-mighty-great-falls-of-the-potomac/.

This border is known as the Atlantic Seaboard Fall Line, formed by the points on eastward-flowing rivers at which navigation becomes impossible because of rapids and waterfalls. This line runs down the mid-Atlantic, as seen in the diagram below, and has shaped the development of this area since its earliest history. The barriers to upstream navigation hindered inland migration by Europeans and spawned cities to their east to facilitate the transfer of goods and people: Georgetown and Alexandria in our area, but also Fredericksburg, Richmond, and Petersburg. Today, Interstate 95 roughly parallels the Fall Line in the mid-Atlantic region.

Image of a map showing the fall lie across North Carolina, Virginia, Matlyand, Delaware, and New Jersey
Diagram of Fall Line, United States Geological Survey, https://pubs.usgs.gov/pp/pp1404-C/pdf/pp_1404-c.pdf, Fig 1, p. C2.

The Fall Line forms along the border between two physiographic provinces that meet in our area. A physiographic province is a geographic region with distinctive soils, topography, and vegetation. The Piedmont province is underlain by hard, crystalline bedrock. In the Coastal Plain, bedrock is deeply covered by softer sedimentary soils. As rivers flowing to the Atlantic over resistant bedrock meet the Coastal Plain, they begin to move more quickly and to cut down through those softer soils, creating waterfalls and rapids as the river descends to sea level [http://www.virginiaplaces.org/regions/fallshape.html]. 

The Great Falls of the Potomac, where the river drops 77 feet in less than a mile [https://www.nps.gov/grfa/learn/nature/naturalfeaturesandecosystems.htm], is the Fall Line’s most dramatic local manifestation. However, the rapids that originally blocked upstream navigation for European immigrants are actually located at Little Falls, slightly north of the Chain Bridge [https://en.wikipedia.org/wiki/Little_Falls_(Potomac_River)]. Over time, the energy of the Potomac has continued to erode the bedrock it flows over, causing the more dramatic waterfalls to migrate westward over millions of years, leaving Great Falls today approximately 14 miles upstream from Washington, DC.

That fact helps underscore the point that it is more accurate to talk about a Fall Zone than a Fall Line. Rather than a knife-edge transition from bedrock to sedimentary soils, the harder rocks of the Piedmont intrude into the Coastal Plain in irregular outcroppings over an area approximately 10 miles wide, creating a ragged boundary with patches of bedrock upthrust into Coastal Plain soils. We can witness this irregular border at Theodore Roosevelt Island, described by the National Park Service as the last bedrock island in the Potomac as it flows eastward to the Chesapeake Bay:  “The island thus marks the Fall Line with bedrock exposures on the northern shoreline (Piedmont) and swamp and tidal marshes on the southern shoreline (Atlantic Coastal Plain)” [http://npshistory.com/publications/gwmp/nrr-2009-128.pdf, p. 14]. Both are illustrated in the photographs below.

When we add the plant diversity that we gain from having vegetation characteristic of both these physiographic provinces in our area, we can fully appreciate the richness of our Fall Zone borderland: it offers a living map to our geological history, serves as a reminder of how our cultural history has been shaped by natural forces, and helps enrich the biodiversity we enjoy as residents of northern Virginia. 

ARMN: Blog Getting to Know Beth Kiser

By Alison Sheahan

I’d be hard-pressed to think of a more terrific way to spend a wintry afternoon than my (pre-pandemic) tea (& goodies!) at Silver Diner with Beth Kiser early this year. I knew of Beth from her efforts to organize the Park Stewards program (Adopt-a-Park leaders who oversee volunteer stewardship work in Arlington, Alexandria, and Falls Church parks and engage with neighboring park communities). But I was pleased to find we had many other overlapping priorities and friendships. I enjoyed getting to know Beth and I’m sure you will too. We began by talking about the more distant past….

Photo of volunteer Kellie Kaye
Hiking at Seneca Rocks WV 2010. Photo courtesy of Kellie Kaye.

Tell us something about your life experience that has shaped your perspective on nature.

I grew up in western North Carolina and spent a ton of time outdoors. My toy Fisher Price people had campfires and root cellars and cooked roasts over a spit. I remember the thrill of uncovering toads and snakes, eating chinquapins, and finding “touch-me-nots” (Impatiens capensis) with my granddad, with the seeds exploding in all directions. I remember hiking with my dad in hemlock forests and drinking icy cold spring water and breathing in the earthy smell of the woods. 

Conservation and restoration always felt to me like a totally normal and practical thing to do. I learned how non-native invasive plants can take over when I first saw kudzu swallowing the hillsides of the Blue Ridge Parkway. When I lived in Wisconsin in the 1990s, I was able to volunteer with a prairie burn. A lightbulb moment was reading Doug Tallamy’s book, Bringing Nature Home, about native plants, the insects that co-evolved to eat them, and the birds that eat only insects. I now feel like anytime I plant anything in our yard, it’s a fun opportunity to build our local ecosystem while getting to watch it up close. (And I love to grow and share native plants!)

Tell us something more about your background.

I work as an economist learning how risks can move through the financial system. I think my experiences in nature and through ARMN have brought me insights in economics, and vice versa. Economics and ecology are both about complex, interconnected systems. 

What are your favorite ARMN volunteer projects? 

Oh gosh, there are so many. I’ve had the opportunity to sample several over time. I love the annual “City Nature Challenge,” the bioblitz event where people in cities around the world collect and upload nature data that can be used for scientific research. It’s a great way to discover and record the cool critters and plants in our area. I’ve also enjoyed stream monitoring, especially getting in the water and turning over rocks to see what’s there. Through the Roving Naturalist program, I was able to take a live snake to the Arlington County Fair to share with the public. It’s so nice to meet people in our wonderfully diverse area and find out what they find exciting (or even scary!) about nature. 

Photo of volunteer Beth Kiser showing a corn snake
Sharing a corn snake at Arlington County Fair in 2016. Photo courtesy of Toni Genberg.

My favorite ARMN project today is the Park Stewards Program. Phil Klingelhofer and I started setting it up in 2017 and it’s really grown, thanks to all the volunteer leaders who’ve shared their amazing skills, knowledge, and hard work, and the natural resources and park managers in our area jurisdictions who’ve offered training and coordination. This work feels really important because it’s something we can actually do locally. Protecting the natural areas in our parks helps take carbon out of the air, prevents stormwater damage, and cools the “urban heat island.” It lets us see migrating birds in the spring and fall and fireflies in the summer. And it helps people connect with nature. 

What has surprised you most about ARMN?

I’m always struck by the incredible range of expertise and leadership skills of people in this community, and the perseverance and hope that ARMN folks bring to their volunteer work.

What do you like most about ARMN? 

I love the opportunity to be outside in nature while working with such kind and thoughtful volunteers. It took me awhile to connect with people after the initial ARMN basic training classes, but once I got into some regular projects, I was all in. 

Tell us something unusual about yourself.

Hmm…Target shooting?  In my early teens I participated with my dad in target shooting competitions using reproduction muzzle-loading rifles. 

Thank you, Beth, for your passion, humor, humility, and wonderful outreach for our precious planet.

Photo of Beth Kiser sitting on a rock in water
Birding in Dyke Marsh in 2018. Photo courtesy of Paul Smith.

Roaming Charges: The Environmental Costs of Outdoor Cats

by Rosemary Jann

Photo of a cat eating a bird
Photo by Gaëtan Priour, courtesy of American Bird Conservancy

Domesticated cats have lived in human communities for so long that they may seem like an integral part of our natural landscape. However, cats are non-native animals that can pose a significant threat to native wildlife, in the process undermining biodiversity and disrupting the balance of our natural environment.  At least in the case of owned cats, there are things owners can do to help right this balance.

Anyone who has watched a cat stalk and pounce on a toy mouse can appreciate how the quick reflexes, sharp teeth, and retractable claws of domestic cats have superbly adapted them to be hunters of small prey. These same hunting abilities played a crucial role in their domestication. According to National Geographic, cats began to frequent human communities in the Fertile Crescent area of the Middle East at least 8,000 years ago, as the development of agriculture resulted in the storage of crops that attracted rodents, and the rodents in turn attracted local wildcats. For thousands of years, cats and farmers enjoyed a mutually beneficial relationship as tamer cats in essence selected themselves for living in proximity to humans. The European domestic cat (Felis catus) was imported into the New World by mariners and colonists, leading eventually to a population explosion of domestic cats in the United States. In 2017, Statistica.com estimated that 94 million cats lived in U.S. homes. National Geographic adds that an additional 70 million feral cats may live in our communities. All these “domestic” cats are actually non-native imports that did not evolve with our local wildlife.

And therein lies the root of an environmental dilemma. Although other factors like habitat loss, pollution, and disease also endanger animals, cats play a significant role in wildlife mortality.  A 2013 review of research by biologists Scott Loss, Tom Will, and Peter Marra estimated that free-roaming cats annually kill between 1.3 and 4 billion birds and between 6.3 and 22.3 billion mammals in the United States alone, making them the largest single source of anthropogenic mortality for those animals. In addition, cats kill numerous insects, reptiles, and amphibians. Exact numbers are difficult to pin down, especially given the challenges of conducting research on feral cats, who cause the highest wildlife mortality. But even the low range represents a significant problem.

In Cat Wars (2016), Marra and Chris Santella show that cat predation has pitted proponents of native wildlife against proponents of feline welfare for over a hundred years. Today, the sharpest controversies involve Trap Neuter and Return (TNR) programs, which vaccinate and neuter feral cats and return them to the community, often in colonies supported with food and shelter. In Cats and Conservationists: The Debate about Who Owns the Outdoors (2020), Anna Peterson and Dara Wald hold out hope for finding common ground in debates over TNR, but they mostly document a deeply-entrenched standoff in which the various sides cannot even agree on what counts as scientific evidence, much less how to act upon it.

There is more clarity in what can be done about the cats that people own. Some cat owners believe that roaming and predation are natural behaviors that should be tolerated, and in a limited sense they are correct. As explained by International Cat Care, , because cats are obligate carnivores who must rely on animal protein, they have been naturally selected for effective hunting abilities. However, because small cats evolved as largely solitary hunters who never knew where their next meal might come from or how difficult it might be to capture, it made sense for them to kill whenever they had the opportunity. This means that their descendants, our domestic cats, are also hard-wired to hunt and kill regardless of whether they are hungry or not. A study in ScienceDirect  that tracked owned cats suggests that as much as 70% of what they kill is not even consumed. So, keeping a house cat well fed is no guarantee that it won’t hunt and kill smaller creatures.

And even when they don’t kill, Marra and Santella (61-62) explain that the mere presence of cats in a landscape can have indirect, sublethal effects, for instance, by reducing breeding fecundity in birds who are frightened into spending less time on the nest and hunting for food for their chicks. Even animals that escape from cats often die from bacteria in their puncture wounds, as noted by Alonso Abugattas  in his Capital Naturalist blog. Smithsonian Magazine adds that outdoor cats can also spread diseases to humans like rabies, plague, and a parasite called Toxoplasma gondii.  

Moreover, it can be argued that the position of domesticated cats in the environment is anything but “natural.” Scientists like Loss and Marra consider house cats (and supported ferals) to be “subsidized predators.” Because people give them food, shelter, medical care, and other support, they have distinct advantages over native predators and can reduce the amount of prey available to them. Cats are generalists who can switch prey more easily than can some native predators. Alonso Abugattas points out that unlike native predators, cats have the leisure to stake out and ambush the same areas (like chipmunk trails or bird feeders) repeatedly. Game camera footage of a cat carrying a dead squirrel in Barcroft Park suggests the toll that free-roaming cats can take on public lands.

Game camera footage courtesy of Alonso Abugattas.

In a natural environment, the size of the predator population would be controlled by the amount of available prey. However, subsidized cat populations can readily exceed the size that a habitat can support without experiencing environmental degradation. As conservationist Paul Noelder puts it, letting cats outdoors “is like letting semis drive in the bike lane. It’s a killer[.]”

The debate over outdoor cats is sometimes framed as a concern for protecting biodiversity versus defending the needs and rights of cats. But there is also a third consideration: free-roaming cats can be vulnerable to many threats, as this poster suggests:

Me.me https://me.me/i/what-an-indoor-only-cat-misses-being-hit-by-a-3285167

Webmd estimates that on average, indoor cats can live as much as three times longer than free-roaming cats. Owned cats can find the enrichment they need indoors if their owners stimulate the cat’s natural predatory behaviors.  Cat Friendly Homesoffers useful guidelines on choosing toys that mimic a cat’s preferred prey and recommends allowing the cat to capture the toy at the end of the game to satisfy its hunting instincts. Bird videos, window perches, and food hidden in puzzle balls can provide mental stimulation for an indoor cat. The American Bird Conservancy’s “Cats Indoors” site lists safe outdoor access products for cats. These include cat harnesses and backpacks and  enclosures like the “Catio” and cat-proof fencing like the Purrfect Fence that provide outdoor spaces where cats and wildlife can be safe.

Owned cats are not the sole driver of wildlife reduction, but they are one significant factor that can be controlled, starting with the recognition that cat predation is more of a human problem than a feline one. Revoking our cats’ roaming privileges can be a crucial step in protecting biodiversity in our natural world.

Birds of A Feather: The Making of a Video on How to Identify Local Birds

by Joan Haffey (ARMN), with input from Charlie Haffey (helpful brother)

When the Covid-19 pandemic struck, the programming coordinator for a senior services center near me asked if I would do some “Bird Zooms” for isolated seniors. Their clients are often locked down in their apartments or worse, in their room, with few, if any, external contacts. The coordinator knew that I was a master naturalist and interested in birds, and we thought watching birds through a window and trying to identify them might be an entertaining activity that one could do alone, especially with a good app like the Cornell University Lab of Ornithology’s Merlin Bird ID.

The senior center had done an excellent job of orienting their clients to online conferencing and providing both tech and security support before and during various Zoom programs they offer. It also had a number of security features in place, such as only allowing the host to share materials on the screen. While using Zoom to walk through the most basic steps of the app was useful, there were still some challenges.

How could I make sure everyone could clearly see, via video conferencing, the basic steps in action on a smartphone app? And how could I simplify the demonstration so the host did not have to manage the meeting while cueing up relevant portions of excellent resources on Cornell’s website?

Enter my brother, Charlie, a retired science teacher who has made many an educational video in his day. I provided a script, and he made a “Quick Look” video:

It proved to be both easy to use and the highlight of the talk! We have both been surprised at the steady pace of people who view the video. We also decided to make it available to anyone who would like to use it for educational purposes. So, here are some suggestions for anyone who wants to pair this video with a talk about how best to use the app:

Where Are Some Places This Video Could Be Used?

  • Senior centers
  • Civic associations
  • Home or online school programs
  • Church groups
  • NextDoor groups
  • Video conferencing with isolated individuals

Evaluations of this Bird Zoom for seniors show that one of the favorite parts of the talk was the cooperation with my brother. In that spirit, I asked him for a few ideas for successful video-conferenced presentations.

What are the best preparations for a presentation like this on an online conferencing platform?

  • It helps to have one person manage the conferencing needs while the other presents. It can be difficult to do both at once, especially monitoring for questions and security breaches.
  • Only have open on the computer the files to be shared during the presentation. This minimizes confusion or the potential for shares of information not meant for the audience.
  • An alternative to having files open on your desktop is to prepare a slideshow that includes all the information you need. Then you only have to open one file.

Do you have any guidance on clearly presenting information via video conferencing platforms?

  • Follow an outline with minimal points
  • Stick to these points
  • Keep the presentation short
  • Minimize visual and verbal information
  • Personalize the presentation as appropriate to connect the audience better with the presenter

We hope this video helps widen the worlds of people who really appreciate birds, both now and in the future!

My Little [Carolina] Chickadees

Text and photos by Noreen Hannigan

I learned from renowned entomology professor and author, Doug Tallamy, that native host plants are critical sources of insects for birds to feed their young. One of the earliest Continuing Education events I can remember attending after I graduated ARMN training in 2015 was a talk by entomology researcher Desiree Narango. Her graduate study (with Doug Tallamy as her advisor), discussed how the availability of native plants in residential landscapes influences the nesting success of Carolina chickadees (Poecile carolinensis). She found that if there was less than 70% native plant biomass, insect populations declined as well as the chickadee population rate.  

I walked out of the lecture hall coo-coo for Carolina chickadees and immediately decided to set up a chickadee nesting house. I live on a somewhat busy street in North Arlington in a 1947-era neighborhood. When we moved here in 1982, we took Carolina chickadees, goldfinches, and titmice for granted because they were in abundance. But my ARMN training opened my eyes to how poor the habitat had become, and how many non-native starlings, grackles, and house sparrows had taken over while I wasn’t paying attention.

I doubted my yard had anything interesting for chickadees, but I pressed ahead. Two things I did quickly were: (1) consult Doug Tallamy’s book, Bringing Nature Home, for a tree that would fit in my small yard and support a decent number of caterpillars, and (2) head to a bird store for a chickadee house. Within a few days of hearing Ms. Narango’s talk, I planted a river birch (Betula nigra) and installed the chickadee house. Then I waited for the avian real estate market to get active in early spring.     

Carolina chickadees are year-round residents and live in flocks for much of the year. In late winter, nesting pairs (who are thought to mate for life) break off and look for nesting sites in natural cavities such as holes in decayed trees, but they will also use man-made bird houses if they are 5-15 feet above the ground and built to the right dimensions. Houses for many kinds of birds are commonly sold in bird stores, or you can make your own. Be sure, though, that you buy or make the right house for the bird you want to attract (and watch out for pushy house sparrows). Bird houses are easy to make if you are reasonably handy and have some basic tools. If you are going to make your own house, be sure to use the suitable dimensions and untreated wood.

You can learn more about Carolina chickadees and nest boxes and from websites I consulted, such as Cornell University’s “All  About Birds,” and the Tennessee Wildlife  Resources Agency site. Because I was impatient, I bought a ready-made chickadee house from a local bird store and—because I wanted to place it where I could see it from my porch—I also bought a mounting pole to put it in view.

Photo of a wooden chicadee house on a pole.
“Store-bought” chickadee house under the crossvine arbor.

I put it up in late winter so any chickadees in the area could scout it out before breeding season. Perhaps I overthought the process, but I worried that the house was too exposed to the elements, so I bought a wrought-iron arbor kit that I assembled and placed over the pole-mounted house. Then I planted a crossvine (Bignonia capreolata), which is semi-evergreen, to provide some protection in spring. It took a couple of years for the crossvine to get established, but it is growing over the arbor now and is casting shade and protection from the rain, as intended. (Yes, I have to keep it trimmed.) The cross braces on the arbor have also provided places for the adults to perch as they go in and out with nesting materials and food for the nestlings, which affords me the ability to observe them better.

The choice of the river birch proved to be a good one. Doug Tallamy lists river birch among the top five Lepidoptera (butterfly and moth)-supporting trees. Indeed, it has proven to be a popular perching and foraging place for chickadees and other birds in my yard. It is a fast-growing species, so it only took one or two years to attain a good size and be discovered by many birds. While nesting, the chickadees fly straight to it dozens (hundreds?) of times a day to peck at the peeling bark and branches to find insect protein for their nestlings. I cannot always see what they are finding on the tree, but they never seem to come away empty-beaked. Bonus: Goldfinch couples are also attracted to it and love to eat the seeds off the catkins (drooping flower clusters produced by trees) in late spring.  

Nesting chickadee couples start looking for nest sites around early April. I see them visit the yard, call to each other, and inspect the bird house. Like any landlord, I eagerly anticipate signs that a couple wants to sign a lease. Some say it isn’t necessary, but I “prime” the inside of my chickadee house with a couple of inches of wood chips. You can use debris from a decaying tree, or even clean hamster bedding from the pet store. Just be sure the material is untreated. One sign that chickadees are seriously considering your house is when they start throwing out your wood chips. Don’t take it personally, though. Being cavity nesters, they will work on making the interior to their liking and then start bringing in moss and other materials to finish it. After this behavior has lasted a week or two, I gently raise the hinged roof panel (after giving a gentle warning knock) every two or three days to look for eggs.

The next thing I do is somewhat controversial: I put up a “wren guard” as soon as the first eggs appear to keep house wrens (Troglodytes aedon) from getting inside and throwing out the eggs. House wrens are a native species, but they are very competitive for nest sites. They use the same-sized holes and cavities that chickadees do, so they will also be interested in these houses. Some naturalists are opposed to using wren guards and recommend letting the birds work it out on their own. I understand that point of view, but confess I am so intent on boosting the chickadee population around my small suburban yard that I use them.

Once I see the eggs and attach the wren guard, I observe that the parents are momentarily puzzled, but they figure out how to fly around it and into the entrance after about five or ten minutes. Using a wren guard is not a guarantee that a wren won’t get in, but it has worked for me several years in a row. Note that it is important to take the wren guard off when the nestlings are a week or two old (too big for a house wren to pick up) because it will interfere with their fledging. If you chose to use a wren guard, keep track of the timing.

To be clear, I like house wrens and don’t wish to harm or eradicate them. This is their native breeding range, and they are valuable to the ecosystem, too. I merely want them to wait until my chickadees have launched before coming in. House wrens can also take over the nests of other birds such as bluebirds and tree swallows. As this website notes, use of a wren guard should not be your first course of action. The best way to prevent predation by house wrens is to put the nest box away from sites that would be attractive to them. But because of my small yard, I have few options for nest box placement. 

I locate my nest box a few yards from my back porch because I’m a nosy landlord and I want to know everything my tenants are doing! While they are feeding their brood of five-ten babies for 16-19 days, they work from dawn until dusk every day bringing in hundreds of caterpillars—thousands before they’re done. The adults are tireless in their parenting duties. In addition to providing those thousands of caterpillars, they also take out all of the babies’ “fecal sacks” (poop in a gelatinous membrane) in order to keep the nest clean. It’s in with food, out with poop, hundreds of times a day for as many as 10 nestlings. That’s an incredible amount of energy and dedication generated by birds that only weigh about a half an ounce.

A photo of a Carolina chickadee with a caterpillar in its mouth.
Chickadee parent with caterpillars for chicks.

Whether it would have happened without using a wren guard, I can’t say, but a lot of new chickadees have fledged from my little house. I am usually fortunate to be watching the day they fledge, and I generally count seven or eight fledglings as they emerge. Unlike robin babies that hop around on the ground until they learn to fly, chickadee young take immediately to the air and wait in nearby trees and shrubs for their family to gather. The parents then lead them to a suitable habitat and continue to feed them in the wild for another two or three weeks. Some years I don’t know where they go after they leave my nest box, but this year the fledglings hung around the vicinity for about a month. I watched as they would transit my yard, usually in the mornings, perching from the river birch, to the red maple, to the holly, etc., at first being fed by the adults, but then learning to pick at branches and twigs for their own food. I could also tell as the days and weeks went by how their calls went from squealy little “dee dee dee” noises to more dignified-sounding “chickadee-dee-dee-dee” adult calls.

Lest you feel sorry for the house wrens who had been eying my chickadee house, I came outside the morning the chickadee family had flown, and right before my eyes, a house wren couple was already carrying its own nesting materials in. I let them stay.  

Five years ago, I rarely heard a chickadee around my house, but I see and hear more and more with each passing year. Not all survive their first year, but some are thought to live two to five years. Every spring I look forward to nesting season the way some people look forward to baseball season. I get my bird house ready for them and position my porch chair for a good view. Little do they know how much joy they bring. For one thing, they are too busy raising their children and cleaning house!

The Secret Lives of Chipmunks

By Rosemary Jann

We have always lived peaceably with our backyard chipmunks. I knew that they had burrows under the cement pad for the AC and behind the garden shed.  But when I found a new burrow hole right up against the foundation of our house, I confess I had the urge to declare war.

Photo of a chipmunk with full cheeks
Copyright David Howell.

Arlington’s local chippies are Eastern chipmunks (Tamias striatus) and members of the squirrel or Sciuridae family. Their scientific name means “striped storer,” a reference to their characteristic field marks: white stripes bordered by black on each side of their backs plus a black stripe down the centerline, as well as white stripes around their eyes. Adults weigh in at 5 oz. or less and measure about 10” long, including their bushy tails, which they hold high while running. And they’re usually on the move when you see them, since their small size makes them vulnerable to predators. According to the Mother Nature Network, these include hawks, owls, foxes, snakes, and, especially in our backyards, free-roaming cats. An article in the Journal of Mammalogy explains that chipmunks have different calls to warn about different predators: a chip for terrestrial foes and a cluck for aerial ones, plus a chip-trill when they’re being pursued. This National Geographic page on chipmunks includes a video with these three calls.

Chipmunks are also constantly on the move because they need to use every daylight hour to collect food, especially in the fall. The National Wildlife Federation describes them as omnivores who will eat fruit, nuts, grain, berries, insects, fungi, small amphibians, and even bird eggs or nestlings if they find them on the ground. According to the Mother Nature Network, their cheeks can expand to three times the size of their heads to carry food.

Photo of a chipmunk with very full cheeks
Photo by Gilles Gonthier (CC by 2.0).

Alonso Abugattas, the Capital Naturalist, notes that since they mostly consume seeds and nuts within their burrows, chipmunks are not a significant source of seed dispersal. But their appetite for mushrooms does help to distribute mycorrhizal fungi that is beneficial to trees and plants.

In their underground burrows, chipmunks create multiple food caches that will sustain them through the winter months. They are not true hibernators, but rather exist in a state of torpor, waking periodically to eat. The National Wildlife Federation mentions scientific studies suggesting that global warming may be undermining chipmunks’ survival rates by disrupting their normal hibernation cycles.

Their underground burrows can be up to 30 feet long and have at least two widely spaced openings. Nesting areas are separate from food caches. The Mother Nature Network describes chipmunks as generally solitary except for mating, which occurs in the spring and sometimes again in late summer.  The female raises 2-5 pups, who leave the nest and go off on their own within 6 weeks.

Although typically forest dwellers, chipmunks have adapted readily to suburban environments and thus can come into conflict with people by eating bulbs, raiding bird feeders, and digging too close to foundations. Although they do carry ticks,  the Humane Society notes that chipmunks themselves are not known to spread diseases to humans, and their burrows seldom cause significant structural damage. The Society advocates tolerance rather than termination and various methods to deter them: move bird feeders at least 15 feet from your house, sweep up spilled seed, avoid plantings close to your foundation, use wire mesh to protect bulbs.

I wound up following the advice of the Bi-State Wildlife Hotline and placing a rag soaked in ammonia and a cup of moth bulbs near the new foundation hole. That way I can remove both without harming the soil once the chipmunks have relocated. The Hotline also mentions various commercial and home-made remedies to discourage them from chewing on decks and fencing.

Everyone has a different level of tolerance when it comes to living with backyard wildlife. In stepping back from the brink of war, I’ve reminded myself that the rewards for learning to coexist with chipmunks are supporting a more diverse ecosystem and enjoying the continuing antics of these tiny, charismatic neighbors.

Why Do the Mockingbirds Rage? And Other Backyard Mysteries

by Rosemary Jann

It must be an indication of how preoccupied I’ve been lately: I didn’t realize the mockingbirds were nesting again until their scratchy chat call exploded over my head as one buzzed me crossing the yard.

Photo of a northern mockingbird
Northern Mockingbird, copyright David Howell.

Northern Mockingbirds are fond of the native honeysuckle (Lonicera sempervirens) in our yard, especially for their first nesting of the season. According to the Audubon Guide to North American Birds, mockingbirds raise upwards of two broods a year but don’t reuse their nests, opting instead for a new site in their territory. The trumpet honeysuckle provides a protective tangle of vines at their preferred nesting height, 3 to 10 feet off the ground. Native to North America, they have adapted especially well to suburban environments, which provide mowed lawns for foraging, tall telephone lines for surveilling their territory, and nearby shrubs for shelter. I don’t know whether these are the same birds that were here in past years, but Wikipedia notes that suburban mockingbirds often return to sites where they previously bred successfully.

Of course, the best-known trait of Mimus polyglottos is signaled by their name, which means “many-tongued mimic.” Although both sexes mimic, the male is especially prolific in adding new songs throughout his lifetime (up to 200 in all, according to Cornell Lab’s guide, All About Birds). In suburban settings, these can include not just the songs of other birds and animals (like cats), but also common sounds like car alarms and ringtones.

Their noisy aggression is equally distinctive, however. Cornell states that scientists debate the purpose of the male’s characteristic flashing of the white patches on his wings. Is it intended to startle insects, to intimidate rivals, or, like his song repertoire, to help attract a mate?

Photo of a northern mockingbird spreading its wings
A Northern Mockingbird spreads its wings. By Manjithkaini, CC BY 3.0.

Their often-displayed aggression against other creatures can also serve multiple purposes. They use their chat call as they run off territorial rivals and while attacking nest predators. I had seen mockingbirds dive-bombing cats; I was puzzled when witnessing a particularly vicious and prolonged attack on a hapless squirrel, until I learned that they too predate on eggs and nestlings. Crows and other larger birds are also nest robbers, which explains why the mockingbirds were so violent in driving off some crows casing their nesting site in our yard last week. Mockingbirds apparently endorse the belief that the best defense is a good offense.

Aggression plays a role not just in natural selection but also in sexual selection. A high level of aggression in the male signals to the female that he is likely to be more invested in the parenting process and therefore deliver more nesting success. This is important, says the Animal Diversity Web page on Northern Mockingbirds, since both build the nest, both feed the chicks, and the male educates the nestlings while the female starts building a new nest. So, if you find yourself annoyed by the aggressive behavior of this noisy backyard neighbor, it may help to understand that the mockingbird’s feistiness plays an important role in its survival—and to wear a hat if you can’t avoid being dive-bombed on the way to the car.

Virtually Exploring Virginia’s Flora and Fauna

Text by Kristin Bartschi; Logo collage by George Sutherland

I don’t enjoy being inside. Getting out in the open air and enjoying nature with my husband and a few friends brings me true joy, so adjusting to quarantine was challenging. Outside of walks around the neighborhood, I spent the first few weeks obsessively reading news stories, scrolling through Instagram, and watching a lot of Netflix and Disney+. But that started to get old. Lately, I’ve been trying to use this extra time to reconnect with my creative passions and pursue new learning opportunities.

My husband, George, and I have started exploring webinars and resources to learn more about our local environment. Recently, we attended a webinar on white-tailed deer in Northern Virginia. We learned about the increasing population of white-tailed deer in our community, the causes of the population boom, the impacts on local wildlife and plants, and solutions that different counties and cities are pursuing. It was a fascinating talk which brought to light how extreme population changes in one species can impact an entire ecosystem.

If you’re interested in learning more about our local and state environment, there are several excellent resources to explore. Here are a few to get you started!  

  • High Five from Nature – Each of these webinars from the Virginia Master Naturalists (VMN) covers five topics related to Virginia flora, fauna, and ecosystems. Subjects include spring butterflies, stream quality, native shrubs, and much more.
  • VMN also offers a continuing education webinar series with classes ranging from marine debris to sea level rise to wilderness rescues. Last week, I watched a 2019 webinar from the VMN High Knob Chapter on maple syrup as a forest product (and learned some interesting facts about harvesting and processing maple syrup).
  • With summer just around the corner, check out Encore Learning’s recent webinar, Safely Enjoy the Outdoors Despite Mosquitoes and Ticks and learn how to identify, control, and protect yourself from mosquitoes and ticks in an environmentally safe way (webinar begins at minute 5:20 in this recording).
  • The Audubon Society of Northern Virginia’s online programs include four classes on spring warblers, including insights on plumage, behavior, and vocalizations.  
  • Master Gardeners of Northern Virginia are offering their April and May public education events online. These sessions are free and open to the public and cover topics from garden design to composting to tomatoes.
  • Plant NOVA Natives offers helpful guidance on using local natives to build habitats and provides landscaping solutions for native planting.
  • You can still participate in citizen science initiatives from home! Use iNaturalist to observe and document the plants and animals you see on a walk (or the birds in your backyard!). The DC City Nature Challenge site offers guidance on using iNaturalist effectively, any time of the year.
  • The Northern Virginia Bird Club puts out a quarterly newsletter that is well-worth a read.
  • Each month, the Potowmack Chapter of the Virginia Native Plant Society offers free lectures on a variety of topics related to native plants. Currently, these are being offered online.
Pictures of logos from city nature challenge, plant nova natives, virginia native plant society, virginia master naturalists, iNaturalist, encore learning, and the northern virginia bird club

I’ve found that taking the time to learn about something like white-tailed deer or making maple syrup or composting, makes me forget about any stress or anxiety I might be feeling about what’s going on in the world right now. It’s a good reminder that although the current situation can feel overwhelming, the world still turns and there are still things to learn and explore within it.

I hope these resources give you not only a reprieve from the news stories we are inundated with every day, but a chance to learn something interesting about the world around us.  Stay safe and be well!

White-tailed Deer and Forest Health in Northern Virginia

by Bill Browning

Deer are a natural and beautiful part of our forest. They are Virginia’s largest herbivore, and despite their size, they are fast, agile, and graceful. They are an integral part of our ecosystem. However, their population has grown to the point where they unfortunately are overwhelming other species, degrading our forests, and harming the environment.

Photo of a herd of deer on a lawn in front of a house
Deer congregating on household steps. Photo courtesy of Donna Owen.

Population History

Deer helped fuel European settlement in the 17th-19th centuries. Our colonial ancestors hunted them for food and clothing, and even used deer skins (buckskins) as a form of money to trade for goods; the slang word for money, “buck,” comes from this era.

Virginia’s Department of Game and Inland Fisheries (DGIF) estimates that there were somewhere between 400,000 and 800,000 deer in Virginia in the early 1600s. We nearly extirpated them from the Commonwealth by the early 20th century as hunting and economic development drove them from our landscape. Deer became so scarce in Virginia that DGIF even had to import deer from the Midwest to satisfy the local hunting community.

During the latter part of the 20th century, as hunting declined and agricultural land was transformed into suburbia, the deer population exploded in our area. Deer are an “edge species” which means they prefer territory where natural woodland habitats meet encroaching human habitats. William McShea, a wildlife biologist with the National Zoo, says that “the eastern United States was [originally] one deep, dark forest. Now it’s deer nirvana. It’s one big edge.” Today, we likely have more than a million deer in Virginia.

Graph showing estimated decline in deer population from 1600 to 1900 followed by growth in deer population from mid 1900s to the 2000s
Conservative DGIF estimate of deer population.

More Deer Mean More Deer Browse

Deer are eating machines. An adult deer eats between 5-7 pounds of vegetation per day. Wildlife biologists at the National Park Service estimate that one square mile of a healthy forest can generate enough vegetation to feed about 15-20 deer. The jurisdiction of Arlington County, for example, has slightly more than one square mile of deer habitat (natural areas), suggesting that it can support little more than 15-20 deer in total. Many of us have spotted more than a dozen deer in our own neighborhoods, much less the whole county. The results are likely similar in other parts of Northern Virginia.

Photo of ARMN volunteer Todd Miners holding vegetation
Todd Minners holding vegetation representing 8 pounds. Photo courtesy of Sandy Minners.

As a result of this overpopulation, deer are destroying the understories in our natural areas. Forest understories are vital for habitat and for ecosystem services. When the forest is degraded, there’s no place for many songbirds to build their nests and no cover for mammals and amphibians to hide from predators. Moreover, there’s less plant material to absorb rainfall, making the Chesapeake Bay more vulnerable to pollutant runoff and our urban neighborhoods more susceptible to occasional flooding.

Through selective feeding, deer affect forest plant communities by reducing tree seedling numbers, species composition, and seedling height. They also affect herbaceous plant composition as they browse on some species and ignore others. The Virginia Native Plant Society notes that deer browse removes hundreds of plants that provide food for insects, birds, and small animals that depend on them, such as orchids, trilliums, oaks, milkweeds, hickories, and blueberries.

A 2016 Penn State Extension Report notes that, when the deer population density exceeds what the land can support, forest regeneration suffers. Decades of overbrowsing by deer have so severely depleted the habitat that many residents have never seen a healthy forest understory. And it is this healthy forest understory that provides the environment from which future canopy trees can emerge. Richard Parker, regional director of the Genesee State Park Region (New York), said that “as the current forest dies, there will be nothing to replace it.” 

In the pair of photos below, the forest on the left provides food and habitat for many species of insects, birds, mammals, reptiles, and amphibians. This well-structured forest can filter sediment and pollutants out before the rainwater reaches the Chesapeake Bay. It can also generate enough seedlings to take over from the current canopy trees in the next generation. Conversely, the forest on the right is what we frequently see in northern Virginia where intense deer browsing means that any native plant that dares to poke itself up out of the ground is nipped off almost immediately by a deer passing by.

Photo of a healthy forest with under story and a browsed forest
Healthy and deer-browsed forests. Photo courtesy of Charles Smith.
Photo of a wood thrush bird in her nest
Wood thrush nest. Photo courtesy of David Howell.

Too many deer are ruining our home gardens, defeating our park restoration efforts, and potentially endangering our health. They eat the plants we put in our yards unless we happen to have a dog patrolling the property or we spray deer repellent on our plants after every rain event. They eat the plants we install to restore our parks, unless we protect the plants with heavily fortified deer cages. And finally, as they wander through our parks and neighborhoods, they defecate where they please; deer can spread a variety of illnesses, such as giardia, in fecal matter that can end up in streams.

Photo of deer exclusion fence around a plant
Deer exclusion fence around a plant in Powhatan Park in Arlington. Photo courtesy of Bill Browning.
Photo of a deer in a playground
Deer in playground area of Boulevard Manor neighborhood in Arlington. Photo courtesy of Ron Battocchi.

Too Many Deer Equals Unhealthy Deer

Many wildlife biologists argue that the deer have so decimated our local forests that they are unable to find sufficient food to remain well nourished. And while that fact may be debated by some other biologists, there is no disputing the fact that deer density is contributing to the spread of chronic wasting disease (CWD) which is similar to mad cow disease. CWD is transmitted through saliva and other fluids, and as deer congregate closer to one another, they are more likely to transmit this disease. CWD is insidious. Once infected, death is certain. CWD first showed up in white-tailed deer in 2001 in South Dakota and Nebraska. It has now spread to 24 states, including Virginia, where it appears to be migrating eastward from the West Virginian border.

A map showing cases of chronic wasting disease in Virginia from 2009 to 2019
Chronic Wasting Disease positive results in Virginia, 2009-19.

Losing—and Regaining—Balance in our Deer Population

Human expansion and economic progress have driven natural predators out of Virginia, giving the deer free rein. We have not had effective predators for deer, such as wolves or mountain lions, in Virginia since the early 20th century. And other predators, such as foxes or coyotes, are ineffective. Foxes prefer smaller mammals and coyotes are unable to bring down anything but a small fawn. If you hear that a recovered fox or coyote carcass happens to have deer meat in their intestines, it most likely came from scavenging.

Given that human population and economic growth has allowed deer to expand in our area, we need human intervention to bring balance into the system. People frequently ask whether contraception or sterilization could be used as a humane way to control the deer population, but it is not humane. According to DGIF wildlife biologists, deer are susceptible to capture myopathy, also known as white muscle disease. This response to being captured, restrained, and handled causes the deer to build up lactic acid in their muscles. This lactic acid affects blood pH and can kill many of the internal organs, especially the heart. While some experts say it is possible to capture deer with low mortality rates in order to treat them with a contraceptive, it has not been shown to be effective in managing deer populations in an open environment. These methods require frequent follow up and can be quite costly. Further, DGIF only approves of medical intervention with deer for research, not for population management.

Given these limitations, local jurisdictions have adopted managed hunting as the best way to control the deer population in our area.

Fairfax County began an archery program after a librarian was killed in a car collision with a deer in 1997. The county’s managed hunting program now includes archery, shotguns, and high-powered rifles that has grown to cover about 100 of its county parks and properties (more than 80% of county parkland). The volunteer archers alone have culled about 1,000 deer per year since 2014 and the county donates venison to the Hunters for the Hungry program. Police and wildlife managers exercise strong oversight and there have been no safety incident or injuries to park patrons (or pets) since the program’s inception.

Montgomery County, MD manages archery, shotgun hunting, and sharpshooting operations in 54 parks, covering more than 50% of the county’s total park area. The county program began in the late 1990s, and hunters have removed over 19,500 deer from the parks and donated 315,000 pounds of venison to the Capital Area Food Bank. County police records document that collisions with deer have declined near the parks where culling takes place, and there have been no injuries to hunters or citizens as part of these programs.

A sign altering the public of a park closure for a deer hunt
Deer hunt sign in Montgomery County, MD. Photo courtesy of Todd Minners.

The National Park Service began its Rock Creek Park deer management program in 2012 and uses professional sharpshooters to hunt at night when the park is closed to the public. Since March 2013, almost 400 deer have been removed from the park and over 10,000 pounds of venison has been donated to D.C. Central Kitchen, a non-profit organization that distributes meals to homeless shelters in the metro area. In the decade between 2009 and 2019, NPS estimates that in Rock Creek Park seedling numbers rose from 2,240 per hectare (2006-2009) to 5,960 per hectare (2016-2019). There have been no hunting accidents in the park.

Arlington County and the City of Alexandria do not have a deer management program at this time.

Perhaps some of our analysis can be best summarized by a quote from Aldo Leopold in the 1940s. Leopold was a wildlife biologist, a professor, and an early conservation thinker, who helped change our country’s land management approach from one of conquering the land to living in harmony with it. He wrote in A Sand County Almanac:

“just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.”

By ignoring the deer overpopulation problem, we are allowing the deer to degrade the environment at the expense of many other native species and the future of our forests.

Spring Ephemerals Are Blooming Now. Enjoy Them Before They’re Gone!

Text and photos by Caroline Haynes.

In this time of “physical distancing,” while on a solitary walk in a natural area or in your own native plant garden, keep an eye out for some of Virginia’s beautiful spring ephemerals. Ephemerals bloom for a fairly short time early in the spring and take advantage of the sunlight before the trees leaf out and block the light on the forest floor. Here are several of the lovely, transient flowers that you may encounter for just a while longer.

One of the showier species is Virginia bluebells (Mertensia virginica). With the pink and blue buds, and blue to purple flowers, they are easy to identify and are typically found along rivers and floodplains. 

The bright yellow of the Golden ragwort (Packera aurea) is also out in full bloom now. Golden ragwort is a prolific spreader, thrives in moist, shady locations and is found in low woods, ravines, and along streams and rivers. Once the flowers fade, the basal leaves provide an attractive ground cover for most of the growing season and extending into mild winters.

Bloodroot (Sanguinaria canadensis), with its distinctive shaped leaves with five to nine deep lobes and showy single flowers, is in the poppy family and can be found in rich woods.

Moss phlox (Phlox subulata) is also blooming now, with shades of pink to blue to purple to white. Moss phlox is very tolerant of hot sun and dry soils and can be found on rock ledges and other open, sunny locations. It also looks pretty in the winter as leaves turn purple with the cold.

Spring beauties (Claytonia virginica) have narrow leaves and delicate pink to white flowers that are out during the day, but close up at night. They’re common in rich woods and wetlands; look for them along trails, too.

Early saxifrage (Micranthes virginiensis), with tiny white flowers in branched clusters can be found tucked among rocks and along shaded banks.

Dutchman’s breeches (Dicentra cucullaria), so-called because they resemble a pair of pantaloons hanging upside down, are especially rewarding with these quaint flowers and delicate foliage. Look for them in moist shady areas.

And while these bloomers bring a lot of joy to the human eye, they have a much more important purpose. If you stop and linger on a sunny day, you may be rewarded with the variety of native insects feasting on the nectar of these early spring flowers.