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.

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.

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!

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.