Improved Conditions Lead to a Significant Increase in Bluebird Population at Langley Fork Park

Article by FMN Stephen Tzikas

Reprinted from Virginia Bluebird Society The Bird Box, Spring 2022, with permission.

In 2021 I volunteered to be a bluebird monitor at Langley Fork Park in McLean, Virginia. It is one of many citizen science programs promoted by the Virginia Master Naturalists and managed by the Virginia Bluebird Society (VBS). As a Chemical Engineer I have various interests in the physical sciences and engineering. As I get older, I am interested in getting more exercise, and one way to do that is to combine it with a life science that requires outdoor exposure. Since I am partial to birds because of a childhood pet parakeet, I decided to monitor bluebirds. Monitoring a bluebird trail and entering the data into Cornell University’s NestWatch was a rewarding new personal experience. At the end of the season, about August 2021, I finally reviewed the NestWatch data and correlated it to my experience of monitoring the trail. It was an extraordinary successful season. I decided to speculate as to why the season’s success was extraordinary.

The Site and the Monitoring Team

Langley Fork Park is 52 acres with a latitude of 38.9 degrees and a longitude of -77.2 degrees. The 10 bluebird nest boxes in the park are evenly distributed along the perimeter of the tree/field boundary. They all have stovepipe baffles and Noel guards. I monitored this trail with Naveen Abraham (trail leader) and Cindy Morrow. We shared our findings every week and had plenty of interactive time with the nests and birds. Our trail leader started monitoring the trail in 2016, the year that data collection for the trail began in NestWatch. However, the trail had been monitored for 10+ years prior to that.

The Results

Author checks box 9. Photo: Ako Tzikas, 5/30/21

In the 2021 season, we had 3 types of nesting birds. Apart for one late but successful nesting attempt by house wrens, the season was dominated by eastern bluebirds and tree swallows. Since 2016, the only other species making use of the nesting boxes was the Carolina wren. The count of 63 fledglings was quite a successful number compared to that of prior years. The NestWatch site sums a total egg count, as well as the total fledgling count. Although we counted eggs and fledglings as best as we could, it was not always possible to count all eggs as the view was obstructed, nor could we always count fledglings accurately as they could be piled on each other. The total number of fledglings, therefore, is a minimum counted number. It could be slightly higher, as indeed it was evident from the bluebird egg count, which was 29 eggs compared to the 26 recorded fledglings. Although we lost a bluebird egg due to predation, one can see a remaining discrepancy of 2, which I believe favors 2 additional fledglings. Likewise, the count of tree swallow eggs (16) were obviously undercounted because of obstructions like large nest feathers. Although we lost 4 eggs due to predation, the total number of fledglings was 33. This leads to small inconsistencies in the NestWatch data and the automated calculations. For this reason, I would recommend that nest monitors make a good effort to count precisely, as well as document in the NestWatch comments the perceived situation for the benefit of other researchers. Nonetheless, the small discrepancies did not prevent an analysis. Finally, together with the accurate count of 4 house wren eggs and a corresponding 4 fledglings, one arrives at the sum of 63 fledglings. We had 17 nesting attempts at the 10 boxes.

For context, the six seasons of monitoring (2016 through 2021) saw 77 next attempts for the 10 boxes, with a sum of fledged at 208 for all species. Of these fledged species, bluebirds accounted for 48, tree swallows for 127, and the balance between house wrens and Carolina wrens. Consequently the 26 bluebird fledglings in 2021 represents 54% of all 48 bluebird fledglings since 2016. This was indeed an outstanding success.


Bird populations have been decreasing worldwide, and along with it important ecosystem processes such as pollination and seed dispersal. To date, the number of birds is estimated to have been reduced by up to 25 percent in overall numbers. It is encouraging then when organizations like the VBS help boost those populations. The VBS trains and organizes volunteers to monitor nest boxes. was fortunate to be able to experience the success of the 2021 bluebird season at Langley Fork Park. As I speculated on the reasons for the success, my investigation consisted of the following areas of review: trail leader management; weather; and food availability.

Last year (2020) was a very disappointing year at Langley Fork Park as there were no successful bluebird nests. Almost every box had tree swallows to start, and later in the season there were a couple of house wren nests. There was only one bluebird attempt, but that attempt was ended by a house wren which poked holes in the bluebird eggs and removed them from the nest. In 2021 we moved a few boxes by a little bit in the beginning of the season. This made all the difference in helping to create a more favorable nest site habitat for the bluebirds. We discussed some possible standard types of actions that could improve the locations for nesting. We decided to move boxes #3, #6, #7, #8, #9 and #10. Afterwards, it was these boxes that the bluebirds embraced, i.e., boxes #3, #6, and #8. Bluebirds also nested in box #7 initially, before a tree swallow evicted the bluebird with the loss of an egg.

When I started monitoring the bluebird trail, I noted everything I saw, including other nearby wildlife, such as foxes. I didn’t realize it at the time, but I

Box 9 Sparrow spooker. Photo: Stephen Tzikas, 5/5/21

was documenting potential predators. But the noticeable issues of predation came from other bird species instead. We lost a male bluebird in Box #8, though we were not sure how it was killed when we found it’s body in the nest box. Nor did we know what species of bird was responsible for it. We don’t know if the bluebird was attacked in the nest box, or sought refuge in it after a struggle outside the box. As noted, we also lost a bluebird nest box with 1 egg when it was taken over by a tree swallow family. Finally, one tree swallow nest was abandoned when its eggs were attacked and damaged. Other than that, we did not have much predation except for some assertive house sparrow attempts at competition in the beginning of the season. To frighten the sparrows away, we successfully used a spooker. Finally, the last aspect of this season’s trail management was the quick elimination of an ant infestation in a couple boxes.

Weather in the form of temperature, precipitation, and snow can clearly play a role in the health and number of birds. With Langley Fork Park being about 3 miles from the Washington DC boundary line, I reviewed historical weather data from Washington, DC from the NOAA and National Weather Service. A precipitation link offers monthly, seasonal, and annual average data back to 1871, plus a comparison to the norm. It shows a significantly wetter season in 2021, and the data can be accessed here: https:// A temperature link likewise offers monthly, annual, and seasonal data at dcatemps.pdf. A review of the annual data shows that Washington’s seasonal temperatures had not been significantly different than prior years or the norm. For those who live here, the finding may be a surprise as it seemed to be a more mild winter in 2021. However, when the snow fall data is reviewed, the trend is different. Many news articles can be found on the internet focusing on how little snow precipitated in the 2021 season, and the general trend of less snowfall over the past few years. Indeed, the lack of snowfall in the 2021 winter was quite noticeable and extraordinary for local residents. I did not have to check the records on this to validate the observation, but I did so anyway. The Washington Post edition of 1/14/2021 reported that as of 1/14/2021, it had been 694 days in a row without at least a half inch of snow in Washington (and the season was still ongoing). This is a record. Apart from the next highest records in 1999 and 1973 at 693 and 617 days respectively, the next 7 longest streaks varied from 428 to 357 days. The Washington DC snowfall norm is 13.7 inches for the season. The 2020-2021 (Jul-Jun) was only 5.4 inches. The data may be reviewed at

Hungry Bluebird mouths wide open at box 3. Photo: Cindy Morrow, 6/21/21

A robust bird population will be dependent on an abundant food supply. Food supply too can be correlated to adequate rainfall and soil fertility. While there were no negative determinants on the food supply in 2021, there was a bounty with the 17 year cicada life cycle emergence, en masse, of the cicadas. Consequently, birds had a new and plentiful food source in the environment. Growth rates of the nestlings were healthy and many of the nest boxes were used twice.


The Virginia Bluebird Society’s Langley Fork Park Bluebird Trail had a successful season in 2021, in great part due to a mild winter, active management, and a once in 17 year cicada ample food source. A total of 63 birds (33 Tree Swallows, 26 Bluebirds and 4 House Wrens) fledged at Langley Fork Park Bluebird trail.




· Stanford Report, January 10, 2005, Bird populations face steep decline in coming decades, study says. Mark Shwartz
· Population limitation in birds: the last 100 years. Ian Newton
· 17-year Cicadas: Bird Buffet or Big Disturbance? May. 18, 2021. Smithsonian’s National Zoo and Conservation Biology Institute. https://
· D.C.’s lack of snow over the past two winters is making history. Capital Weather Gang. https://

Dark Skies and Birds – Writers Needed

Photo:  Luke Franke
Fairfax County Park Authority is expanding its education on the importance of dark skies. Light pollution has negative effects on wildlife, plants, people, energy consumption, and human health. They are looking to celebrate international dark sky awareness week Home – International Dark Sky Week with some educational blogs and events.
Are there any Bird lovers out there who would be willing to write a blog (300-500 words) for the park authority about the effect of light pollution on birds?
This is a good year to do this as National Audubon Society is partnering on this effort as well as being the theme for this years world migratory bird day.
Notify Tammy Schwab at [email protected]  if you are interested.
World Migratory Bird Day 2022 is focusing on the impacts of light pollution on migratory birds. Artificial light is increasing globally by at least two percent a year, presenting a problem for birds. Here are four simple actions everyone can take to help birds at night.
1. Reduce the amount of light outside your home or place of business. Turn off all non-essential nighttime lights. For essential lights, such as security lighting, use timers or motion detectors to keep usage to a minimum. And always use the minimum wattage necessary for the task at hand.
2. Change the color of your lights from cool to warm. Studies suggest that green and blue light attracts more nocturnally migrating birds than red, orange, or yellow light. Use light bulbs that emit warm lighting to minimize disturbance to birds.
3. Direct all lighting downward. Place lights to illuminate the floor or ground and use lighting shields to prevent shining into the sky.
4. Share the message to “dim the lights for birds at night.” Throughout the year we will highlight the steps that individuals and communities can take to reduce the impacts of light pollution on our shared birds. Share these messages through social media and other outlets to increase awareness of this important issue.
For more information on light pollution and how to fight this totally reversible type of pollution visit the international International Dark Sky Association – International Dark-Sky Association and for a local perspective learn more about Fairfax county’s outdoor lighting standards here Outdoor Lighting Standards | Planning Development (

Photographing and Viewing Wildlife: Gear, Tips and Ethics, April 14th

Photo:  Gordon Atkins, GBBC

Thursday, April 14,2022
7 – 8:30pm
ASNV Members: $10
Non-members: $20
Register here.

Wildlife photographer, filmmaker, and Nikon Ambassador Kristi Odom will be joined by photographer Molly Riley to discuss all things related to bird photography, from lens and camera choices, to autofocus settings. They will not only talk about how to get great shots, but how to do so ethically. This talk is all about gear, behavior (the wildlife as well as our own), and respect.  Hosted by Audubon Society of Northern Virginia.

Millions of Trees at Risk in Northern Virginia? Introducing Tree Rescuers!

Photo courtesy of Plant NOVA Natives

Northern Virginia’s oldest and best-loved trees are in danger, and the threat is in plain sight – and yet there are few who can see it.

But help is on the way! Tree Rescuers – a new community education and outreach program – is shining a light on non-native invasive vines, which pose a mortal threat to millions of mature trees in Northern Virginia.

More than 130 people from neighborhoods across Northern Virginia have already volunteered with Tree Rescuers, a new campaign sponsored by Plant NOVA Trees and aimed at preserving our area’s mature trees.

“We were amazed at how many people were ready to do something like this for the trees but didn’t know how to get started,” said Margaret Fisher, one of the coordinators of Plant NOVA Trees. “This is a great time to start, since the leaves are down and the vines can be seen more easily.”

As many as three million trees in Northern Virginia may be at risk, said Fisher.

Many people are unaware that invasive vines like English Ivy can eventually make a tree hazardous (and expensive to remove). Tree Rescuers volunteers learn how to identify problematic vines, then walk their neighborhoods spotting trees that need help.

The Tree Rescuers don’t remove any vines themselves, but they warn landowners by dropping off a brochure explaining the problem and ways to fix it.

Data gathered by Tree Rescuers will also help improve knowledge of the actual number of trees at risk, since the collected data is being aggregated and mapped. A map of neighborhoods surveyed can be viewed here.

Tree Rescuers is part of Plant NOVA Trees, a five-year campaign by local governments and nonprofit organizations to increase tree cover in Northern Virginia. Native trees are a key part of the solution to many community problems, from extreme weather and air and water quality to the health of birds, wildlife, and the Chesapeake Bay.

For more details about Tree Rescuers, or to volunteer, click here.

Caterpillars Count! – Virtual Presentation, April 14th

Photo: Ed Haas

Thursday, April 14, 2022
7 – 8 pm
Ages 16-Adult
Register here by April 12th; enter activity number 206201006 in the search.

Learn about Reston’s participation in the national citizen science project, Caterpillars Count! Volunteers are needed to collect weekly data on the abundance and phenology of caterpillars and other arthropods during the spring and summer. Held via Zoom. To learn more or get registration assistance, contact the Walker Nature Center at [email protected] or 703-476-9689.

Fairfax County Watershed Cleanup, Various Dates

The Nature Conservancy is partnering with Fairfax County Park Authority to do a wonderful watershed cleanup around 15 different Fairfax County parks!

Registration for the annual Fairfax County Watershed Cleanup is now available at They need nearly 500 volunteers to help clean up plastic bottles, cans and other debris. It’s a great way to give back to the community, and it’ll be a pretty fun day as well!

Event capacity is limited, and they request that you register individually or in family units. Before registering a large group of 10+ people, please double check that everyone in your group is committed and will attend. This prevents situations where one group takes half the available spaces and then cancels last-minute, and they have no one to fill in.

Site Location Date Time Total Volunteers Needed Approximate # volunteer spaces left at press time
Hidden Pond Nature Center Springfield 3/26/2022 9 a.m.-12 p.m. 45 FULL
Chandon Park Herndon 4/2/2022 9-11 a.m. 25 25
Huntley Meadows Alexandria 4/3/2022 9-11:30 a.m. 50 15
South Lakes Drive Park Reston 4/9/2022 9-11 a.m. 25 22
Pine Ridge Park Annandale 4/9/2022 8 a.m.-10 a.m. & 10 a.m.-12 p.m. 25 each 25
ECL Chantilly 4/16/2022 9-11 a.m. 20 FULL
Riverbend Park Great Falls 4/16/2022 10 a.m.-12 p.m. 15 4
Scott’s Run NP McLean 4/16/2022 10 a.m.-12 p.m. 25 19
Ossian Hall Park Annadale 4/16/2022 8 a.m. -10 a.m. & 10 a.m.-12 p.m. 25 each 25
Laurel Hill Lorton 4/23/2022 9 a.m. -10:30 a.m. 25 13
Springvale Park Springfield 4/27/2022 8 a.m.-11 a.m. 20 17
Providence RECenter Falls Church 4/30/2022 9:30-11:30 a.m. 30 26
Roundtree Park Falls Church 5/1/2022 9:30-11:30 a.m. 30 16
Lake Fairfax Reston 5/7/2022 9-11 a.m. 55 44
Lake Accotink Park Springfield 5/8/2022 9-11 a.m. 25 7

Spring Volunteer Opportunities with the FCPA

Photo:  Robert Collins on Unsplash

The Fairfax County Park Authority has dynamic public programs that need volunteers.  Here is a sample of spring opportunities at Hidden Oaks and for International Dark Sky Awareness Week.  A more complete list is here.  For other opportunities tailored to your interests, talk to the Volunteer Coordinator at your favorite Fairfax County park.

Hidden Oaks Nature Center
7701 Royce St., Annandale, VA
Contact: Suzanne Holland, [email protected] 

Sat. April 23 Culmore Community Day from 10-2
at Woodrow Wilson Library, Knollwood Dr., Falls Church, VA

Two opportunities include assisting showing native wildlife to visitors. This will be inside the library and helping children release live native ladybugs outside the side door directly from our nature display room. The other is to assist with surveying attendees as to their thoughts and behaviors regarding county parks with a goal of increasing equitable park opportunities.

Sat. April 23 : Annandale Greenway Earth Day Cleanup from 11:30-12:30at 7200 Columbia Pike, Annandale, VA

Assist FMN Marilyn Schroeder in presenting as well as representing for Hidden Oaks at the kickoff presentation for a clean-up between Green Spring Gardens and Annandale Community Park.

Sun. May 15 from 12:30-4:15 (multiple sessions) DinoFest

Need 3 volunteers . Low key program with need to assist preschool age kids with activity at separate stations outside in Nature Playce. Mostly sedentary.

International Dark Sky Awareness Week
Multiple locations
Contact Tammy Schwab, [email protected]

Fairfax County Parks will be celebrating International Dark Sky Awareness Week April 22-30th. FCPA will be having events needing volunteers on April 22 and 23 and also the 29th.

(FMNs record hours as E110:  FCPA Nature Programs.  In the Description, include the name of the park and the name of the program.  In Direct Contacts, write the number of people you spoke to or who attended the program.)

Symphony of Frogs – Families, April 2nd

Photo courtesy of Fairfax County Park Authority

Saturday, April 2, 2022
Huntley Meadows Park
3701 Lockheed Blvd., Alexandria, VA

Registration: Register Online

Cost $9.00

Come discover Huntley’s amphibian orchestra. Join a naturalist for a discussion and a guided walk to listen for serenading frogs and toads. Learn the calls of a bull frog, southern leopard frog, green frog, tree frog, American toad and more.

Mason Neck Eagle Fest, May 7th

Photo courtesy of Eagle Fest

Saturday, May 7, 2022
10am – 6pm
Mason Neck State Park
7301 High Point Rd, Lorton, VA

The Eagle Festival will be live and in-person this year! Please mark your calendar for a wonderful day at Mason Neck State Park. There will be live animal presentations all day long, as well as live music, demonstrations, and interactive exhibits from more than 20 environmental organizations.

Plastics! Plastics! Everywhere.

Article and photos by FMN Mike Walker

Like last year, I saved every scrap of “plastic” that came in to my home in January and February. Fortunately I have a wonderful screen porch to store this stuff outside during the cold weather. As you can see above, in two months, I collected a shocking total of about 60 cubic feel of “plastic” stuff, ranging from bubble wrap, packaging waste (even from organic products) prescription bottles, shrink wrap, etc. I even had a plastic hose from my washing machine, plastic “throw-away” sunglasses from the doctor for eye dilation and plastic clips from ink for my printer. A real potpourri of plastic trash.  My wife and I do not go out of our way to buy plastic products, of course, I submit that we are typical consumers. Collecting two months worth of material is a vivid reminder of what is coming into our lives and how difficult it is to avoid an avalanche of plastic material.

After two months of collecting,  I sorted the plastic into what can actually be recycled….see my picture below….a small fraction of waste…15 bottles and some caps. While manufacturers offer “helpful” codes on the bottom of many plastic products, most plastic is simply not recyclable and in Fairfax County becomes waste to be incinerated.

Being aware of our use patterns for “stuff”…whether it be plastic, water consumption, gasoline or other resources is the first step in becoming aware of our impact on the earth and the search for serious reductions in consumption. Taking the time to simply collect the plastic that comes into your home for a period of time can become a real eye opener to the sheer volume and variety of plastics – including non-recyclable plastics – that are encountered everyday. It can really make you mindful to look for ways to reduce your consumption, too.