Fly By Night: A Designer's Look at Bats in Seattle Parks
A senior capstone research project presented to the UW Landscape Architecture Department
Special Thanks to my faculty sponsor, Brooke Sullivan; my departmental advisor, Nick Dreher; my UWASLA mentor, Amy Lindmuth; and UW LA department chair, Ken Yocom: your collective support and encouragement for this project was truly a gift. Additional thanks to Rich Desanto, Kendra Hanna and Rachel Atlas -- I couldn't have done it without you!
About the Project
Inspiration: Art, Science & Creativity
I was inspired to pursue this project in part by a talk given at the UW by landscape architect and designer David Buckley Borden . His playful, eye-catching installation pieces at the Harvard Forest combine science communication with keen design in the way that trained landscape architects are particularly poised to do. He encouraged the students in the audience to follow their individual interests, even if they don't seem to fit the scope of traditional design practice, and to be bold with design concepts. I took his lecture to heart and I owe him some credit in my decision to take on this this project.
Bats occupy a strange space in our culture, even in environmentalist spaces. They are often classified as pests and as dangerous disease vectors, with little regard given for their unique biological niche and diversity. There are over 200 species of bats, which is evidence enough on its own that nature finds them valuable.
An excerpt from a zine being made by artists Sonya and Nina Montenegro (known professionally at The Far Woods) best summarizes the other-worldly, ephemeral quality of bats that enchants some, yet disturbs others:
These despised inbetweeners, Shrouded in nighttime; Existing on the edges - The edges of Animal & bird, Day & night; The edges of Dark & light, Earth & heaven; Mystery, myth & superstition, Existing in a liminal space, That makes us uncomfortable, In its in-betweenness.
I first began exploring bats in Seattle in Spring 2019, in an ecological design studio. Since then, with the COVID-19 pandemic, the cultural reputation of bats has taken a huge hit. I believe that landscape architects have a responsibility to the non-human life present in the landscapes they design. I found bats to be a niche worthy of exploring, since they need any positive representation they can get.
An Exercise in Pedagogy
As undergraduate students, there are limited opportunities for research on topics of personal interest in the College of Built Environments. It was important to me to challenge myself to pursue a topic I care about, create my own structure for research, and to connect that work to landscape architecture. I knew early on that I would need to provide myself with a support structure and to set the tone for the kind of work I wanted to produce.
This approach resulted in a personal contract agreement, which served as a set of guidelines for the scope of my research, explicitly outlining that I am not conducting true scientific research, but rather exploring a line of inquiry. I also established how I would treat myself and my mental health during this process, in case I began to struggle to complete work of my own volition.
I also established that the investigative approach to this work would be process-based, and less focused on a single final product. I structured the work into three main tasks: an annotated bibliography, field study sessions, and creative interpretation of findings.
Myotis yumanensis, or Yuma Myotis
Bat-round Information
Bats in the Pacific Northwest
According to The Burke Museum, there are 15 bats in the Vespertilionidae (evening bat) family present in Washington. The majority of these are Myotis, or “little brown” bat species. They are all insectivorous and relatively small, compared to some of the larger species seen in the southern US, such as the well-known Mexican Free-Tailed bat.
However, there’s a lot to love about the bats in the Pacific Northwest. Some of my favorites are the Townsend’s Big-eared Bat (Corynorhinus townsendii), the Little Brown Myotis (Myotis lucifugus), and the Hoary Bat (Lasiurus cinereus).
These bats range in sensitivity to disturbance and habitat needs — some bats, such as the Big Brown bat (Eptesicus fuscus), are considered “habitat generalists” and can live in a variety of forest types, as they don’t have a particular preference for insects. Others are more dependent on ready access to water, like the Yuma Myotis (Myotis Yumanensis), or prefer certain kinds of trees for roosts, like the Long-legged Myotis (Myotis volans) which roosts in Ponderosa Pine snags.
Summer in Seattle
Bats have high metabolisms and are subject to dramatic changes in body temperature. This characteristic requires them to seek out thermally stable roosts and to form colonies in order to retain heat during hibernation. The need for abundant food in the warm season and a thermally stable roost in colder months makes many PNW bats migratory. They form large colonies in caves and rock cavities on the east side of the Cascades in winter, and in the spring they emerge and move in small groups to lower elevations in western Washington, where the abundance of water and forest makes insect foraging worth the trip.
As a result, bat populations in Seattle are largely seasonal, peaking in late spring and into summer as newly pregnant females form nursery roosts, eating nearly their own body weight in insects on a good night. Some bats that have found roosts in attics, bridges and under shingle siding may overwinter in the city, but they risk being disturbed during their hibernation, which can be very deliterious to their survival.
The annual spatial cycle of a bat in Washington. Bats can live from 10-40 years and change roost locations every few years.
The weaving flight of what is likely a California or Yuma Myotis at Golden Gardens is a perfect example of how bats can maneuver through brushy wetland areas.
Typical Bat Activity
If you see a bat on a summer evening in Seattle, it’s going to be on the hunt for insects. Most bats emerge to hunt moths, beetles, caddisflies, mosquitoes and other flying insects around dusk, and then again before dawn. The fluttery, unpredictable flight path of a bat is the result of their finely tuned echolocation skills and their highly manueverable wings, which are structured more like a human hand than a bird’s wing. They can catch an insect in their “palm” and scoop it into their mouth with only a minor loss in flight speed. Many of the bats in Seattle are adapted to flying in cluttered riparian habitats, close to the ground and over water. Agression towards humans during foraging is practically unheard of, and they are undeterred by human presence — if a bat swoops down close to you, it’s probably just going after a mosquito that was attracted to you, so say thank you next time!
The audio recording below is an example of how a bat uses high-frequency "clicks" to locate insects in air. This frequency is higher than human hearing, and is made audible using an ultrasonic microphone that amplifies the sound for species indentification.
The Annotated Bibliography
Lasionycteris noctivagans, or Silver-haired Bat
Purpose
Before I could begin my field study sessions, I needed to establish some background information about what is already known, or being explored, regarding bats in urban landscapes. An annotated bibliography allowed me to survey a variety of studies conducted in the last decade on bats in urban, natural environments around the world. I reviewed 11 articles and summarized the major findings for each; I then synthesized this work into a few "Key Findings" to keep in mind as I sought out landscapes in Seattle that may have bat activity.
Results
Collectively, there are some strong commonalities in the findings of recent research into bat behavior in urban landscape. It appears that water is the largest determinant in bat presence and activity. The size of the water body can determine the types of bats present. Bordering vegetation can be a determinant for faster-flying bat species, while smaller species that are adapted to navigating cluttered vegetation are not deterred. Denser forests appear to be unattractive to most bat species, and that widely spaced, discontinuous woodlands are most enable to bat activity.
Artificial light seems to be an area of focus for the most recent research published on bat activity. It seems largely unanimous that artificial lighting at night is a major manipulating force in bat behavior, as some species such as Eptesicus, Nyctalus and Pipistrellus take advantage of the insects presence at light sources. Meanwhile, Myotis species, which I understand to be one of the more abundant bat types in Seattle, are very light avoidant and sensitive to lighting changes. White light emitted from cool-toned LED lights can attract large amounts of insects, and may reduce the availability of insect foraging for light-avoidant species in dark spaces.
Bats are often referred to as good bioindicator species, since their diversity in diet and environmental preference can be used to track anthropogenic changes to the landscape. If bats are not present in a place where there are otherwise attractive landscape features, it points to an unacknowledged issue in the surrounding environment. However, I found little to strongly quantify or even explain the concept of bio-indicators in depth, and I believe I could do more background research to understand this ecological concept.
- Proximity to open, slow water
- Minimal artificial light pollution
- Availability of roosting spaces, either man made or natural
- Thermally consistent roosting spaces (snags, rocks in sunny areas)
HABITAT GOALS:
- DESIREABLE OUTCOMES:
- Species richness
- Regular foraging activity
- Reproductive success
- "repeat customers" / roost establishment
Tools & Methods
The field sessions were the heart of this project. I established a methodology for my field visits in order to set myself up for success.
The Amateur Bat Watcher's Tool Box
Most of these tools were borrowed or purchased on eBay.
With limited funds available, I sought out cheap, readily available tools that I could purchase online. I purchased a thermal imaging camera and an old cell phone to run it; I also invested in an ultrasonic microphone to detect bat calls. The thermal camera ended up not being a high enough resolution for the photos I wanted to take; I ended up using the ultrasonic microphone, my cell phone camera and the DSLR borrowed from the UW for data collection and recording. If I had pursued a research grant or sought out resources from other bat researchers, I may have been better equipped for my sessions. However, I found that these tools produced satisfactory documentation of my work.
Field Sessions
I chose three sites to conduct my field sessions at (see descriptions below). Each site would be visited three times over the course of several weeks.
I created a field observation session form to fill out in order to record when and were I conducted each session. I recorded weather conditions and moon illumination, specific observation coordinates and types of data collected.
In general, these sessions were conducted around sunset on non-rainy evenings and lasted, on average, an hour to an hour and a half on site. The first site visit would be focused on establishing specific observation points, with following sessions aimed at gathering data and exploring potential secondary observation points.
Data Collection
While the focus of these field sessions was to notice the experiential qualities of each site, I needed to record various types of evidence for my own reference and to share as results. I took photos, recorded video, and recorded audio using the bat detector, collecting information both about the environmental conditions of each site along with as much bat activity as I could find.
The Sites
I chose three parks in the Seattle area as my research sites. I made sure that these locations were spatially distant from each other, varied in landscape type and were a mix of familiar and new to me. I didn't know any specific locations where I could see bats at these parks, which made these choices investigative. Using the knowledge from my annotated bibliography about what landscape elements encourage bat activity guided my choices, but I wouldn't know if I was correct until I was on site.
Magnuson Park - Sand Point
Top row: the large frog pond at my primary observation point; looking North across the pond; weather conditions at dusk when bat emergence began Middle row: One of the frog ponds reflecting the large field lights from the nearby baseball diamond; the wetland area north of the frog ponds next to the sports fields; the resident beaver at the large frog pond Bottom row: A typical wetland clearing along the frog pond trail -- too brushy for bat activity; an enclosed pathway along the frog pond trail; evidence of beaver activity in the wetland area
Diagram of my field study area in the western end of the park. My primary observation points are marked with red dots.
Located in Northeast Seattle, Magnuson park was the largest site of the three, as it includes sports fields, extensive engineered wetlands, and a shoreline area. I focused my research on the frog and promontory ponds located at the western end of the park. This area is densely vegetated with wetland plants, Red Alder trees, and willow shrubs. The ponds are small clearings, largely populated by frogs, and are connected with a serpentine trail. The Promontory pond is a larger water body made up of three connected, but naturally dammed, water bodies. There is no artificial lighting along the Frog Pond trail, but large overhead lights from the sports fields to the North of the wetlands do shine into the area from a distance. Lake Shore Drive is a moderately trafficked road that creates the eastern border of the wetlands.
I had visited Magnuson Park many times in the past and had heard from my advisor, Brooke, that there were likely bats here, although I had not observed them myself.
Duwamish Hill Preserve - Tukwila
Top row: the bat house and western entrance to the the park as seen from the central bluff, with the industrial lot in the background; a closer view of the bat house installation; a North-facing view of the bat house in its meadow landscape; native camas blooming on site; the pathway leading down from the central bluff into the fire ring area/"the valley" Bottom row: the bat house at dusk, showing the lighting from the lot next door; a mass of gnats present at the top of the hill; one of the pathways leading to the upper view point; a view of the Madrone trees present on the hill.
A diagram of Duwamish Hill Preserve, including my primary observation points, marked with red dots.
This 10.5 acre park located just south of the Seattle area is relatively new, designed by Forterra and opening in 2010. It was designed as a restoration site of a former quarry and includes a variety of cultural landscapes including a camas prairie, a wet sedge meadow, and a rocky outcrop forested with Madrone trees. The park is bordered by a large industrial business lot, with overhead lights strongly illuminating the western site of the park. A low-traffic, two-way street separates the park from the Duwamish River,
I had heard from a classmate that they installed a bat house on site in summer 2020, so I chose this site in order to see if the bat house had any occupants.
Golden Gardens Wetlands - Ballard
A diagram of the wetland area at Golden Gardens park, located at the Northern end of the beach. My observation points are marked with red dots.
Top row: looking north towards the water on the northern side of the beaver pond; a view of the snags in full sun; a typical view at dusk at the beaver pond; the large woody debris and evidence of beaver activity at the wetland Bottom row: a dusk view of the deciduous canopy looking east; more evidence of beaver activity at the ponds; the view of the wetlands approaching from the parking lot, headed north.
The smallest research site of the three, the wetlands at Golden Gardens are located at the Northernmost tip of the beach, just beyond the end of Golden Gardens Park Rd. There are medium-sized ponds with a pedestrian bridge between them, and a large open field to the west. An active rail road borders the wetland area to the east. There is no artificial lighting nearby. The eastern edge of the site is populated by snags and deciduous trees. I had never visited this site before and was unsure if there would be any bat activity at all; I consider this site to be the "wild card" of the three.
Findings
Eptesicus fuscus, or Big Brown Bat
Of the three sites I visited, Golden Gardens by far had the most bat activity that I observed. Magnuson Park certainly had bat activity throughout the wetlands, but my observations were limited. I was sorry to see that the bat house at Duwamish Hill Preserve was unoccupied, and I saw no bat activity during my visits.
Who's There?
The species listed below were automatically identified by the Echo Meter Touch 2 app used to record calls picked up by ultrasonic microphone. This ID function uses the frequency of the sound detection to make a guess against the standard pulse rate and kHz of a certain species -- it is fallible. It's possible to manually vet the recordings if one has experience with identifying bat calls, but I do not have such knowledge at this point. Some bat observations I made were unable to be identified by the microphone, or were not recorded as a result of user error.
As was expected from my research, the presence of extensive, slow-moving water with established wetland shrubs (willow, alder, snowberry, grasses, etc) correlated strongly with observed bat activity. Larger established trees that had a more disparate canopy and clear space over water bodies were signals of potential bat foraging locations in my field sessions. Overly brushy locations without a strong spatial corridor, like at the smaller frog ponds at Magnuson, seemed to have no bat activity in my observation. Interestingly, both of the sites with water bodies present (Magnuson and Golden Gardens) also had a resident beaver, which could be considered another sign of ecosystem health. Bright artificial lighting, like that present at Duwamish Hill Preserve and the sport fields at Magnuson were deterrents to bat activity.
Bat activity at Magnuson Park seemed to migrate through various spaces in the wetland area. I would observe a bat or two for about half an hour before they seemingly disappeared. My attempts to locate more activity later in the evening were unsuccessful. I did observe a single bat in a secondary location on my final site visit, circling high above an open area bordered on one side by larger deciduous trees. I hadn't observed behavior like that before, but the bat was too far away to be identified by my microphone.
The "one woman show" (briefly joined by two of her friends), observed on May 6th at Magnuson park. Video color has been edited for clarity and contrast.
Activity at Golden Gardens was consistent and frequent. The deciduous snag area on the far side of the beaver pond, close to the train racks, proved to be a veritable playground for California and Yuma myotis. They would regularly circle through a clearing, swinging wide out over the pond before weaving through the trees, close to the ground. The snags on site clearly have fostered a community of bats, and I would say this is a prime example of how even small landscape fragments can function as crucial habitats for bats. These bats had an incredible maneuverability, making tight s-curves overhead and moving relatively slowly. At one point as I was leaving the site over the pedestrian bridge that crosses the beaver pond, I tried to spot the bats from a distance. My headlamp was on and pointed down into the water; it was less than 5 minutes before they were using the light source to forage for insects right in front of me. It was an example of their adaptability and opportunistic intelligence and predators, and it truly impressed me.
California and Yuma myotis using my headlamp to their advantage at Golden Gardens on May 13th. Video edited for contrast and clarity.
I saw no bats in my two visits to Duwamish Hill Preserve. The bat box had no guano at its base, a sign that it was unoccupied. My theory is that the strong flood lighting that spills over from the industrial lots, paired with a lack of defined corridor space, makes potential predation too prevalent at this site. That being said, it's also very likely that any bats in the area simply haven't discovered the box yet, and it may become occupied in the future. There is a trestle bridge over the Duwamish river across the street that seems like a much more attractive roost for bats, although I observed no activity over the river either. I also believe that the absence of water in the park drastically limits the bats that may choose to roost there, and the road between the river and the bat box may serve as an ecological barrier due to light & sound. It's possible that moving the bat box farther away from the lights would help, or if larger plantings were established to screen the lighting and create a stronger canopy corridor. On site there was a huge mass of gnats at the top of the hill -- a feast for a population of bats that aren't there yet.
Bringing in Others
While I conducted this research mainly alone, I sought out opportunities to share my work with others. It was helpful to field questions from others, and practice synthesizing my findings verbally.
UW Undergraduate Research Symposium
In May, I presented my research abstract and portion of my project at the 24th UW Undergraduate Research Symposium. I wanted to represent the landscape architecture department to the larger UW community, and this was a great opportunity for me to organize and share my work in progress. The feedback I received from attendees and moderators was enthusiastic, with many people asking questions about bat species, how I got into this work, and bat life cycles. I was the only landscape architecture student who presented at the symposium, and I would highly encourage other students of the Built Environments college to participate in the future. For this presentation I submitted a 5 minute video, which you can watch on YouTube here .
Community Bat Walk
The invitation I shared on Instagram, with a photo taken by me.
It was important to me to engage my community of classmates and share the experience I had in the field with others. I advertised a "bat walk" on Instagram for people to attend and find out more about my work. We met at Golden Gardens on a clear Thursday evening, where I first fielded questions about my research and my bat knowledge. It was a beautiful evening enjoyed by all, and from the feedback I received it was an educational experience as well. It was really special to share this space with others, and I hope to conduct more bat walks for friends and colleagues in the future.
Having a bat chat before our walk at Golden Gardens. Photo taken by Brooke Sullivan.
The group finding their seats before the evening show.
Media Gallery
Click here for a gallery of images and videos I recorded during my field studies.
My Suggestions
Site Installations
In my field sessions, I was almost entirely alone, seeing no one else out observing the bats. By the time dusk fell, people had left the park. It appears to me that most people are simply unaware of the bat activity in their nearby parks. While basic education about common bat myths (that they get tangled in people's hair, that they are aggressive, that every bat carries rabies) is important, I wanted to move beyond square one and bring some unexpected levity to acknowledging bat presence in our parks.The public safety aspect of encouraging bat observation is tricky to navigate. Bat seek out darkness, not because they can't see in lighter conditions, but because it protects them from predation by owls and cats. I pushed my own boundaries of comfort walking around in these parks at night, even though I was well-equipped and aware of my surroundings. I would like to further explore creative ways to bring bat awareness to others using art and installation that is also accessible and safe. These proposals serve as just the starting point for this design process.
This neon marquee at Magnuson park was inspired by David Buckley Borden's work. It's intended as a playful sign, evoking the "open all night" signage of late night clubs and diners. Using pop culture and humor in ecological education may foster more positive feelings and conversation around bat populations than the standard graphic signage seen in most parks.
This LED installation was inspired by the irregular flight path of the California myotis that occupy the Golden Gardens wetland in the summer. The installation could be put up in the off-season to highlight the dark area and make a hard-to-track quality of bat activity visible to others, even from a distance.
Conclusions
Myotis californicus, or California Myotis
Expanding the Research
In this work I explored only three parks in Seattle; there are numerous others in the city that are worth exploring and documenting for bat presence. Carkeek Park, Green Lake Park, and Seward Park are all locations known to have bat activity, as reported by members of Bats Northwest. Additionally, there are numerous locations where bats may not currently be found but could be encouraged to inhabit with proper site maintenance, such as Discovery Park or lower Woodland Park.
Refining my Methods
As an un-funded, independently-led project, there was extensive room for improvement in conducting this research. Difficulty with capturing clear photos of bats at the site resulted from limited experience with nighttime photography and limited resources for field lighting; in the future I would like to use a remote strobe light and adjusted camera settings in order to capture, clear, illuminated photos of bats in flight.
One portion of the project plan that lacked follow-through was the interview portion; I had intended to spend time talking to landscape designers, ecological consultants and bat researchers to hear their ideas on how parks could be better utilized for bat habitat, and how they'd like to see landscape architects advocate for bats in their work. These meetings did not materialize, simply due to limited time and energy. In the future I would like to focus a project solely on interviews and discussion about bats with local experts.
My Experience
On a personal level, beyond the challenge of conducting research, I simply wanted to spend my last quarter at the UW outside, in parks, searching for wonder and delight in the nature available to me. I wanted to allow my senses and perception to guide me, and to allow for emergence in my work. I approached this project with a general sense of unknowing and unsureness in how it would turn out, but a strong sense of faith in my ability to find meaning and opportunity if I looked for it -- a perspective I didn't have when I began the landscape program in 2018.
Every time I saw bats at a research site, I felt a sense of awe and excitement in what I was observing. There were times where gratitude for the opportunity to observe nature in this way overcame me. When I look back on the lived experience of this work, one of my sessions at Golden Gardens comes to mind. I had started the night unengaged and tired, not even sure if I would stay more than an hour. What happened was that I had my most active night yet, capturing the most audio and video evidence so far. However, my DSLR battery died early on, leaving me just with my phone. After an hour of attempting to capture recordings, I decided to sit down at the base of a tree, turn off my headlamp, and simply watch the bats circling above me in the clearing next to the beaver pond. The stars were coming out, bats were swooping by me, and the trees were gently rustling in the wind. It's moments like that which feed my heart and my spirit, and it's a memory I know will stay with me for a long time after I leave the UW.