During the pandemic, my partner, Bayla, and I began taking daily walks down to Yale’s campus. We often noticed dead birds at the base of the glass walls that wrap the Yale School on Management building when we passed by.

Overlooked casualties of building all-glass buildings. Female and male Ruby-throated hummingbirds with broken beaks, killed by flying into @YaleSOM building. pic.twitter.com/Idl8q0mqWu

— A. Z. Andis Arietta, PhD (@azandisarietta) May 9, 2021

Because we both have working relationships with the Peabody Museum of Natural History, we began saving the bird specimens for the museum’s collection. Through that partnership, we learned that the School of Management building is one of the most lethal pieces of architecture on Yale Campus. We also met Viveca Morris at the Yale Law Ethics and Animals Program who had been helping to organize city-wide bird-strike data collections and spearheading a push to adopt bird-friendly building ordinances in New Haven.

Another @YaleSOM window strike casualty. Yellow warbler.#illustration #watercolour #watercolor #watercolorartist #birdsketch #birdart #deadbird #birdpainting #yellowwarbler #migratorybirds #warblersofinstagram #darkart #baylaart pic.twitter.com/QiX58rc9VX

— Bayla Arietta (@BaylaArt) May 26, 2020

One of the main barriers enacting mitigatory measures at the SOM building was that the lack of hard accounting of the total number of birds killed allowed the administrators of the building to downplay the problem. So, along with Viveca, we began a systematic survey of bird strikes at SOM. I’ll write more about that in a future post.

We also began thinking about the larger picture. How could we get more folks to recognize the magnitude of deaths due to thoughtless architecture? And how could we inspire folks to demand businesses, architects, and municipalities to adopt bird-friend design?

Bayla began painting some of the specimens we found. She posted a painting of five warblers we collected on a single day at SOM. The response was huge. That image seemed to have struck a chord. We realized that art could be a way to simultaneously introduce the topic and inspire emotions toward enacting change.

Bayla contacted Talon and Antler galleries in Portland, Oregon which feature some of our favorite contemporary artists and tend toward natural themes.

They agreed to let us curate a show with us. Over the next few months, Bayla contacted artists whose work fit the theme. In total, 62 artists contributed original pieces to the show titled, “Fractured Aviary”, which hung for the month of June 2022.

If you missed the show, you can see some of my favorites below:

HealingVeronica Steiner watercolor

CrashDarla Jackson plaster, clay, resin, acrylic

Window Strike IBayla Arietta watercolor, gouache, gold leaf

Window Strike IIBayla Arietta watercolor, gouache, gold leaf

Window Strike IIIBayla Arietta watercolor, gouache, gold leaf

The Last Song IIRebecca Reeves hand-beaded ceramic

Yallow WarblersVasilisa Romanenko

Regressive ReincarnationsTeagan White watercolor, gouache, charcoal

The WinoSteve Martinez acrylic, spray paint

In MemoriamMadison Erin Mayfieldgouache

Hollow BonesKatrina Haffner gouache, ink

Caecus VitrumErica Williams ink, gold foil on Bristol

Highway 21 MemorialJay Rasgorshek gouache

Silent DownVeronica Park screen print

Hothouse 3Josie Morway oil, enamel

FracturedBrin Levinson graphite

III of SwordsLauren Marx watercolor, ink, pencil

ImpactMiranda Brandon photo

Fractured Aviary: Ruby-throated Hummingbird-ThroatedHummingbird_04-webJane Kim Kim fabricated this amazing kaleidoscope of glass shards around her hummingbird painting. The dots on the outside represent window glazing patterns to prevent bird strikes.

Fractured Aviary: Ruby-throated HummingbirdKim fabricated this amazing kaleidoscope of glass shards around her hummingbird painting. The dots on the outside represent window glazing patterns to prevent bird strikes.

Broken SpellsJake Messing acrylic

I Am LostKate MccGwire feather

Our chapter tells the story of green frogs and the feral condition of their life with suburban human neighbors. We especially highlight the way that the human built-environment of lawns, pavement, sewers, and septic systems is infused into the biology of green frogs (a topic that Max and Dave have studied in depth). As a counter example, I told the story of the wood frog, a species that has escaped a feral fate by clinging to the remnants of wild space away from humans (a topic I study in depth).

I rarely get to write about wood frogs outside of academic articles, so it was a pleasure to contribute to this piece. I think it is some of my best natural history writing. I’ve excerpted my section below (or, read the chapter):

“To better understand why our housing patterns influence frogs, it is worth taking a frog’s-eye-view of suburbanization. Most frogs exhibit distinct life-stages. Like humans, frogs begin development as shell-less and fragile eggs, but while human embryos float within the protection of a womb, frog embryos are buoyed among the vegetation and flotsam of ponds. The embryos have an umbilical relationship to the water that surrounds them. Nutrients and oxygen easily pass through the transparent jelly and are consumed through delicately branching gills. Any contaminants in the water also suffuse the embryos.
Even before their eyes or mouths have formed, the developed embryos hatch as free-swimming larvae not much larger than a grain of rice. Hatchlings are vulnerable. Thus, frogs hedge their bets by producing hundreds of eggs per clutch, hoping that at least a few will win the lottery of life. Some species, like wood frogs, additionally safeguard their offspring by choosing impermanent pools that are devoid of fish as relatively safe nurseries.

Those hatchlings that survive develop into recognizable tadpoles with bulbous bodies and slender tails. A pond’s version of cows, tadpoles graze along the bottom with scraper-like teeth. They consume algae and detritus along with any solid matter that washes into the pond basin. A long digestive tract allows the tadpoles to incorporate nutrients into a growing body. Where ponds neighbor septic systems, this means that human waste makes up a prodigious portion of a tadpole’s body.

The transition from a tadpole to a frog is a remarkable change. It makes the squeaking voice and acne of human puberty seem like a blessing. Every system in the tadpole’s body transforms. The tail gives way to bony limbs. The narrow, disc-shaped mouth morphs into a wide, insect-capturing, gape. The goggle eyes, so fine-tuned to underwater vision, mutate into something much like our own. Even the long and coiled digestive tract shortens and distends. At the end of this metamorphosis, the aquatic vegetarian leaves the water’s edge and becomes a terrestrial carnivore.

Green frogs are parochial and prefer a pond-side life. For a short time as juveniles they might range far and occupy any standing water from lakes and ponds to swimming pools and tire ruts. Upon adulthood though, they settle along freshwater shores where they patiently wait for dragonflies and other insects to approach within range of a lunging gulp. Since green frogs inhabit permanent ponds, they can breed throughout the summer, and without the threat of the pond drying out from beneath them, their tadpoles can be leisurely in development. When snow falls and the pond freezes, both adults and overwintering tadpoles take refuge deep in the insulating layer of pond muck. Because a green frog’s life is so reliant on a pond, they can survive in just about any permanent water with at least a narrow perimeter of vegetation. As long as a homeowner neglects the tufts of grass along the bank, green frogs are more than happy to remain neighbors.

Unlike green frogs, wood frogs become sylvan nomads after metamorphosis. As their home ponds dry up in the summer and fall, they wander the forest floor hunting among the leaves, only briefly returning to recently filled pools in early spring to breed. During the winter months, wood frogs burrow just under the blanket of leaves dropped in fall. This enables them to be the first out of hibernation as the forest thaws in spring. For these reasons, wood frogs rely on leaf-littered landscapes. Manicured lawns where leaves are regularly raked and bagged make inhospitable places for them. Where the balance of forest gives way to lawns, wood frogs disappear…”

Overall, this was a really fun project to work on that gave me a chance to switch up my writing style. It was also a lot of fun to be able to collaborate with my partner, Bayla, who painted the featured image for the chapter.

The online version of the book is a little counter-intuitive to navigate (I think this was intentionally designed as a rhetorical device), but if you can figure it out, it is worth checking out some of the other cool stories of our feral world!

But it turns out, when you take the time to look closely, evolution is taking place all around us, fast enough for us to see and measure. What’s more, evolution may even happen faster around us since we humans tend to create novel and often extreme selection environments that encroach into natural habitats (or entirely new habitats for those species that hitchhike into citeis with us). Johnson and Munshi-South (2017) reviewed the growing list of studies uncovering rapid evolution of wildlife in response to urbanization.

I showed the article to my partner (Baylaart.com) who used it as a theme for her most recent piece which is comprised of organisms subject to contemporary urban adaptations. Both the article and the painting are exceptional work that I’ll walk through below.

When faced with new environmental challenges, populations of organisms are faced with two options: move or adapt. (The third, extreme alternative is extinction). Urban wildlife populations are either residual populations that existed prior to urban development or new populations that colonized after a city emerged.

A classic example of urban adaptation is industrial melanism in the peppered moth (Biston bitularia) (Kettlewell 1955, 1958). As soot poured out of cities during the industrial revolution, the light colored polymorphism of the peppered moth offered poorer camouflage than the black, soot-colored morph. As a consequence, the dark morph came to dominate urban populations. As industry cleaned up its act, the trend reversed.

We can see the effects of urbanization in modern cities, today. White-footed mice (Peromycus leucopus), a North American native, in urban settings are marked by much less genetic variation, and therefore, lower evolutionary potential (Munshi-South et al. 2016). On the flip-side, this reduced variation could be the result of selection sweeping all unadapted alleles from the population, leaving a more genetically homogenous population as a result of the evolutionary process. Even animals that look unchanged may have evolved subtle adaptations. For instance, blackbirds (Turdus merula) in cities exhibit a molecular level difference in a gene associated with harm avoidance behavior compared to their natural brethren (Mueller et al. 2013).

Some species have adapted so well to urbanization, that they are almost synonymous with cities world-wide. For instance, the German cockroach (Blatella germanica), Rock dove (Columba livia), and Norway rat are veritable mascots of cities. Urban roaches and rats have evolved resistance to pesticides (Booth et al. 2011; Rost et al. 2009), and roaches in cities have even evolved an aversion to glucose in response to selection by sugar-baited traps (Wada-Katsumata et al. 2013). Rock doves in the cities have evolved defenses, not to human extermination attempts, but to predation by city-dwelling falcons (Palleroni et al. 2005).

Some populations precede city creation. Red-backed salamanders (Plethodon cinerus) in Montreal, Canada managed to persist as the city was constructed around them, but their populations have been isolated genetically, resulting in low variation (Noel & Lapointe, 2010). Across the Atlantic fire salamanders (Salamandra salamandra) also had a city (Oviedo, Spain) built atop their population starting over a millennia ago and managed to persist despite severe restriction in gene flow (Lourenco et al. 2017). Animals don’t need hundreds of years to adapt to new development, though. Water dragons (Intellagama lesueurii) inhabiting newly established city parks built as recently as 2001 in Brisbane, Australia have developed genetic difference in body shape and total size (Littleford-Colquhoun et al. 2017). Similarly, a small population of dark-eyed juncos (Junco hyemalis) established in the 1980s have been thoroughly studied (due largely to their location on the UC San Diego campus) and found to have evolved shorter wings, shorter tails, and alternate plumage pattern in just the past few decades (Rasner et al. 2004; Yeh 2007).

Other species, like the common wall lizard (Podarcus muralis) and striped mouse (Apodemus agrarius), seem to have been able to adapt to the development of Trier city in Germany (for lizards (Beninde et al. 2016)) and Warsaw, Polans (for mice (Gortat et al. 2014)) and now disperse through the city architecture in a similar way to their natural environment. Cityscapes can offer very similar (although much more angular) habitat to an organism’s natural habitat. For instance, Anoles (Anolis cristatellus) perch on the vertical trunks of trees in the forest. The flat walls of building in Puerto Rico offer a similar niche; however, artificial walls tend to provide less grips for lizards. In response, urban Anoles have evolved longer limbs and stickier toepads to cling to homes and businesses (Winchell et al. 2016).

Small animals are not the only wildlife subject to urban impacts. The movement of many large mammals, such as bobcats (Lynx rufus) (Serieys et al. 2014), are restricted by roadways, despite our best efforts to promote connectivity. In some cases, large and mobile animals are able to break into the new habitats afforded by cities. Red foxes (Vulpes vulpes) colonized the city of Zurich, Switzerland less than two decades ago and in that time their urban populations have exploded (Wandeler et al. 2003). While the original urban populations were likely established by just a few intrepid foxes, now that the urbanite populations are large enough, they have established genetic connectivity with their rural counterparts, essentially extending the larger population’s range to include the city.

In addition to landscape alterations that reduce gene flow and incur selection, urban settings can actually increase genetic mutation rates (which is ultimately the raw substrate for evolutionary adaptation). As an example, the rate of mutation in herring gulls (Larus argentatus) that nest in a heavily industrialized site in Ontario is double their less urban counterparts likely due to exposure to toxic chemicals in the environment (Yauk & Quinn 1996).

Let’s not forget that animals are not alone in their evolutionary response to urbanization—plants have also demonstrated adaptations to cities. Clover (Trifolium repens) in urban populations have evolved a reduction in cyanogenesis, a process that makes the plant less palatable to herbivores but in trade-off leaves the plant less tolerant of freezing temperatures (Thompson et al. 2016), which makes sense since there aren’t many large grazers wandering city streets and urban settings tend to act as heat islands.

In order to reduce seeds falling on infertile concrete streets and sidewalks, Holy hawksbeard (Crepis sancta) a weed in Montpellier, France have evolved to produce less dispersing seeds (Cheptou et al. 2008). In addition, the urban plants evolved an increase in photosynthesis and larger flowers (Lambrecht et al. 2016). Virginia pepperweed (Lepidium virginicum), is a common weed in many U.S. cities. A study of genetic divergence between urban and rural settings found that urban plants were more closely related than the more geographically proximal rural populations (Yakub & Tiffin 2016). In addition, the city pepperweed had developed a different shape and growing season to rural plants.

It’s clear that almost anywhere you look in cities, wildlife is evolving in response to our presence. This bestows us with a massive responsibility and indebts us to an ethic of conservation, not of species themselves, but to preserve as much unencumbered wild habitat as possible (for instance, as designated Wilderness). Where saving wild space is impossible, we must work on mitigating the effects of our urban infrastructure (for instance).

Literature cited:

Beninde, J., Feldmeier, S., Werner, M., Peroverde, D., Schulte, U., Hochkirch, A., et al. (2016). Cityscape genetics: structural vs. functional connectivity of an urban lizard population. Mol. Ecol. 25, 4984–5000.

Booth, W., Santangelo, R. G., Vargo, E. L., Mukha, D. V., and Schal, C. (2011). Population genetic structure in german cockroaches (blattella germanica): differentiated islands in an agricultural landscape. J. Hered. 102, 175–183.

Cheptou, P.-O., Carrue, O., Rouifed, S., and Cantarel, A. (2008). Rapid evolution of seed dispersal in an urban environment in the weed Crepis sancta. Proc. Natl. Acad. Sci. U. S. A. 105, 3796–3799.

Gortat, T., Rutkowski, R., Gryczyńska, A., Pieniążek, A., Kozakiewicz, A., and Kozakiewicz, M. (2015). Anthropopressure gradients and the population genetic structure of Apodemus agrarius. Conserv. Genet. 16, 649–659.

Johnson, M. T. J., and Munshi-South, J. (2017). Evolution of life in urban environments. Science 358.

Kettlewell, H. B. D. (1955). Selection experiments on industrial melanism in the Lepidoptera. Heredity 9, 323.

Kettlewell, H. B. D. (1958). A survey of the frequencies of Biston betularia (L.) (Lep.) and its melanic forms in Great Britain. Heredity 12, 51.

Lambrecht, S. C., Mahieu, S., and Cheptou, P.-O. (2016). Natural selection on plant physiological traits in an urban environment. Acta Oecol. 77, 67–74.

Littleford-Colquhoun, B. L., Clemente, C., Whiting, M. J., Ortiz-Barrientos, D., and Frère, C. H. (2017). Archipelagos of the Anthropocene: rapid and extensive differentiation of native terrestrial vertebrates in a single metropolis. Mol. Ecol. 26, 2466–2481.

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Mueller, J. C., Partecke, J., Hatchwell, B. J., Gaston, K. J., and Evans, K. L. (2013). Candidate gene polymorphisms for behavioural adaptations during urbanization in blackbirds. Mol. Ecol. 22, 3629–3637.

Munshi-South, J., Zolnik, C. P., and Harris, S. E. (2016). Population genomics of the Anthropocene: urbanization is negatively associated with genome-wide variation in white-footed mouse populations. Evol. Appl. 9, 546–564.

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Yakub, M., and Tiffin, P. (2017). Living in the city: urban environments shape the evolution of a native annual plant. Glob. Chang. Biol. 23, 2082–2089.

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