June 28, 2018

Bird Species Diversity in New York City Parks

What accounts for species diiversity, specifically species richness, in an urban park? Is it the size of the park? Is it habitat diversity within the park? Is it the location of the park relative to birds' migration route?

I am interested in these questions because of my interest in urban ecology, but also specifically because I am involved in a long-term wildlife survey project in Washington Square Park, a 9.75-acre located in NYC.

Looking at the park acreage, you would expect that Central Park at 843 acres would have the most bird species. It does. You probably also know that those 843 acres are packed with different types of bird-friendly habitats. But acreage and habitat abundance can't be the entire story. Bryant Park at 9.6 acres is 1.1% the size of Central Park, yet it has 55% of the number of species of Central Park. Bryant Park is a well-established hotspot for a very broad range of birds. Read the guide to birding in Bryant Park by NYC Audubon. The guide points out several "best birding spots" in the park: perennial borders, the London planetree allees surrounding the park, honey locust stands, and a limited access maintenance area. Other parks have these elements and more so what else could account for such high numbers in Bryant Park?

The NYC Audubon guide provides a clue. Bryant Park is located in midtown Manhattan and is densely surrounded by some of the city's tallest buildings. The park appears as an oasis during nighttime migration flights.
After a long night’s flight, nighttime migrants flying over Manhattan must seek a place to rest and feed among the City’s landscape of cement and glass. The results can be almost surreal.
The other small parks on the chart aren't similarly located.

Another major factor which is not directly related to the biogeography of the park is the data generation process, specifically who records the data and when is a bird species recorded on a checklist. Consider the first aspect. The bird numbers presented here were taken from eBird Hotspot Maps. eBird is a contributory citizen science project meaning members of the public are submitting the data. Maybe people who bird in Bryant Park log their data with eBird more than birders in other parks. 2112 Bryant Park checklists have been submitted to eBird versus 428 in Madison Square Park and 289 in Washington Square Park. An element that connects this first issue with the one I explore in the next paragraph is the defining characteristics of the data recorder. If the person is an expert birder, she might spot more birds than a newer birder. If the checklists for a park are derived primarily from expert-led bird walks then more birds might be recorded in that park.

The second component of the data factor is what counts as a species sighting. Who is contributing the majority of species records in each park and what criteria are they using? WSP Eco Projects follows a standardized bird survey protocol but this is not the case for each member of the public birding in a NYC park. For the purposes of the long-term wildlife survey, we only record birds that are seen within the boundaries of the park with the exception of the resident nesting pair of Red-tailed Hawks. Other birders might record flyovers and birds identified by sound only.

Species diversity in these NYC parks seems to derive from a combination of factors -- within-park habitat, the urban form of the surrounding matrix, the number of eBirders in the park. It's worth comparing Bryant and Central Parks again. Bryant Park has 2112 checklists to Central Park's staggering 13,583 checklists. Bryant Park only has 15% the number of checklists as Central Park yet it has 55% the number of total bird species of Central Park. There's something about Bryant Park!

I don't envy Bryant Park's location in the city but I do think Washington Square Park can be made more bird-friendly through habitat management. WSP Eco Projects has an advocacy mission, too. In our first two permit reports, we encouraged the NYC Parks Department to consider expanding its herbaceous perennial beds in terms of size and native species. We also recommended planting more fruit-bearing and evergreen woody species. We will continue to make the case for bird-friendly plantings in Washington Square Park.

P.S. As I wrote this post, the chart became outdated. Madison Square Park now has 100 bird species.

May 22, 2018

Arbor Month Photos

It's almost too sentimental to write but every day is Arbor Day for me. I am passionate about trees. One of my favorite tree places is Washington Square Park. 

During Arbor Month I posted a tree-related photograph to the Instagram feed of Washington Square Park Eco Projects. National Arbor Day is the last Friday in April but your state might observe it at a different time of year. Check out this Arbor Day calendar.

I began the month with a Magnolia stellata flower. I followed a single flower on a star magnolia in the park from bud to bloom. I did the same for other trees in the park including crabapple and Yoshino and Kwanzan cherries. I began this phenology project last year. I was much more systematic this year. There is room for refinement, however. I'd like to watch the same bud over time but I haven't figured out a discreet and safe way to mark the buds of interest.

The showy-flowering trees were well represented in the Arbor Month photos but I also paid homage to the so-called inconspicuous flowers. If you know what you are looking for, the flowers of maples, oak, and dogwoods are not so hidden.

While the Arbor Month collection is filled with close-ups of buds, blossoms, and new leaves, I also showcased individual trees or groves of trees.

Regrettably, I did not plant a tree this year. I have not planted a tree for Arbor Day in a very long time. I think the last time I did so was when I worked as the urban forester for the City of Boston in the early aughts. Have you planted a tree this year? Was it in honor of Arbor Day?

May 17, 2018

Green Neighborhood Tour of Greenwich Village

I am a huge fan of walking tours, especially ones set in cities. I typically veer towards nature-oriented ones, so for example, I joined a guided bird walk in Battery Park on Tuesday and saw a record number of species (for me), of which at least 11 of the 33 species were warblers. The tour I share in this post was billed as "A 'GreenNeighborhoodod Tour." It was led by Bettina Johae, co-founder of aplusnyc.net, an architecture and art tour company based in NYC.

We met on a gorgeous Saturday morning in the Sasaki Garden at Washington Square Village, the first parking garage roof garden (in the U.S., I think). The garden was completed by the landscape architecture firm of Sasaki, Walker and Associates in 1959. Ms. Johae provided an overview of the tour and discussed the natural history of Manhattan and the Greenwich Village neighborhood. The island of Manhattan was known as Mannahatta or "island of many hills" by the Lenape. Greenwich Village was marshland with a creek coursing through it. A couple of years ago I walked a self-guided tour of artist Beatrice Glow's Lenapeway and contemporary native gardens.

From the Sasaki Garden, we headed south to another superblock, the New York University Silver Tower designed by architect I.M. Pei. At the center of the superblock are several small greenspaces one of which is locally known as the "oak grove" filled with red and willow oaks and a young white oak. A former lawn area was transformed into the Urban Farm Lab in 2013. My family has been assigned a plot in this garden and I'll share updates as soon as we break ground.

The next stop was the Time Landscape, a land art project developed by Alan Sonfist. I've been researching this landscape and learned that Sonfist conceived of it as a monument to "the history of the natural environment at that location" pre-European settlement. He had hoped that there would be many such monuments installed throughout the city but Time Landscape is the only one. This idea of a living memorial to pre-settlement nature in what are now dense residential neighborhoods has not been communicated very well by the artist. Some people perceive the site to be a place of "weeds." Others, including me, value it for its very passive aspect. As far as I know, only one layperson has a key to the gate. Plants, both cultivated and spontaneous, and wildlife get to enjoy it at their pace.

We walked north and stood across the street from the Center for Architecture. While not a landscape, Ms. Johae pointed out that a geothermal heating system was installed in 2003. From there we went to my favorite park in the city - Washington Square Park. I was pleasantly surprised when Ms. Johae used the Washington Square Park Eco Map to illustrate her points about Minetta Creek. I've written many posts about Washington Square Park.

The next stop two stops were examples of POPS or privately owned public spaces. An encounter at the first stop highlighted one of the challenges of these spaces. We were told by a security guard that we could not gather in the plaza space of 300 Mercer Street. This is a publicly accessible space but it is not signed to indicate public use. Ms. Johae advised the guard our right to be in the space even when he said he would call the police. He did not.

There were four stops remaining and I'll focus on two of them. One was the facade landscape of 41 Bond Street. This one of my favorite facades in the neighborhood. The bluestone cladding is inviting though I've never touched it. I'm always afraid that security personnel from the building would come out with harsh questions. This is a luxury building; the average sale price per square foot is $2,661. Each window has a landscape planter. The building has a green roof as does the entrance marquee.

The final stop was a place I have been wanting to visit. My son had been there before me. It is Walter de Maria's The New York Earth Room. The installation is on the second floor and the 3,600 square foot room is filled with 280,000 pounds of earth, peat, and bark. The dirt has been in the space since 1977. My first impulse was to sink my hand into the earth but you are not allowed to touch the art. Also, photographs are not allowed. View the sculpture here. The smell of the sculpture is overwhelming; you feel as if you've stepped into a moist temperate forest, or an old, unfinished New England basement.

My daughter accompanied me on this tour and she did so with minor fuss. I include this information here as a testament to the vibe and content of the tour. Also, there were two older girls (by a few years) on the walk and my daughter delighted in engaging with them. Ms. Johae was knowledgeable and affable. The walk went longer than advertised but most participants stayed until the end and even lingered.

Do you take walking tours in your home city?

April 24, 2018

Natural and Artificial Materials in Bird Nests

It can be tricky to find the live video of the NYU Hawk Cam. Here's the link. One of the first times I attempted to watch the live feed, I watched several minutes of a video from the 2017 season. All was not lost, however. The clip I watched showed in stark relief the trash the Red-tails had used to construct and decorate their nest. The “wrong” video inspired this post about nesting materials.

Not all birds build nests. Of the species that do build nests, not all of them decorate their nests. Decoration can accomplish one or more of several goals: (1) camouflage the nest, (2) attract a mate, (3) signal status, or (4) improve health outcomes. Zebra Finch males are responsible for nest building and they choose nesting materials that match in color the background of their nest locations, according to research by Bailey et al. 2014. The building, maintenance, and defense of its elaborate nest communicate to bowerbird females the fitness of the male architect as studied by Borgia et al. and reported in the New York Times. Male Black Kites in Spain almost exclusively use white plastic to signal their prowess. White plastic was chosen over other colors of plastic because of its "long-distance visibility." Sergio et al. observed that "Kites with much plastic in their nest were rarely challenged, while those with little were challenged daily, even hourly" as reported by Wired.com. House Sparrows and House Finches have been found by Suárez-Rodríguez et al. (2012) to use cigarette butts to reduce parasite populations in their nests.

Typically, nest-building birds use natural materials such as sticks, feathers, moss, leaves, etc. to construct and decorate their nests. However, in the last two examples in the previous paragraph, we see that birds are incorporating artificial materials in their nests. Josué Corrales, writing for The Nature of Cities, points out that the use of artificial materials by birds is influenced by proximity to a source of such materials. This can be the case whether the nest is located in a city or in a "natural area". In addition, birds are making substitutions because particular types of natural materials such as clay are in limited supply in urbanized areas.

Corrales concludes his essay arguing that the use of artificial materials can negatively impact reproductive success. Earlier he provided two examples of poor outcomes for birds who use plastic materials. Plastic can increase the temperature in the nest which is harmful to egg maturation and chicks could become entangled in plastic items. On the flip side, he notes that the use of novel materials could camouflage the nest from predators. Also, items like cigarette butts act as a parasitic repellent. Suárez-Rodríguez et al. (2017) found a downside to the use of cigarette butts, however. Although the nicotine in the butts reduces the numbers of ectoparasites, direct exposure to the same nicotine during breeding activities such as nest building and incubation was observed to be toxic to the House Sparrows and House Finches in the study.

The first female of the pair of Red-tails at Washington Square Park died from heart failure following surgical amputation of her foot. One of her feet became necrotic after the leg had been entangled in plastic line for several weeks reported the New York Times. In the lead image of the Times article, the same plastic material is seen in the structure of the nest.

The typical form of a Red-tailed Hawk's nest is a "bulky bowl of sticks, lined with finer materials, often with leafy green branches added," according to Audubon.org. In the lead image of this blog post, you can see that the 2017 nest was a large bowl constructed of sticks and lined with a wide assortment of plastic and plastic-derived materials. The current nest has fewer novel materials but artificial materials have been used to construct, line, and possibly decorate the nest. There are no fine plastic strings or lines in the current nest so the risk of entanglement is quite low. There don't appear to be any green materials in the nest though if there had been they are probably no longer brown. I am a regular watcher of the live feed and haven't noticed green materials being brought to the nest. The nest is across the street from 9.75-acre Washington Square Park. The park's vegetation is largely deciduous but there are evergreens including pine, spruce, cedar, and holly. I'll have to pay close attention to nest refreshment activities. In Life Histories of Familiar North American Birds, Arthur Cleveland Bent writes, "Some nests are profusely and beautifully lined with fresh green sprigs of white pine, which are frequently renewed during incubation and during the earlier stages in the growth of the young.frequently renewed during incubation and during the earlier stages in the growth of the young."

April 2, 2018

White-throated Sparrow Field Marks

The White-throated Sparrow is often overlooked in a flock seemingly populated by House Sparrows despite its striking field marks. The next time you encounter a gathering of sparrows, give it a closer look, preferably from a distance with binoculars.

The White-throated Sparrow is a winter bird in New York City. I observe them often in my favorite birding patch, Washington Square Park. The species is one of fourteen species recorded in the park this winter. Another hotspot for them in my neighborhood is the Washington Square Village Sasaki Garden. The birds that winter in our area will migrate northward for the breeding season. When I look at data from September 2016 to February 2018, there are big population spikes between October and February and the number of individuals drops dramatically in the intervening months.

A member of the New World Buntings and Sparrows, the White-throated Sparrow is in the same family as birds such as Fox Sparrow, Dark-eyed Junco, White-crowned Sparrow, and Swamp Sparrow. I specifically listed these four species because they have been observed in Washington Square Park.

The presence of three field marks and a foraging behavior are distinctive of the White-throated Sparrow. Like the White-crowned Sparrow, it does have a bold black and white crown. Similar to the Song Sparrow, the tan-morph of the White-throated Sparrow has tan crown stripes. However, no other related species has the combination of black and white crown stripes, bright white throat patch, and yellow lores, though the latter feature is less noticeable in the tan morph. I'll take about morphs more below.

A friend refers to the species' foraging behavior as the "White-throated Sparrow shuffle". Don't the toes look perfect for scratching and disturbing leaves?

Coming back to the presence of morphs in this species -- the White-throated Sparrow is polymorphic. This plumage polymorphism is unaffected by age or season. Both sexes exhibit the trait; you will find male and female exhibiting white-stripe and tan-stripe crown plumage. One fascinating aspect of this polymorphism is its role in mating preference. Males of both morphs prefer the white-stripe female while females of both morphs prefer the tan-stripe male. The female white-stripe is more aggressive than her tan-morph counterpart and will outcompete her for a tan-morph male. The white-stripe female's territorial behavior is more attractive than the passive boundary making behavior of the tan-stripe female. The tan-stripe male is the desirable mate because he is more involved in nesting activities. These factors contribute to the bi-morphic pairings observed during the breeding season.

Its wings are not among its defining field marks. Yet, I am struck by their beauty: coverts of mostly black vanes with edges of russet and tipped with white to form two sets wing bars. What do you think?

Sources used in this post are:

March 27, 2018

Washington Square Park Red-tailed Hawk Nest

Update: The three eggs hatched and the eyases fledged June 16th, June 19th, and June 21th. 

Update: A third egg was laid on March 30th. 

With the laying of two eggs in the Washington Square Park Red-tailed Hawk nest, now seems like a good time to share a nesting profile of the species and particulars about the park's resident hawks.

Image: Washington Square Park Red-tailed Hawk Nest, March 27, 2018, 11:45 AM

Red-tailed Hawks lay one brood or set of eggs each season. The number of eggs in the brood ranges from one to five. The WSP hawks have laid between two and three eggs annually since 2011. Red-tailed Hawks are monogamous, mating for life. The male hawk (named Bobby) has not changed since the mating pair formed, but there have been three female hawks.

Violet, the first female hawk, laid three eggs in 2011 but only one survived to be named Pip. (Pip is an ornithological term referring to the hole in the egg made by the hatchling's egg tooth.) Violet died at the end of 2011. During her rehabilitation off the nest, a female hawk, eventually named Rosie, arrived in the territory and paired up with Bobby.

Rosie laid two eggs in 2012. The eggs hatched and fledging was successful. In 2013, she laid three eggs and all of them hatched. Rosie laid two eggs in 2014 both of which hatched. Rosie left the territory in the fall of that year.

By February of 2015, Bobby had a new mate, Sadie/Aurora. The pair incubated three eggs but only two hatched and fledged. Sadie again laid three eggs in 2016.  However, only one hatched. That chick fledged in June. 2017 marked the third consecutive year that Sadie laid three eggs. Despite successfully incubating two of the three eggs, one of the hatchlings died. The third egg never hatched.  It's safe to say that hawk watchers are delighted by and anxious about this nesting cycle. The dates and numbers provided so far were gleaned from posts on the Roger_Paw blog.

Here's the information in table form so it's easier to visualize.

2011 Bobby + Violet 3 11Violet died
2012 Bobby + Rosie2 21
2013 Bobby + Rosie 3 33
2014 Bobby + Rosie 2 22Rosie left the territory
2015 Bobby + Aurora/Sadie 3 22Female known by two different names
2016 Bobby + Aurora/Sadie 3 11
2017 Bobby + Aurora/Sadie 3 21
2018 Bobby + Aurora/Sadie 3 33Lay: 3/24, 27, 30; fledge: 6/16, 19, 21

The male and female hawks share nest-building duties. The male also participates in incubating the eggs but this task is mostly done by the female hawk. Incubation begins with the first egg and lasts anywhere from 28 to 35 days. Chicks are nestled for a period of up to 46 days.

The traditional location of a Red-tailed Hawk's is in a tall tree with a fairly sweeping view of the surrounding landscape. Red-tailed Hawks also nest on cliff ledges and on human-made structures such as window ledges. In the case of the Washington Square Park Red-tailed Hawks, the nest is on a ledge of the Bobst NYU Library. The ledge is quite deep and affords a view of the almost 10-acre park. Within the hawks' territory are many tall buildings that provide advantageous perches. The hawks have used the same nest each season which is typical of this species. They repair it annually. I have seen them collecting and arranging nesting material. The nest extends beyond the width of the window ledge; you can see it if you look up while standing on West Fourth Street.

Related link: Natural and Artificial Materials in Bird Nests

Will the female hawk lay another egg this season? To see the nest happenings, watch the hawk cam.

Nest information provided in this post sourced from All About Birds here and here.

March 22, 2018

City Creatures edited by Gavin Van Horn and Dave Aftandilian

I am drawn to stories that expand and deepen my knowledge about urban wildlife. CITY CREATURES edited by Gavin Van Horn and Dave Aftandilian does this well. The hefty edition of essays, poetry, paintings, and photographs illuminate the range of animals living in cities and our multiple relationships with them. I am happy to present a book review.

Image: City Creature book cover via University of Chicago Press

Gavin Van Horn and Dave Aftandilian are natural fits for a book of this ilk. Van Horn is director of Cultures of Conservation for the Center for Humans and Nature and is writer and editor of the center's blog, City Creatures. He's the co-editor (with John Hausdoerffer) of Wildness: Relations of People and Place (2017) and the forthcoming The Channel Coyotes: Otherworlds of the Urban Wild. Aftandilian is associate professor of anthropology and director of the Human-Animal Relationships (HARE) minor at Texas Christian University. He's the editor of What Are Animals to Us? Approaches from Science, Religion, Folklore, Literature, and Art.

The subtitle of CITY CREATURES is "Animal Encounters in the Chicago Wilderness." The latter part of the subtitle refers to the Chicago Wilderness coalition formed in 1996 to do regional-scale conservation and restoration work. The perhaps purposeful use of the word "wilderness" forces one to discard notions of the city as a place antithetical to wilderness. With this book, Van Horn and Aftilidian argue that the city-region is "a hot spot for biodiversity," not a "biological desert."

The animals that are storied in this book are not all traditionally wilderness species nor are typically wild creatures found in their natural habitats. The first story of the book is about chickens which seems the most domestic of animals without being a pet. But essential to CITY CREATURES is all the ways in which humans and non-human animals are in relation with each other. Other stories in the 'Backyard Diversity' section deal with squirrel, opossum, raccoon, hawk, scarab, and wasp. The next section, 'Neighborhood Associations', also features animals of daily encounters though the spaces we tend to encounter them are a bit beyond our domestic/home realm. Still squirrel but also coyote, bee, cricket, pigeon, feral cat.

The third section, 'Animals on Display," is a striking shift from the creatures considered in the first two section. The spaces of animal encounters are zoos, aquariums, and museums. The animals are live and dead. I have an uneasy relationship with zoos and aquariums. I visit them and have taken my children to them, but I'm never sure if I should. Museums on the other seem more comfortable territory, though the provenance of the collections aren't without their controversies. I particularly enjoyed the stories about museum specimen collections because I am learning to prepare museum quality bird study skins for a teaching collection. Rebecca Beachy's "A Living Taxidermy" documents the process of creating a study skin from a salvaged Ringneck Pheasant. The preceding story, "Nature on Pause" by Peggy Macnamara, is illustrated with the author's beautiful paintings of bird mounts, study skins, nests and eggs as well as pinned butterflies and frogs preserved in jars housed at the Field Museum.

The fourth section represents another dramatic transition. The stories shift from corralled spaces to the more open spaces of parks, forests, and "natural areas." Soil as an expansive space is also featured in photographs of Sharon Bladholm's casts of insects. Andrew S. Yang's "Letting the City Bug You" is a phenomenal exploration of collecting insects, as an adult, in the city.
An interest in insects seems like an odd mix of the quaint, the trivial, the gross, and certainly the uncultured....to pay attention to insects seems like the symptom of an unfettered curiosity that is acceptable in a kid but seems awkwardly deviant in an adult.
And yet as singular or even unsocial as seeking insects might seem at first, I have found that its public nature can lead to unexpected connection. Mobile and spontaneous, new social spaces have opened in surprising ways....Passersby look twice,smilesquint, and just as often stop and ask what we were doing. They want to look at what we are looking at, and consequently they see something they wouldn't otherwise find.
Many of the urban natural history books I've read focus on terrestrial animals, often vertebrates. CITY CREATURES gives significant page time to non-vertebrates and to aquatic animals. The habitat types in 'Water World's range from lake to river, from creek to pond. Possibly my favorite story in this fifth section of the book is "Canoeing through History: Wild Encounters on Bubbly Creek" by Michael A. Bryson, though many more birds than fish are mentioned in the story. I like this story for a few reasons. I enjoy visual elements in stories and the author's map drawing of the creek and its environs is a figure in the story. The map is annotated with significant places mentioned in the story. "Canoeing through History" is smoothly narrated with detailed information about what the participants saw in the water and along the creek's banks. The author narrates in the first person but he also uses the collective "we" which I found engaging. Finally, I appreciated the author's consideration of the socio-politcal dynamics that affect nature appreciation and access.

Van Horn and Aftandilian describe the sixth section of the book as coming "full circle" because the stories consider two sets of animals: (1) ones that inhabited the landscape before urbanization, were locally extirpated, and have been reintroduced (bison) or are reclaiming territory (coyote) and (2) ones that have become naturalized (monk parakeet) or are feral populations of formally kept species (pigeons). Dave Aftandilian's story and illustration of an inhabited monk parakeets' nest is not to be missed. This section, and the book, ends with a painting titled Indiana Dunes by African American painter, Blake Lenoir. You can find images of some of Lenoir's paintings here. The verdancy and faunal diversity, with a deep blue thread of water, depicted in the painting speaks a thousand words about the pre-colonial landscape of Illinois.

There really is so much to recommend about CITY CREATURES  In additional to its astounding central content, a rich resource list is provided at the end of each story and at the conclusion of the book. The mix of story, poetry, and art is unique to this book, I think. And well executed. An artwork or artworks preceding or following a poem or story is either about the topic of the writing or related thematically. A couple of my favorite groupings are:

  • "Keeping Chickens" by Terra Brockman followed by Colleen Plumb's photograph "Holding Backyard Chicken" and a photograph of Alma Dominguez's exhibit "Consumes mi dolor...mi merge/You consume my pain...my death" which features chickens.
  • Between "Canoeing through History" by Michael A. Bryson and "Calumet" by John Rogner is a poem titled "The Fish in the Cage" by Todd Davis sandwiched on each side by two artworks: Riverwalk Gateway, the South Branch of the River and Riverwalk Gateway by Ellen Lanyon as well as Pond Reflection and Flood by Eleanor Spiess-Ferris.
I wish I could collect many of the artwork in the book as postcards or as small canvases to hang in my apartment. The list of favorites is too long to list here. One of the more inspiring ones is Diana Sudyka's illustration titled Birds Spotted While Hiking Wooded Isle, Hyde Park, Illinois. You can view the Hyde Park bird print here.

Although CITY CREATURES is clearly grounded in the Chicago region, the overarching themes of the city as ecologically rich and dynamic space and the multiplicity of relationships between humans and non-human animals are relevant in many, certainly North American, cities. I especially appreciate that the book does not present a dismal ecological outcome. While it does point out the damaging impact that humans have had and continue to have on ecosystems, the first-person narratives in the book clearly illustrate not only the fostering role of humans but also the agency of wild animals in reclaiming and staking out territories in cities.

A complimentary copy of CITY CREATURES was provided by Gavin Van Horn.