Monthly Archives: February 2014

How the White-Crowned Sparrow changes its tune to be heard through the urban din

Last October, I was invited by Laurel Serieys (a graduate student at UCLA)  to present a paper at The Wildlife Society’s 20th Annual Conference in a symposium on how urbanization can cause wildlife populations to diverge by altering behavioral, physiological, and genetic aspects of populations occurring in cities compared to non-urban areas. This is an emerging field of research as we are beginning to build a better understanding of how different cities are as habitats for many species, and the different ways by which they may adapt to city life – or not. This approach is part of the research strategy which should help explain some of the broader patterns we are observing in the distribution of biodiversity in the world’s cities.

I spoke about the effects of urban noise on bird song, based on the excellent Masters thesis project by my (now former) graduate student Jenny Phillips, who studied migratory White-Crowned Sparrows spending the winter in California’s Central Valley. Jenny has since gone on to a Ph.D. program at Tulane University, working in the lab of Elizabeth Derryberry, who was on her MS thesis committee (and with whom I intend to continue collaborating to extend this research).

Photo of White-Crowned Sparrow sitting in a fence

A white crowned sparrow framed in the demarcated landscapes of California’s Central Valley. Photo by Madhusudan Katti, 2008.

I just remembered that TWS was recording talks and sessions throughout the conference, and went looking to see if my talk was recorded. Indeed it was! So if you are interested in hearing about some of Jenny’s and my work on urban bird song, have a listen to my talk on this page, which shows you my slides coupled with my ghati-accented voice:

Singing in the urban din: the effects of anthropogenic noise on song structure in urban birds

Note: the audio had glitches when I tried listening through Safari, but worked fine on Google Chrome; YMMV.

Here’s my abstract for that talk:

Female birds often use male song as an indicator of mate quality; thus the study of song provides insights into reproductive success. Song structure is constrained by the acoustic environment with selection favoring songs that transmit best through available channels given ambient noise and atmospheric conditions. Ecology_specifically those components of the environment that influence sound transmission_thus influences the cultural evolution of songs. One relatively new selection pressure on many birds’ song, is anthropogenic noise, from car traffic as well as industrial machinery and other urban sources. Urban noise resonates at low frequencies and has been shown to influence song frequencies in sedentary populations of song sparrows, great tits, and blackbirds. Increase in ambient noise has also been shown to diminish discriminatory ability in female zebra finches. I first present a brief conceptual overview of the potential and documented effects of urban noise on bird song and behavior. I then share results from ongoing studies of the effects of noise on song in White-crowned Sparrow, Zonotrichia leucophrys gambelii, a long distance migrant wintering in urbanizing areas of central California. Songs and noise were recorded across the urban-rural noise gradient in Fresno-Clovis Metropolitan Area and compared for acoustic differences in frequency and duration. Modulated note components of the song, the buzz and trill, decreased in bandwidth with increasing noise. The duration of the buzz portion can also be predicted by noise and habitat type. This trend towards short, pure tones in noisy areas is likely an adaptation to be better heard through the roar of the city. Playback experiments also found increased latency to respond to territorial simulations under high ambient noise levels. This may contribute to a breakdown of territoriality in urban habitats. Anthropogenic noise is likely to be an important driver of population divergence due to urbanization.

More birds and plants in the world’s cities than expected – a new paper from my NCEAS team

Tea with sparrows

A special present to celebrate this Darwin Day: the publication of the first paper from my global collaboration to study patterns and processes in biodiversity among the world’s cities. This first fruit of a collaboration that started 3 years ago under the aegis of the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara has just been published in the Proceedings of the Royal Society B:

M. F. J. Aronson, F. A. La Sorte, C. H. Nilon, M. Katti, M. A. Goddard, C. A. Lepczyk, P. S. Warren, N. S. G. Williams, S. Cilliers, B. Clarkson, C. Dobbs, R. Dolan, M. Hedblom, S. Klotz, J. L. Kooijmans, I. Kuhn, I. MacGregor-Fors, M. McDonnell, U. Mortberg, P. Pysek, S. Siebert, J. Sushinsky, P. Werner, and M. Winter 

A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers

Proc R Soc B 2014 281: 20133330-20133330 doi: 10.1098/rspb.2013.3330

The paper has 24 co-authors, from 10 countries, and involved a number of other collaborators who contributed data in some way. It is easily the biggest scale project I’ve ever been involved with, and one that promises to be very productive over the next few years. We started in 2011 by building perhaps the largest database of bird and plant diversity in cities, with 147 cities analyzed in this paper, and have continued to work on analyzing the data and expanding the database. This paper is the first in what we plan to be a series of articles analyzing the distribution of bird and plant species in urban areas worldwide to develop a deeper understanding of how cities interact with biodiversity. As such, this overview article has been a big first step in getting our work through peer review and into publication so the rest of the world—you—can read and see what we have discovered.

It is gratifying to see that there is broad interest in our results. The BBC News posted a report covering our paper even before the paper was available online, and the BBC World Service will shortly be interviewing Mark Goddard, one of the coauthors. Meanwhile, the Australian Broadcasting Corporation’s program The World Today spoke to coauthor Nick Williams earlier today, and you can hear his interview online in the show’s podcast. US media hasn’t quite woken up yet, so let’s see how much interest there is on these shores.

I will be writing more about this research, and explaining our findings in greater detail in a blog post or two over the coming few days (as and when I find time to finish writing the posts in between classes and committee meetings). For now, let me share this press release I helped put together for NCEAS:

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Julie Cohen
(805) 893-7220
julie.cohen@ucsb.edu
Pat Leonard
(607) 254-2137
pel27@cornell.edu

February 12, 2014

Cities Support More Native Biodiversity Than Previously Thought
Researchers at UCSB’s NCEAS compile the largest global dataset of urban birds and plants, which shows world’s cities retain a unique natural palette.

(Santa Barbara, Calif.) — The rapid conversion of natural lands to cement-dominated urban centers is causing great losses in biodiversity. Yet, according to a new study involving 147 cities worldwide, surprisingly high numbers of plant and animal species persist and even flourish in urban environments — to the tune of hundreds of bird species and thousands of plant species in a single city.

Contrary to conventional wisdom that cities are a wasteland for biodiversity, the study found that while a few species — such as pigeons and annual meadow grass — are shared across cities, overall the mix of species in cities reflects the unique biotic heritage of their geographic location. The findings of the study conducted by a working group at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS) and funded by the National Science Foundation were published today in the Proceedings B, a journal of the Royal Society of Biological Sciences.

“While urbanization has caused cities to lose large numbers of plants and animals, the good news is that cities still retain endemic native species, which opens the door for new policies on regional and global biodiversity conservation,” said lead author and NCEAS working group member Myla F. J. Aronson, a research scientist in the Department of Ecology, Evolution and Natural Resources at Rutgers, The State University of New Jersey.

The study highlights the value of green space in cities, which have become important refuges for native species and migrating wildlife. This phenomenon has been named the Central Park Effect because of the surprisingly large number of species found in New York’s Central Park, a relatively small island of green within a metropolis.

Unlike previous urban biodiversity research, this study looks beyond the local impacts of urbanization and considers overall impacts on global biodiversity. The research team created the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities).

Findings show that many plant and animal species, including threatened and endangered species, can flourish in cities, even as others decline or disappear entirely. Cities with more natural habitats support more bird and plant species and experience less loss in species as the city grows. Overall, cities supported far fewer species (about 92 percent less for birds and 75 percent less for native plants) than expected for similar areas of undeveloped land.

“We do pay a steep price in biodiversity as urbanization expands,” said coauthor Frank La Sorte, a research associate at the Cornell Lab of Ornithology. “But even though areas that have been urbanized have far fewer species, we found that those areas retain a unique regional flavor. That uniqueness is something that people can take pride in retaining and rebuilding.”

Conserving green spaces, restoring native plant species and adding biodiversity-friendly habitats within urban landscapes could, in turn, support more bird and plant species. “It is true that cities have already lost a substantial proportion of their region’s biodiversity,” said Madhusudan Katti, a faculty member in the Department of Biology at California State University, Fresno. “This can be a cup half-full or half-empty scenario. If we act now and rethink the design of our urban landscapes, cities can play a major role in conserving the remaining native plant and animal species and help bring back more of them.”

The human experience is increasingly defined within an urban context, the authors noted. They maintain it is still possible for a connection to the natural world to persist in an urban setting, but it will require planning, conservation and education.

“Given that the majority of people now live in cities, this group’s synthesis of data on plant and urban plant and animal diversity should be of broad interest to ecologists as well as urban and landscape planners,” said Frank Davis, NCEAS director.

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Note to editors: Frank Davis is available at frank.davis@nceas.ucsb.edu or at (805) 892-2502. Downloadable images are available at http://www.news.ucsb.edu/node/013947/cities-support-more-native-biodiversity-previously-thought.

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Of course, feel free to also contact me if you have questions about the paper or our ongoing research into global urban biodiversity patterns, and if you need a reprint pdf of the paper. I would love to hear your thoughts on this work.

Urban gardens

 

Are you ready for a Superb Owl?

Snowy Owl portraitSnowy Owl profileSnowy Owl sidelong glanceTwo Snowy Owls in the citySnowy Owl (female?) in the snowdriftClaws under the snowy curving wings
Downward sweep of snowy wings

Chicago winter 2013, a set on Flickr.

This seems like a good day to share these portraits of a beautiful Snowy Owl (and companions) I met on the Chicago lake shoreline while visiting the windy city in early December.

I thought it was cold that day, with the windchill dropping the thermometer to -20°F (or so). That was weeks before the polar vortex formed. I hope these fluffy beauties have done well through these freezing weeks, perhaps even moved farther south as many of their cousins did this winter.

In any case, Happy Superb Owl Day!