Friday, May 7, 2010

How the wealth of your neighborhood and the water in your yard affect bird diversity

I wrote the following essay summarizing some early conclusions from the Fresno Bird Count for the April issue of the Yellowbill, the newsletter of Fresno Audubon. My student Brad Schleder presented some of these results as part of his masters thesis exit seminar earlier this week, and we also had a poster at the College of Science & Mathematics research poster symposium earlier today. So I thought I should also share this essay with you here:

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The American West faces a water crisis. Drought, urban growth, climate change and the continued demands of agriculture have combined to heighten the competition among water users. In California’s San Joaquin Valley, court-ordered water diversions under the Endangered Species Act have radically decreased water deliveries to many Valley farmers. A recent settlement providing for the restoration of the San Joaquin River and ongoing drought (in a region subject to repeated cycles of drought) have only exacerbated public debate about water and spurred the search for ways to conserve it. Valley farmers are experimenting with dry land farming methods, while valley cities are seeking ways to reduce urban water use. In the Fresno-Clovis Metropolitan Area, the City of Clovis already meters water use (but has relatively low water rates) and the City of Fresno will start metering water in 2013. How does our use of water (amount and method of use) affect other species such as birds that also occupy our urban landscapes? What can we do to improve the environment for ourselves and for sustaining biodiversity in the long run?

The Fresno Bird Count (FBC, http://www.fresnobirds.org/) was established by my laboratory at Fresno State in spring 2008 to begin long-term monitoring of bird species in the Fresno-Clovis metro area in part to address such questions about human actions and their effects on biodiversity. The FBC was modeled after the Tucson Bird Count which is now in its 10th year, as a citizen science project where volunteer birders from the community collaborate to gather data on bird distribution and abundance using statistically rigorous sampling and standardized census methodologies. As in Tucson, our volunteers count all the birds they can detect while standing at pre-determined fixed locations for 5 minutes each (i.e., a 5-min point count; see the FBC website for details of the protocol). Each point is a randomly selected location within a 1 km X 1 km square cell that is part of a 460 square kilometer (approx. 178 square miles) grid covering most of Fresno-Clovis and some outlying areas. In the first two years of the FBC, we have managed to survey about 180-200 of these points, and are seeking more volunteers to expand our coverage, because the more finely we can cover the highly variable urban landscape, the better our understanding of just what constitutes habitat for birds in the city and how various bird species use the spaces and resources we leave for them.

The FBC started with two broad goals: to keep track of how many birds of which species occur in the area and how their numbers change under ongoing urban growth; and, to provide basic bird data for more detailed studies focused on the connections between what we do in the urban environment and how birds respond to resulting changes in habitats. The first of such studies has just been completed by my graduate student and FBC coordinator Brad Schleder in the form of a Masters thesis. Brad focused on how we water our lawns and yards, and how the resulting residential landscapes attract different kinds of birds. After spending much of last summer driving around the city to various bird count locations to measure aspects of the habitat such as the number of trees, canopy cover, amount and height of grass, and degree of watering, Brad found some interesting patterns that may give pause even to some long-term birdwatchers living in the area. Of course, it may not surprise you to learn that we find more species of birds towards the north and north-west, in a slight trend of increasing diversity as we approach the river. On the other hand, would you have guessed that bird diversity is a good indicator of the wealth of a neighborhood? That indeed seems to be the case: more species of birds are found in wealthier neighborhoods than in poorer ones, and this is a pattern I’ve also found in Phoenix, Arizona! The reason here may have something to do with how people water their household landscapes. Brad found that poorer neighborhoods don’t water their yards quite as much as wealthier ones. This surprised us because, without metering, the cost of water is not a constraint for residents in Fresno - yet we already see a pattern predicted to occur as a result of metering! Perhaps the direct cost of water is not the only thing affecting the habitat in poorer neighborhoods; rather, landscaping one’s yard and maintaining it regularly is a costly enterprise regardless of how much water costs. If anything, the metering of water (if coupled with a rate structure designed to encourage water conservation) will only add to the burden and exacerbate the contrast in landscapes between rich and poor parts of the city! And the birds will likely notice the changes in the urban landscape and respond by changing their residential address too.

These first results from the FBC support a conclusion that is emerging from similar studies in other cities throughout the US: that biodiversity in cities is unevenly distributed, and tends to favor the rich. In other words, in addition to economic hardship, the poor also face an environmental injustice because birds (and other wildlife) will also flock preferentially to the richer neighborhoods where they may find more diverse landscaped yards with plenty of water and food. That may not be good news for Fresno and other valley cities facing tough economic challenges right now, with high levels of unemployment and rising poverty. Yet, there is also an opportunity here for city planners and developers to rethink the pattern of urban growth and plan for amenities such as more public parks and roadside landscaping that will support more biodiversity and provide greater access to nature for those who may need it the most in these troubled times.

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Published in the April issue of the Yellowbill.

Posted via web from a leaf warbler's gleanings

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