The goal of the Houston Bird Survey is to determine the distribution of birds that live in the Houston area. We have completed four summer (June) and three winter (January) surveys and the data submitted by our 241 participants have been entered into a geographic database and analyzed. We have data from 357 survey sites in summer and 259 survey sites in winter. A total of 235 species have been recorded. We are essentially ignoring migrants that simply pass through our area once or twice a year although a few late stragglers have crept into our surveys.
To achieve this goal we have focused on Harris County and contiguous areas of the surrounding counties. This creates the 'pool' of species that are available in the area. Some forest species to our north and coastal species to the south barely creep into our study area. The data for each species will be mapped for Harris County. These maps are being created for taxonomically or ecologically similar groups of birds and posted on our web site.
Birders have long recognized that certain birds do quite well in urban areas while others are unable to persist. The maps will document which species are able to survive in the urban environment. Ultimately, we may be able to identify the ecological requirements that determine the success or failure of a particular species in the urban setting. To this end, I am writing a series of essays entitled The Birdwatcher as Ecological Detective that each focuses on a particular ecological assemblage of birds. The essays will appear at monthly intervals on the web site as maps are prepared and interpreted.
It has proven difficult to establish boundaries along an urban-suburban-rural and exurban gradient. I have arbitrarily established four ecological zones for Harris County. The central inner city core is a 1.7 square mile area bounded by Interstate 10, Interstate 45 and US Highway 59. It is primarily a zone of impervious surfaces (concrete and asphalt) surrounding small green patches of suitable bird habitat. Our surveys have documented 21 bird species in this downtown area, 17 in summer and 15 in winter. (see Zone Table).
The 97.4 sq mile area encompassed by the Loop 610 is undoubtedly urban but more hospitable to birds. The surveys have documented 71 species in summer and 90 species in winter. (Habitats all across the Gulf coast typically have more birds during the winter than in summer).
Expanding outward, it may be tempting to designate the 532.8 sq mile zone between the Loop 610 and the Beltway 8 as suburbs, as it once was, but the birds indicate a different story. The 98 species found there during summer and 83 species in winter are barely greater than within the Loop. While the suburbs spill outward beyond the Beltway, large patches of rural habitat also persist and the number of bird species, known as species richness, essentially doubles, to 140 species in summer and 184 in winter. Harris County is 1729 sq miles in area but our maps incorporate a bit more of surrounding counties and our surveys extend considerably farther, from The Woodlands to Brazos Bend State Park.
We invite you to explore the Zone Table and the range maps to identify those species most adaptable to the urban environment.
We thank our many volunteers (see Participant list) for their diligent contributions to this Citizen Science project. As analysis proceeds we will emphasize the interesting scientific questions that can be addressed by this growing database.
