Essays from Friedrich

Habitat Restoration: A Lesson in Ecology

Black-capped Vireo Habitat: Restoration in Progress at Friedrich Wilderness Park

The Black-capped Vireo (BCV), Vireo atricapillus, is an endangered songbird that once was found relatively regularly in Friedrich Wilderness Park (FWP).  In the mid to late 1980’s, data collectors doing general bird countsobserved the BCV in as many as three different parts of FWP.  However, by 1990, BCVs seemed to have abandoned the park. 

In 1992, a restoration project was initiated to restore habitat suitable for reproductive use by BCVs in FWP.  With the U.S. Fish and Wildlife Service as the primary driver, the City of San Antonio, the Friends of Friedrich Wilderness Park and City Public Service worked together to form a management plan that was acceptable to all parties.  To document the progress of the management project, JayNe NeaL, Park Naturalist-Ecology, and volunteers recently surveyed for BCVs in the FWP BCV Management Areas (Management Areas). 

Photo by Artie Richards© Black capped vireo.

There are three Management Areas, all of which are closed to the public because of the sensitivity of the BCV and of the ecosystem on which the species relies.  During the 2004 BCV breeding season, the survey team visited the Management Areas more than 15 times and spent over 50 hours looking and listening for BCVs.  When they saw or heard a BCV, the team collected data regarding the location of the BCV as well as the bird’s behavior.   At all times, the team took special care to collect data in a way that would not negatively impact BCVs.  For example, when a BCV began to shrad (a term that describes a BCV alarm call) and/or vocalize repeatedly as an investigator approached, the investigator backed away immediately. The data indicate that there appear to be three different BCV territories, all located in one of the Management Areas.  The data also suggest that other BCVs are “checking out” the other two Management Areas by flying through or spending varying amounts of time in these Management Areas. However, the data also show that BCVs seem to be spending little or no time in some places where the vegetation looks like good BCV habitat.

There are several possible reasons for the findings.  For example, BCVs are described as colonial birds and most of the observed territorial activity occurred in the Management Area that is closest to the location of a surviving BCV colony (located just outside the park).  Also other birds, may be affecting BCVs in the FWP Management Areas.  For example, the FWP survey team observed what may be negative effects of Great-tailed Grackles (Quiscalus mexicanus) and White-eyed Vireos (Vireo griseus) on BCVs. 

The FWP team also observed the impact humans are having on the restoration efforts.   On the one hand, humans who go off-trail into the Management Areas negatively affect the BCVs by disturbing the BCVs and/or degrading their habitat.  On the other hand, humans like the Friends of Friedrich and volunteers, positively affect BCVs by contributing time and funds towards development and implementation of restoration plans.  Thanks to the collaboration of the Friends of Friedrich, the City of San Antonio, and other partners, our goal is to continue progress towards restoration of Black-capped Vireo breeding habitat in Friedrich Wilderness Park.

(Note: for more information about the BCV, consult the Texas Parks and Wildlife website at http://www.tpwd.state.tx.us/nature/endang/animals/birds/bcv.htm.)

By JayNe NeaL, October 2004

JayNe NeaL is the Park Naturalist for Ecology, City of San Antonio Parks and Recreation Department Natural Areas