Optimal Management Strategies for Biodiversity Within a Powerline Right-of-Way Matthew C. Perry, Peter C. Osenton, Frederick W. Fallon, Jane E. Fallon, and Alice K. McDonald USGS Patuxent Wildlife Research Center, Laurel, MD 20708

BACKGROUND
FINDINGS

BACKGROUND

A 500 kilovolt (kV) overhead transmission line was constructed by the Baltimore Gas and Electric Company (BGE) during 1994-95 as a portion of the last section of a 500 kV loop around Washington, D.C. One segment of this line goes through the North Tract of the Patuxent Research Refuge (Patuxent) adjacent to an existing 230 kV transmission line constructed in 1972.

Vegetation sampling is included in the experimental design to help assess the effects of various management techniques.

Patuxent is a 5120 hectare (12,800 acre) research facility within the U.S. Department of the Interior and located in Laurel, Maryland. Within the North Tract, the right-of-way created by both lines is approximately 8.5 kilometers (5.3 miles) long and 92 meters (300 feet) wide, covering 77 hectares (193 acres). Management techniques used to control vegetation include: complete mow, strip mow, low volume foliar spray, selective basal spray, and tree topping. These techniques are being evaluated to identify changes in habitat that could positively or negatively affect wildlife distribution and abundance. Changes in the flora and fauna of the right-of-way are being evaluated with traditional survey and trapping techniques. Vegetation is surveyed in the fall, while wildlife is surveyed and trapped in all seasons.

BGE Right-of-Way Mammals

*Traps were operated July 1996-November 1996, April 1997-August 1997.

Bird surveys were done using line transect sampling.	Reptiles and amphibians were caught in pitfall and funnel traps located along drift fences.

 Average Number of Birds per Visit*

*From July 1, 1995 - June 30, 1996, 31 total visits (6 in summer, 12 in fall, 4 in winter, 9 in spring).

BGE Right-of-Way Amphibians

*Traps were operated July 1996-November 1996, February 1997-August 1997.

Researchers captured mammals in live traps set up along the powerline.	Researchers retrieve a Northern black racer from a trap.

FINDINGS

Surveys of birds, mammals, amphibians, and reptiles were conducted during 1995-97 to determine species of wildlife using the various habitats of the powerline right-of-way. One hundred and one bird species were recorded during line transect sampling along the right-of-way. Fifteen species were recorded in numbers greater than ten individuals per visit in at least one season of the year. Two additional bird species (woodcock and whip-poor-will) were recorded during special nocturnal surveys.  

Powerline right-of-way management techniques include mowing, spraying, and topping of trees.

Fourteen species of mammals were captured in live traps during the study and two other mammal species (red fox and white-tailed deer) were observed but not captured. Twelve species of amphibians and seven species of reptiles were trapped in pitfall or funnel traps. Although more mammals were captured in 1997 than in 1996, there were less amphibians and reptiles captured during the second survey year.

Differences in the distribution of species seemed to be related to the physical and hydrological features of the right-of-way. Although no major differences in the distribution of wildlife species resulted from the vegetation management, differences are expected in the future as differences in vegetation become more pronounced. Data from this study will be of value to resource managers attempting to provide optimal habitat for biodiversity, while managing vegetation to lessen the negative impacts of trees growing too close to powerlines. Hopefully. techniques that are economically beneficial for powerline right-of-way managers will result in habitat that is optimum for wildlife populations using these areas.

BGE Right-of-Way Reptiles

*Traps were operated July 1996-November 1996, February 1997-August 1997.