Some Environmental Factors Affecting the Daily and Seasonal Movements of the Salt Marsh Greenhead, Tabanus nigrovittatus12

Abstract

At the Brigantine National Wildlife Refuge, Atlantic County, New Jersey, dark colored traps were effective in measuring flight activity of Tabanus nigrovittatus Macquart. Peak flight activity is between 8 AM and 4 PM and occurs between the ecotone and first 75 ft of the marsh. Few flies were taken at heights greater than 4 ft. Major natural or man-made breaks in the dense vegetation along the marsh serve as primary routes of upland movement. A road served as the break in this study. Movements through and over upland vegetation do not account for any substantial amount of upland penetration. Once within a major break, flies gain access to less dense vegetation further in the upland through openings in the vegetation along the break. When the vegetation of the ecotone and upland remains intact, greater numbers of flies become restricted to the marsh and immediately adjacent areas. A prediction model was generated by regression analysis and accounted for 77.32% of the variability of the total catch per day. Cloud cover and temperature were the most influential environmental factors affecting movements of T. nigrovittatus.