Assessing the status and distribution of nesting herons in urban areas of lower Tidewater, Virginia (2018 breeding season)
Abstract
Twenty-five species of colonial waterbirds nest in Virginia including herons, egrets, ibises, gulls, terns, skimmers, cormorants, and pelicans. A coalition of agencies, organizations and individuals has systematically surveyed waterbird nesting colonies throughout the Coastal Plain periodically since 1993. The objectives of these surveys have been to develop timely data resources that may be used for environmental review and to assess long-term trends in breeding populations. The 2018 survey represents a continuation of the series. The objective of the sub-project reported here was to survey heronries throughout urban areas of lower Tidewater including the cities of Newport News, Hampton, Norfolk, Virginia Beach, and Portsmouth. We surveyed lower Tidewater for heron colonies between 10 April and 3 July, 2018 by systematically driving or walking through neighborhoods and other urban areas. We mapped and surveyed 90 heronries that supported great egrets, yellow-crowned night herons and green herons. Colony size varied from 2 to 259 breeding pairs with 79% below 10 pairs and 93% below 20 pairs. The total number of breeding pairs has increased by nearly 30% since 2003 but is comparable to the number found in 1993. The number of colonies has increased steadily over time and is more than double that found in 1993. The increase is due entirely to the proliferation (30 vs 86) of yellow-crowned night herons over this time. The number of colonies of great egrets (7 vs 3) and green herons (11 vs 4) has declined over this same time. Population changes of herons within urban areas should be viewed within the larger context of the state-wide population. Great egrets continue to expand their breeding range westward in Virginia and the broader population has increased significantly over the past 30 years. However, tension continues between urban-nesting pairs and landowners and several breeding locations have been lost. Urban-nesting pairs of yellow-crowned night herons represent a significant percentage of the state-wide population. Yellow-crowns have been declining within other breeding locations but have experienced resurgence within urban areas. Although green herons breed widely throughout the state, population estimates have always been poor due to the difficulty of surveying for them. Several important breeding sites within urban areas have been lost over the past 30 years resulting in a significant decline of the known population. Causes for these losses remain unclear.
