Seasonal Surveys of Shorebird and Coastal Waterbird Utilization of Dredged Material Islands in the Baptiste Collette Bayou, U.S. Army Corps of Engineers (USACE) New Orleans District, Louisiana Active

The Science Issue and Relevance: Bird populations across North America have declined substantially over the last 30 years and those found along the northern coast of the Gulf of Mexico are no exception. The combined effects of urban development, human disturbance events (e.g., oil spills), and global climate change, which includes sea-level rise and tropical storms that are increasing in severity and frequency, have caused areduction in coastal habitat suitable for birds across the annual life cycle. With suitable coastal habitat at a premium, land managers and conservation planners are in critical need of tools that can help address habitat loss and increase avian population sizes. One possible solution is to utilize coastal engineering that can build and maintain coastal infrastructure to sustain wildlife and enhance habitats. Understanding how existing dredge spoil islands and maintenance programs, such as those in Baptiste Collette Bayou, may benefit avian populations, for instance the federally listed Piping Plover and Red Knot, is key to striking the balance between engineering for human infrastructure/hydrology needs and to create/enhance critical habitat that can support wildlife populations.

Sources/Usage: Public Domain.

Methodology for Addressing the Issue: Five bird islands and two mainland open areas that recently received dredge material were constructed in the Baptiste Collette Bayou in the U.S. Army Corps of Engineers New Orleans District. The first of these islands were constructed beginning in 1978 as part of the Beneficial Use of Dredged Material program under the Clean Water Act Section 404 during efforts to deepen navigation channels for access to the New Orleans port and the Intracoastal Waterway System (ICWW). Gunn Island, built in 2016, is part of this island system and was constructed to facilitate further shoaling in the bar channel and to avoid enlarging other islands in the bayou. Keeping islands relatively small and isolated promotes use by breeding coastal birds and reduces mammalian predation. From 2018 to 2020, Gunn Island received an additional 1,000,000+ cubic yards of dredged material during regular maintenance dredging of the Baptiste Collette Bayou channel, raising the elevation to more than 8 feet, and providing over 12 acres of nesting habitat for coastal birds. To assess use of dredge material areas, avian ecologists from USGS WARC are conducting bird surveys across the annual life cycle, which will provide information on habitat use relative to the engineering activities.

Future Steps: After data collection is complete, we will assess how avian abundance may be related to vegetative and geomorphological measures across the study area. The results will provide much needed information to assist natural resource managers and coastal engineers in designing restoration and island construction projects that balance human infrastructure/hydrology needs and creation of critical habitat.