Introduction
The Glossy Ibis is a distinctive bird found hunched in shallow marshes and wet fields, where it feeds on insect larvae and small crustaceans. This species first inhabited North America in the early 1800s, and since that time, it experienced a dramatic range expansion. Currently, it is distributed throughout the Eastern Hemisphere (Patten and Lasley 2000; Davis and Kricher 2020). In Virginia, it only arrived as a breeder starting in 1956 on Hog Island (Watts et al. 2024). Today, it is a common summer resident in the Coastal Plain (Rottenborn and Brinkley 2007), albeit one that has suffered ongoing declines.
Breeding Distribution
The Glossy Ibis was well-covered during the Second Atlas by the 2018 Virginia Colonial Waterbird Survey, a coastal census conducted by the Center for Conservation Biology in collaboration with the Virginia Department of Wildlife Resources and The Nature Conservancy. The survey identifies nesting locations of this and other species that breed in colonies. Because the Glossy Ibis only breeds within the survey area, there was no need to model its distribution. For information on where the species occurs in Virginia’s Coastal Plain, please see the Breeding Evidence section.
Breeding Evidence
The Glossy Ibis nests exclusively within the survey area covered by the Virginia Colonial Waterbird Survey in 2018, and this survey documented the locations of breeding colonies of this species. Therefore, the species is unlikely to have nested in blocks without confirmed breeding evidence. Additional breeding confirmations were reported by Atlas volunteers in other years of the Second Atlas period.
Glossy Ibis breed in mixed-species rookeries on the Eastern Shore barrier islands and Chesapeake Bay islands. During the Second Atlas, breeding was confirmed in just four blocks in the two counties on the Eastern Shore (Northampton and Accomack, Figure 1). In the Chesapeake Bay, they bred on Tangier Island and Watts Island. Most nesting pairs were on the Atlantic Coast, where they bred on Wreck Island and in Wire Narrows Marsh along the Chincoteague causeway. Other Atlas confirmations outside of these nest sites were from adults feeding alongside young away from the nest.
During the First Atlas, the species was observed breeding at additional sites along the Atlantic Coast where it was not confirmed during the Second Atlas (Figure 2).
As a declining colonial nester, the Glossy Ibis is difficult to observe for all but researchers and boaters. There were few observations of this species’ breeding behaviors during the Second Atlas. Birds were present on nests from May 6 to July 3, and dependent young were observed from June 9 to July 31 (Figure 3). For more general information on the breeding habits of the Glossy Ibis, please refer to All About Birds.
Figure 1: Glossy Ibis breeding observations from the Second Atlas (2016–2020). The colored boxes illustrate Atlas blocks (approximately 10 mi2 [26 km2] survey units) where the species was detected. The colors show the highest breeding category recorded in a block. The numbers within the colors in the legend correspond to the number of blocks with that breeding evidence category. Nesting is unlikely outside of confirmed blocks.
Figure 2: Glossy Ibis breeding observations from the First Atlas (1985–1989). The colored boxes illustrate Atlas blocks (approximately 10 mi2 [26 km2] survey units) where the species was detected. The colors show the highest breeding category recorded in a block. The numbers within the colors in the legend correspond to the number of blocks with that breeding evidence category.
Figure 3: Glossy Ibis phenology: confirmed breeding codes. This graph shows a timeline of confirmed breeding behaviors. Tick marks represent individual observations of the behavior.
Population Status
The Glossy Ibis had too few detections during the Atlas point count surveys to develop an abundance model. However, the distribution and size of Glossy Ibis colonies derived from the 2018 Virginia Colonial Waterbird Survey are displayed on the CCB Mapping Portal.
After its discovery as a breeder in 1956, the species increased to a high in the mid-1970s, after which its population size began to plummet. Based on Virginia Colonial Waterbird Surveys, from 1993 to 2018, the known breeding population of Glossy Ibis declined by 64% (1008 to 366 breeding pairs). By 2023, its population was at only 182 pairs (a decrease of 82% since 1993) (Watts et al. 2019, 2024).
Figure 4: Glossy Ibis population trend for Virginia’s Coastal Plain. This chart illustrates the number of breeding pairs as estimated by the Virginia Colonial Waterbird Survey (Watts et al. 2024). A data point is not included for 1998, as the Survey covered a smaller geographic area in that year. The vertical light blue bars represent the periods corresponding to the First Atlas (1985–1989) and Second Atlas (2016–2020).
Conservation
Glossy Ibis is a Tier 1 Species of Greatest Conservation Need (Critical Conservation Need) in Virginia’s 2025 Wildlife Action Plan, indicating it faces an extremely high risk of extinction or extirpation (VDWR 2025). Fortunately, most breeding sites are under permanent protection from development, with predator management and disturbance mitigation programs in place. The primary threats to the Glossy Ibis breeding population in Virginia are loss of breeding sites and weather-related disturbances. The effects of marsh subsidence, erosion, and sea-level rise have had the greatest effects on Glossy Ibis nesting on islands in the Chesapeake Bay (Watts et al. 2024). Tidal flooding also threatens colonies in the marshes and barrier islands seaward of Virginia’s Eastern Shore. Potential future management may include the protection of suitable inland marshes to replace lost or degraded coastal sites.
Interactive Map
The interactive map contains up to six Atlas layers (probability of occurrence for the First and Second Atlases, change in probability of occurrence between Atlases, breeding evidence for the First and Second Atlases, and abundance for the Second Atlas) that can be viewed one at a time. To view an Atlas map layer, mouse over the layer box in the upper left. County lines and physiographic regional boundaries (Mountains and Valleys, Piedmont, and Coastal Plain) can be turned on and off by checking or unchecking the box below the layer box. Within the map window, users can hover on a block to see its value for each layer and pan and zoom to see roads, towns, and other features of interest that are visible beneath a selected layer.
View Interactive Map in Full Screen
References
Davis, W. E., Jr., and J. C. Kricher (2020). Glossy Ibis (Plegadis falcinellus), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.gloibi.01.
Patten, M. A., and G. W. Lasley (2000). Range expansion of the Glossy Ibis in North America. North American Birds 54:241–47.
Rottenborn, S. C., and E. S. Brinkley (Editors) (2007). Virginia’s birdlife: an annotated checklist. 4th edition. Virginia Society of Ornithology.
Virginia Department of Wildlife Resources (VDWR). 2025. Virginia wildlife action plan. Virginia Department of Wildlife Resources, Henrico, VA, USA. 506 pp.
Watts, B. D., B. J. Paxton, R. Boettcher, and A. L. Wilke (2019). Status and distribution of colonial waterbirds in coastal Virginia: 2018 breeding season. College of William & Mary and Virginia Commonwealth University CCBTR-19-06. Williamsburg, VA, USA.
Watts, B. D., B. J. Paxton, R. Boettcher, and A. L. Wilke (2024). Status and distribution of colonial waterbirds in coastal Virginia: 2023 breeding season. College of William and Mary and Virginia Commonwealth University CCBTR-24-12. Williamsburg, VA, USA.
