Plants and Animals
Nycticorax nycticorax Black-crowned night-heron
The Black-crowned night-heron is a medium-sized heron, with a stocky build, relatively short neck and legs, and sexually monomorphic plumage. Adults are easily identified by their black cap, upper back, and shoulders, gray wings, rump, and tail, and white to pale gray underparts. The bill is stout and black, eyes are red, and legs are yellow-green for most of the year, but pink during the height of the breeding season. The best known Black-crowned night-heron vocalization is its "quawk" call, most often given at night while in flight or from a perch, but may also let out a "rok-rok" when threatened or "wok-wok" when disturbed.
Status and Rank
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S3 - Vulnerable
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Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Nesting typically occurs near the coast of the Great Lakes but adults may forage inland during the nestling stage and both adults and immature birds may show up during migration.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Significant efforts should be made to protect the natural and man-made islands where Black-crowned night-herons commonly nest from disturbance and contamination. These islands are also used by gulls and terns which are a significant food source in the form of eggs and chicks. Vegetation management should focus on maintaining shrubs and small trees for nesting and may include periodic selective cutting or relying on ice and wind storms. Nesting areas should not be disturbed just before or during egg laying as this may cause nest abandonment or increase predation. Maintaining healthy, diverse coastal marshes will also benefit the night-herons. Limiting development and recreation activities that may disturb nesting should also be considered. Controlling predators should be considered if predation is or becomes a limiting factor in the successful reproduction of Black-crowned night-herons.
Migration from first week of April to fourth week of April
Nesting from first week of May to fourth week of July
Migration from first week of September to fourth week of October
A number of techniques have been used to survey nesting colonial waterbirds, including ground surveys on foot or by boat and aerial surveys using fixed-wing aircraft or helicopters. Black-crowned night-herons typically feed at night but may feed throughout the day during the late nesting season.
Visual, aerial surveys
Survey Period: From first week of May to first week of July
Time of Day: Daytime
- Bibby, C.J., N.D. Burgess, and D.A. Hill. 1992. Bird Census Techniques. Academic Press, New York.
- Monfils, M.J. 2004. Special Animal Abstract for Nycticorax nycticorax (Black-crowned night-heron). Michigan Natural Features Inventory, Lansing, MI. 6pp.