Plants and Animals
Setophaga cerulea Cerulean warbler
Cerulean warblers often prove difficult to identify by sight since they forage, sing, nest and roost high in the canopy of mature forests. These birds are small and short-tailed with two wide white wing bars and white tail-spots. The adult males are bright blue above and white below with a black necklace that extends between the shoulders and across the breast. Because of the difficulty in viewing Cerulean warblers, the best tool with which to locate and identify them is their song. The song, given only by the male, opens with an accelerating series of short buzzes, all on one pitch and closes with a single longer higher buzz, "zray zray zray zreeee".
Status and Rank
State Status: T - Threatened (legally protected)
Global Rank: G4 - Apparently secure
State Rank: S3 - Vulnerable
|County||Number of Occurrences||Year Last Observed|
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.
While Cerulean warblers seem to prefer mesic sites over more xeric sites they are most commonly found in the canopy of large tracts of mature deciduous forest.
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.
Primary threats on the breeding grounds include: (1) loss of mature deciduous forest, especially along stream valleys; (2) fragmentation and increasing isolation of remaining mature deciduous forest; (3) emphasis on even-aged management and shorter rotation periods; (4) environmental degradation from acid rain and stream pollution; (5) loss of key tree species; especially oaks, sycamores, elms, and American chestnuts; and (6) nest parasitism by the Brown-headed Cowbird. Contaminants, predation, competition, diseases/parasites, weather, and human disturbance are additional potential limiting factors. Large tracts (>4,000 ha) of mature forest with minimal perimeter to area ratios should be preserved while smaller tracts (700 ha) will support smaller populations. Protecting old growth floodplain habitat required by this species will also benefit many other Neotropical migratory birds whose populations are declining. Low-intensity land uses such as single-tree selective timber removal may be compatible with Cerulean Warbler management especially if the openings created approximate natural treefall gaps created by windstorms. The use of Best Management Practices (BMP's) by foresters is recommended. Enforcement of existing wetland protection regulations also should help protect lowland hardwood forests for Cerulean Warblers.
Migration from fourth week of April to second week of May
Nesting from third week of May to fourth week of June
Migration from fourth week of July to fourth week of September
A standard survey methodology for warblers is to systematically place observation points every ¼ mile throughout suitable habitat. At each observation point an observer listens for 10 minutes and records all birds observed and/or heard within 50 meters and beyond 50 meters of the survey point. Another simple method is to simply walk, or in some cases, use a canoe to conduct a count along a transect through suitable habitat during the breeding season, recording individuals observed and/or heard. The use of taped playback calls in appropriate habitat can also be an effective method for surveys although they should be used with discretion to avoid disturbing birds needlessly. All surveys should be conducted between sunrise and 10:30 am during good to fair weather conditions (e.g., low winds, dry).
Listen for call at observation points
Survey Period: From third week of May to third week of June
Time of Day: Morning (sunrise)
- Bibby, C.J., N.D. Burgess, and D.A. Hill. 1992. Bird Census Techniques. Academic Press, New York.
- Hyde, D., Thomson, D., and J. Legge. 2000. Special Animal Abstract for Dendroica cerulea (Cerulean warbler). Michigan Natural Features Inventory, Lansing, MI. 4pp.