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Black-crowned Night Heron - Nycticorax nycticorax
Species of Concern Native Species Global Rank :
G5
State Rank :
S3B
(see State Rank Reason below)
Agency Status USFWS :
MBTA
USFS :
BLM :
FWP SWAP :
SGCN
PIF :
3
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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
State Rank Reason (see State Rank above)
Species is a rare breeding resident of wetlands complexes across northern and southwest Montana. based on incidental observation data most breeding sites appear to have continued occupancy over the last decade. Species faces few significant threats.
General Description
The Black-crowned Night-Heron is a medium sized wading bird (length 58 to 66 cm) of stocky build, with a relatively large head, and fairly short neck and legs. Males and females are similar in plumage, with the males of slightly larger size. The adults are dominated by gray plumage, complete with black crown, black bill, and yellow to yellow-green legs. The eye, which start out as a grayish-olive at hatching, quickly turn to light yellow, bright yellow, orange, and finally to bright red by 2 to 3 years of age (Davis 1993). During the breeding season, adults also have long white occipital plumes (average of 2 to 3) extending from the distinctly black crown (Davis 1993, Sibley 2000). Juveniles have broad streaks of light brown-over-white on the breast and the wing coverts are covered in large, white spots. They lack the gray, black, and white plumage distinctive in the adults (Sibley 2000).
The common call of the Black-crowned Night-Heron includes a "
Qua, Quak, Quark " or "
Squawk ," on the part of adults. An advertising call, identified as a hissing "
Plup ", is given from the nest, while the common call is given in flight or while perching (Davis 1993). The vocalization of the young varies as the birds age, from newly hatched to grown young, from a "
Pip, Pip, Pip " to a "
Chuck, Chuck-a-chuck, Chuck, Chuck " (Davis 1993).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see
Marks et al. 2016, Birds of Montana. Diagnostic Characteristics
The distinctive black crown and back, in addition to the gray body and yellow legs, make it hard to confuse this species with any other found in the state. The species to which it is most similar in appearance is the Yellow-crowned Night-Heron (Nyctanassa violacea ), but this species lacks a black back, has a bold head pattern with a white cheek patch, and is very rare in Montana, having been recorded on only three occasions (Montana Bird Distribution Committee 2012). Young Black-crowned Night-Herons may sometimes be confused with American Bittern (Botaurus lentiginosus ), but the American Bittern has a long, conspicuous mark on the side of the neck, bold stripes on the breast, dark flight feathers compared to the rest of the back, and lacks the large, pale spots on the underparts (Davis 1993, Sibley 2000).
Species Range
Montana Range
Range Descriptions Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations: 1199
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding
Indirect Evidence of Breeding
No Evidence of Breeding
WINTER (Dec 15 - Feb 15)
Regularly Observed
Not Regularly Observed
(Observations spanning multiple months or years are excluded from time charts)
Migration
The earliest records for Montana indicate arrival in April, with sightings throughout the summer months and extending into September, when most of the individuals begin their southerly movement (Johnsgard 1992, Montana Bird Distribution Committee 2012). In 2000, one individual was found in the Chester area that stayed until October (Montana Bird Distribution Committee 2012).
Habitat
Although highly adaptable to a variety of habitats, the Black-crowed Night-Heron is likely to use shallow bulrush (Scirpus spp.) or cattail (Typha spp.) marshes, most often within a grassland landscape (Johnsgard 1992). In addition, they will also nest in cottonwoods, willows, or other wetland vegetation that allows them to nest over water or on islands that may afford them protection from mammalian predators (Davis 1993, Casey 2000). Most colonies are located in large wetland complexes, typically with a one-to-one ratio of open water and emergent vegetation (Davis 1993).
Ecological Systems Associated with this Species
Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system,
even if point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at:
mtnhp.mt.gov/requests ) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
Literature Cited
Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
Food Habits
This heron feeds opportunistically on small animals, usually fishes, amphibians, and invertebrates obtained in shallow water, but will also prey on small mammals and young birds on land.
Ecology
Aptly named, the large-eyed Black-crowned Night-Heron is crepuscular, hunting at dusk when it is generally too dark for other herons to catch prey. A gregarious species, the Black-crowned Night-Heron's earlier arrival to the breeding territories than other herons, in combination with its nocturnal hunting behavior, may lesson competition with other species within the nesting colonies (Davis 1993).
Reproductive Characteristics
In Montana, breeding activities have been observed in May, June, and July. Preferring similar marsh habitat and possibly gaining protection from predators by nesting in a shared colony, Black-crowned Night-Herons often nest in close association with White-faced Ibis (Plegadis chihi ) and Franklin's Gull (Larus pipixcan ) (Davis 1993). Additionally, they have also been found to nest in colonies amidst Great Blue Herons (Casey 2000). With up to 30 known active nests in some years, Bowdoin National Wildlife Refuge has the largest recorded colony of breeding Black-crowned Night-Herons in the state (Montana Bird Distribution Committee 2012).
Management
Maintaining habitat integrity (appropriate water levels, and areas free from high levels of predation and harassment) at known nest locations is critical to their continued use (Casey 2000). No specific management actions have been identified for Black-crowned Night-Heron in Montana, but like many wetland dependent species, management of water resources that provide for natural seasonal water levels is essential for maintaining appropriate nesting sites (Davis 1993, Casey 2000).
Stewardship Responsibility
References
Literature Cited AboveLegend:
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