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Black Tern - Chlidonias niger
Species of Concern Native Species Global Rank :
G4G5
State Rank :
S3B
(see State Rank Reason below)
Agency Status USFWS :
MBTA; BCC10; BCC11; BCC17
USFS :
BLM :
SENSITIVE
FWP SWAP :
SGCN3
PIF :
2
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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 has a small breeding population size and negative short-term population trends.
Details on Status Ranking and Review
Black Tern (Chlidonias niger ) Conservation Status Review
Population Size
Score C - 250-1,000 individuals
Comment 95 pairs documented in 2009 and 73 pairs documented in 2010 without all potential suitable nesting habitat being surveyed in either year puts total number of breeding individuals in the 250 to 1,000 individual population size class.
Range Extent
Score G - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment 380,531 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide
Area of Occupancy
Score G - 2,000-20,000 km squared (500,000-5,000,000 acres)
Comment 326 square kilometers based on Species Occurrence polygons with known breeding activity in the Heritage Program database.
Long-term Trend
Score E - Relatively Stable (±25% change)
Comment Wetland habitats within the range of the species in Montana are within +/- 25% of pre European levels.
Short-term Trend
Score D - Declining. Decline of 10-30% in population, range, area occupied, and/or number or condition of occurrences
Comment Breeding Bird Survey (BBS) data for Montana is of low credibility at -2.3% per year or -26% per decade. BBS trend data of moderate credibility across Northern Rockies show an insignificant decline of -2.2% per year over last 10 years. Prairie Potholes shows a significant -3.8% decline per year over past ten years.
Threats
Score F - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.
Comment Altered hydrology, nest site disturbance, and climate change related drought all represent threats to Montana populations.
Severity Low - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
Comment If water levels are maintained then species should recover or remain stable relatively quickly, certainly within 10-50 years.
Scope Moderate - 20-60% of total population or area affected
Comment 20-60% of wetland breeding habitats likely to be affected by ongoing drought and climate change.
Immediacy Moderate - Threat is likely to be operational within 2-5 years.
Comment Ongoing.
Intrinsic Vulnerability
Score B - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
Comment Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance within 5-20 years or 2-5 generations. Species has good dispersal capabilities such that extirpated populations generally become reestablished through natural recolonization.
Environmental Specificity
Score B - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.
Comment Narrow Specialist. Species is dependent on large or small wetland complexes with floating vegetation for nesting.
Raw Conservation Status Score
Score
3.5 – 0.5 (population size) + 0.0 (Geographic Distribution) - 0.25 (short-term trends) + 0.0 (threats) = 2.75
General Description
The head and body of breeding Black Terns are black, fading to gray on the rump. The undertail coverts are white. The upper surface of the wings and tail are dark gray, and the wing linings are pale gray. The leading margin of the wing from the body to the first digit is white. The bill is black and the feet are a dark reddish-purple (Goodwin 1960, Farrand 1983). Females are somewhat duller black than males, but this difference is often difficult to distinguish in the field (Goodwin 1960). Black Terns begin their prebasic (postbreeding) molt in late June when eggs begin to hatch. White feathers appear first around the eyes and cheeks, then on the forehead, neck, throat and breast, and finally on the abdomen. Heavily molting adults take on a peculiar, piebald appearance. The prebasic molt is completed during fall migration (Goodwin 1960). In basic (winter) plumage, the underparts are pure white except for a small, dark patch on each side of the breast. The back becomes a shade of gray similar to the wings and tail. A blackish cap joins black ear coverts on the otherwise white head (Goodwin 1960, Farrand 1983). The juvenile plumage is similar to the basic plumage, but the feathers of the back are darker and the wing coverts and cap are barred and scalloped brown (Goodwin 1960, Farrand 1983). The total length of adults is 23 to 26.5 cm (9 to 10.5 inches).
Vocalizations include shrill, somewhat metallic alarm notes, described as "
kik " or "
keek ", depending upon intensity and level of motivation, and a complex of contact calls described as "
kyew ", followed by one to four additional syllables, as "
kyew-dik ", "
kyew-dik-ik ", etc. (Goodwin 1960). The "
kik " call commonly serves as a signal of impending danger in the nesting area. It may also be given during the ascent portion of the courtship flight. The "
keek " call is similar to, but more shrill and forceful than, the "
kik " call, and is given during aggressive attacks on enemies in close proximity to the nest. The frequency of repetition increases as they become more aggressive. The "
kyew " calls are given as parents approach and leave the nest, during foraging flights, by adults accompanied in flight by young, by parents calling to young at or near the nest, by parents at the nest during incubation, brooding and feeding, and during the courtship flights (Goodwin 1960).
Black Tern eggs are ovate with a tendency toward ovate-pyriform (Bent 1921). Ground color varies from dark olive to light buff with markings of dark brown and gray. Markings vary from small dots and scrawls to very large blotches and are often particularly heavy around the larger end of the egg (Goodwin 1960). The average dimensions for 122 eggs in the U.S. National Museum were 34 x 24 mm (Bent 1921).
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 head and underbody, with gray wings, back, and tail easily distinguishes this species from any other tern species. Their size is also a key to recognition. They are very small compared to other tern species in the state. Only the Interior Least Tern (Sterna antillarum athalassos ) is of similar size. Color will preclude any misidentification between these two species.
Species Range
Montana Range
Range Descriptions Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations: 1465
(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
Little information is known about Black Tern migratory patterns in Montana. They are more likely to move north from wintering locations through the interior of the U.S. (Heath et al. 2009), so early sightings should occur in southern portions of the state. Migrating Black Terns have been observed just north of Dillon as early as April. However, the majority of spring migration observations have been in May and June. Black Terns have been observed in transit in July and August albeit fewer observations, probably due to peak breeding. The latest recorded observation was in September near Medicine Lake National Wildlife Refuge in Sheridan County (Montana Bird Distribution Committee 2012). Migration in fall is less concentrated through the interior of the country as birds also move to coastal areas (Heath et al. 2009).
Habitat
Black Tern breeding habitat in Montana is mostly wetlands, marshes, prairie potholes, and small ponds. However, several locations are on man-made islands or islands in man-made reservoirs. Across all Montana sites where Black Terns are present, approximately 30%-50% of the wetland complex is emergent vegetation. Vegetation within known breeding colonies includes alkali bulrushes, canary reed-grass, cattail spp., sedge spp., rush spp., reed spp., grass spp., Polygonum spp., Juncus spp. and Potamogeton spp., indicating a wide variety of potential habitats are usable by Black Terns. Water levels in known breeding localities range from about 0.5 m to greater than 2.0 m with most having depths between 0.5 m and 1.0 m (Montana Natural Heritage Program Point Observation Database).
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.org/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
During breeding season, insects and freshwater fish; rest of year diet consists mainly small marine fish and insects.
Ecology
Highly social species that nests semicolonially and often forages in flocks (Heath et al. 2009).
Reproductive Characteristics
Overall, little information about Black Tern reproduction is known for Montana, as very few studies concerning the species exist. Recent work has focused on location surveys and general population size (Feighley 1998, Rauscher 2000). DuBois (1996) did nesting surveys for Black Terns at a single location in the state (Freezout Lake). In Montana, Black Terns usually begin their reproductive cycle in early to mid-June. However, in 1991 five documented observations of nesting occurred in May (Montana Bird Distribution Committee 2012). DuBois (1996) recorded egg-laying as early as June 2nd.
Management
Active management for Black Terns in Montana is currently limited to continued population monitoring and water level fluctuation control. Several Black Tern colonies are under federal or state control and monitoring of the population at those locations is completed annually. This monitoring can range from basic observation counts to nest location surveys. At some sites, federal or state agencies also monitor and regulate water levels during the breeding season for Black Terns, as well as other wetland species and waterfowl. Both population monitoring at perennial breeding locations and water level regulation should be continued on an annual basis and be expanded to other locations where Black Terns breed in the state.
References
Literature Cited AboveLegend: chlidonias niger surinamensis (Gmelin). Ph.D. dissertation, Cornell University, Ithaca, New York. 193 pp.Chlidonias niger ). The Birds of North American Online (A.Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North American Online: http://bna.birds.cornell.edu/bna/species/147 (Accessed 21 March 2016)
Additional ReferencesLegend: Do you know of a citation we're missing? Chlidonias niger ). Species Account Number 147. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online databaseEffects of recreation on Rocky Mountain wildlife: a review for Montana . [Montana]: Montana Chapter of the Wildlife Society.
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