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White-faced Ibis -
Species of Concern Native Species Global Rank
State Rank Reason below)
Agency Status USFWS
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State Rank Reason (see State Rank above)
Due to limited distribution of breeding sites, the species is potentially at risk of declines.
Details on Status Ranking and Review
White-faced Ibis ( Plegadis chihi) Conservation Status Review
Review Date = 12/20/2011
Score C - 250-1,000 individuals
CommentColonial waterbird surveys in 2009 and 2010 (Wightman and Tilly 2010) documented 115 and 225 breeding pairs, respectively. That is a minimum adult population size of around 450 adults, certainly less than 1,000 adults. Range Extent
Score U - Unknown Area of Occupancy
Score E - 100-500 km squared (about 25,000-125,000 acres)
Comment396 square kilometers based on Species Occurrence polygons with known breeding activity in the Heritage database Long-term Trend
Score F - Increase (increase of >25%)
CommentLarge wetland complex habitats relatively stable since European arrival. Short-term Trend
Score E - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation
CommentNo BBS data for Montana. Nest trend data in the Heritage database for Montana colonies with regular breeding and nest monitoring data indicate stable populations with lots of fluctuations. New areas were reported in recent FWP waterbird surveys, but breeding was not definitively identified. 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.
CommentAltered hydrology as a result of climate change, nest site disturbance, and contaminants (e.g., elevated selenium) in some areas all represent threats to the species.
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.
CommentWhen water conditions are right adults seem to be able to make use of available nest sites.
Scope Moderate - 20-60% of total population or area affected
CommentMany (20-60%) of nesting areas are subject to ongoing drought and disturbance by human activities.
Immediacy Moderate - Threat is likely to be operational within 2-5 years.
CommentOngoing 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).
CommentModerately 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.
CommentNarrow specialist. Species is dependent on large wetland complexes which are relatively rare in Montana. Raw Conservation Status Score
3.5 - 0.5 (population size) + 0.0 (area of occupancy) + 0.0 (short-term trend) + 0.0 (threats)
The White-faced Ibis is a medium-sized wading bird with dark maroon or brown plumage, a long neck and legs, and a long, decurved bill. Males are almost always larger than females and adults are larger than juveniles for the first 6 to 9 months (Ryder and Manry 1994). The adult body length ranges from 46 to 56 cm (18.1 to 22.0 inches) with wingspans ranging from 94 to 99 cm (37 to 39 inches). Weight varies ranging from 450 to 525 grams (1.0 to 1.2 lb.) and the bill length averages between 15 to 18 cm (6 to 7 inches) (Ryder and Manry 1994). Male and female plumages cannot be distinguished. In the adult breeding plumage, the head, neck, upper back, wing coverts, and undersides are a dark maroon or brown with a metallic green and bronze sheen. The head of the White-faced Ibis has bare facial skin that is reddish or purple. White feathers on the head separate the forehead from the face and also encircle the eye. The eye itself is red (Ryder and Manry 1994). The bill is cream with some shades of red (Pratt 1976) and the legs are bright red. The non-breeding plumage is similar to the breeding plumage without the presence of the white face feathers. Also, the overall plumage is less glossy (Oberholser 1974), and the bill and legs become an olive-gray color (Pratt 1976). The juvenile plumage has a fuscous foreneck and anterior surface. The back, tail and wings are a dull metallic, greenish-olive and often appears oily (Palmer 1962, Oberholser 1974). When observing immature White-faced Ibises, it can be extremely difficult to separate from the closely related Glossy Ibis.
White-faced Ibises have a limited vocalization array. Single birds, pairs, and flocks often give an "
" or "
" sound (Oberholser 1974). During nest building, they often give a guttural babbling sound. Vocalizations during interspecific aggression are long "
" sounds and the greeting call by the male to the female is a "
geeeeek, geeeeek, geeeeek
" sound (Belknap 1957).
White-faced Ibis eggs are elliptically-ovate to round shaped and range in color from a pale bluish-green to a deep turquoise, with no markings (Bent 1926, Belknap 1957, Kotter 1970, King et al. 1980). Dimensions average 51.2 to 52.26 mm by 36.0 to 37.0 mm (Kaneko 1972, Belknap 1957), and weights average 28.4 to 43.7 grams (Kotter 1970). White-faced Ibises are a single brood species, but will attempt to renest after an early nest failure.
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.
The White-faced Ibis is very similar in appearance to the closely related Glossy Ibis and identification can be difficult. Distinguishing characteristics which separate the two species include the red iris versus a more brownish or dark iris, bright red legs versus more grayish ones, the bare facial skin colored red and trim of white feathers which surround the eye versus a darker face with only small white lines connecting the bill to the eye (Ryder and Manry 1994), and the olive-gray bill versus a more brown colored bill (Sibley 2000).
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding
Indirect Evidence of Breeding
No Evidence of Breeding
WINTER (Dec 15 - Feb 15)
Not Regularly Observed
(Observations spanning multiple months or years are excluded from time charts)
White-faced Ibises usually leave their wintering grounds in late March to early April. The earliest White-faced Ibis observation in Montana was at Lee Metcalf National Wildlife Refuge in March, but the most concentrated arrival in Montana occurs in May (Montana Bird Distribution Committee 2012). In late summer, White-faced Ibises will disperse throughout the state before beginning the fall migration to their wintering habitat (Ryder and Manry 1994). In Montana, most begin their southern movement in August and by September they are usually gone from the state (Montana Bird Distribution Committee 2012). On April, 5th, 1964 at least one White-faced Ibis was observed in the Three Forks area (Skaar 1969) and in 1967, two individuals were observed at Benton Lake National Wildlife Refuge until October 6th (Benton Lake NWR 1988).
The White-faced Ibis breeding habitat is typically freshwater wetlands, including ponds, swamps and marshes with pockets of emergent vegetation. They also use flooded hay meadows and agricultural fields as feeding locations. Ibises nest in areas where water surrounds emergent vegetation, bushes, shrubs, or low trees. In Montana, White-faced Ibises usually use old stems in cattails (
Typha spp.), hardstem bulrush ( Scirpus acutus) or alkali bulrush ( S. paludosus) over shallow water as their nesting habitat (DuBois 1989). Water conditions usually determine whether nesting occurs in a particular area. Therefore, White-faced Ibis nesting sites can often move around from year to year. However, they are a fairly adaptable species and the primary breeding requirement is colony and roosting site isolation. During migration, White-faced Ibises use more varied habitats for resting and feeding sites, ranging from wooded streams, mudflats, and grassy fields to small marshes and sewage ponds (Duebbert 1968, Locatelli and Blankenship 1973, Ducey 1988, Baumgartner and Baumgartner 1992).
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,
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:
) 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.
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.
No information regarding food habits exists for White-faced Ibises in Montana. However, in other areas of the species' range, they typically feed in freshwater marshes on crayfishes, frogs, fishes, insects, newts, earthworms, crustaceans, etc. (Terres 1980). In the Central Valley of California, they preferentially selected foraging sites with significantly higher midge (Chironomidae) and significantly lower Oligochaete biomass (Safran et al. 2000). White-faced Ibises can fly 5 to 25 miles between the nesting or roosting and foraging sites (Trost 1989).
No information is available for White-faced Ibis ecology in Montana. Ecological sources from other habitat locations state that nesting colonies are often shared with Black-crowned Night-Herons and Franklin's Gulls, both of which may prey on White-faced Ibis chicks or eggs (Trost 1989). Although gregarious, and may travel in flocks of up to 300 individuals, White-faced Ibis generally flock in smaller numbers.
Only recently has the White-faced Ibis reproduced in Montana. Prior to 1970, no breeding records existed for the state. Even into the early 1980's only a few scattered breeding instances were observed. Since the mid-1980's, White-faced Ibis numbers in known colonies have increased and new colonies have been located (DuBois 1989). Two theories exist to explain this apparent recent range expansion into Montana. The first describes the very transient behavior of the species. White-faced Ibises are extremely dependent on appropriate wetland habitat and water level consistency. When wetlands in the Great Basin and in particular the Great Salt Lake rose to record levels in the early 1980's, large White-faced Ibis colonies were flooded. This flooding closely coincided with the marked population increases in Montana, presumably due to the northern movement of Great Basin/Utah birds. The other theory regarding White-faced Ibis presence in Montana states simply that they have always been here and have been overlooked (DuBois 1989). Regardless of the reason, the White-faced Ibis does breed at several locations in Montana, with colonies usually about 50 pairs or less. However, due to the few locations and only recent presence, no information regarding White-faced Ibis reproduction exists for the state.
In other areas of the species' range, where reproductive studies have been conducted, information includes clutch sizes ranging from typically 3 to 4 (range of 2 to 7) (Trost 1989). The incubation period is 21 to 22 days, and normally only two young survive to fledging (Trost 1989). The young are semi-altricial and fledge after 28 days; birds do not breed until they are 2 years old (Trost 1989, Ryder and Manry 1994). Nests are typically spaced 0.5 to 10 m apart, with density often increasing toward the center of the colony (Ryder and Manry 1994). Nest structures are highly variable, and are typically composed of the dominant vegetation in the colony; outside diameter may range from 27 to 50 cm, and nests are 10 to 25 cm deep (Ryder and Manry 1994). Nests may be woven into emergent vegetation, be made on a platform or bent over adjacent vegetation or may be placed on a more solid platform or on the ground (Ryder and Manry 1994).
Although no management activities are in place specifically for White-faced Ibises in Montana, water level manipulation in nesting areas for other species is ongoing. Because all White-faced Ibises in Montana currently breed in colonies located within water units managed for waterfowl, active management of water level can and does impact the breeding ibises in the management area. Conscious management of water levels for waterfowl to include White-faced Ibises would maintain or enhance nesting habitat for this species. White-faced Ibises are a Species of Management Concern in U.S. Fish and Wildlife Service Region 6 (USFWS 1995).
Literature Cited Above
Legend: View Online Publication Baumgarnter, F. M. and A. M. Baumgarnter. 1992. Oklahoma bird life. University of Oklahoma Press, Norman, Oklahoma. Belknap, H. W. 1957. Observations on the white-faced ibis ( Plegadis chihi) in Louisiana. M.S. thesis. Louisiana State University, Baton Rouge, Louisiana. Bent, A. C. 1926. Life histories of North American marsh birds. Bulletin of the United States National Museum 135. 490 pp. Benton Lake National Wildlife Refuge. 1988. White-faced ibis sightings. Internal memo. DuBois, K. 1989. Arising, alighting ibis. Montana Outdoors 20(6):30-33 Ducey, J. E. 1988. Nebraska birds breeding status and distribution. Simmons-Boardman Books, Omaha, NE. Duebbert, H. F. 1968. White-faced ibis in McIntosh County, North Dakota. Prairie Naturalist 1:14. Kaneko, K. D. 1972. Nesting of the white-faced ibis ( Plegadis chihi) on Utah Lake. M.S. thesis. Brigham Young University, Provo, Utah. King, K. A., D. L. Meeker, and D. M. Swineford. 1980. White-faced ibis populations and pollutants in Texas, 1969-1976. Southwest Naturalist 25: 225-239. Kotter, B. L. 1970. An ecological natural history of the white-faced ibis ( Plegadis chihi) in northern Utah. M.S. thesis. University of Utah, Salt Lake City, Utah. Locatelli, M. S. and T. E. Blankenship. 1973. White-faced ibis in Humboldt County, California. Murrelet 54:11-12. Marks, J.S., P. Hendricks, and D. Casey. 2016. Birds of Montana. Arrington, VA. Buteo Books. 659 pages. Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map. Oberholser, H.C. 1974. The bird life of Texas. 2 volumes. University of Texas Press, Austin, Texas. Palmer, R.S. 1962. Handbook of North American birds. Volume 1. Loons through flamingos. Yale University Press, New Haven. 567 pp. Pratt, H. D. 1976. Field identification of white-faced and glossy ibises. Birding 8:1-5. Safran, R. J., M. A. Colwell, C. R. Isola, and O. E. Taft. 2000. Foraging site selection by nonbreeding white-faced ibis. Condor 102:211-215. Sibley, D.A. 2000. The Sibley guide to birds. National Audubon Society and Alfred A. Knopf, Inc., New York, NY. 544 pp. Skaar, P.D. 1969. Birds of the Bozeman latilong: a compilation of data concerning the birds which occur between 45 and 46 N. latitude and 111 and 112 W. longitude, with current lists for Idaho, Montana, Wyoming, impinging Montana counties and Yellowstone National Park. Bozeman, MT. 132 p. Terres, J.K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York. 1109 pp. Trost, C. H. 1989. White-faced ibis. In: Clark, T. W., A. H. Harvey, R. D. Dorn, D. L. Genter, and C. Groves, eds. Rare, sensitive, and threatened species of the Greater Yellowstone Ecosystem. p. 57-58. Northern Rockies Conservation Cooperative, Montana Natural Heritage Program, The Nature Conservancy, and Mountain West Environmental Services. 153 pp. U.S. Fish and Wildlife Service, Office of Migratory Bird Management. 1995. Migratory nongame birds of management concern in the United States: the 1995 list. U.S. Government Printing Office: 1996-404-911/44014. 22 pp. Additional References
Legend: View Online Publication Do you know of a citation we're missing? American Ornithologists Union. 1983. Checklist of North American birds, 6th Edition. 877 PP. American Ornithologists’ Union [AOU]. 1998. Check-list of North American birds, 7th edition. American Ornithologists’ Union, Washington, D.C. 829 p. Banks, R. C., and M. R. Browning. 1995. Comments on the status of revived old names for some North American birds. Auk 112:633-648. Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp. Casey, D. 2004. Coordinated bird monitoring in Montana - special habitat/species monitoring: wetlands and colonial nesters. Montana Bird Conservation Partnership and University of Montana. pp 12 plus appendix. Coons, S., J.P. Donnelly, and V.J. Dreitz. 2021. Monitoring change across North America's white-faced ibis (Plegadis chihi) breeding colony network; a framework for priority wetland conservation. Technical Report, University of Montana and Intermountain Joint Venture. 21 p. Coons, S.P. 2021. Monitoring the wetland landscape: white-faced ibis (Plegadis chihi) breeding habitat as a model assemblage. M.Sc. Thesis. Missoula, MT: University of Montana. 89 p. Davis, C.V. 1961. A distributional study of the birds of Montana. Ph.D. Dissertation. Corvallis, OR: Oregon State University. 462 p. Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster Inc. New York. 785 pp. Goodell, J. 2012. Morse Land Company Breeding Bird Inventory And Analysis. High Desert Museum. Bend, OR. 42 pp + Appendices. Goosen, J.P., D.E. Ealey, H. Judge and D.C. Duncan. 1995. Distribution and breeding status of the White-faced Ibis, Plegadis chihi, in Canada. Can. Field-Nat. 109(4):391-402. Hand, R.L. 1969. A distributional checklist of the birds of western Montana. Unpublished. Available at Mansfield Library, University of Montana, Missoula. Hays, R., R.L. Eng, and C.V. Davis (preparers). 1984. A list of Montana birds. Helena, MT: MT Dept. of Fish, Wildlife & Parks. Henny, C. J., and G. B. Herron. 1989. DDE, selenium, mercury, and White-faced Ibis reproduction at Carson Lake, Nevada. Journal of Wildlife Management 53:1032-1045. Idaho Fish & Game. Idaho's water birds: the colony nesters. Nongame Wildlife Leaflet 2. 12 p. Johnsgard, P.A. 1979. Birds of the Great Plains: breeding species and their distribution. University of Nebraska Press, Lincoln. 539 pp. Johnsgard, P.A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp. Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society. Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana bird distribution, 6th edition. Montana Audubon, Helena, MT. 144 pp. Lokemoen, J.T. 1979. The status of herons, egrets, and ibises in North Dakota. Prairie Nat. 11(4): 97-110. Montana Bird Distribution Committee. 1996. P. D. Skaar's Montana Bird Distribution, Fifth Edition. Special Publication No. 3. Montana Natural Heritage Program, Helena. 130 pp. Mora, M. A. 1995. Residues and trends of organochloride pesticide and polychlorinated biphenyls in birds from Texas, 1965-88. Technical Report 14. Washington, D.C.: U.S.D.I. National Biological Service. 26 p. O¿Shea, T. J., and T. A. Vaughan. 1999. Population changes in bats from central Arizona: 1972 and 1977. Southwestern Naturalist 44:495-500. Oechsli, L.M. 2000. Ex-urban development in the Rocky Mountain West: consequences for native vegetation, wildlife diversity, and land-use planning in Big Sky, Montana. M.Sc. Thesis. Montana State University, Bozeman. 73 p. Paton, P. W., C. Kneedy, and E. Sorensen. 1992. Chronology of shorebird and ibis use of selected marshes at Great Salt Lake. Utah Birds 8(1):1-19. Ragnal, Wendy, and Troy Brandt, Wetland Services, Helena, MT., 1998, Tucker Crossing Ranch Wetland Mitigation Project for Montana Dept. of Transportation: Highway 93 - Hamilton to Lolo: 1998 - Year Two Monitoring Report - Addendum. In Tucker Crossing Site WS# Lower Clark Fork, Ravalli County. Fin.Dist.1 Admin. Dist.1 Reichel, J. D. 1996. Preliminary colonial nesting bird survey on the Bureau of Land Management Lewistown District: 1995. Unpublished report, U.S. Bureau of Land Management, Lewistown, Montana. Root, T. L. 1988. Atlas of wintering North American birds: An analysis of Christmas Bird Count data. University of Chicago Press, Chicago. 312 pp. Ryder, R.A. 1967. Distribution, migration and mortality of the White-faced Ibis (Plegadis chihi) in North America. Bird-Banding 38: 257-277. Ryder, R.R. and D.E. Manry. 1994. White-faced Ibis ( Plegadis chihi). Species Account Number 130. 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 database Schmidt, R.A. 1980. First breeding record of the White-faced Ibis in North Dakota. Prairie Nat. 12(1): 21-23. Sibley, C.G., and B. L. Monroe. 1990. Distribution and taxonomy of birds of the world. Yale Univ. Press, New Haven. xxiv + 1111 pp. Sibley, D. 2014. The Sibley guide to birds. Alfred A. Knopf, New York, NY. 598 pp. Skaar, P. D. 1975. Montana bird distribution. Published by author, Bozeman, Montana. Skaar, P. D., D. L. Flath, and L. S. Thompson. 1985. Montana bird distribution. Montana Academy of Sciences Monograph 3(44): ii-69. Taylor, D. M., C. H. Trost, and B. Jamison. 1989. The biology of the white-faced ibis in Idaho. Western Birds 20:125-133. U.S. Forest Service. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. U.S. Department of Agriculture, Forest Service Agricultural Handbook 688. 625 pages. Watts, C.R. and L.C. Eichhorn. 1981. Changes in the birds of central Montana. Proceedings of the Montana Academy of Sciences 40:31-40. Weller, M.W., B.H. Wingfield and J.B. Low. 1958. Effects of habitat deterioration on bird populations of a small Utah marsh. Condor 60: 220-226. Web Search Engines for Articles on "White-faced Ibis"
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