Missouri Department of Conservation

Taxonomy

Common Name: EGRET, SNOWY

Phylum: CHORDATA

Class: AVES

Order: PELECANIFORMES

Family: ARDEIDAE

Genus: EGRETTA

Species: THULA

SubSpecies: THULA

Taxonomic Authority: (MOLINA)

Taxonomy References: 004 , 003 , 039

Status

NONGAME
STATE ENDANGERED
STATE RANK S1
GLOBAL RANK G5

Status References: 028 , 018 , 038

Habitat Summary

"Inhabit marshes, swamps and lowland forests with shrubs and robust emergent vegetation. Prefer vegetation average 3.92 m tall and nest trees averaging 6.77 cm dbh."

Primary Habitat: "Wetland matrix"

References: 014 , 016 , 017

Distribution

General Occurrence in State:

"Rare summer resident in southeast, rare summer visitant elsewhere *01*."

County Occurance

County Occurence
Known Likely Unknown Not Likely Historic Extirpated
BOLLINGER ADAIR
BUCHANAN ANDREW
CAPE GIRARDEAU ATCHISON
CHARITON AUDRAIN
CLINTON BARRY
DUNKLIN BARTON
HOLT BATES
JACKSON BENTON
MACON BOONE
MISSISSIPPI BUTLER
NEW MADRID CALDWELL
PEMISCOT CALLAWAY
PERRY CAMDEN
PIKE CARROLL
RANDOLPH CARTER
SCOTT CASS
ST. CHARLES CEDAR
ST. CLAIR CHRISTIAN
ST. LOUIS CLARK
STODDARD CLAY
VERNON COLE
COOPER
CRAWFORD
DADE
DALLAS
DAVIESS
DEKALB
DENT
DOUGLAS
FRANKLIN
GASCONADE
GENTRY
GREENE
GRUNDY
HARRISON
HENRY
HICKORY
HOWARD
HOWELL
IRON
JASPER
JEFFERSON
JOHNSON
KNOX
LACLEDE
LAFAYETTE
LAWRENCE
LEWIS
LINCOLN
LINN
LIVINGSTON
MADISON
MARIES
MARION
MCDONALD
MERCER
MILLER
MONITEAU
MONROE
MONTGOMERY
MORGAN
NEWTON
NODAWAY
OREGON
OSAGE
OZARK
PETTIS
PHELPS
PLATTE
POLK
PULASKI
PUTNAM
RALLS
RAY
REYNOLDS
RIPLEY
SALINE
SCHUYLER
SCOTLAND
SHANNON
SHELBY
ST. FRANCOIS
STE. GENEVIEVE
STONE
SULLIVAN
TANEY
TEXAS
WARREN
WASHINGTON
WAYNE
WEBSTER
WORTH
WRIGHT

References for distribution: 027 , 029 , 032 , 002 , 005 , 006 , 008 , 009 , 011 , 013 , 007 , 012 , 001

Distribution by Watersheds

Wyaconda R.
Miss. R. from Des Moines R. to MO. R.; and North R.
North Fork from Headwaters to South Fork
South Fork from Headwaters to North Fork
Salt R.
Cuivre R.
Dardenne Creek
Miss. R. from St. Louis to River Aux Vases
Meramec R.
Miss. R. from River Aux Vases to Ohio R.
Castor R. and Castor R. Diversion Channel
Miss R. from Ohio R. to Arkansas Border
St. John's Ditch and Blue Ditch
St. Francis R. from Wappapello Dam to Arkansas Border
Little R.
Mo. R. from Nishnabotna R. to Nodaway R.
Nodaway R.
Mo.R. from Nodaway to Kansas City
Platte R.
One Hundred and Two R.
Northwest Corner of Jackson County
Grand R. from Headwaters to Shoal Creek
Grand R. from Shoal Creek to MO. R.
Chariton R. from Shuteye Creek to Mo. R.
Little Chariton R.
Little Osage R.
Marmaton R.
Osage R. from Headwaters to Warsaw, MO.
Sac R.
Pomme De Terre R.
South Grand R.
Mo. R. from Kansas City to Little Chariton R.
Mo. R. from Gasconade R. to Miss. R.

Comments: "Likely to occur in units listed, based on county occurrence."

Distribution by Ecoregions

Central Till Plains, Mississippi River Alluvial Plains, Osage Plains, Ozark Highlands

Comments: ""

Distribution by Potential Natural Vegetation

Bluestem Prairie/Oak Hickory Forest
Cedar Glades
Oak-Hickory Forest
Oak-Hickory-Pine Forest
Southern Floodplain Forest
ALL

Distribution by Natural Divisions of Missouri

Glaciated Plains
Glaciated Plains: Western
Glaciated Plains: Grand River
Glaciated Plains: Eastern
Glaciated Plains: Lincoln Hills
Big Rivers
Big Rivers: Upper Missouri
Big Rivers: Lower Missouri
Big Rivers: Upper Mississippi
Big Rivers: Lower Mississippi
Ozark Border
Ozark Border: Missouri River
Ozark Border: Mississippi River
Ozark
Ozark: Springfield Plateau
Ozark: Upper Ozark
Ozark: St. Francois Mountains
Ozark: Elk River
Ozark: White River
Ozark: Lower Ozark
Mississippi Lowlands
Mississippi Lowlands: Crowley's Ridge
Mississippi Lowlands: Lowlands
Osage Plains

Habitat Associations

Species is associated with "Terrestrial/Aquatic" habitats.

National Wetlands Inventory Association:

Lacustrine
Palustrine

Aquatic Associations:

"Lacustrine, littoral", "Aquatic bed, rooted vascular"
"Lacustrine, littoral", "Aquatic bed, floating vascular"
"Lacustrine, littoral", "Emergent, nonpersistent"
"Lacustrine, littoral", "Unconsolidated bottom, cobble/gravel"
"Lacustrine, littoral", "Unconsolidated bottom, sand"
"Lacustrine, littoral", "Unconsolidated bottom, mud"
"Lacustrine, littoral", "Unconsolidated shore, mud"
"Lacustrine, littoral", "Unconsolidated shore, organic"
"Lacustrine, littoral", "Unconsolidated shore, vegetated"
"Palustrine", "Aquatic bed, algal"
"Palustrine", "Aquatic bed, rooted vascular"
"Palustrine", "Aquatic bed, floating vascular"
"Palustrine", "Emergent, persistent"
"Palustrine", "Emergent, nonpersistent"
"Palustrine", "Forested, broad-leaved deciduous"
"Palustrine", "Scrub/shrub, broad-leaved deciduous"
"Palustrine", "Scrub/shrub, needle-leaved evergreen"
"Palustrine", "Scrub/shrub, dead"
"Palustrine", "Unconsolidated bottom, cobble/gravel"
"Palustrine", "Unconsolidated bottom, mud"
"Palustrine", "Unconsolidated shore, organic"
"Palustrine", "Unconsolidated shore, vegetated"
"Riverine, lower perennial", "Aquatic bed, rooted vascular"
"Riverine, lower perennial", "Unconsolidated bottom, mud"
"Riverine, upper perennial", "Unconsolidated bottom, cobble/gravel"
"Riverine, intermittent", "Streambed, bedrock"

References for Aquatic Associations: 033 , 014 , 016 , 017 , 023

Habitat Types:

Wooded Riparian and Bottomland Hardwood
Swamp
Pond, Lake, Reservoir
Marsh

References for Habitat Types: 014 , 016 , 017 , 019

Terrestrial Natural Communities:

Forest
Bottomland Forest
Wet-Mesic Bottomland Forest
Wet Bottomland Forest
Wetland
Marshes
Freshwater Marsh
Pond Marsh
Swamps
Swamp
Pond Swamp
Shrub Swamp
Pond Shrub Swamp

References for Terrestrial Natural Communities: 014 , 016 , 017 , 019

Food Habits

Trophic Level:

"Carnivore"

Larval Food Habits

Comments for larval food habits:
""

References for larval food habits:

Juvenile Food Habits

Salientia (frogs, toads, peepers, tree frogs); Larva stage
Insects Insects; Larva stage
Odonata (dragonflies, damselflies); Larva stage
Hemiptera (water bugs, water boatmen, stink bugs); Not Specified
Coleoptera (beetles); Not Specified
Osteichthyes (bony fishes); Not Specified
Atheriniformes (killifishes, livebearers, silversides); Not Specified
Caudata (salamanders, newts, mudpuppies, sirens); Not Specified
Serpentes (snakes); Not Specified
Oligochaetes (earthworms); Not Specified
Malacostraca (lobster, shrimp, crayfish, crabs); Not Specified
Odonata (dragonflies, damselflies); Not Specified
Orthoptera (grasshoppers, crickets, mantids); Not Specified
Salientia (frogs, toads, peepers, tree frogs); Adult Stage
Insects Insects; Adult Stage

Comments for Juvenile Food Habits:
""

References Juvenile Food Habits 026 , 021

Adult Food Habits

Insects Insects; Larva stage
Odonata (dragonflies, damselflies); Larva stage
Diptera (flies, midges, mosquitos, gnats); Not Specified
Hymenoptera (sawflies, ants, wasps, bees); Not Specified
Osteichthyes (bony fishes); Not Specified
Amphibians; Not Specified
Salientia (frogs, toads, peepers, tree frogs); Not Specified
Reptiles; Not Specified
Oligochaetes (earthworms); Not Specified
Snails; Not Specified
Malacostraca (lobster, shrimp, crayfish, crabs); Not Specified
Orthoptera (grasshoppers, crickets, mantids); Not Specified
Sauria (lizards, skinks); Not Specified
Serpentes (snakes); Not Specified
Mammals; Not Specified
Cricetidae (woodrats, mice, voles, lemmings); Not Specified
Aquatic Insects; Not Specified
Terrestrial Insects; Not Specified
Insects Insects; Adult Stage
Odonata (dragonflies, damselflies); Adult Stage

Comments for Adult Food Habits:
""

References Adult Food Habits 016

Niche Requirements

Egg Niche Requirements

References for egg niches requirements:

Feeding Larvae Niche Requirements

References for feeding larvae niche requirements:

Resting Larvae Niche Requirements

References for resting Larvae niche requirements:

Feeding Juvenile Niche Requirements

Other niche requirements specified in comments(99999)
Water depth: shallow
Inland wetlands: swamp
Inland wetlands: marsh
General habitat association specified in comments(00270)
Isolation from humans required; should be relatively inaccessible

References for feeding juvenile niche requirements: 030 , 014 , 016 , 017 , 022

Resting Juvenile Niche Requirements

Inland wetlands: swamp
Inland wetlands: marsh
General habitat association specified in comments(00270)

References for resting juvenile niche requirements: 014 , 016 , 017 , 022

Breeding Adult Niche Requirements

Other niche requirements specified in comments(99999)
Aquatic vegetation: bulrush (Scirpus)
Aquatic vegetation: buttonbush (Cephalanthus)
Aquatic vegetation: willow (Salix)
Aquatic vegetation specified in comments(00120)
Inland wetlands: swamp
Inland wetlands: marsh
General habitat association specified in comments(00270)
Height of nest trees specified in comments(00580)
Dbh of nest trees specified in comments(00590)
Isolation from humans required; should be relatively inaccessible

References for feeding Adult niche requirements: 024 , 030 , 014 , 016 , 017 , 021 , 022 , 023

Feeding Adult Niche Requirements

Floodplain specified in comments(00220)
Floodplain wetlands: remnant wetlands
Floodplain wetlands: non-connected scour hole
Floodplain wetlands: farmed temporary
Water depth: shallow
Water depth specified in comments(00230)
Inland wetlands: swamp
Inland wetlands: marsh
Inland wetlands: pond, lake, reservoir
General habitat association specified in comments(00270)
Isolation from humans required; should be relatively inaccessible

References for feeding adult niche requirements: 035 , 036 , 014 , 016 , 017 , 022

Resting Adult Niche Requirements

Floodplain specified in comments(00220)
Floodplain wetlands: remnant wetlands
Floodplain wetlands: non-connected scour hole
Floodplain wetlands: farmed temporary
Water depth: shallow
Water depth specified in comments(00230)
Inland wetlands: swamp
Inland wetlands: marsh
Inland wetlands: pond, lake, reservoir
General habitat association specified in comments(00270)
Isolation from humans required; should be relatively inaccessible

References for resting adult niche requirements: 014 , 016 , 017 , 022

Niche Requirement Summary

Aquatic vegetation specified in comments(00120)
Aquatic vegetation: bulrush (Scirpus)
Aquatic vegetation: buttonbush (Cephalanthus)
Aquatic vegetation: willow (Salix)
Dbh of nest trees specified in comments(00590)
Floodplain specified in comments(00220)
Floodplain wetlands: farmed temporary
Floodplain wetlands: non-connected scour hole
Floodplain wetlands: remnant wetlands
General habitat association specified in comments(00270)
Height of nest trees specified in comments(00580)
Inland wetlands: marsh
Inland wetlands: pond, lake, reservoir
Inland wetlands: swamp
Isolation from humans required; should be relatively inaccessible
Other niche requirements specified in comments(99999)
Water depth specified in comments(00230)
Water depth: shallow

Comments about Life History:

Code Comment
004 May chase prey *16,22* also hover *16*
007 In AL, nest in May *25*
037 Move north after nesting season before beginning fall migration *17*
005 Usually forage in open areas and along edge of openings *21*
011 Often build nest on an old nest platform *21* occasionally nest on the ground *14*
015 Other nest materials include reeds, rushes, cane *14,16*
017 Incubation 18 days *14* in FL, average incubation 22.4 days *21*
018 Clutch size 3-6 *14,22* usually 4-5 *14,21, 22,23*
027 Initial territory defended by male shrinks to immediate area around nest, which is defended by pair *16*
031 Mortality of young 62%, mostly due to starvation *21*. In VA survival from 2 weeks old to dispersal age was .8-1.0; survival after leaving colony was .25-.60 *31*.
033 Arrive in IL and at one Missouri nesting colony in April *15,17* leave IL in aug. and sept. *17*
099 Nest in colonies *14,15,16,17,21,22,23,24,25*. Often found in colonies with little blue herons *16*. Usually nest in more exposed parts of the heronry *21*. Young leave nest when 20-25 days old *22*. In VA young fledged and left colony at 53-58 days *30*. One Missouri colony was located in a pine grove surrounded by irrigation ditches *15*

Life History Information

Territoriality: defends feeding territory
Territory size specified in comments(027)
Mortality rate specified in comments(031)
Migration patterns specified in comments(033)
Dispersal specified in comments(037)
Other life history information specified in comments(099)
Origin in state: native
Seasonal distribution in state: spring/summer/fall
Foraging strategy: stalking
Foraging strategy specified in comments(004)
Foraging sites: water
Foraging sites specified in comments(005)
Breeding season specified in comments(007)
Mating system: monogamy
Duration of pair bond: pair for one season
Display site: nest
Nest/den site: shrubs
Nest/den site: trees
Nest/den site: emergent aquatic vegetation
Nest/den site specified in comments(011)
Nest materials: twigs
Nest materials: sticks
Nest materials specified in comments(015)
Gestation/incubation period specified in comments(017)
Clutch/litter size specified in comments(018)
Number of broods/litter per year: one
Development of young at birth/hatching: altricial
Parental care of young: both parents
Territoriality: defends breeding and nesting territory

Comments about Life History:

Code Comment
004 May chase prey *16,22* also hover *16*
007 In AL, nest in May *25*
037 Move north after nesting season before beginning fall migration *17*
005 Usually forage in open areas and along edge of openings *21*
011 Often build nest on an old nest platform *21* occasionally nest on the ground *14*
015 Other nest materials include reeds, rushes, cane *14,16*
017 Incubation 18 days *14* in FL, average incubation 22.4 days *21*
018 Clutch size 3-6 *14,22* usually 4-5 *14,21, 22,23*
027 Initial territory defended by male shrinks to immediate area around nest, which is defended by pair *16*
031 Mortality of young 62%, mostly due to starvation *21*. In VA survival from 2 weeks old to dispersal age was .8-1.0; survival after leaving colony was .25-.60 *31*.
033 Arrive in IL and at one Missouri nesting colony in April *15,17* leave IL in aug. and sept. *17*
099 Nest in colonies *14,15,16,17,21,22,23,24,25*. Often found in colonies with little blue herons *16*. Usually nest in more exposed parts of the heronry *21*. Young leave nest when 20-25 days old *22*. In VA young fledged and left colony at 53-58 days *30*. One Missouri colony was located in a pine grove surrounded by irrigation ditches *15*

References for life history: 024 , 025 , 030 , 031 , 002 , 014 , 001 , 015 , 016 , 017 , 021 , 022 , 023 , 037

Management

Beneficial Management Practices:

Shrub/brush - develop and maintain water holes, ponds, potholes, etc.
Water - develop/maintain lakes/ponds
Water - develop/maintain wetlands
Water - develop/maintain freshwater marsh
Water - control sedimentation
Water - control pollution (thermal, physical, chemical)
Water - control water levels
Water - develop/maintain streamside vegetation
Water - stabilize streambanks
Water - restrict human disturbance
Forest - seasonal restriction of human use of habitats
Forest - develop and maintain water holes, ponds, potholes, etc.
Forest - maintain riparian habitats
Forest - maintain streambanks
Forest - maintain streamside vegetation
Forest - reforestation
Forest - maintain old growth forests

Beneficial Management References: 027 , 016 , 017 , 021 , 023

Adverse Managment Practices:

Water - application of herbicides
Water - application of pesticides
Water - application of insecticides
Water - dredging and filling
Water - control aquatic plants
Water - navigational improvements (channelization, dams, locks)
Water - burning marshes or wetlands
Water - stream channelization
Water - drainage of wetlands, marshes, ponds, lakes
Forest - application of herbicides
Forest - application of pesticides
Forest - application of insecticides

Adverse Management References: 027 , 005 , 016 , 017 , 021 , 023

Comments on Management:
Beneficial to maintain wetlands *16,17,21,23,27* in a managed wetland in northeast MO, use for foraging increased after completion of drawdowns, when mudflat exposure was great. For drawdowns initiated June 15-20, slower drawdowns (9-10 days) produced a greater response. In wetland complexes, management units should be drawn down sequentially. Maintaining a complex of seasonal wetlands, riverine sloughs and forested wetlands is beneficial. *37*.

References for Management Comments: 027 , 016 , 017 , 021 , 023

References

Reference Code Citation
001 Easterla, D.A., M.B. Robbins and R.A. Anderson. 1992. Annotated Check-List Of Missouri Birds. The Audubon Society Of Missouri.
002 Unpb Rathert, J. Mo Dept. Of Conservation, 1110 S. College Ave., Columbia, Mo 65201. (573)-882-9880.
003 American Ornithologists Union. 1983. Checklist Of North American Birds (6th Ed.) Allen Press, Lawrence, KS. 877 Pp.
004 American Ornithologists Union. 1973. Thirty-Second Supplement To The A.O.U. Checklist Of North American Birds. Auk 90:411-490.
005 Unpb Wilson, Jim D. Mo Dept. Conserv. P.O. Box 180. Jefferson City, Mo 65102. (573)751-4115.
006 Birds Of Squaw Creek National Wildife Refuge. 1975. U.S. Fish And Wildlife Service. Rf-663560-2.
007 Duck Creek Bird Checklist. 1979. Missouri Dept. Of Conservation, Jefferson City, Mo.
008 Heye, P.L. 1975. A Preliminary List Of The Birds Of The Cape Girardeau, Missouri Area. S.E. Mo State Univ., Cape Girardeau, Mo.
009 Kleen, V.M. 1976. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 30(5):961-965.
010 Kleen, V.M. 1979. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 33(2):181-185.
011 Kleen, V.M. 1979. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 33(5):775-778.
012 Kleen, V.M. 1975. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 29(4):858-862.
013 Kleen, V.M. 1974. The Changing Seasons - Middlewestern Prairie Region, Amer. Birds 28(4):807-810.
014 Harrison, H.H. 1975. A Field Guide To Birds Nests In The United States East Of The Mississippi River. Houghton - Mifflin Co., Boston 257 Pp.
015 Peterson, C.T. 1965. An Unusual Colony Of Little Blue Herons. Wilson Bull. 77:192.
016 Palmer, R.S. (Ed.) 1962. Handbook Of North American Birds, Vol. 1. Yale Univ. Press. New Haven and London. 567 Pp.
017 Graber, J.W., R.R. Graber and E.L. Kirk 1978. Illinois Birds: Ciconiiformes. IL Nat. Hist. Survey Biol. Notes No. 109. 80 Pp.
018 The Wildlife Code of Missouri. Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102. 573-751-4115.
019 Kelly, G. (Ed.) 1986. Animal Habitat Relations Handbook. Mo Dept. Of Conservation and U.S.D.A. Forest Service. Jefferson City, Mo. 293 Pp.
020 Thom, R.H. and J.H. Wilson. 1980 The Natural Divisions Of Missouri. Trans. Mo Acad. Sci. 14:9-24.
021 Jenni, D.A. 1969. A Study Of The Ecology Of Four Species Of Herons During The Breeding Season At Lake Alice, Alachua County, Florida. Ecol. Monogr. 39(3):245-
022 Bent, A.C. 1927. Life Histories Of North American Marsh Birds. U.S. Nat. Mus. Bull. 135. 385 Pp.
023 Burger, J. 1979. Resource Partitioning: Nest Site Selection In Mixed Species Colonies Of Herons, Egrets, And Ibises. Amer. Midl. Nat. 101(1):191-210.
024 Mccrimmon, D.A. Jr. 1978. Nest Site Characteristics Among Five Species Of Herons On The North Carolina Coast. Auk 95:267-280.
025 Imhoff, T.A. 1976. Alabama Birds, 2nd Ed. Univ. Of Alabama Press, University, Alabama. 445 Pp.
026 Telfair, R.C. Ii. 1981. Cattle Egrets, Inland Heronries, And The Availability Of Crayfish. Southwest Nat. 26(1):37-41.
027 Unpb Fredrickson, L.H. Univ. Of Mo Gaylord Research Lab., Puxico, Mo 63960 (573-222-3203).
028 Missouri Natural Heritage Program. 2007. Missouri Species and Communities of Conservation Concern Checklist. Missouri Department Of Conservation. Jefferson City, Missouri. 51 Pp.
029 Unpb Missouri Department of Conservation Heritage Database. P.O. Box 180, Jefferson City, Mo 65102.
030 Erwin, R.M., J.G. Haig, D.B. Stotts and J.S. Hatfield. 1996. Dispersal And Habitat Use By Post-Fledging Juvenile Snowy Egrets And Black-Crowned Night Herons. Wilson Bull. 108(2):342-356.
031 Erwin, R.M., J.G. Haig, D.B. Stotts and J.S. Hatfield. 1996. Reproductive Success, Growth And Survival Of Black-Crowned Night Herons (Nycticorax Nycticorax) And Snowy Egret (Egretta Thula) Chicks In Coastal Virginia. Auk 113(1):119-130.
032 Jacobs, B. and J.D. Wilson. 1997. Missouri Breeding Bird Atlas 1986-1992. Mo Dept. Of Conservation. Natural History Series No. 6. Jefferson City, Mo. 430 Pp.
033 Anderson, J.T., T.C. Tacha, G.T. Muehl and D. Lobpries. 1996. Wetland Use By Waterbirds That Winter In Coastal Texas. Nat. Biol. Serv. Information and Technology Report 8. 40 Pp.
035 Unpb Ehrhardt, E. 1996. Abundance And Distribution Of Waterbirds On Three Habitats Of Missouri River Floodplain Following A Major Flood. M.S. Thesis, Univ. Of Missouri-Columbia. 126 Pp.
036 Humburg, D.D., K. Bataille, D.L. Helmers and D.A. Brunet. 1999. Wetland Ecology Studies In The Missouri River Floodplain: Evaluation Of Seasonal Habitat Use By Waterbirds On The Missouri River Floodplain Mo Dept. Conserv. Final Rept. Proj. W-13-R-53, Study 18, Job 4. 130 Pp.
037 Herring, G. and H.K. Herring. 2007. Novel snowy egret foraging behavior. The Wilson Journal of Ornothology 119(1): 116-117.
038 Missouri Natural Heritage Program. 2011. Missouri species and communities of conservation concern checklist. Missouri Department of Conservation. Jefferson City, Missouri. pp. 55.
039 Chesser, R.T., R.C. Banks, F.K. Barker, C.Cicero, J.L. Dunn, A.W. Kratter, I.J. Lovette, P.C. Rasmussen, J.V. Remsen, Jr., J.D. Rising, D.F. Stotz and K.Winker. 2010. 51st Supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 127(3):726-744.