Illinois Natural History Survey - University of Illinois

Least bittern
Ixobrychus exilis

 

Taxonomy
Occurence in Illinois
Status
Habitat associations
Guilds
Food-habits
Environmental associations
Life history
Management practices
References


TAXONOMY

 

  • Phylum: Chordata
  • Class: Aves
  • Order: Ciconiiformes
  • Family: Ardeidae
  • Genus: Ixobrychus
  • Species: Ixobrychus exilis
  • Authority: Gmelin

Comments on taxonomy:
Other names: dwarf bittern; least heron; little bittern *03*.

 


OCCURENCE IN ILLINOIS

Uncommon migrant and summer resident *02*.


STATUS

Items in bold indicate applicable categories
Forest Service Categories: S = recommended for regional sensitive status, F = forest listed species, M = management indicator species

Federal Status:

Endangered Threatened Proposed for listing
Candidate for proposal Recovery plan approved Recovery plan received (USFWS)
Recovery plan in preparation Under notice of review Delisted
Migratory EPA indicator Forest Serv.- Shawnee species

State Status:

Endangered Threatened Proposed

Other:

Game Furbearer Nongame protected
Sportfish Commercial Pest None of the above

Comments on status:
The least bittern is protected by the Illinois Wildlife Code of 1971 *05*, and the Migratory Bird Treaty Act of 1918 *06*.

 


HABITAT ASSOCIATIONS

Items in bold indicate applicable categories

General habitat:

Unknown Terrestrial Aquatic Riparian

USFS timber inventory forest size class:

Unknown Unstocked Seedling Sapling
Seedling/sapling Pole Mature Over mature

Land use and land cover:

Unknown   Urban Residential
Commercial
Industrial
Transportation, communication
Complex industrial/commercial
Mixed
Other
Agricultural Crop, pasture
Orchards, groves, nurseries
Feedlot
Other
Rangeland Herbaceous
Shrub and brush
Mixed
Forestland Deciduous
Evergreen
Mixed
Water Stream
Lake
Reservoir
Bay
Wetland Forest
Non-forest
Barren Salt flat
Beach
Sand
Rock
Mine
Transit
Mix

 


Forest cover types:

Cover typeStructural stageCanopy closureSeason
Sweetgum-yellow poplar Young tree
(1-9" dia.)
Unknown Unknown
Sweetgum-yellow poplar Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Swamp chestnut oak-cherrybark oak Young tree
(1-9" dia.)
Unknown Unknown
Swamp chestnut oak-cherrybark oak Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Sweetgum-willow oak Young tree
(1-9" dia.)
Unknown Unknown
Sweetgum-willow oak Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Overcup oak-water hickory Young tree
(1-9" dia.)
Unknown Unknown
Overcup oak-water hickory Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Bald cypress Young tree
(1-9" dia.)
Unknown Unknown
Bald cypress Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Bald cypress-tupelo Young tree
(1-9" dia.)
Unknown Unknown
Bald cypress-tupelo Mature
(9" dia. & 100 yrs. old)
Unknown Unknown
Water tupelo-swamp tupelo Young tree
(1-9" dia.)
Unknown Unknown
Water tupelo-swamp tupelo Mature
(9" dia. & 100 yrs. old)
Unknown Unknown

Associated tree species: No records.

National wetland inventory classifications:

SystemSubsystemClassSubclassWater regime modifiersWater chemistry
Palustrine   Emergent vegetation Persistent Unknown/unspecified Unknown/unspecified
Palustrine   Scrub/shrub Broad-leaved deciduous Unknown/unspecified Unknown/unspecified

Comments on species-habitat associations:
Found primarily in cattail marshes *02*.

Important plant and animal association: No comments.

High value habitats

HabitatStructural stageSeason
Wetland Not applicable
(HVAL-HAB cover)
Spring
Wetland Not applicable
(HVAL-HAB cover)
Summer
Wetland Not applicable
(HVAL-HAB cover)
Fall
Marsh Not applicable
(HVAL-HAB cover)
Spring
Marsh Not applicable
(HVAL-HAB cover)
Summer
Marsh Not applicable
(HVAL-HAB cover)
Fall

Species-habitat interrelations: Found primarily in cattail marshes *02*; shy, secretive bird, hides in tall cattails and sedges *03*; feeds at edge of water, retreats into vegetation after capturing prey *03,12*. Nests in dense growth of marsh emergents, above shallow water but near to open water *03,09*

 


GUILDS

Feed-guilding:

HabitatStructural stageSeasonFeed-guilds
Wetland Not applicable
(HVAL-HAB cover)
All Water column- arthropods
Water column- invertebrates other than zooplankton or arthropods
Water column- fish
Water column- amphibians
Water column- mammals
Water surface- arthropods
Water surface- invertebrates other than zooplankton or arthropods
Water surface- fish
Water surface- amphibians
Water surface- mammals
Marsh Not applicable
(HVAL-HAB cover)
All Water column- arthropods
Water column- invertebrates other than zooplankton or arthropods
Water column- fish
Water column- amphibians
Water column- mammals
Water surface- arthropods
Water surface- invertebrates other than zooplankton or arthropods
Water surface- fish
Water surface- amphibians
Water surface- mammals

Comments on feed-guilding:
Feed at edge of water in marshes; darts head toward water; captured fish is swallowed head first; besides small fishes, eats amphibians, aquatic insects and other invertebrates. Retreats into vegetation after capture *03,12*.

Breed-guilding:

HabitatStructural stageSeasonBreed-Guilds
Wetland Not applicable
(HVAL-HAB cover)
Spring/summer Surface of water column-river/lake/marsh, unconsolidated rooted herbaceous plants
River/lake/marsh, vascular plants- emergent, nonwoody
Terrestrial surface, marshy areas with hydrophytes but not hydric soils
Marsh Not applicable
(HVAL-HAB cover)
Spring/summer Surface of water column-river/lake/marsh, unconsolidated rooted herbaceous plants
River/lake/marsh, vascular plants- emergent, nonwoody
Terrestrial surface, marshy areas with hydrophytes but not hydric soils

Comments on breed-guilding:
Nest in marshes; in cattails, bulrushes *03*; occasionally nest on ground; nest may be built on top of old nests of other birds *09,18*; natural clump of dead vegetation usually forms base of nest *18*; reports of nest heights vary- 6-24 in. *18*; <1 ft. *20*; 30-91 cm *17*; 8-14 in. *09*; nest made of dead vegetation around nest site *17,09,18*; nest throughout marsh, not just on edge *17*.

 


FOOD-HABITS

Trophic level is CARNIVORE

Food itemLife stage/plant part
Annelida (segmented worms) Unknown
Annelida: hirudinea (leeches) Unknown
Mollusca: Gastropoda (snails) Unknown
Crustaceans Unknown
Malacostraca (isopods, amphipods, crayfishes) Unknown
Insecta Unknown
Odonata (dragonflies, damselflies) Unknown
Orthoptera (grasshoppers, crickets, cockroaches) Unknown
Hemiptera Unknown
Lepidoptera (butterflies, moths) Unknown
Diptera (flies, midges, mosquitoes) Unknown
Osteichthyes (bony fishes) Unknown
Cypriniformes (carps, minnows, loaches) Unknown
Perciformes (basses, sunfishes, perches, sculpins) Unknown
Amphibians Juvenile
Amphibians Adult
Caudata (salamanders,newts,mudpuppies,sirens,hellbenders) Unknown
Salientia (frogs, toads) Juvenile
Salientia (frogs, toads) Adult
Mammals Unknown
Important:
Crustaceans Unknown
Insecta Unknown
Osteichthyes (bony fishes)
Juvenile:
Malacostraca (isopods, amphipods, crayfishes) Unknown
Osteichthyes (bony fishes) Unknown
Salientia (frogs, toads) Adult
Adult:
Annelida (segmented worms) Unknown
Annelida: hirudinea (leeches) Unknown
Mollusca: Gastropoda (snails) Unknown
Crustaceans Unknown
Malacostraca (isopods, amphipods, crayfishes) Unknown
Insecta Unknown
Odonata (dragonflies, damselflies) Unknown
Orthoptera (grasshoppers, crickets, cockroaches) Unknown
Hemiptera Unknown
Lepidoptera (butterflies, moths) Unknown
Diptera (flies, midges, mosquitoes) Unknown
Osteichthyes (bony fishes) Unknown
Cypriniformes (carps, minnows, loaches) Unknown
Perciformes (basses, sunfishes, perches, sculpins) Unknown
Amphibians Juvenile
Amphibians Adult
Caudata (salamanders,newts,mudpuppies,sirens,hellbenders) Unknown
Salientia (frogs, toads) Juvenile
Salientia (frogs, toads) Adult
Mammals Unknown

Comments on food habits: 
General: USBS survey of stomach contents = 40% fish, 10% crustaceans, 21% insects, 12% aquatic bugs *09*; also eat amphibians, leeches, slugs; occassionally shrews and mice *03,09*.
Juvenile: Young are fed regurgitated food by parent *09*. See [FH]
Adult: See [FH]


ENVIRONMENTAL ASSOCIATIONS

General:

  • Aquatic habitat: shallows with emergent vegetation (littoral zone)
  • Aquatic habitat zone: see comments
  • Water depth preference: see comments
  • Aquatic habitats: freshwater marsh
  • Aquatic habitats: marsh
  • Herbs-leguminous forbs: see comments
  • Human associations: see comments
  • Unknown

Limiting:

  • Human associations: see comments

Egg

  • Unknown

Feeding juvenile:

  • Aquatic habitat: shallows with emergent vegetation (littoral zone)
  • Aquatic habitat zone: see comments
  • Aquatic habitats: freshwater marsh
  • Aquatic habitats: marsh

Resting juvenile:

  • Aquatic habitat: shallows with emergent vegetation (littoral zone)
  • Aquatic habitat zone: see comments
  • Aquatic habitats: freshwater marsh
  • Aquatic habitats: marsh

Feeding adult:

  • Aquatic habitat zone: see comments
  • Aquatic habitats: freshwater marsh
  • Aquatic habitats: marsh
  • Herbs-leguminous forbs: see comments

Resting adult:

  • Herbs-leguminous forbs: see comments

Breeding adult:

  • Water depth preference: see comments
  • Aquatic habitats: freshwater marsh
  • Aquatic habitats: marsh
  • Herbs-leguminous forbs: see comments

Comments on environmental associations:
General: All activities occur in herbaceous ground cover *14*; found in marshes *02,17,18,19*; limiting factor is habitat *17*; least bittern habitat is adversely affected by marsh drainage, pollution, insecticides, and development activities *09*.
Feeding juvenile: Feed in cattails, buttonbush, sawgrass, smartweed, and sedges *09,17, 19*
Resting juvenile: Rest in cattails, buttonbush, sawgrass, smartweed, and sedges *09,17, 18,19,20*
Feeding adult: Cattails, buttonbush, sawgrass, smartweed, sedges *09,17,18,19,20*
Resting adult: Cattails, buttonbush, sawgrass, smartweed, sedges *09,17,18,19,20*
Breeding adult: Use cattails *09,17,19*; buttonbush, sawgrass, smartweed *09* and sedges *17*; usually nest over water 3-28 in. deep *18*; in an Iowa study most nests over water 16-20 in. deep *20*; most nests 6 in. - 20 ft. from open water *18*.


LIFE HISTORY

Origin: Native *02*.

Physical description: Smallest heron; buffy wing patches, dark crown and back; length = 11-14 in. (male larger within span); wingspread = 16-18 in.; bill = 41-47.3 mm; tarsus = 37-42.7 mm; weight = 1.5 - 4 ounces *09*

Reproduction: Breeding season, in Virginia, eggs laid mid-May to mid- July, young in nest mid-June to mid-August *11*; copulation occurs on nest, prior to and during laying, continues into early incubation; eggs = 4-5, 31.3 x 23.93 mm; shell = smooth, not glossy; color = pale, bluish green, usually laid one egg/day *08*; incubation period = 16- 18 days *10*; average number offspring = 3-4; may be single or double brooded; breeding behavior = seasonal monogamy; male chooses nesting site *09*

Behavior: Home range = one study found 2.5 acres/nest *09*; foraging = wader, freshwater marshes, does not remain at pool after capture, quickly retreats into vegetation *12*; nesting = on dense vegetation, 8-14 in. above shallow water; close to open water; usually singly but in suitable habitat high density may result in colonial appearance material = dried and living plants; round to oval (6-8 in.); Male 2/3 - 3/4 of nest; building continues after young have hatched; development of young = 2nd day - young grasp twigs; 5th day - able to leave nest, returning quickly; 6th day - leave nest readily; 8th day - leave and hide in vegetation; 10-14 days - nestling period, parents feed young away from nest *09*

Limiting factors: Habitats adversely affected by marsh drainage, pollution, insecticides and development activities of man *09* population parameters: hatching success = 84% *09* aquatic/terrestrial associations: long-billed marsh wren known to puncture eggs *09*

Diseases and Parasites: Helminths - nematodes *15*; ectoparasites *16* general disease and parasite reference *13*

Other: Little nest sanitation; shy, solitary bird; runs rapidly along ground *09*.

 


MANAGEMENT PRACTICES

Beneficial:

  • Maintaining undisturbed/undeveloped areas
  • Maintaining early stage of ecological succession
  • Maintaining natural ecological succession
  • Controlling land use and human activities
  • Controlling pollution
  • Controlling sedimentation
  • Developing/maintaining wetlands
  • Developing/maintaining mudflats
  • Maintaining bogs
  • Restricting human disturbance during migration, breeding, and nesting

Adverse:

  • Channelization
  • Navigational improvements such as channelization and locks and dams
  • Dredging
  • Controlling aquatic plants
  • Draining ponds/lakes
  • Draining wetlands
  • Burning of wetlands to maintain successional stages
  • Application of insecticides

Comments on management practices:
Have been adversely affected by marsh drainage, pollution, and insecticides *09*.

 


REFERENCES

0. VIRGINIA FOSTER, C. 101 CHEATHAM HALL, BLACKSBURG, VA 24060 WAYNE, L.D. 900 GLADE RD, BLACKSBURG, VA 24060

1. MISSOURI

2. BOHLEN, H. 1978. AN ANNOTATED CHECK-LIST OF THE BIRDS OF ILLINOIS. ILLINOIS STATE MUS. POP. SCI. SER., VOL. IX. 156 PP.

3. TERRES, J. 1980. AUDUBON SOCIETY: ENCYCLOPEDIA OF NORTH AMERICAN BIRDS. ALFRED KNOPF, NEW YORK. 1109 PP.

4. AMERICAN ORNITHOLOGISTS' UNION. 1984. CHECK-LIST OF NORTH AMERICAN BIRDS. 6TH ED. ALLEN PRESS, INC. LAWRENCE, KS. 877 PP.

5. ILLINOIS DEPT. CONS. 1980. CONSERVATION LAWS. CH.61. WILDLIFE. ART II. PAR 2.2. REPRINTED FROM ILLINOIS REVISED STATUTES, 1979. WEST PUBL. CO., ST PAUL, MN. 123 PP.

6. US FISH WILDLIFE SERVICE. 1983. CODE OF FEDERAL REGULATIONS. TITLE 50. WILDLIFE AND FISHERIES. CHAP 1, PP. 11-18. 50 CFR 10.13. LIST OF MIGRATORY BIRDS. SPECIAL PUBL. FEDERAL REGISTER. GENERAL SERVICES ADMIN. OCTOBER 1.

7. HAMEL, P.B. AND H.E. LEGRAND, JR., M.R. LENNARTZ, AND S.A. GAUTHREAUX, JR. 1982. BIRD-HABITAT RELATIONSHIPS ON SOUTHEASTERN FOREST LANDS. SOUTHEAST. FOREST EXP. STA. GEN. TECHNICAL REP. SE-22. U.S. DEP. AGRIC., U.S. FOREST SERV., ASHEVILLE, N.C. NUMBER OF PAGES 417 SOURCE FORM: PAPER.

8. CHAPMAN, F.M. 1966. HANDBOOK OF BIRDS OF EASTERN NORTH AMERICA. DOVER PUBL., NEW YORK.

9. PALMER, R.S. 1962. HANDBOOK OF NORTH AMERICAN BIRDS. VOL. I. YALE UNIV. PRESS, NEW HAVEN, CONN.

10. BENT, A.C. 1926. LIFE HISTORIES OF NORTH AMERICAN MARSH BIRDS. BULL. 135. U.S. NATL. MUS., WASHINGTON, D.C. NUMBER OF PAGES: 490 SOURCE FORM: PAPER.

11. ORNITHOLOGY, VIRGINIA SOCIETY OF. 1979. VIRGINIA'S BIRDLIFE: AN ANNOTATED CHECK-LIST. VIRGINIA SOCIETY OF ORNITHOLOGY, LYNCHBURG, VA.

12. BULL, J., AND J. FARRAND, JR. 1977. THE AUDUBON SOCIETY FIELD GUIDE TO NORTH AMERICAN BIRDS-EASTERN REGION. ALFRED A. KNOPF INC., NEW YORK.

13. FOWLER, M.E. 1978. PENGUINS, CRANES, STORKS, AND FLAMINGOS (SPHENISCIFORMES, GRUIFORMES, CICONIIFORMES, AND PHOENICOPTERIFORMES). PAGES 155-163 ZOO AND WILD ANIMAL MEDICINE. FOWLER, M.E., ED. W.B. SAUNDERS CO., PHILADELPHIA.

14. LEGRAND, H.E., JR., AND P.B. HAMEL. 1980. BIRD-HABITAT ASSOCIATIONS ON SOUTHEASTERN FOREST LANDS. DEP. ZOOL., CLEMSON UNIV., CLEMSON S.C. NUMBER OF PAGES: 276 SOURCE FORM: PAPER.

15. DEARDORFF, T.L., AND R.M. OVERSTREET. 1980. CONTRACAECUM MULTIPAPILLATUM (=C. ROBUSTUM) FROM FISHES AND BIRDS IN THE NORTHERN GULF OF MEXICO. J. PARASITOL. 66(5):853-856.

16. PETERS, H.S. 1936. A LIST OF EXTERNAL PARASITES FROM BIRDS OF THE EASTERN PART OF THE UNITED STATES. BIRD-BANDING 7:9-27.

17. 13M

18. 15M

19. 16M

20. 20M

 


 

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