We monitored nest sites of endangered Interior Least Terns on a 5 095 ha alkaline flat in north-central Oklahoma, USA. After nest loss, Least Terns commonly renested and experienced 30% apparent nest success in 1995–1996 (n = 233 nests). Nest success and predation differed by location on the alkaline flat in 1995 and overall, but nest success and flooding did not differ by microhabitat type. Predation was highest at nests ≤ cm from debris (driftwood/hay) in 1995. No differences in nesting success, flooding, or predation were observed on comparing nests inside and outside electrified enclosures. Coyotes and Striped Skunks were confirmed nest predators, and Ring-billed Gulls were suspected nest predators. We identified one location on the alkaline flat of about 1 000 ha with consistently lower nest losses attributable to flooding and predation and the highest hatching success compared with other parts of the alkaline flat; it was typified by open ground and bisected by several creeks. Management activities that minimize flooding and predation in this area could further enhance nest success and theoretically increase overall productivity of this population of Least Terns. However, the efficacy of electrified enclosures and nest-site enhancements, as currently undertaken, is questionable because of considerable annual variation in use by and protection of Least Terns.
REFERENCES
G. Blanco
,
P. Yorio
,
M. Bertellotti
1999. Effects of research activity on hatching success in a colony of South American Terns. Waterbirds 22: 148–150. Google Scholar
R. L. Boyd
1990. Habitat management and population ecology studies of the Least Tern in Kansas and Oklahoma, 1990. Kansas Dept. Wildlife and Parks Nongame Wildlife Progr. Report, Baldwin City. Google Scholar
D. H. Brunton
1997. Impacts of predators, center nests are less successful than edge nests in a large nesting colony of Least Terns. Condor 99: 372–380. Google Scholar
J. Burger
1989. Least Tern populations in coastal New Jersey: monitoring and management of a regionally-endangered species. J. Coastal Res. 5: 801–811. Google Scholar
K. M. Carney
,
W. J. Sydeman
1999. Review of human disturbance effects on nesting colonial waterbirds. Waterbirds 22: 68–79. Google Scholar
P. B. Grover
,
F. L. Knopf
1982. Habitat requirements and breeding success of Charadriiform birds nesting at Salt Plains National Wildlife Refuge. J. Field Ornithol. 53: 139–148. Google Scholar
L. A. Hill
1985. Breeding ecology of Interior Least Terms, Snovy Plovers, and American Avocets at Salt Plains National Wildlife Refuge, Oklahoma M.Sc. Thesis, Oklahoma State Univ., Stillwater. Google Scholar
L. A. Hill
1993. Status and distribution of the Least Tern in Oklahoma. Bull. Oklahoma Ornithol. Soc. 26: 1–24. Google Scholar
L. Hoffmann
,
H. Hafner
,
T. Salathe
1996. The contribution of colonial waterbird research to wetland conservation in the Mediterranean region. Colonial Waterbirds, Spec. Publ. 1. 19: 12–30. Google Scholar
D. H. Johnson
1979. Estimating nest success: the Mayfield Method and an alternative. Auk 96: 651–661. Google Scholar
D. H. Johnson
,
T. L. Shaffer
1990. Estimating nest success: when Mayfield wins. Auk 107: 595–600. Google Scholar
E. M. Kirsch
1996. Habitat selection and productivity of Least Terns on the lower Platte River, Nebraska. Wildl. Monogr. 132: 1–48. Google Scholar
E. M. Kirsch
,
J. G. Sidle
1999. Status of the interior population of Least Tern. J. Wildl. Manage. 63: 470–483. Google Scholar
A. T. Klett
,
D. H. Johnson
1982. Variability in nest survival rates and implications to nesting success. Auk 99: 77–87. Google Scholar
M. T. Koenen
1995. Breeding ecology and management of Least Terns, Snowy Plovers, and American Avocets. M.Sc. Thesis, Oklahoma State University, Stillwater. Google Scholar
M. T. Koenen
,
D. M. Leslie Jr
.,
M. Gregory
1996a. Habitat changes and success of artificial nests on an alkaline flat. Wilson Bull. 108: 292–301. Google Scholar
M. T. Koenen
,
D. M. Leslie Jr
.,
R. B. Utych
1996b. Methods used to improve Least Tern and Snowy Plover nesting success on alkaline flats. J. Field Ornithol. 67: 281–291. Google Scholar
N. B. Kotliar
,
J. Burger
1984. The use of decoys to attract Least Terns (Sterna antillarum) to abandoned colony sites in New Jersey. Colonial Waterbirds 7: 134–138. Google Scholar
D. M. Leslie Jr
.,
G. K. Wood
,
T. S. Carter
1997. Attributes of Least Tern colonies along the Arkansas River, Oklahoma. Proc. Ann. Conf. Southeast. Assoc. Fish and Wildl. Agencies 51: 467–475. Google Scholar
D. M. Leslie Jr.,
G. K. Wood
,
T. S. Carter
2000. Productivity of endangered Least Terns (Sterna antillarum athalassos) below a hydropower and flood-control facility on the Arkansas River. Southwest. Nat. 45: 483–489. Google Scholar
J. T. Lohemoen
,
H. A. Doty
,
D. E. Sharp
,
J. E. Neaville
1982. Electric fences to reduce mammalian predation on waterfowl nests. Wildl. Soc. Bull. 10: 318–323. Google Scholar
H. F. Mayfield
1961. Nesting success calculated from exposure. Wilson Bull. 73: 255–261. Google Scholar
H. F. Mayfield
1975. Suggestions for calculating nest success. Wilson Bull. 87: 456–466. Google Scholar
H. W. Miller
,
D. H. Johnson
1978. Interpreting the results of nesting studies. J. Wildl. Manage. 42: 471–476. Google Scholar
A. N. Powell
,
C. L. Collier
2000. Habitat use and reproductive success of Western Snowy Plovers at new nesting areas created for California Least Terns. J. Wildl. Manage. 64: 24–33. Google Scholar
W. C. Schefler
1969. Statistics for the biological sciences. Addison Wesley Publishing Company, Reading, Massachusetts. Google Scholar
S. H. Schweitzer
1994. Abundance and conservation of endangered Interior Least Terns nesting on salt flat habitat. Unpubl. Ph.D. Thesis, Oklahoma State University, Stillwater. Google Scholar
S. H. Schweitzer
,
D. M. Leslie Jr
.
1996. Foraging patterns of the Least Tern (Sterna antillarum) in north-central Oklahoma. Southwest. Nat. 41: 307–314. Google Scholar
S. H. Schweitzer
,
D. M. Leslie Jr
.
1999. Nesting habitat of Least Terns (Sterna antillarum athalassos) on an inland alkaline flat. Am. Midl. Nat. 142: 173–180. Google Scholar
B. C. Thompson
,
J. A. Jackson
,
J. Burger
,
L. A. Hill
,
E. M. Kirsch
,
J. L. Atwood
1997. Least Tern (Sterna antillarum). In:
A. Poole
,
F. Gill
(eds).
The Birds of North America No. 290, Acad. Nat. Sci., Philadelphia, Pennsylvania. Google Scholar
United States Fish & Wildlife Service. 1985. Interior population of the Least Tern determined to be endangered. Federal Register 50: 21784–21792. Google Scholar
United States Fish & Wildlife Service. 1990. Interior population of the Least Tern (Sterna antillarum): recovery plan. United States Fish and Wildlife Service, Twin Cities, Minnesota. Google Scholar
R. B. Utych
1993. Compatibility of selenite crystal digging with breeding ecology of Least Terns and Snowy Plovers at Salt Plains National Wildlife Refuge. M.Sc. Thesis, Oklahoma State University, Stillwater. Google Scholar
H. Wendeln,
P. H. Becker
1999. Does disturbance by nocturnal predators affect body mass of adult Common Terns? Waterbirds 22: 401–410. Google Scholar
B. R. Winton
1997. Breeding ecology of Great Horned Owls and Barred Owls in relation to nesting Interior Least Terns at Salt Plains National Wildlife Refuge, Oklahoma: 1995 and 1996. M.Sc. Thesis, Oklahoma State University, Stillwater. Google Scholar
B. R. Winton
,
J. Rupert
,
D. M. Leslie Jr
.
2000. Breeding ecology and management of Snowy Plovers in north-central Oklahoma. J. Field Ornithol. 71: 573–584. Google Scholar
