The black duck in the Chesapeake Bay of Maryland: Breeding behavior and biology
Tóm tắt
The breeding behavior and biology of black ducks,Anas rubripes, were observed from 1953–1958 on the upper Eastern Shore of Chesapeake Bay in Maryland. Ducks were trapped, banded and marked during the study in an essentially estuarine habitat, which was frost-free from mid-April to early November. The general habitat adjoining the Bay consisted of cultivated fields, pine woods with dense underbrush, extensive marshes in some areas, and duck blinds. Resident black ducks began to pair in the late summer and reached a peak in early April just before the height of the breeding season. Few if any young were observed to pair in the early fall. In the spring the male defended a territory for each clutch, generally using some promontory along the shore. The male remained nearby while the female built her nest, gradually deserting his mate during incubation. Eventually the pairing bond disappeared, although some males probably paired again with renesting hens. Females renested one or more times when the eggs were destroyed or even when the ducklings disappeared on the first day after hatching. At least eight out of 51 marked ducks were known to have renested. The dates of first laying varied from March 9 to March 27. The nesting peaks occurred about April 20. The first hatching occurred in early April; the last in early August. The date by which 50 percent of the nests were started was significantly earlier in 1953 than in 1957 or 1958 but no other differences were significant. Comparison of the peaks of hatching and of laying showed that in 1958 a loss of early clutches occurred. Nests were built most extensively in woods, less so in fields and marshes and markedly on duck blinds. They were constructed from adjacent material (leaves, grass, twigs, pine needles) in shallow basins, which were occasionally used by renesting females. Usually the nest site was covered by honeysuckle, poison ivy, brush, or grasses. Spacing between nests was determined by available cover; sometimes they were placed within a few feet of each other. The density varied from 0.6 to 15.2 nests per acre. The average number of eggs in a clutch declined from 10.9 to 7.5 during the season (360 clutches). Young females laid smaller average clutches (9.2) than adults (9.7). Primary clutches were larger (9.1) than secondary clutches (8.1) for the same females. The incubation period averaged 26.2 days (51 clutches). Neither size of clutch nor season had a significant effect on incubation period. About 5.6 percent of the eggs did not hatch. The fate of nesting was determined for 574 nests. During the six years, 38.0 percent hatched at least one egg, 11.5 percent were abandoned, and 50.0 percent were destroyed (34.0 percent by crows). Although complete and incomplete clutches were equally susceptible to predation, over half (51.8 percent) of the destruction of complete clutches occurred in the first week of incubation. An average of 9.6 percent of eggs in successful clutches was taken by crows. Estimations of production indicated that 100 females would raise 510 young to flying age and that the population in the area would decline if the mortality rate of females from flying age to breeding exceeded 78 percent.
Tài liệu tham khảo
Barnes, W. B. 1948. Unusual nesting behavior of a wood duck.Auk, 65:449.
Bennett, L. J. 1938. The bluewinged teal, its ecology and management.Collegiate Press, Inc.Ames, Iowa, 144 pp.
Bent, A. C. 1923. Life histories of North American wild fowl.U. S. Mus. Bull. 126:50–64.
Engeling, G. A. 1949. The mottled duck- a determined nester.Texas Game and Fish 7(8):6–7.
Fernald, M. L. 1950. Gray's manual of botany, Eighth Edition,Amer. Book Co., New York.lxiv+1632.
Girard, G. L. 1939. Notes on the life of the shoveler.Trans. N. Amer. Wildl. Conf. 4:118–22.
Gollop, J. B. and W. H. Marshall, 1954. A guide for aging duck broods in the field.Miss. Flyway Council Tech. Sec. 14 pp.
Hochbaum, H. A. 1944. The canvasback on a prairie marsh.Amer. Wildl. Institute, Wash. D. C. 201 pp.
Höhn, E. O. 1947. Sexual behavior and seasonal changes in the gonads, and adrenals of the mallard.Proc. Zool. Soc. Lond. 117 (2–3):218–304.
Johnsgard, P. A. 1960. A quantitative study of sexual behavior of mallards and black ducks.Wilson Bull. 72(2):133–55.
Kalmbach, E. R. 1937. Crow-waterfowl relationships, based on preliminary studies on the Canadian breeding grounds. U.S. Dept. Agric. Circ.433:1–35.
Kendeigh, S. C. 1941. Length of day and energy requirements for gonad development and egg-laying in birds.Ecology, 22(3):237–48.
Kortright, F. H. 1943. The ducks, geese and swans of North America.Amer. Wildl. Inst. Wash. D. C. vii+476.
Leopold, A. 1933. Game management.Charles Scribner's Sons, N. Y. 481 pp.
Mendall, H. L. 1949. Breeding ground improvements for waterfowl in Maine.Trans. N. Amer. Wildl. Conf. 14:58–64.
Peters, H. S. andT. D. Burleigh. 1951. The birds of NewfoundlandHoughton Mifflin Co.Boston, Mass.450 pp.
Ramsay, A. O. 1956. Seasonal patterns in the epigamic displays of some surface-feeding ducks.Wils. Bull. 68(4):275–81.
Shreve, F., M. Chrysler, F. Blodgett andF. Besley. 1910. The plant life of Maryland.Johns Hopkins Press, Baltimore, 532 pp.
Snedecor, G. 1956. Statistical Methods. Fifth Edition.The Collegiate Press, Ames, Iowa.xiii +534.
Sowls, L. K. 1950. Techniques for waterfowl nesting studies.Trans. N. Amer. Wildl. Conf. 15:478–89.
—. 1955. Prairie ducks; a study of their behavior, ecology and management.Stackpole Co.Harrisburg, Penna.193 pp.
Stewart, R. E. 1958. Distribution of the black duck.U. S. Dept. Int. Fish and Wildl. Serv. Circ. (51):1–8.
— andC. S. Robbins. 1958. Birds of Maryland and the District of Columbia,U. S. Dept. Int. Fish and Wildl. Serv. N. Amer. Fauna (62):vi+401 pp.
Stotts, V. D. 1956. The black duck,Anas rubripes, in the upper Chesapeake Bay.Proc. S. E. Assoc. of Game and Fish Comm. 10:234–42.
— 1958A. The time of formation of pairs in black ducks.Trans. N. Amer. Wildl. Conf. 23:192–97.
— 1958B. Use of offshore duck blinds by nesting waterfowl in the Maryland portion of the Chesapeake Bay and its estuaries.Proc. S. E. Assoc. of Game and Fish Comm. 12:280–85.
Stotts, V. D. 1959. Black duck studies: final report.Md. Pittman-Robertson Project W-30-R-7. 241 pp. (Typewritten).
Trautman, M. B. 1949. Further observations on the spring courtship behavior of the black duck about South Bass Island, Ohio.Wilson Bull. 61(3):201.
Trautman, M. B. 1955. Personal communication.April 21.
Van Huizen, P. J. 1932. Report on the black duck nests on the Blackwater Migratory Bird Refuge, Cambridge, Md.Manuscript filed in Biol. Surv., Wash., D. C.
Williams, C. S. andW. H. Marshall. 1937. Goose nesting studies on Bear River Migratory Waterfowl Refuge.Jour. Wildl. Mgmt..1:77–86.
Wright, B. S. 1946. Waterfowl investigations in eastern Canada, Newfoundland, and Labrador.Trans. N. Amer. Wildl. Conf. 12:356–65.
— 1954. High tide and an east wind, the story of the black duck.Stackple, Co. Harrisburg, Penna.xiii +162 pp.