Population study and management of Atlantic Flyway Canada geese
Title:
Population study and management of Atlantic Flyway Canada geese
Author:
Hestbeck, Jay B.
Appeared in:
Journal of applied statistics
Paging:
Volume 22 (1995) nr. 5-6 pages 877-890
Year:
1995-11-01
Contents:
Numbers of wintering Canada geese ( Branta canadensis ) in different regions of the Atlantic Flyway have significantly changed since the 1950s. During the 1980s, numbers increased in the mid-Atlantic and declined in the Chesapeake regions. A neckband study during the 1980s tested hypotheses that differential survival or movement caused changes in wintering numbers. The earlier studies and a reanalysis of the movement data using MSSURVIV indicated that the changes in wintering numbers did not result from differential survival or movement. A new neckband study, started in 1991, was designed to test hypotheses that the increases in wintering geese in the mid-Atlantic resulted from increasing numbers of resident geese and that the decline in migrants was related to higher harvest rates. Numbers of wintering geese continued to increase in the mid-Atlantic and declined in the Chesapeake region. Analyses of winter-banded, migrant geese indicated that 47 000 (SE = 14 000) geese per year moved from the mid-Atlantic to the Chesapeake region, thus rejecting the short-stopping hypothesis for this period. The probability of mid-Atlantic neckbanded resident geese remaining in the mid-Atlantic during winter was 0.988 (0.005). No differences in average survival were detected for migrants wintering in different regions during 1991-1994. Resident geese had higher survival than migrant geese in the Chesapeake region but not in the mid-Atlantic region. Harvest age ratios were low for Maryland and Quebec during the 1990s with record lows occurring during 1992. The only survival rate that could be estimated during the period of harvest restrictions was for 1992. Differences in survival were not detected between the periods of liberal harvest, 1985-1987, and the one year estimate under restrictive harvest. Because of the low age ratio, comparable numbers of adults were harvested during periods of restrictive and liberal regulations. Migrants appeared to be declining in all wintering regions, and residents appeared to be increasing. The different trends may be due to production differences.
Journal description