Our Liviiifi Ri'siHines — Binl\ 



caiuuh'ii.sis and B.c. interior) that breed in the 

 subaretic regions of Canada and resident geese 

 (primarily Be. maxima and B.C. inoffitti) that 

 breed in southern Canada and the United States 

 (Stotts 1983). The number of resident geese in 

 Maine to Virginia has increased considerably 

 from maybe^ 50.000 to 100.000 in 1981 

 (Cono\er and Chasko 1985) to an average of 

 560.000 in 1992-93 (H. Heusman. 

 Massachusetts Division of Fisheries and 

 Wildlife, personal communication). This rapid 

 increase in resident geese suggests that the 

 migrant population has declined more than the 

 40% decline observed in total wintering geese 

 from 1981 to 1993. 



Population Changes 



Changes in population numbers result from 

 changes in production, survival, and movement, 

 acting singly or in combination. Consequently, 

 understanding the reason for population 

 changes involves detecting variation in survival, 

 production, and movement over time and relat- 

 ing that variation to changes in wintering num- 

 bers. During the 1970's. the decrease of winter- 

 ing geese in the South and increase in the 

 Chesapeake region appeared to result from 

 increased survival of geese in the Chesapeake 

 and possibly from movement or short-stopping 

 of geese from the South to the Chesapeake 

 (Trost et al. 1986). Short-stopping occurs when 

 migrant geese winter in a more northern loca- 

 tion than their traditional, more southern, 

 migration terminus. 



During the I980"s. the decrease of wintering 

 geese in the Chesapeake appeared to result from 

 an 11% decrease in average survival from 1963- 

 74 to 1984-88 (Hestbeck^l994a). This decrease 

 in survival conesponded to a 36% increase in 

 average harvest rate for the Atlantic Flyway 

 fronri963-74 to 1984-88 (Fig. 2). Overall, the 

 flyway harvest rate, as a 3-year average, 

 increased from 19% in 1962-64 to 34% in 1982- 

 84, and then slowly declined to 31% by 1990- 

 92. The eastern Canada harvest rate has slowly 

 increased from 4.2% in 1968-70 to 8.1% in 

 1990-92. The slight decline in the harvest rate in 

 the flyway since 1982-84 has been partially off- 

 set by harvest rate increases in eastern Canada. 



The decrease in number of geese wintering 

 in the Chesapeake region in the 1980"s was not 

 related to changes in production. Production for 

 migrants, measured from the Canadian data, 

 remained constant over the period of population 

 decline in the Chesapeake (Fig. 3). Average pro- 

 duction recently declined during 1991-92 for 

 geese harvested in Quebec. I also used harvest 

 age ratios for the mid-Atlantic and Chesapeake 

 regions to test for differences in production 

 between these regions (Hestbeck 1994b). If the 



changes in vsintering number lesuUed Irom 

 changes in production, the average annual 

 change in the age ratios would be higher for the 

 mid-Atlantic region than for the Chesapeake 

 region. The average annual changes were not 

 different between these regions, however, indi- 

 cating that regional production differences were 

 not present. 



The decrease in number of geese wintering 

 in the Chesapeake region in the 1980's was not 

 caused by migrant geese short-stopping in the 

 mid-Atlantic instead of returning to the 

 Chesapeake. From neck-band data, the proba- 

 bility of returning or moving to the different 

 regions was estimated and indicated that, 

 although geese traditionally returned to the 

 same wintering area, they also changed winter- 

 ing areas from year to year (Hestbeck 1994b). 

 In years with harsher winters, geese wintered 

 farther south than during milder winters 

 (Hestbeck et al. 1991). Overall, the probability 

 of returning or moving to the Chesapeake 

 region was higher than the probability of return- 

 ing or moving to any other region. When popu- 

 lation size, survival, and movement were com- 

 bined to estimate net movement among regions, 

 the estimated net movements among regions 

 were small and did not correspond to the 

 changes in numbers of wintering geese. Taken 



t-lsiiig ricck-bandcd guosc (Branta 

 caiuulensis). 



0,40- 



Fig. 2. Hanest rate of Canada 

 geese in ttie Atlantic Flyway. \^b2- 

 92 (Harvest and Midwinter 

 Surveys, U.S. Fish and Wildlife 

 Service. Office of Migratory Bird 

 Management) and eastern Canada. 

 1968-92 (Harvest Survey. Canadian 

 Wildlife Service. National Wildlife 

 Research Centre). 



