Movements, Productivity, and Band Recovery Analysis of Giant Canada geese in Eastern South Dakota

Populations of giant Canada geese (Branta canadensis maxima) have increased dramatically in eastern South Dakota since reintroduction efforts began in the 1960's. May breeding population levels of resident Canada geese exceeded the population management goal set by the South Dakota Game, Fish, and Parks (SDGFP) by the mid 1990's and continued to increase into the 2000's. This population increase was accompanied by an increase in goose related conflicts. A September hunting season was implemented in 1996 in an effort to decrease the resident Canada goose population. After implementation, a number of hunters and biologists were unhappy with the September goose season after the first few years, not only because of its early date, but because some believed the early September season was causing resident Canada geese to move out of open hunting areas due to hunting pressure. These hunters believed the September season resulted in a reduction in the total fall harvest of resident geese in South Dakota; however, there was not any data to support this view. After hearing these complaints, and not knowing the local movements of resident Canada geese, SDGFP implemented this study. Objectives were to determine the post-molt movements, band recovery analysis, productivity, and occurrence of molt migrations of resident giant Canada geese in eastern South Dakota. The primary objective was to describe where, when, and to what extent resident geese were making post-molt movements, particularly in relation to the September hunting season. A combination of satellite and VHF telemetry and band recoveries of marked geese were used to provide information on goose movements, band recovery analysis, and productivity. Canada geese were captured in 7 counties in eastern South Dakota during the summer molting period, 2000-03. A total of 148 VHF and 41 satellite transmitters were fitted on adult, female geese with broods, and 3,839 geese were leg banded. Movements of all VHF and PTT marked geese were monitored weekly from July through fall freeze up. Any post-molt movement􀃒 40 km from the goose's capture wetland prior to 15 October was considered a biologically significant movement for this study. Forty-five percent of all marked geese made significant post-molt movements. Forty-six percent of the marked geese that made significant movements moved prior to the start of the September hunting season, while 43% moved during the first week of the September season indicating the start of the season may have triggered their post-molt movement. Significant movements were primarily in a northerly direction (57%) while 21 % of post-molt movements were in a southerly direction. The farthest documented post-molt movement was 474 km north. Program MARK was used to estimate survival and recovery rates during 2000-03. The annual survival rate for adult geese averaged (± SE) 0.523 ± 0.034 and 0.676 ± 0.056 for geese banded as locals. Recovery rate estimates averaged 0.160 ± 0.017 for adults and 0.178 ± 0.018 for geese banded as locals. South Dakota accounted for 77% and 69% of the harvest distribution for direct and indirect band recoveries, respectively. Harvest rates were high and averaged 44.8% during fall 2000-04. Forty-six percent of the total band recoveries were harvested during the September hunting season. The productivity of 88 VHF marked females was monitored during spring 2001-04. Apparent and Mayfield nesting success estimates averaged 71 % and 63%, respectively. Mean total clutch size averaged 5.73 ± 0.17 while the number of goslings leaving the nest averaged 5.02 ± 0.25. Forty-nine percent of marked females nested on or around the shoreline of their previous summers capture wetland. The remaining 51 % nested on peripheral wetlands ranging from seasonal wetlands to permanent lakes. Mean distance from the capture wetlands to nest sites across years was 1.5 km± 0.18. Molt migrations were documented with VHF and satellite telemetry and by indirect band recovery locations from north of South Dakota. Three incubating Canada geese were captured and fitted with satellite transmitters, and their nests were destroyed to induce a molt migration. One of the 3 geese made a 2,080 km molt migration to Nunavut Territory, Canada. Telemetry of VHF marked females during the breeding season indicated that 56% of nonbreeding, 81 % of unsuccessful, and 19% of successful females embarked on a molt migration. Eighty-six indirect band recoveries were from north of South Dakota (46 N), indicating a broad distribution of probable molting areas to the north. This study clearly demonstrated that South Dakota resident geese are making considerable post-molt movements, which occurred primarily in a northerly direction. Interpretation of the effects of hunting pressure on post-molt movements was difficult for 2 reasons. The framework of the September season changed during this study and there were no geese marked from counties without the September hunting season. No single factor completely explained the cause of significant post-molt movements, but the opening of the September hunting season did cause a punctuated movement of geese the opening weekend of the season. Post-molt movements prior to any season starting may have been in response to a learned tradition. Based on the band recovery analysis, it was apparent that survival rates have decreased, and recovery and harvest rates have greatly increased compared to previous estimates from eastern South Dakota. This study also clearly demonstrated the involvement in molt migrations by South Dakota resident geese. I speculate that 50-60% of the spring population of resident geese is embarking on molt migrations annually. I recommend the SDGFP continue summer banding operations of Canada geese to document post-molt movements, molt migrations, and to better understand the impacts of the September hunting season on the resident goose population. Further studies incorporating satellite telemetry are needed to specifically document the molting locations of South Dakota resident geese. A better understanding of these movements should improve management efforts for resident giant Canada geese in eastern South Dakota.

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