Demographic consequences of translocation of overabundant Canada geese breeding in urban areas

摘要

Translocation is a common tool for managing nuisance Canada geese (Branta canadensis) in urban areas across North America. However, no previous research has assessed how translocation affects survival and philopatry at donor and release sites. Such information is required for managers to decide if translocation is a suitable intervention to reach their management objectives. We used a joint multistate-dead recovery mark-recapture analysis to retrospectively measure the effects of translocation on survival and fidelity of immature and adult Canada geese (n=2,946 marked individuals). Between 2009 and 2013, geese from Wascana Centre, an urban park in Regina, Saskatchewan, Canada, were subject to translocation to Cumberland Lake, a remote lake more than400km away. Survival varied between immature (mean annual survival=0.31, 95% CI=0.24–0.40) and adult (mean annual survival=0.72, 95% CI=0.69–0.75) geese, but translocation had no effect on survival probability. However, translocated immature geese hada lower mean probability of returning to Wascana (0.11, 95% CI=0.07–0.18) compared to adult geese (0.83, 95% CI=0.77–0.88). Translocation is unlikely to lead to a reduction in population density in our system given that translocation does not influence survival and adults return at high rates after being moved. If translocation is the only management option available, then the focus should be on immature geese. If translocation is used as a management option to minimize the number of geese that wouldneed to be lethally removed, then managers should translocate immature geese and cull adult geese to reach management objectives.