Behavioral response of canada geese to egg‐oiling and nest removal

Abstract

ABSTRACTControlling overabundant goose populations remains a wildlife management challenge. Although reducing adult survival is considered more effective than reducing fecundity, egg‐oiling, and egg removal are often preferential techniques for controlling temperate nesting Canada geese (Branta canadensis) in urban and peri‐urban settings. Little is known about the effect of these methods on the subsequent behavior of geese and their potential effects on population dynamics. We aimed to determine how long Canada geese nesting in southern Quebec, Canada remain at the nest site following egg‐oiling, whether birds submitted to egg‐oiling or nest removal persist in the area to molt and whether they return to breed in the study area the following year, and if so, how far do they nest from their previous nest location. We studied 996 nests initiated by 442 neck‐collared females between 2006 and 2012 including 76 that were oiled, 91 that were removed, 143 that suffered complete loss of the clutch by predators, were flooded, or abandoned, and 686 that were successful. We found that egg‐oiling delayed nest abandonment past the expected hatching date and that the delay increased when applying the treatment later in incubation. We observed only 10 cases of renesting and most occurred after nest flooding. Females that had their nests removed or whose nest failed had a greater probability of leaving the study area to molt elsewhere than females that were successful or those that had their eggs treated with oil. The probability that a female survived and returned to nest in the area was not related to the fate of its nest in the previous year and was estimated at 0.71 (95% CI = 0.67–0.74). The mean distance between successive nesting attempts was not related to the previous year nest fate and averaged 78 ± 8 m. Nest success and thus recruitment was reduced during years with the experimental treatments, but strong philopatry indicates that treatments must be repeated every year to have an effect on the local population growth. If the goal is to keep the geese longer at their nest site, then coating eggs with oil as late as possible in incubation will result in geese remaining at the nest site well past the expected hatch date. If the goal is to cause the geese to leave the nest site, then nest removal should be favored. © 2018 The Wildlife Society.