Northern Prairie Wildlife Research Center
Artificial goose nests were used to determine what factors might increase predation after visits to nests of Cackling Canada geese (Branta canadensis minima), such as whether leaving the nest uncovered, marking the nest location with a flag, or placing the nest on an island or peninsula would increase the rate of predation. Predators destroyed more of the nests with eggs exposed to view (61%) than of the nests with eggs covered with goose down (35%) (P < 0.05). The rate of predation was only slightly higher among nests located on peninsulas than on islands and equal proportions of flagged and unflagged nests were destroyed. Investigators seemed to attract predators and caused an increase in predation at uncovered nests immediately after a visit to the nest. Covering the eggs with down seemed to negate the attraction of predators when visiting the nest. Among 46 nests destroyed, 78% were destroyed by birds and 22% by mammals. Islands seemed to provide refuge from mammalian predators. Investigators should minimize their impacts on nesting success and should measure the extent of their impact as part of their studies.