A population of non-native Canada geese is wreaking havoc on the Campbell River Estuary, according to the results of a two-year goose monitoring study.

Cynthia Bendickson, executive director of Greenways Land Trust which coordinated the goose banding project, said that 200 Canada geese were banded in the estuary and monitored for 18 months to track the birds’ migrating patterns.

Results showed that the majority of the birds were non-native geese flocking to the estuary to lose and replace flight feathers, a process known as moulting.

“After moulting in 2015, a small proportion of these birds remained locally resident – eight per cent – in the Campbell River area, with the rest ranging widely all over the Pacific Flyway including Vancouver Island, the Salish Sea and into the states of Washington and Oregon,” Bendickson said. “These results demonstrate that there is a population of introduced Canada geese on the West Coast which disperse extensively and are likely impacting many sensitive ecosystems, not just resident geese that are causing localized issues.”

The 100-hectare estuary has seen an explosion of migratory Canada geese in recent years. In 2016, more than 1,400 geese were recorded in the estuary during the birds’ early summer moult. The return rate that year was 26 per cent, including a pair that had overwintered on the west coast of Washington state.

“Peak counts during the moult increased over the period 2013-2016 from 1,081 to 1,442, an increase of over 30 per cent,” Bendickson said.

The ultimate goal is to reduce the amount of geese in the estuary, particularly those non-native geese that impact plant vegetation in the estuary – a sensitive habitat for fish and other wildlife species.

“Suspected ecological impacts from these non-native introduced Canada geese in estuarine ecosystems include disruptions to nutrient cycling, reductions in estuary productivity, erosion and reduced habitat value for other species, particularly for juvenile salmonids,” Bendickson said.

In order to monitor and reduce introduced Canada goose populations, Greenways is suggesting the city advocate at the upcoming Association of Vancouver Island and Coastal Communities (AVICC) workshop for a regional program that would bring together stakeholders to develop and implement long-term, evidence-based management actions.

The environmental organization also recommends the designation of a Wildlife Management Area in the Campbell River Estuary to examine and identify issues before ecological damage occurs, bring additional resources in to the community to manage the estuary, and continue the work to restore and care for the estuary.

Banding by the numbers

• 200 geese collared

• 831 sightings of collared birds (as of January, 2017)

• 180, or 90 per cent, birds re-sighted

• 17 harvested by hunters

• 5 otherwise deceased

• 29 sighted in the U.S.

• 51 returned to Campbell River in the summer of 2016

• 885 km – furthest distance migration (Cave Junction, Ore.)