"Goose steps" needed for knowledge of bird problem
"Goose steps" needed to increase knowledge of bird problem
Scientists say research is needed to clear up “grey areas” on managing a large black and white goose that damages farm pasture and city parks.
The Canada goose was first introduced to New Zealand in 1876 and is expanding its range, particularly in eastern areas of both North and South islands. The goose competes with livestock for crops and pasture; fouls farm paddocks, city parks and sports fields; and increases the risk of bird strike around airports. It can carry diseases including avian influenza, campylobacter, salmonella and E.coli that may infect people and animals including our rare native birds.
The goose’s classification as a game bird is currently under review by the Conservation Minister. At present it can only be hunted under license from Fish & Game. Fish & Game can order culls if hunters fail to control geese to acceptable levels, but local hunters opposed recent attempts to cull birds in Christchurch.
Landcare Research scientists Drs Eric Spurr and Jim Coleman have reviewed goose population trends, damage and control in New Zealand. They say that while goose damage is multifaceted, surprisingly little research has been done on the true economic impacts, and how to manage goose numbers more effectively than at present.
“Currently, the goose population is well above the levels agreed to by farming interests,” Dr Spurr says. “As hunting alone does not keep numbers in check, research will help to refine other methods. Preventing birds breeding, scaring birds, and culling all have advantages and disadvantages – for example scaring may simply shift birds around.
“Also, there is no specific measurement of whether current goose management is actually minimising adverse effects.”
Dr Spurr also says the reasons for variations in the level of goose-related damage are not fully understood.
“We do know there are seasonal changes in goose diet. For example, on a study of 69 hectares of pasture, geese ate an average 90 kilograms of pasture per day in spring, and more than five times that in autumn. Goose impacts may be worse in drought years, and the ability of land to cope with goose numbers varies considerably. This tells us that managing goose populations to a pre-agreed number may not always be the most effective approach.
“Better information on control methods, population trends and of course the cost of goose damage will help enlighten decisions on the goose’s future status and management.”
Spurr, E.B; Coleman, J.D. 2005. Review of Canada goose population trends, damage, and control in New Zealand. Landcare Research Science Series No. 30. Manaaki Whenua Press, Lincoln, New Zealand. 31 pp.
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