RETURN FROM THE BRINK:

Habitat competition between Canada Geese and Anseriformes

members

Erica Judd, Lindsie Parks, Vicky Harden

Do increasing populations of Canada Geese (Branta canadensis) affect populations of other members of Anseriformes in Oklahoma?

Some populations of Canada Geese have grown so large that there are organizations

that strive to decrease their numbers by excessive hunting and pesticide use to keep them from destroying the local environment.

United States Distribution Map for Branta canadensis

In the last 50 years flocks of Canada Geese have become established in many urban and suburban areas of North America.

They graze on lawns as their primary food source.

Previous studies suggest that food passage rates through the digestive tract are maximized at the expense of efficient digestion (Owen 1972, 1975, Sibly 1981).

This indicates the constant need to graze and results in a large amount of waste produced.

Methods

Christmas Bird Counts were collected for wintering birds in Oklahoma in the last 20 years.

We chose to use wintering birds due to scarcity of food and the lack of competition for nesting areas.

Methods

Regression analyses were done Population of Canada Geese in OK Population of other geese and ducks in OK

ANOVA was run on each group To determine significance of population

increase or decrease Spearman’s rank correlation

Is there a correlation between Canada Goose population and other ducks and geese in OK?

Results

Regression analysis of Canada Geese shows a slight increase in population

ANOVA found no significance in this increase P = 0.6332

Regression analysis and of other ducks and geese shows a decrease in population.

ANOVA found a significant decrease also P = 0.0019

No significant increase inCanada Goose population

Year

1985 1990 1995 2000 2005 2010

Can

ada

Gee

se p

er

hour

-100

-50

0

50

100

150

200

250

300

x column vs y column Year vs Number per hour Canada Geese 95% Confidence Band 95% Prediction Band

Significant decrease inOther Anseriformes members

Year

1985 1990 1995 2000 2005 2010

Duc

ks a

nd G

eese

per

hou

r

-100

-50

0

50

100

150

200

250

300

x column 1 vs y column 1 Year vs Number per hour ducks and geese 95% Confidence Band 95% Prediction Band

Spearman’s rank correlation

Two-tailed correlation analysis done with significance level of 0.05

We found no significant correlation between the number of Canada Geese and other Anseriformes in Oklahoma (P = 0.517)

Discussion

Overall, we found no correlation between the increasing population of Canada Geese and the other ducks and geese in Oklahoma .

This provides some evidence that Canada Geese do not negatively affect the populations that compete with them for food in Oklahoma during the non-breeding season.

• Other studies have shown that the grazing of geese has an impact on the nitrogen content and growth rate of some grasses.

• This would reduce the amount of more palatable grasses as well as the total amount of grasses available for consumption.

• It is unclear whether or not this would cause an increase in competition among Canada Geese and other members of Anseriformes. • Correlations with the weather patterns , mean lake temperatures , and water quality should also be done in order to decide if one of these factors is having an effect on the populations.

• Quantitative measurements of the vitality and breeding success of all species of Anseriformes should also be done in order to justify the effect that Canada Geese have on them.

Other Possibilities