Managing Double-crested Cormorants at Tommy Thompson Park

Session: 05. - Within Reach: The Path to De-listing Toronto and Region as a Great Lakes Area of Concern

Andrea Chreston, Toronto and Region Conservation Authority, [email protected]
Karen McDonald, Toronto and Region Conservation Authority, [email protected]
Ralph Toninger, Toronto and Region Conservation Authority, [email protected]
Gail Fraser, Faculty of Environmental Studies, York University, [email protected]

Abstract

Tommy Thompson Park is home to the largest colony of breeding Double-crested Cormorants (hereafter cormorant) in North America.  A native species, the cormorant has suffered since European settlement; initially from intense hunting pressures and later from reproductive failures caused by DDT resulting in near extirpation in the Great Lakes.  While the population has recovered in the last couple of decades, it is not without real and perceived issues.  As ecosystem engineers, tree nesting cormorants can cause deforestation.  With a goal to achieve a balance between the continued existence of a healthy, thriving cormorant colony and the other ecological, educational, scientific and recreational values of Tommy Thompson Park (namely preservation of tree canopy), Toronto and Region Conservation has been successfully implementing a Cormorant Management Strategy since 2009. Unlike other cormorant management programs in North America, TRCA’s management approach is non-lethal and uses deterrent techniques to prevent cormorants from nesting in healthy trees at Tommy Thompson Park, while encouraging ground nesting.  Since management began in 2009, the population has doubled, and ground nesting has increased from supporting 15% to 76% of the population.

1. Keyword
cormorants

2. Keyword
management

3. Keyword
Lake Ontario

4. Additional Keyword
Toronto

5. Additional Keyword
monitoring

6. Additional Keyword
non-lethal deterrence