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Location
Hot Springs, AR
Start Date
6-4-2003 12:00 AM
Description
Exponential growth of the Interior double-crested cormorant (Phalacrocrax auritus) breeding populations in the past 20 years has resulted in intensified conflicts with human interests. Increasing nesting populations and seasonal impacts of fall migrating cormorants in New York and Vermont have raised significant concern among fish and wildlife resource managers, stakeholders and the general public. Property damage, interspecific competition, decreased plant and animal species diversity, and predation on sport fish are the primary concerns. The need for cormorant management techniques that are effective, socially acceptable, and practical to implement at the local level remains a considerable challenge for wildlife managers in the Great Lakes Region. To address these concerns on Lake Ontario, Oneida Lake and Lake Champlain, cormorant damage management programs have been designed to limit nest numbers, colony locations and loafing/ feeding sites. Habitat management and alteration, egg and nest removal, egg oiling, and an integrated harassment program using multiple scaring tools are used in combination to meet individual site objectives. We compared the techniques relative to cost, effectiveness, and desired outcome. On breeding colonies, removal of eggs and nest materials deterred cormorant nesting effectively, but required persistence. Egg oiling reduced hatching rates to less than 2%, resulting in lower breeding numbers over time. Habitat alteration in the form of overstory tree removal did not prevent nesting attempts by cormorants, but did facilitate nest removal. Scare devices and harassment were used effectively to eliminate nesting on a privately owned island on Lake Champlain, but less intensive harassment was not effective on Lake Ontario. Harassment using pyrotechnics, human effigies, Mylar tape, propane cannons, and chasing with boats used at loafing and feeding areas was very effective in moving migrating cormorants from Oneida Lake during the month of September over five consecutive years. Costs to implement a program ranged from less than $1,000 to $12,000 annually, depending on the site and the objectives. Our experiences with cormorant management on and near breeding colonies suggest that relatively inexpensive site-specific control can be used to reduce local impacts. Concurrent flyway-level cormorant population management remains desirable to lessen the incidence of local impacts and to address the broader scope of concerns occurring across their range.
Recommended Citation
Farquhar, J. F., Chipman, R. B., Crenshaw, W. J., Slate, D., & Coleman, J. T. H. (2003). Management of breeding and fall migrating double-crested cormorants in New York and Vermont - Eight years of lessons learned. In Fagerstone, K.A. & Witmer, G.W. (Eds.), The Tenth Wildlife Damage Management Conference (79-86). Hot Springs, AR: National Wildlife Research Center.
Included in
Management of Breeding and Fall Migrating Double-Crested Cormorants in New York and Vermont - Eight Years of Lessons Learned
Hot Springs, AR
Exponential growth of the Interior double-crested cormorant (Phalacrocrax auritus) breeding populations in the past 20 years has resulted in intensified conflicts with human interests. Increasing nesting populations and seasonal impacts of fall migrating cormorants in New York and Vermont have raised significant concern among fish and wildlife resource managers, stakeholders and the general public. Property damage, interspecific competition, decreased plant and animal species diversity, and predation on sport fish are the primary concerns. The need for cormorant management techniques that are effective, socially acceptable, and practical to implement at the local level remains a considerable challenge for wildlife managers in the Great Lakes Region. To address these concerns on Lake Ontario, Oneida Lake and Lake Champlain, cormorant damage management programs have been designed to limit nest numbers, colony locations and loafing/ feeding sites. Habitat management and alteration, egg and nest removal, egg oiling, and an integrated harassment program using multiple scaring tools are used in combination to meet individual site objectives. We compared the techniques relative to cost, effectiveness, and desired outcome. On breeding colonies, removal of eggs and nest materials deterred cormorant nesting effectively, but required persistence. Egg oiling reduced hatching rates to less than 2%, resulting in lower breeding numbers over time. Habitat alteration in the form of overstory tree removal did not prevent nesting attempts by cormorants, but did facilitate nest removal. Scare devices and harassment were used effectively to eliminate nesting on a privately owned island on Lake Champlain, but less intensive harassment was not effective on Lake Ontario. Harassment using pyrotechnics, human effigies, Mylar tape, propane cannons, and chasing with boats used at loafing and feeding areas was very effective in moving migrating cormorants from Oneida Lake during the month of September over five consecutive years. Costs to implement a program ranged from less than $1,000 to $12,000 annually, depending on the site and the objectives. Our experiences with cormorant management on and near breeding colonies suggest that relatively inexpensive site-specific control can be used to reduce local impacts. Concurrent flyway-level cormorant population management remains desirable to lessen the incidence of local impacts and to address the broader scope of concerns occurring across their range.