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The Problems Of Being Successful: Managing Interactions Between Humans And Double-Crested Cormorants, Douglas Siegel-Causey
The Problems Of Being Successful: Managing Interactions Between Humans And Double-Crested Cormorants, Douglas Siegel-Causey
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
The natural history, behavior, and ecology of double-crested cormorants (Phalacrocorax auritus) predispose this species for conflict with human sport and commercial fisheries. Cormorants breed early in life, have large broods, are efficient predators even in marginal conditions, seem to be able to adjust colony sizes quickly in response to local conditions, and have limited requirements for feeding and nesting habitats. A survey of the past history of successes and failures in managing cormorants reveals that economic impact is greatest with aquaculture and least in sport fisheries. Research during the past 5 years suggests that some control methods like …
Impact Of Double-Crested Cormorant Predation On The Yellow Perch Population In The Les Cheneaux Islands Of Michigan, Glenn Y. Belyea, Susan L. Maruca, James S. Diana, Philip J. Schneeberger, Steve J. Scott, Richard D. Clark Jr., James P. Ludwig, Cheryl L. Summer
Impact Of Double-Crested Cormorant Predation On The Yellow Perch Population In The Les Cheneaux Islands Of Michigan, Glenn Y. Belyea, Susan L. Maruca, James S. Diana, Philip J. Schneeberger, Steve J. Scott, Richard D. Clark Jr., James P. Ludwig, Cheryl L. Summer
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
The Michigan Department of Natural Resources, in conjunction with the University of Michigan and the U.S. Fish and Wildlife Service, initiated a research study to determine the impact of double-crested cormorants (Phalacrocorax auritus) on the yellow perch (Perca flavescens) population in the Les Cheneaux Islands area of northern Lake Huron. Aerial and nesting colony counts were conducted to monitor cormorant abundance. Creel census counts and tagging of 8,400 perch were used to study perch abundance. We collected 373 cormorants to study food habits via stomach-content analysis. We found that (1) cormorants fed heavily on yellow perch …
Double-Crested Cormorant Culling In The St. Lawrence River Estuary: Results Of A 5-Year Program, J. Bedard, A. Nadeau, M. Lepage
Double-Crested Cormorant Culling In The St. Lawrence River Estuary: Results Of A 5-Year Program, J. Bedard, A. Nadeau, M. Lepage
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
Modeling indicated that lowering the doublecrested cormorant population from 17,361 to 10,000 pairs could be attained only by a combination of techniques: culling breeding birds in arboreal colonies to lower breeding stock and egg spraying in accessible ground nests to lower recruitment. The 5-year program was launched in 1989; culling was halted 4 years later because the population had fallen below the threshold of 10,000 breeding pairs. A greater vulnerability of males to shooting (203:100) probably accounted for the faster-than-predicted drop in numbers. Egg spraying spanned the entire 5-year period, during which 25,095 nests were treated with inert mineral oil. …
Nesting Populations Of Double-Crested Cormorants In The United States And Canada, Laura A. Tyson, Jerrold L. Belant, Francesca J. Cuthbert, D.V. (Chip) Weseloh
Nesting Populations Of Double-Crested Cormorants In The United States And Canada, Laura A. Tyson, Jerrold L. Belant, Francesca J. Cuthbert, D.V. (Chip) Weseloh
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
Double-crested cormorants (Phalacrocorax auritus) are receiving increasing attention in North America because of depredations at aquaculture facilities and alleged impacts on sport and commercial fisheries. We obtained recent (most since 1994) estimates for the number of nesting double-crested cormorants in the United States and Canada from published references and by conducting telephone interviews with State and Provincial biologists. Using published data, we also determined annual rates of change in the number of cormorants since about 1990. The estimated minimum number of nesting pairs (colonies) of double-crested cormorants was 372,000 (852). Most cormorants nested in the Interior region (68 …
Diet Of The Double-Crested Cormorant In Western Lake Erie, Michael T. Bur, Sandra L. Tinnirello, Charles D. Lovell, Jeff T. Tyson
Diet Of The Double-Crested Cormorant In Western Lake Erie, Michael T. Bur, Sandra L. Tinnirello, Charles D. Lovell, Jeff T. Tyson
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
Sport and commercial fishing interest groups are concerned about potential impacts double-crested cormorants (Phalacrocorax auritus) may have on fish species. Our objectives for this study were to determine the diet of the cormorant in western Lake Erie and the diet overlap and competition for resources with piscivorous fish, such as walleye (Stizostedion vitreum.) The stomach contents of 302 double-crested cormorants collected in western Lake Erie consisted primarily of young-of-the-year gizzard shad (Dorosoma cepedianum), emerald shiner (Notropis atherinoides,) and freshwater drum (Aplodinotus grunniens). In the spring, freshwater drum were the most …
Double-Crested Cormorant Impacts On Sport Fish: Literature Review, Agency Survey, And Strategies, John L. Trapp, Stephen J. Lewis, Diane M. Pence
Double-Crested Cormorant Impacts On Sport Fish: Literature Review, Agency Survey, And Strategies, John L. Trapp, Stephen J. Lewis, Diane M. Pence
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
In response to concerns expressed by anglers, the U.S. Fish and Wildlife Service conducted an extensive review of published studies done throughout the United States and Canada on the impacts of double-crested cormorants (Phalacrocorax auritus) on sport-fish populations in open waters. The literature review indicated that fish species valued by sport and commercial anglers make up a very small proportion of the cormorants’ diet and that these birds have a minor effect on fish populations compared to the effects of sport and commercial fishing, natural predation, and other mortality factors. The Service sent a questionnaire to State agencies, …
Possible Effects Of Catfish Exploitation On Overwinter Body Condition Of Double-Crested Cormorants, James F. Glahn, Mark E. Tobin, J. Brent Harrel
Possible Effects Of Catfish Exploitation On Overwinter Body Condition Of Double-Crested Cormorants, James F. Glahn, Mark E. Tobin, J. Brent Harrel
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
Concurrent with the rapid growth of the Mississippi catfish industry during the 1980’s, there was evidence of similar growth of double-crested cormorant (Phalacrocorax auritus) populations wintering in the delta region of Mississippi. Observational and food habits studies indicate that this expansive industry, incorporating more than 100,000 acres of ponds, provides an enormous food base for overwintering populations estimated in recent years to exceed 50,000 birds. As much as 75 percent of the diet in certain roosting areas of the Mississippi delta consisted of catfish, and according to bioenergetic models cormorants can exploit as much as 940 metric tons …
A Geographic Information System To Monitor Nest Distributions Of Double-Crested Cormorants And Black-Crowned Night-Herons At Shared Colony Sites Near Toronto, Canada, S. Jarvie, H. Blokpoel, T. Chipperfield
A Geographic Information System To Monitor Nest Distributions Of Double-Crested Cormorants And Black-Crowned Night-Herons At Shared Colony Sites Near Toronto, Canada, S. Jarvie, H. Blokpoel, T. Chipperfield
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
In the early 1990’s, it became apparent that the rapid colonization of Tommy Thompson Park on Lake Ontario near Toronto by double-crested cormorants (Phalacrocorax auritus) would eventually affect the existing colonies of blackcrowned night-herons (Nycticorax nycticorax) owing to competition for nest sites and destruction of nest trees. As a result, monitoring of these two species was expanded in 1992 by individually marking all nest trees (using permanent metal tree tags) and by recording the numbers of heron and cormorant nests for all nest trees. In 1996, professional surveyors determined the exact locations of nest trees. We have developed …
Colonial Waterbird Nesting On West Sister Island National Wildlife Refuge And The Arrival Of Double-Crested Cormorants, Mark C. Shieldcastle, Larry Martin
Colonial Waterbird Nesting On West Sister Island National Wildlife Refuge And The Arrival Of Double-Crested Cormorants, Mark C. Shieldcastle, Larry Martin
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
Recent survey data have shown the importance of West Sister Island National Wildlife Refuge, Lake Erie, to nesting waders. About 40 percent of all herons and egrets nesting in the U.S. Great Lakes are found there, including the Great Lakes’ largest colonies of great blue heron (Ardea herodias), great egret (Ardea alba), and black-crowned nightheron (Nycticorax nycticorax), and the largest of two snowy egret (Egretta thula). West Sister Island’s importance to Ohio has grown in recent decades with the loss of smaller mainland colonies of waders, especially the black-crowned night-heron. The double-crested …
Fish Losses To Double-Crested Cormorant Predation In Eastern Lake Ontario, 1992–97, Robert M. Ross, James H. Johnson
Fish Losses To Double-Crested Cormorant Predation In Eastern Lake Ontario, 1992–97, Robert M. Ross, James H. Johnson
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
We examined 4,848 regurgitated digestive pellets of double-crested cormorants (Phalacrocorax auritus) over a 6-year period (1992–97) to estimate annual predation on sport and other fishes in the eastern basin of Lake Ontario. We found more than 51,000 fish of 28 species. Using a model that incorporates annual colony nest counts; fledgling production rates; adult, immature, and young-of-year residence times (seasonal); estimates of mean number of fish per pellet and mean fish size; and a fecal pathway correction factor (4.0 percent), we estimate total annual number of fish consumed by cormorants in the eastern basin of Lake Ontario to …
Review Of The Population Status And Management Of Double-Crested Cormorants In Ontario, C. Korfanty, W.G. Miyasaki, J.L. Harcus
Review Of The Population Status And Management Of Double-Crested Cormorants In Ontario, C. Korfanty, W.G. Miyasaki, J.L. Harcus
Symposium on Double-Crested Cormorants: Population Status and Management Issues in the Midwest
We prepared this review of the status and management of double-crested cormorants (Phalacrocorax auritus) in Ontario, with management options, in response to concerns expressed about possible negative impacts of large numbers of the birds on fish stocks, and vulnerable, threatened and endangered species. Double-crested cormorants are native to Ontario and were first recorded breeding on Lake of the Woods in northwestern Ontario in the late 1700’s. The birds spread eastward to colonize all of the Great Lakes by the 1930’s. A decline in cormorant populations on the Great Lakes from the 1950’s to the 1970’s has been attributed …