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Full-Text Articles in Life Sciences

Isotopic Discrimination In The Double-Crested Cormorant (Phalacrocorax Auritus), Elizabeth C. Craig, Brian S. Dorr, Katie C. Hanson-Dorr, Jed P. Sparks, Paul D. Curtis Oct 2015

Isotopic Discrimination In The Double-Crested Cormorant (Phalacrocorax Auritus), Elizabeth C. Craig, Brian S. Dorr, Katie C. Hanson-Dorr, Jed P. Sparks, Paul D. Curtis

Brian S Dorr

The diet-tissue discrimination factor is the amount by which a consumer’s tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured discrimination factors in blood (whole blood, red blood cells and plasma), liver, muscle and feathers of Double- crested Cormorants (Phalacrocorax auritus) for stable isotope ratios of carbon, nitrogen and sulfur. Cormorants exhibited discrimination factors that differed significantly among tissue types (for carbon and nitrogen), and differed substantially (in the context of the isotopic variation among relevant prey species) from those observed ...


Influence Of Simulated Double-Crested Cormorant, Phalacrocorax Auritus, Predation On Multiple-Batch Production Of Channel Catfish, Ictalurus Punctatus, Brian S. Dorr, Carole R. Engle Jun 2015

Influence Of Simulated Double-Crested Cormorant, Phalacrocorax Auritus, Predation On Multiple-Batch Production Of Channel Catfish, Ictalurus Punctatus, Brian S. Dorr, Carole R. Engle

Brian S Dorr

The double-crested cormorant, Phalacrocorax auritus, is considered the primary depredating bird species on commercially produced channel catfish, Ictalurus punctatus, in the southeastern USA. We simulated different levels of cormorant predation on losses at harvest and economic effects on channel catfish production in a multiple-batch cropping system. We observed significant (P<0.05) declines in catfish production at increasing levels of cormorant predation in this study. This decline was mitigated by increased individual growth of catfish at higher predation rates (i.e., lower catfish densities). This mitigating effect produced a non-linear relationship with total kg of catfish harvested per pond resulting in a non-linear incremental increase in breakeven price related to predation. Costs of production ($/kg) increased with increasing predation levels up to very high levels of predation with a cumulative maximum increase in breakeven price of $0.143/kg. These results indicate that losses at harvest due to cormorant predation occur immediately but are mitigated in part by compensatory growth of individual catfish. Losses due to cormorant predation in multi-batch systems can be considerable, but there is not a 1:1 relationship between losses and kg of catfish harvested due to compensatory actors.


Impacts Of Colonial Waterbirds On Vegetation And Potential Restoration Of Island Habitats, Christopher R. Ayers, Katie C. Hanson-Dorr, Sadie O'Dell, Charles D. Lovell, Michael L. Jones, Jason R. Suckow, Brian S. Dorr May 2015

Impacts Of Colonial Waterbirds On Vegetation And Potential Restoration Of Island Habitats, Christopher R. Ayers, Katie C. Hanson-Dorr, Sadie O'Dell, Charles D. Lovell, Michael L. Jones, Jason R. Suckow, Brian S. Dorr

Brian S Dorr

Colonial waterbirds have impacted forested island ecosystems throughout their breeding range, changing vegetation, and soil characteristics and bird communities.Our objectives were to (1) determine effects of three levels of colonial waterbird exclusion on overall vegetation diversity and growth, and survival of a candidate restoration species (black elderberry; Sambucus nigra canadensis); (2) investigate effects of different planting techniques on survival and growth of black elderberry; and (3) determine effects of waterbird colonization on soil chemistry. In 2012, we investigated effects of three levels of waterbird exclusion (none control plots [CON]; partial, which excluded waterbirds larger than gulls [PEX]; and full ...


Wintering Ecology Of Adult North American Ospreys, Brian E. Washburn, Charles J. Henny, Mark S. Martell, Richard O. Bierregaard, Brian S. Dorr, Thomas J. Olexa Dec 2014

Wintering Ecology Of Adult North American Ospreys, Brian E. Washburn, Charles J. Henny, Mark S. Martell, Richard O. Bierregaard, Brian S. Dorr, Thomas J. Olexa

Brian S Dorr

North American Ospreys (Pandion haliaetus) typically migrate long distances to their wintering grounds in the tropics. Beyond the general distribution of their wintering range (i.e., the Caribbean, South America, and Central America), very little is known about the wintering ecology of these birds. We used satellite telemetry to determine the duration of wintering period, to examine the characteristics of wintering areas used by Ospreys, and to quantify space use and activity patterns of wintering Ospreys. Adult Ospreys migrated to wintering sites and exhibited high wintering site fidelity among years. Overall, Ospreys wintered on river systems (50.6%) more than ...


Geographic Segregation And Evidence Of Density-Dependent Changes In Sex Ratios In An Abundant Colonial Waterbird, Brian S. Dorr, Katie C. Hanson-Dorr, Travis L. Devault, Alban Guillaumet, Scott C. Barras Dec 2014

Geographic Segregation And Evidence Of Density-Dependent Changes In Sex Ratios In An Abundant Colonial Waterbird, Brian S. Dorr, Katie C. Hanson-Dorr, Travis L. Devault, Alban Guillaumet, Scott C. Barras

Brian S Dorr

Demographic information, such as geographic segregation of sexes and sex ratio data, is needed to develop, model and evaluate conservation and management strategies for wildlife. A variety of physiological, behavioral and environmental factors can influence segregation of sexes and sex ratios, many of which originate with density- dependent processes. Departure from 50:50 sex ratios of double-crested cormorants (Phalacrocorax auritus) collected during control efforts in breeding and wintering areas across their eastern range of the USA were evaluated using using a Z-test as well as Stouffer’s weighted Z-tests. In addition, a specifically-designed randomization test was used to evaluate density-dependent ...


The Cumulative Effects Of Management On The Population Dynamics Of The Double-Crested Cormorant Phalacrocorax Auritus In The Great Lakes, Alban Guillaumet, Brian S. Dorr, Guiming Wang, Terry J. Doyle Jan 2014

The Cumulative Effects Of Management On The Population Dynamics Of The Double-Crested Cormorant Phalacrocorax Auritus In The Great Lakes, Alban Guillaumet, Brian S. Dorr, Guiming Wang, Terry J. Doyle

Brian S Dorr

Wildlife species have been subject to control efforts throughout human history due to real or alleged human–wildlife conflicts. The Double-crested Cormorant Phalacrocorax auritus in the interior of North America is no exception, with recent population growth leading to increased conflicts and consequently the development of many control programmes. These control programmes are usually conducted at local scales, often with little or no effort to assess their cumulative effects at the population level. We attempted the first comprehensive assessment of the cumulative effects of control at various spatio-temporal scales, focusing on 199 colonies of Double-crested Cormorant monitored during a 29-year ...


Double-Crested Cormorant Distribution On Catfish Aquaculture In The Yazoo River Basin Of Mississippi, Brian S. Dorr, Loren W. Burger, Scott C. Barras, Kristina Casscles Godwin Mar 2012

Double-Crested Cormorant Distribution On Catfish Aquaculture In The Yazoo River Basin Of Mississippi, Brian S. Dorr, Loren W. Burger, Scott C. Barras, Kristina Casscles Godwin

Brian S Dorr

No abstract provided.


Efficacy, Effort, And Cost Comparisons Of Trapping And Acetaminophen-Baiting For Control Of Brown Treesnakes On Guam, Larry Clark, Peter J. Savarie, John A. Shivik, Stewart W. Breck, Brian S. Dorr Jan 2012

Efficacy, Effort, And Cost Comparisons Of Trapping And Acetaminophen-Baiting For Control Of Brown Treesnakes On Guam, Larry Clark, Peter J. Savarie, John A. Shivik, Stewart W. Breck, Brian S. Dorr

Brian S Dorr

Abstract: Brown treesnakes (Boiga irregularis) are an invasive species to the island of Guam. Because they have extirpated the native forest avifauna on Guam and are a threat to other Pacific islands, the development of efficient and cost-effective methods to control them is desired. We compared the efficacy, cost, and effort required to remove brown treesnakes on 6-ha plots in forest scrub on Guam, using 2 methods: trapping and poison baiting. Toxic baits consisted of dead neonatal mice adulterated with 80-mg acetaminophen. To assess efficacy, we used mark-recapture methods to estimate snake abundance on plots 12 days before and 12 ...


The Direction Of Research And Management Of Double-Crested Cormorants Heading Into The 2000s: Symposium Overview And Future Information Needs, Brian S. Dorr, Christopher Somers Jan 2012

The Direction Of Research And Management Of Double-Crested Cormorants Heading Into The 2000s: Symposium Overview And Future Information Needs, Brian S. Dorr, Christopher Somers

Brian S Dorr

Abstract.—An overview is provided of a symposium on the direction of research and management of Double-crested Cormorants (Phalacrocorax auritus) heading into the 2000s. The current symposium built on previous efforts and described a number of focus areas of informational need, including cormorant impacts on natural resources, demographics of cormorants, assessment of control efforts, assessment of fish consumption and bioenergetics, and cormorant spatial ecology and influences on movements. The cormorant symposium highlighted a shift in research focus relative to earlier symposia, from evaluating potential impacts on commercial and natural resources to evaluating management actions in attaining desired goals. In addition ...


Modification Of Net Configurations Of The Coda Netlauncher© To Enhance Bird Capture, Amanda M. Prisock, Brian S. Dorr, James C. Cumbee Jan 2012

Modification Of Net Configurations Of The Coda Netlauncher© To Enhance Bird Capture, Amanda M. Prisock, Brian S. Dorr, James C. Cumbee

Brian S Dorr

Abstract: We modified and evaluated capture nets fi red from the Coda Netlauncher® as a tool for capturing various avian species. We modified the netlauncher by using customized nets to maximize the area of the capture zone. We captured 137 birds, comprising 12 species, in 23 attempts between July 2008 and October 2009 using this method. Capture success rates varied from 25 to 69% were comparable to success rates reported for other capture methods for these species. However, individual capture success for different net configurations varied greatly from 3 to 65%. Minimal injuries and 2 bird fatalities were reported. The ...


Management Of Double-Crested Cormorants To Improve Sport Fisheries In Michigan: Three Case Studies, Brian S. Dorr, Shauna L. Hanisch, Peter H. Butchko, David G. Fielder Jan 2012

Management Of Double-Crested Cormorants To Improve Sport Fisheries In Michigan: Three Case Studies, Brian S. Dorr, Shauna L. Hanisch, Peter H. Butchko, David G. Fielder

Brian S Dorr

No abstract provided.


Towards Optimized Population Control Efficiency In Space And Time: A Modelling Framework Adapted To A Colonial Waterbird, Alban Guillaumet, Brian S. Dorr, Guiming Wang Jan 2012

Towards Optimized Population Control Efficiency In Space And Time: A Modelling Framework Adapted To A Colonial Waterbird, Alban Guillaumet, Brian S. Dorr, Guiming Wang

Brian S Dorr

The double-crested cormorant is a native North American waterbird that recently underwent a dramatic population expansion. Population control efforts in the USA and Canada attempt to mitigate cormorant damages to natural resources and aquaculture. However, there is currently no coordination among the various stakeholders involved in management activities as well as no attempt to optimize population control efficiency. In this paper, we present for the first time a spatially explicit stage-structured metapopulation model parameterized for the cormorant. We developed simulation tools to get insights into the efficiency gain that can be expected from a better planning of management activities in ...


Summer And Migrational Movements Of Satellite-Marked Double-Crested Cormorants From A Breeding Colony Managed By Egg-Oiling In Lake Ontario, Usa, Brian S. Dorr, Jimmy D. Taylor Ii, Scott J. Werner, D. Tommy King, James F. Farquhar, Irene M. Mazzocchi, Russell D. Mccullough Jan 2012

Summer And Migrational Movements Of Satellite-Marked Double-Crested Cormorants From A Breeding Colony Managed By Egg-Oiling In Lake Ontario, Usa, Brian S. Dorr, Jimmy D. Taylor Ii, Scott J. Werner, D. Tommy King, James F. Farquhar, Irene M. Mazzocchi, Russell D. Mccullough

Brian S Dorr

Abstract.—A two-year satellite telemetry study was initiated in May 2000 at a Double-crested Cormorant (Phalacrocorax auritus) breeding colony on Little Galloo Island (LGI) in eastern Lake Ontario, New York, USA, which is managed by egg-oiling. The objective was to describe cormorant (N = 26/year) movements, specifically during the period of reproductive management by egg-oiling and seasonally (breeding, migration and wintering). Egg-oiling at two-week intervals resulted in a hatch success on LGI of 5.7% for 2000 and 2001, combined. The majority (97%) of core use areas of marked cormorants contained LGI throughout three egg-oiling treatments (six weeks), and 71 ...


Determinants Of Local And Migratory Movements Of Great Lakes Double-Crested Cormorants, Alban Guillaumet, Brian S. Dorr, Guiming Wang, Jimmy D. Taylor Ii, Richard B. Chipman, Heidi Scherr, Jeff Bowman, Kenneth F. Abraham, Terry J. Doyle, Elizabeth Cranker Jun 2011

Determinants Of Local And Migratory Movements Of Great Lakes Double-Crested Cormorants, Alban Guillaumet, Brian S. Dorr, Guiming Wang, Jimmy D. Taylor Ii, Richard B. Chipman, Heidi Scherr, Jeff Bowman, Kenneth F. Abraham, Terry J. Doyle, Elizabeth Cranker

Brian S Dorr

We investigated how individual strategies combine with demographic and ecological factors to determine local and migratory movements in the double-crested cormorants (Phalacrocorax auritus). One hundred and forty-five cormorants were captured from 14 nesting colonies across the Great Lakes area and fitted with satellite transmitters. We first tested the hypotheses that sexual segregation, density-dependent effects, and the intensity of management operations influenced home range size during the breeding season. The influence of these factors appeared to be limited in part due to random variability in foraging and dispersal decisions at individual and colony levels. We also designed a statistical framework to ...


Ameliorating The Effects Of The Digenetic Trematode, Bolbophorus Damnificus On The Channel Catfish Industry, Lester Khoo, David J. Wise, Linda M. Pote, Andrew J. Mitchell, Todd S. Byars, Marlena C. Yost, Cynthia M. Doffitt, Brian S. Dorr Jan 2011

Ameliorating The Effects Of The Digenetic Trematode, Bolbophorus Damnificus On The Channel Catfish Industry, Lester Khoo, David J. Wise, Linda M. Pote, Andrew J. Mitchell, Todd S. Byars, Marlena C. Yost, Cynthia M. Doffitt, Brian S. Dorr

Brian S Dorr

No abstract provided.


A New Policy For Management Of Double-Crested Cormorants In The United States And An Example Of Its Implementation., Shauna L. Hanisch, Brian S. Dorr, Peter H. Butchko Jan 2011

A New Policy For Management Of Double-Crested Cormorants In The United States And An Example Of Its Implementation., Shauna L. Hanisch, Brian S. Dorr, Peter H. Butchko

Brian S Dorr

In the fall of 2003, the U.S. Fish and Wildlife Service (USFWS), in cooperation with USDA-Wildlife Services (USDA-WS), completed an Environmental Impact Statement (EIS) for the management of Double-crested Cormorants (DCCOs) in the United States. The USFWS subsequently published new regulations to implement the EIS proposed strategy. One part of the new regulations, a “public resource depredation order” (PRDO), allows state wildlife agencies, tribes, and USDA-WS to control DCCOs on a localized level to protect fish, wildlife, plants, and their habitats in 24 states. We’ll discuss this new policy and will highlight the management activities, including monitoring and ...


Evaluation Of Harassment Of Migrating Double-Crested Cormorants To Limit Depredation On Selected Sport Fisheries In Michigan, Brian S. Dorr, Ashley Moerke, Michael Bur, Chuck Bassett, Tony Aderman, Dan Traynor, Russell D. Singleton, Peter H. Butchko, Jimmy D. Taylor Nov 2010

Evaluation Of Harassment Of Migrating Double-Crested Cormorants To Limit Depredation On Selected Sport Fisheries In Michigan, Brian S. Dorr, Ashley Moerke, Michael Bur, Chuck Bassett, Tony Aderman, Dan Traynor, Russell D. Singleton, Peter H. Butchko, Jimmy D. Taylor

Brian S Dorr

No abstract provided.


Management Effects On Breeding And Foraging Numbers And Movements Of Double-Crested Cormorants In The Les Cheneaux Islands, Lake Huron, Michigan, Brian S. Dorr, Tony Aderman, Peter H. Butchko Jan 2010

Management Effects On Breeding And Foraging Numbers And Movements Of Double-Crested Cormorants In The Les Cheneaux Islands, Lake Huron, Michigan, Brian S. Dorr, Tony Aderman, Peter H. Butchko

Brian S Dorr

No abstract provided.


Use Of Fatty Acid Profiles To Distinguish Between Selected Game Fish And Farm-Raised Channel Catfish, Randy S. Stahl, Brian S. Dorr, Scott C. Barras, John J. Johnston Jan 2006

Use Of Fatty Acid Profiles To Distinguish Between Selected Game Fish And Farm-Raised Channel Catfish, Randy S. Stahl, Brian S. Dorr, Scott C. Barras, John J. Johnston

Brian S Dorr

No abstract provided.


Foraging Ecology And Depredation Management Of Great Blue Herons At Mississippi Catfish Farms, James F. Glahn, Brian S. Dorr, John B. Harrell, Lester Khoo Jan 2002

Foraging Ecology And Depredation Management Of Great Blue Herons At Mississippi Catfish Farms, James F. Glahn, Brian S. Dorr, John B. Harrell, Lester Khoo

Brian S Dorr

No abstract provided.


Size Selectivity Of Crappie Angling, Leandro E. Miranda, Brian S. Dorr Jan 2000

Size Selectivity Of Crappie Angling, Leandro E. Miranda, Brian S. Dorr

Brian S Dorr

Abstract.—Over 6,000 black crappies Pomoxis nigromaculatus and white crappies P. annularis were tagged in five lakes and reservoirs to quantify size selectivity of angling. Total length of fish tagged ranged from 20.0 to 39.8 cm; fish caught by anglers ranged from 20.0 to 38.8 cm. Return rates were low at lengths near 20 cm, increased gradually to a peak between 26 and 32 cm, and decreased for longer fish. This pattern was consistent among the five lakes and reservoirs and did not differ between species. Observed size-selective exploitation resulted in the lopsided removal of ...


Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin Mar 1999

Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin

Brian S Dorr

No abstract provided.


Evaluation Of A Methyl Anthranilate-Based Bird Repellent: Toxicity To Channel Catfish Ictalurus Punctatus And Effect On Great Blue Heron Ardea Herodias Feeding Behavior, Brian S. Dorr, Larry Clark, Igor Mezine Dec 1998

Evaluation Of A Methyl Anthranilate-Based Bird Repellent: Toxicity To Channel Catfish Ictalurus Punctatus And Effect On Great Blue Heron Ardea Herodias Feeding Behavior, Brian S. Dorr, Larry Clark, Igor Mezine

Brian S Dorr

No abstract provided.