RECENT DEVELOPMENTS WITH REGARD TO DOUBLE-CRESTED CORMORANTS

- U.S. Fish and Wildlife Service releases final environmental impact statement and management plan (17 March 2003). For press release, Q&A, and full text, see http://migratorybirds.fws.gov/issues/cormorant/cormorant.html

- U.S.Fish and Wildlife Service releases draft environmental impact statement and nationwide management plan
    - Comments filed by the Ornithological Council (28 February 2002)
    - Comments filed by the American Ornithologists' Union Conservation Committee (27 February 2002)

Texas State Legislature passes resolution to remove Migratory Bird Treaty Act protection for Double-crested Cormorants (1999)
 

Egg oiling in Lake Ontario and Lake Champlain, Summer 1999
The U.S. Fish and Wildlife Service (FWS), in response to requests from wildlife agencies in New York and Vermont, proposes to issue permits authorizing each state to limit the reproduction of cormorants in the major nesting colony within its boundaries beginning 1 May 1999.

According to Ronald E. Lambertson, FWS Northeast Regional Director, the permits would allow the states to oil cormorant eggs, but not to destroy adult birds or chicks, on Little Galloo Island in eastern Lake Ontario, N.Y., and Young Island in Lake Champlain, Vt.  Since 1994, FWS has issued permits to the New York State Department of Environmental Conservation (NYSDEC) to destroy cormorant nests, eggs, and adult cormorants as they have started to establish colonies on Lake Ontario islands other than Little Galloo island.  This new request would allow NYSDEC to oil the eggs in up to 7,500 cormorant nests on Little galloo Island in order to improve the Eastern Basin adult smallmouth bass population and to increase and maintain nesting opportunities for Black-crowned Night Herons, Caspian Terns, Common Terns, waterfowl, and shorebirds, and to reduce impact to vegetation.

In mid-April, he Service  released draft environmental assessments for New York and Vermont on its proposals to issue depredation permits to the states. The environmental assessments are available for public review and comment through Thursday, 29 April 1999.

UPDATE:  On 3 May 1999, the U.S. Fish and Wildlife Service issued permits to the states of New York and Vermont to control their double-crested cormorant populations by placing oil on eggs to limit  reproduction, according to U.S. Fish and Wildlife Service Northeast Regional Director Ronald E.
Lambertson.

"The Service authorized the egg-oiling to reduce the number of cormorants that are displacing other colonial waterbirds," according to Lambertson.

New York Department of Environmental Conservation received permission to oil eggs of 7,500 nesting cormorant pairs on Little Galloo Island in New York's Lake Ontario.  New York had also asked to kill 300 adult cormorants as a preliminary step in a broader cormorant control project to reduce predation on smallmouth bass, a popular sport fish.  The Service did not grant that permit, citing the need to first develop a comprehensive plan, along
with an environmental impact statement, to manage the cormorant population in the eastern United States, including the Great Lakes region.

In a separate decision, Vermont Department of Fish and Wildlife received a permit to oil eggs of 3,000 nesting cormorant pairs on Young Island in Vermont's Lake Champlain, also to reduce the impact of cormorants on other birds and their habitat.   Vermont additionally had asked to oil the eggs of ring-billed gulls on the island if the population numbers more than 8,000 pairs.  The Service did not approve that request, because the gull population appears stable at 7,500 pairs, according to Lambertson.

The permits were issued following a public review and comment period on the Service's draft environmental assessments of the two situations that generated more than 200 comments reflecting a full spectrum of opinions on the issue, Lambertson said.  The states requested a decision by May 1 in order to complete the oiling before chicks hatch.

Because cormorants are protected under the federal Migratory Bird Treaty Act, the birds, their nests and eggs may not be destroyed without a permit from the Service, according to Lambertson.  If non-lethal means are ineffective at controlling birds, the Service considers authorizing local control of migratory birds if they jeopardize other protected species, property or human health and safety.

Comments filed by the Ornithological Council:

Dick Dyer
Refuge Program Supervisor
U.S. Fish and Wildlife Service
300 Westgate Center Drive
Hadley, MA 01035-9589

BY FAX and E-MAIL

Dear Mr. Dyer,

The Ornithological Council appreciates the opportunity to comment on the proposed migratory bird depredation permit requested by the New York State Department of Environmental Conservation (NYSDEC) to reduce the population of Double-crested Cormorants in the Eastern basin of Lake Ontario.  The Ornithological Council consists of ten leading scientific ornithological societies in North America - the American Ornithologists' Union, Association of Field Ornithologists, CIPAMEX, Cooper Ornithological Society, Pacific Seabird Group, Raptor Research Foundation, Society of Canadian Ornithologists, Society for Caribbean Ornithology, Waterbird Society and Wilson Ornithological Society - that together have a membership of nearly 6,500 ornithologists.  It is our mission to provide scientific information about birds to legislators, regulatory agencies, industry decision makers, conservation organizations and others, and to promote the use of that scientific information in the making of policies that affect birds.  We also represent the concerns of ornithologists to the regulatory agencies and other organizations that authorize research activities involving wild birds.

We were unable to conduct a comprehensive assessment of the Draft Environmental Assessment (or, for that matter, to meet your deadline of 29 April 1999) due to the fact that it was not released until 14 April and did not reach us until 19 April.  Your 14 April cover letter to reviewers notes that the NYSDEC has already allowed for public input on its permit application, but we fail to see how that satisfies the obligations of the U.S. Fish and Wildlife Service (the "Service") under the National Environmental Policy Act.

Executive summary
These comments evaluate the data relied upon by the U.S. Fish and Wildlife Service in describing the potential impacts of the issuance of the permit requested by the New York State Department of Environmental Conservation (NYSDEC).  We conclude that FWS has not adequately evaluated the impacts of the proposed action, and that the impacts described by the EA are not supported by the data, as to the effects on the cormorant population, on other avian species, and with regard to the smallmouth bass populations.  Therefore, Alternative 3 (the "no action" alternative) is the only alternative that is justified at this time.

Lack of data to support assumptions of impacts on cormorant population and local distribution
Our first concern is the paucity of data upon which the Service apparently intends to rely.  The EA does not clearly state how the proposed action will affect fish populations or bird populations on other islands.  It appears from the EA that control measures on these other islands have been effective without the need for reduction of the population on Little Galloo beyond that already allowed by the previous permits.  Two islands (Gull and Bass) were not used by cormorants in 1998 and the number of nests on Calf Island decreased by more than 50% from 1997 to 1998.  There was also a short but sharp decline in the number of nests on Little Galloo Island over the past two nesting seasons (1997 and 1998), again without additional population reduction efforts beyond those already permitted.  (The illegal take of cormorants on or about 19 July 1998 consisted primarily of fledglings, so it would not have affected the number of nests counted).  On p. 11, the EA states that the local and regional impact of displacement of Great Blue Heron rookeries is not known.  The local and regional impacts of Black-crowned Night Herons, Cattle Egrets and Snowy Egrets are unknown. It further states that if tern colonies are facing competition from cormorant colonies, the consequences are unknown and, on Little Galloo Island, the tern colonies are increasing.

There are also no data to show that the nests on these other islands in the Eastern basin were those of cormorants from the Little Galloo Island colony.  No banding data or other marking efforts are described, so it is not demonstrated that the additional control efforts on Little Galloo Island will prevent colonization efforts.  The cormorants that appeared on these other islands could have come from any number of other colonies in the region.

Lack of data to support assumptions of impacts of fish populations
The EA also fails to assess the effect of the proposed action on the fish populations.   It states that the cormorant populations have increased significantly in recent years on Lake Ontario in both the U.S. and Canada.  However, researchers have not demonstrated a causal effect between the increasing cormorant populations and the decline in smallmouth bass and yellow perch.  We have reviewed the NYSDEC Final Report: To assess the impact of Double-crested Cormorant predation on the smallmouth bass and other fishes of the eastern basin of Lake Ontario (February 1999).  We disagree with the Service's statement (p.24) that "a series of studies by the NYSDEC and USGS have demonstrated that in recent years, predation by cormorants has probably been a major contributor to juvenile mortality and depressed population levels of adult bass in the Eastern basin."

This report summarizes the results of 11 studies on creel surveys, diet analysis of cormorant pellets, and fisheries biology of the common and economically important fish in the eastern basin of Lake Ontario, including the waters around Little Galloo Island.  The primary sources of data that associate cormorants with economically important fish species are diet analysis obtained from analysis of regurgitated pellets and analysis of regurgitated food from chicks and, rarely, adults.  Cormorants feed underwater and direct evidence of feeding activities is unobtainable.

In diet analysis of regurgitated food and pellets, the proportion of smallmouth bass found in cormorants ranges from 0.4% of the total diet (1996) to 2.2% (1994), with the median amount around 1.0%.  The primary food item for Double-crested Cormorants, as in all cormorants, is small bottom feeding fish and other species not rated as highly desirable by sportsfishermen (e.g., Alewife, trout perch, sculpin).  Smallmouth bass and yellow perch are taken in small and moderate amounts respectively, but very likely at size and age ranges unlikely to affect the population structure of these fish populations.  Fingerling mortality is quite high in the smallest size classes, and the additional take by cormorants even with increased populations has been shown to be a negligible impact on numbers.

The evidence shown that purports to reconstruct the size classes from otolith size is presumptive and speculative.   The size/length ratio between otoliths and body size is significant, thus it should be possible to measure the size of otoliths contained in regurgitated food and pellets and reconstruct the size of the fish.  There are several problems with this approach as pointed out in the report.  First, the identification of the otoliths to species is easiest with undamaged otoliths from large fish.  Reliable identification is reduced as the otoliths are degraded by digestive action in the cormorant stomach, and with smaller size classes of fish prey.  As is pointed out in the report, otoliths from small-sized smallmouth bass are nearly indistinguishable from other small size classes of fish, and the longer the otoliths are digested, the more problematic their identification.  As a consequence, most of the studies offered to support the impact of cormorants on smallmouth bass are based on very small sample sizes usually less than 10 individuals.  Further, there is no attempt to quantify or address the variation in size of otoliths and estimated size of fish at take. .  This means that all of the discussion on whether cormorants take adult-sized birds or not is speculative and biased.

The study also fails to take into account the presence of otoliths as secondary consumption (evidence for the prey's prey; in other words, smallmouth bass otoliths could have been digested by trout that were subsequently taken by a cormorant) Hatch and Weseloh discuss the limitations of otolith analysis in the Double-crested Cormorant species account (in press).  A recent European conference on cormorants resulted in a publication criticizing the use of otoliths as a basis for dietary analysis and proposed standardized methods of dietary analysis (Carss et al. 1997).

At best, the Final Report correlates decreased catch of these species with the growth in the cormorant populations in the eastern basin, where the cormorant populations are concentrated.  It does not come close to showing a causal connection. According to the Draft EA, the cormorant colony at Little Galloo Island began increasing dramatically in 1974, growing from 22 nests in 1974 to 5,443 nests in 1992 and then to 8,410 nests in 1996.  A study showing the changes in the  smallmouth bass population over that same time period would be needed.  Such a study would also have to account for the changes in fishing effort over that period, as well as the presence of other predator species and changes in water quality.  It would also have to account for the effect of the avian predation on the predator fish species on bass fingerling.  These predator fish species are apparently a far more important prey base for the cormorants than are the smallmouth bass and yellow perch.  On p. 24, the EA acknowledges that other factors, including seasonal temperature variation, changes in forage fish abundance, and shifts in community structure may impact smallmouth bass recruitment, and that overfishing may also be a factor.  Yet, there is no apparent discussion of limiting fishing efforts.  If the goal is to increase these fish populations, then all factors contributing to the downward trend that are within the control of the FWS and the NYSDEC should be assessed, and appropriate corrective action taken.  Assuming that it is found that the cormorant predation is not a significant factor, then the cormorant control is not warranted.

Furthermore, the EA does not demonstrate that the proposed action is likely to result in increasing populations of smallmouth bass and yellow perch.  This is, in part, due to the fact that the causal connection between the increasing cormorant population and the declining fish populations has not been established. It is also due to a lack of assessment of the potential decrease in predation by the adult birds (both this summer and also in following years, as a result of the presumed slowing of the rate of population increase that would follow the eradication of an entire year's production). The EA's own calculations show that, at most, this action will slow expansion of the cormorant population to other islands (p.23).  The EA further states that to have a lasting benefit to the adult bass population, some level of cormorant control would need to be an ongoing management action.  If it is found that the increase in the cormorant population is a significant contributing factor to the decline of the desirable fish species, then the best solution is long-term management.  This hastily-conceived plan to eliminate an entire year-class of birds does not appear to be based on a scientific assessment that it is likely to result in improved survival of juvenile smallmouth bass in the Eastern basin.

Finally, the EA fails to assess the impact of a reduced cormorant population on the predator fish species that prey on bass fingerlings.  It may be that by releasing the cormorant control on these predatory fish (which are apparently preferred by cormorants over bass by a wide margin) that the bass fingerlings will sustain even higher rates of predation.  In short, if it can't be said with a reasonable degree of scientific certainty that cormorants have been a significant factor in the decline of the smallmouth bass, then it can't be said that controlling the cormorant populations will have a significant effect on the smallmouth bass population

Lack of data to support assumptions about impact to plant communities
The EA states the possible impacts to native plant communities, but does not detail specific impacts to Little Galloo Island.

Need for comprehensive assessment and region-wide management
In fact, as the Service no doubt knows, this situation is complex and involves far more than the cormorant population on Little Galloo Island.  It calls for a more careful and thorough assessment than has been done here.  Dr. Francine Cuthbert is nearing completion of a draft of  the comprehensive review contracted for by the Service, and it is scheduled to be completed this fall.  It is likely to provide a much stronger basis for the design of a cormorant management plan (assuming that the results of the review justify cormorant management).  As Region 5  is planning a long-term management strategy, and as this particular EA does not provide a sufficient scientific basis for the proposed action, it might be advisable to refrain from issuing this particular permit. If this is part of a five-year plan, the entire plan ought to be reviewed comprehensively and not have a piecemeal permit amendment. Moreover, this situation should be addressed on a region-wide and international basis rather than piecemeal permit applications (reactive).  The EA contains no information on the management of the Canadian colonies and what the effect of the proposed action might have on these colonies.

No justification provided for this "emergency-like" decision
Finally, we would note that the Service has effectively precluded meaningful review of this EA by allowing only two weeks for review.  This situation has been developing for many years, and the Service has been issuing depredation permits to New York State for several years.  For some reason, NYSDEC did not submit its application to the Service until 22 March 1999, and the Service has attempted to assess the need and impact in three weeks.  We recognize that a longer comment period might mean that the permit can not be issued this year.  The EA does not suggest that what it tantamount to emergency action is justified - nowhere is there a statement that a failure to issue this permit will result in a such a severe decline in the smallmouth bass population that subsequent management actions would be unsuccessful.

Shooting of adult birdsWe recognize that the proposed action (Alternative 2) does not contemplate the shooting of adult birds and chicks.  We concur with the EA (p.23) that this could cause significant disturbance to other birds using the island and could have other negative impacts.  The NYSDEC should not be allowed to shoot cormorant adults and chicks.  This is a large-scale operation that will negatively affect breeding and ecology of nearby species.

We again thank the Service for allowing us to comment on this proposed action.  We hope our comments have been helpful to the Service.

Sincerely,

Ellen Paul
Executive Director
 

References

     Carss, D.N. et al. 1997.  Techniques for assessing cormorant diet and food intake; towards a consensus view.  Suppl. Ric. Biol. Selvaggiana 26:197-230.

     Hatch, J. and D. Weseloh. In press.  Species Account, Double-crested Cormorant. Birds of North America. (cited with permission of the authors)

Texas State Legislature passes resolution to remove Migratory Bird Treaty Act protection for Double-crested Cormorants; Texas Governor George W. Bush signs resolution

Adopted by the Texas House on 23 May 1999,  by the Texas Senate on 27 April 1999, and signed by Texas Governor George W. Bush on 24 May 1999

HOUSE CONCURRENT RESOLUTION
 1-1           WHEREAS, The Lone Star State has been blessed with an
 1-2     abundance of unique natural resources, including a plentiful array
 1-3     of streams, rivers, ponds, and lakes that provide countless
 1-4     opportunities for entertainment and recreation such as boating,
 1-5     various water sports, and sport fishing; and
 1-6           WHEREAS, In addition to being an exciting and fulfilling
 1-7     activity for anglers young and old, sport fishing is also an
 1-8     economic boon for local communities and the state as a whole; over
 1-9     two million people annually fish in the freshwater bodies of Texas,
1-10     spending almost $2 billion per year on fishing related goods and
1-11     services and sustaining over 50,000 full-time jobs; and
1-12           WHEREAS, Over the past several years, a bird known as the
1-13     double-crested cormorant, also referred to as the "water turkey,"
1-14     the "sky rat," and the "fire ant with wings," has flocked to Texas
1-15     in growing numbers to winter in the warmer climate; its feeding
1-16     habits and increasing numbers are decimating sport fish populations
1-17     in many areas, especially where fish are stocked on a regular
1-18     basis, and the exploding population of this pest is also decimating
1-19     fish raised by commercial aquaculture facilities; and
1-20           WHEREAS, Although the economic losses suffered by aquaculture
1-21     facilities are more immediate and easier to quantify, the sport
1-22     fishing industry is an enterprise that is also suffering
1-23     economically; of the limited number of studies that have been
1-24     conducted regarding the feeding habits of cormorants, the research
 2-1     in Texas does not specifically address the problems occurring in
 2-2     many stocked lakes and ponds and therefore does not measure the
 2-3     detrimental economic effects of the bird; now, therefore, be it
 2-4           RESOLVED, That the 76th Legislature of the State of Texas
 2-5     hereby request the United States Fish and Wildlife Service to
 2-6     include the economic impact of the cormorant on sport fishing in
 2-7     its ongoing evaluation of the double-crested cormorant and that the
 2-8     agency create a contingency plan for addressing site-specific
 2-9     cormorant problems in sport fishing areas; and, be it further
2-10           RESOLVED, That the United States Fish and Wildlife Service
2-11     consider the removal of the double-crested cormorant from the
2-12     protection of the Migratory Bird Treaty Act if the national
2-13     economic losses warrant severe control methods to keep the
2-14     cormorant population at a manageable level within a given region;
2-15     and, be it further
2-16           RESOLVED, That the secretary of state forward an official
2-17     copy of this resolution to the director of the United States Fish
2-18     and Wildlife Service.
 
 

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