New York State
Ornithological Association

For the birders and birds of the Empire State

ConservationPosted 11/19/09
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Double-crested Cormorant
Management in NY—Results Lacking
Andy Mason, NYSOA Conservation Committee
Published in the October 2009 issue of NY Birders

Double-crested Cormorants, photo copyright Cornell Lab of Ornithology

In 2004, the NY State Department of Environmental Conservation began a large-scale effort to reduce populations of Double-crested Cormorants in the state. The given reasons were a growing population of this native fish-eating species, and studies contending the birds were reducing populations of sport fish in Lake Ontario and elsewhere, to the detriment of anglers. A secondary reason was cormorant damage to nesting habitat for other colonial species.

The original plans focused on destruction of cormorant nests and eggs, and hazing or disturbance of birds to drive them from concentration areas. Several hundred cormorants were expected to be killed as part of the program. This represented a major expansion of earlier research-based control efforts.

The DEC plan was questioned by nearly every bird conservation organization in the state, and beyond. (NYSOA’s earlier resolution on cormorant management can be found at www.nybirds.org/Articles/Conservation/ resolutions/cormorant1998.htm.) The science behind the agency’s contention of fisheries conflicts was highly dubious, with data extrapolated to fit the sport fishing community’s argument that cormorants were “decimating” small-mouth bass and other sport fish populations. It was clear that politics and fishing interests were driving state policy in this matter. Those arguing against disproportionate cormorant management pointed out the fact that sport fish constituted a minor part of their diet, and that the size of fish consumed was below that sought by anglers. In addition, other reasons for reductions in Lake Ontario fish populations, including significant success in cleaning the lake by reducing excessive nutrient loading, and the introduction of zebra mussels, were given short shrift.

However, the plan was implemented over the objections of conservation organizations, many citizens, and even other respected scientists. In the years since, DEC’s cormorant control program has expanded dramatically, with nearly 10,000 cormorants killed and over 75,000 nests destroyed. This activity is well beyond the scope of the original plan and the understanding of the public and conservationists.

After five years of this management, DEC has succeeded in lowering cormorant populations, although other factors such as disease and natural population fluctuations also have come into play. However, the agency has not presented any evidence of changes to fisheries, or success of other colonial nesting birds as a result of these actions. In communications to the US Fish and Wildlife Service justifying continued cormorant killing and nest destruction, they rely on anecdotal observations and “suggest” that sport fish populations may be increasing.

Meanwhile, there is evidence that the growth in cormorant populations actually represents a return to levels that existed prior to use of DDT, which dramatically reduced their numbers, and prior to earlier persecution of the species before they were legally protected. It also appears cormorant populations are stabilizing by selfregulation, a natural process for all species. This self-regulation may well be disturbed by human management activity.

Disturbance and nest abandonment by other colonial bird species as a result of cormorant shooting and hazing is also a problem downplayed by DEC. Adaptation and co-existence with cormorants by other species has been displayed. The natural changes that occur with bird colonies are not considered by DEC, nor are impacts from climate change, invasive species and pollution control efforts on habitat and food supply. Displacement of cormorants, from management activities, to previously unoccupied water bodies has also occurred.

In short, this heavy-handed and scientifically dubious activity on the part of the agency charged with protecting our wildlife lacks a sound basis for continuation. It has not been shown to have met the stated goals put forth as justification for the wholesale decimation of a naturally-occurring, protected bird species in the state. At a time when DEC is reducing its efforts to protect other birds and wildlife, due to staffing and budget cuts, can an expensive and unconvincing program such as this be justified?

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