Ed McNamara

February 27, 2002

On December 28, 2001, the D.C. Circuit Court of Appeals handed down a decision which requires the U.S. Fish and Wildlife Service (FWS) to protect an exotic species that is wreaking havoc on essential habitat needed for birds protected under the Migratory Bird Treaty Act (MBTA).[1]  The result of this decision is that the mute swan, an exotic species with a detrimental impact on other protected bird species, must now be protected under the MBTA.  The fault does not lie with the court, but rather the nature of the MBTA itself.  The statute, although successful at protecting migratory species, fails to take ecological considerations into account.

In the late 1800s and early 1900s, hunting of migratory birds was largely unregulated.[2]  Hunting during nesting seasons was common, and market hunters were having a tremendous impact on game birds in their quest to bring food to the table.[3]  The indiscriminate killing of birds expanded to nongame species when bright plumage in women's hats became a fashion necessity.[4]  Consequently, hundreds of thousands of birds were slaughtered for their plumage.[5]

In order to protect the rapidly declining bird populations, the MBTA was passed in 1918.  The protection is not linked to population numbers, but rather whether a given species is listed by the FWS.  If a species is listed, then members of that species may be killed only during regulated hunting seasons or if the FWS issues a depredation permit allowing a set number of birds to be killed.

The pressures on bird populations in 1918 were primarily due to direct killing; habitat destruction was not considered at all.[6]  With the institution of hunting seasons, bag limits, and other devices mandated by the MBTA, the majority of bird populations have increased and, for the most part, flourished.  As a result, the significant threat to bird populations has now become habitat degradation--caused by both humans and nuisance species, including mute swans.

In 1962, five mute swans were released into the Chesapeake Bay.[7]  The current population in the Bay, as of 2001, is 4,500.[8]  Although prized for aesthetic reasons,[9] the mute swan is becoming an increasing concern for wildlife managers due to their adverse impact on native wildlife and the habitat on which they depend.

[T]here is increasing evidence of conflicts with native wildlife, habitat destruction due to feeding habits and behavior, ... If uncontrolled, mute swans pose a serious threat to the ecological integrity of many areas, including the National Wildlife Refuge System and other Federal lands committed to the maintenance of natural wildlife diversity.[10]

The problem is not confined to the Chesapeake Bay.  Southern New England and the upper Midwest are also seeing increases in mute swan populations.[11]

The impetus for the case before the court was an attempt by the FWS to lower the population level of mute swans in order to protect bird populations at the Blackwater National Wildlife Refuge.[12]  Joyce Hill, the individual who brought the suit against the FWS, claimed that "the decline in mute swans reduces Hill's aesthetic enjoyment of her property,"[13] and demanded that FWS list mute swans under the MBTA.

Hill argues that the case is a "straight-forward question [of] whether the Mute Swan (Cygnus olor) is a member of the family anatidae ... and hence are covered as a protected species under the ... [MBTA]."[14]  The effect of this failure to list the mute swan "has led to numerous adverse actions - including killing and egg destruction - against Mute Swans, thus injuring those who, like plaintiff, derive immense aesthetic and cultural value from the presence of Mute Swans in our environment."[15]

Hill's argument rests on the plain language of the treaty with Canada, specifically, a 1995 amendment which "revised the definition of migratory birds to include 'Anatidae, or waterfowl (ducks, geese and swans).'"[16]  Since mute swans are a member of the order anatidae, it follows that they should be protected under the MBTA.  FWS counter-argued that mute swans are non-native species that have a detrimental effect on native wildlife.  These facts are well established and acknowledged by the court.  However, the MBTA does not address the issue of "native v. exotic" species.  Nor is there any consideration of the impacts that a listed species might have on other protected species.  The court, faced with these statutory inadequacies, determined that the mute swan must be protected under the MBTA.

From a legal perspective, the inclusion of the mute swan in the MBTA was a sensible outcome.  Under a Chevron analysis, FWS' actions did not comport with the plain language of the MBTA, nor were they "based on a permissible construction of the statute."[17]

This decision allows exotic species to be listed regardless of their impact on habitat and other wildlife.  Consequently, wildlife management decisions are made without regard to ecological considerations.  Any decisions concerning wildlife management must be made after due consideration of the community as a whole, rather than individual species.

One of the most famous formulations of this emphasis on the community can be found in Aldo Leopold's Land Ethic.[18]  He states that: "A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community.  It is wrong when it tends otherwise."[19]  Leopold's emphasis on community was created through an understanding of ecology, an understanding informed by countless years in the field as both a forester and hunter.

As a forester, Leopold was able to see firsthand the harmful effects of mismanagement of wildlife.  In one section of his classic work A Sand County Almanac, Leopold describes the effect of an irruption of deer, after the community has been unbalanced by the removal of predators.[20]

I have watched the face of many a newly wolfless mountain, and seen the south facing slopes wrinkle with a maze of new deer trails. I have seen every edible bush and seedling browsed, first to anemic desuetude, and then to death. I have seen every edible tree defoliated to the height of a saddlehorn. Such a mountain looks as if someone had given God a new pruning shears[sic], and forbidden Him all other exercise. In the end the starved bones of the hoped-for deer herd, dead of its own too-much, bleach with the bones of the dead sage, or molder under the high-lined junipers.[21]

In an attempt to protect a desired species, Leopold and other wildlife managers produced an ecological disaster.  Just as deer can lay waste to a mountain, an overabundance of swans can produce a devastated shoreline.  An understanding of the connections between the species, its habitat, and other wildlife is necessary to make an informed decision on the protection of a given species.

The MBTA has been invaluable in its protection of bird species.  However, the statute fails when confronted with a migratory species that damages the structure of the community as a whole.  Protection of a species shouldn't focus solely on their biological classification as a migratory bird, but rather should include an understanding of the role that a species plays in the community.  A decision that is informed by this understanding would enable the FWS to reject protection for exotic, nuisance species such as mute swans.

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[1] Hill v. Norton, 2001 WL 1657305 (D.C. Cir. December 28, 2001).

[2] See, James B. Trefethen, Wildlife Regulation and Restoration, in ORIGINS OF AMERICAN CONSERVATION 22-28 (Henry Clepper, ed., 1966).

[3] Id. at 24-25.

[4] Id. at 25.

[5] Id.

[6] For a legislative history of the MBTA, see Benjamin Means, Prohibiting Conduct, Not Consequences: The Limited Reach of the Migratory Bird Treaty Act, 97 MICH. L. REV. 823, 830-833 (1998).
[7] Matthew C. Perry, Peter C. Osenton, and Edward J.R. Lohnes. The Exotic Mute Swan (Cygnus olor) in Chesapeake Bay, U.S.A. USGS Patuxent Wildlife Research Center at http://www.pwrc.usgs.gov/resshow/perry/muteswan.htm (last visited Feb. 14, 2002).

[8] Id.

[9] Hill, 2001 WL 1657305, at *2.
[10] Control of Mute Swans on Federal Lands, Memorandum from the US Fish & Wildlife Service to Regional Directors (March 1998) available at http://www.dnr.state.md.us/wildlife/fwsmsfedland.html.
[11] Id.
[12] Hill, 2001 WL 1657305, at *3.
[13] Id. at *5.
[14] Id.
[15] Id. (quoting Brief for Appellant).
[16] Id. at *5 (quoting Protocol Amending the 1916 Convention for the Protection of Migratory Birds in Canada and the United States, Dec. 14, 1995, art. I, § 1, U.S. - Can., Sen. Treaty Doc. 104-28).
[17] Id. at *6 (quoting Chevron U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 843 (1984)).

[18] Aldo Leopold was a prominent conservationist in the first half of the twentieth century and influential in the implementation of wildlife management in the United States.

[19] Id. at 224.
[20] Id. at 130-32.