NON-LETHAL TECHNIQUES TO REDUCE ANIMAL PROBLEMS
by Priscilla Feral
The mute swan (Cygnus olor) is one of the most attractive and widely appreciated inhabitants of Chesapeake Bay. But, despite its celebrated beauty, and legions of admirers, there are those who want to repress this bird. And there are those who seek to kill it.
The principal rationales used to justify repression of mute swans are
1. they are a non-native species, and
2. they are responsible for the ecological degradation of Chesapeake
Accepted: mute swans are immigrants. But there is no empirical evidence to justify any allegations that the species is making a substantive contribution to the ecological dysfunction of Chesapeake Bay. They are exotics, but they are not invasive.
Mute swans are indeed a non-native species that did not co-evolve with the Chesapeake Bay ecosystem. But, for that matter, neither did the motorboats and water-skiers now found on the Bay.
-- Nor did house sparrows, or pigeons, or ring-necked pheasants.
-- Nor did the starlings, or suburban cats and dogs.
-- Nor did humans of Asian, African and European descent, all of whom cluster in and around the beautiful bay in numbers far greater than those of the mute swans.
The non-native species of suburbia have overwhelmed so much natural habitat, and replaced it. Current planning for the Chesapeake Bay watershed envisions that the present human population of 15 million will become 18 million by the year 2025. Land use planning seeks to protect only 20 percent of the watershed's area in a natural state. The remaining 80 percent is doomed to be planted with lawns composed of well-fertilized European grasses, and exotic vegetation such as Japanese cherry blossoms, Chinese ginkgos, English roses, Scotch Pines, Irish yews, Norway spruces and many other introduced trees and ornamental shrubs. That's the fortunate acreage.
Less fortunate acreage will be paved - if it hasn't been so already.
Commercial and industrial zones are paved with asphalt and concrete.
Agricultural zones are paved with tons of fertilizer. Of the two, it appears that contemporary agricultural methods are the greater hazard for Chesapeake Bay.
Chesapeake Bay and its 64,000 square mile watershed harbor hundreds of introduced species. But among all these, the mute swans are being singled out for persecution. The various arguments supporting such persecution are, at best, inadequate.
--Some persons claim that Chesapeake Bay's mute swans are crowding out other waterfowl, especially the smaller and less aggressive tundra swans. But the mid-winter waterfowl survey conducted in Maryland this year censused 20,800 tundra swans, up by 5,200 since last year's count of 15,600. The increase in tundra swans alone is more than the total population of mute swans. Furthermore, there is no scientific documentation of mute swans crowding out any other species - although there is abundant documentation of other waterfowl species nesting in close proximity to mute swans, sometimes within 16 feet. Mute swans are aggressive toward perceived threats during nesting season. But other waterfowl are not perceived as threats, and, therefore, they are tolerated.
--Some persons suggest mute swans may be crowding out species classified as threatened or endangered. Again, there is no empirical data documenting these allegations. There are no substantive studies to support such allegations. Do responsible conservationists pursue lethal control methods based on hearsay evidence?
--There are those who raise incredible Malthusian predictions based upon current growth rates, and forecast a plague of mute swans descending upon Chesapeake Bay. But honest wildlife biologists will acknowledge that impressive growth rates are perfectly natural for species with low populations. Once the swans start to fill their ecological niche, the growth rate will taper off and stabilize within its dynamic limits. The eventual maximum population will likely be quite modest because mute swans require rather large nesting territories from which they will exclude conspecifics. Mute swans are naturally thinly spaced.
--Yet other people complain that the mute swans eat submerged aquatic vegetation (SAV). But there are barely 4,000 mute swans. They constitute less than one-half of one percent of the 879,000 waterfowl counted in Maryland this past January. And most of those nearly one million waterfowl also consume aquatic vegetation.
Let's take a closer look to the Submerged Aquatic Vegetation (SAV) issue, because it touches the heart of Chesapeake Bay's tragic ecological condition.
Chesapeake Bay naturally should have approximately 600,000 acres of SAV. Of this, only about 72,000 acres remain. More than a half million acres disappeared long before the mute swans started nibbling. And people in authority know very well the reasons for the loss of that vegetation.
A perceptive study conducted by Brush and Hilgartner of Johns Hopkins University documents a gradual, but accelerating loss of SAV in Chesapeake Bay over the past two centuries. The identify nutrient overloading, and particularly run-off containing significant concentrations of nitrogen and phosphorus, as being the main culprit. These nutrient overloadings have exceeded SAV tolerance capacities, precipitated eutrophication, and resulted in the extermination of many SAV colonies around the bay.
Although there have been various attempts to control the discharge of nutrients into Chesapeake Bay, such as by decreasing the amount of fertilizers used on agricultural land within the bay's watershed, as well as removal of nitrogen and phosphorus from point sources, control of animal wastes, and reduction of atmospheric nitrogen emissions, Brush and Hilgartner nevertheless found that, "over the past 10 years, there is no general trend in reduction of either nitrogen or phosphorous, and in many cases, an increase."
This disturbing trend continues. The recently-released 2000 Chesapeake Bay Health Index provides documentation of this distressing situation:
--The Bay's current Health Index says the amount of toxins entering the Bay have not been reduced.
--The index says sediments entering the bay have increased, and the Bay's water is characterized as "turbid." Turbid water restricts the penetration of sunlight to underwater vegetation. Without sunlight, there's no photosynthesis. Without photosynthesis, plants - including submerged aquatic vegetation - die.
--The Bay's Health Index reports that nutrient overloadings of nitrogen and phosphorus remain essentially unchanged this year, despite the targeted reductions and deadlines, which have been missed. Nutrient overloadings contribute to algae blooms, some of which are toxic, and all of which contribute to eutrophication. They have especially been linked to the blooms of Pfiesteria piscicida, the toxic dinoglagellate implicated for large fish kills in Chesapeake Bay.
--The Bay's Health Index notes dissolved oxygen levels in the Bay are very low, another indicator of eutrophication. By coincidence, extremely low levels of dissolved oxygen normally follow the Pfiesteria blooms. Without dissolved oxygen, aquatic animals such as fish, cannot breath. And that likely is one of the reasons why Chesapeake Bay's fish population is very low. Fish that venture into those waters are suffocated.
--The Bay's Health Index reports "no charge" to any conservation initiatives including wetlands, forest buffers, resource lands and underwater grasses.
Curiously, the decline in underwater grasses in Gunpowder, Chester and Potomac rivers have not been attributed to grazing by mute swans. These losses are partially offset by impressive gains in underwater grass recovery in Tangier Sound, which is attributed to local reductions in nutrient overloading and sediment pollution.
--The Bay's Health Index says aquatic animal populations are much the same, with rockfish and oysters registering "no change" in their depressingly low population levels. Blue crab populations have declined. The only increase involves transient shad, and this is attributed mostly to the reopening of the Susquehanna River to fish migration for the first time in a century.
The only "plus" in the entire 2000 Chesapeake Bay Health Index relates to the restoration of a natural process that was interrupted one hundred years ago. Does that tell us something?
Mute swans have nothing to do with the tragic state of Chesapeake Bay, and shooting one of them or all 4,000 will not contribute to the Bay's recovery.
The swans are being used as scapegoats to divert attention from what really needs to be done if Chesapeake Bay is to be saved.
And it can be saved.
There are many very useful guides toward fostering recovery, and it is likely that the $8.5 billion recovery program being championed by the Chesapeake Bay Foundation is a good way to go. It will be expensive.
There long has been an axiom among educators: "Education is very expensive.
But the alternative is even more so."
The same concept can be applied to conservation. The consequences of letting Chesapeake Bay die will be painfully expensive - financially expensive, ecologically expensive, socially expensive. Ask the Europeans.
Countries of Western Europe faced similar challenges some decades ago.
Europe started dumping wastes into rivers and destroying habitats while America was still pristine. So the consequences caught up with the Europeans sooner. In the 1960s, the Thames River in England was declared "biologically dead." The Waal/Rhine estuary was in a similar situation, as were other estuarine ecosystems throughout Western Europe.
Recovery work on the Thames started in 1963, and other projects followed soon thereafter. Research indicated they suffered essentially the same problems experienced in Chesapeake Bay - toxins from industry, suspended sediments, nutrient overloads from both agriculture and residential communities. Water in Dutch estuaries was so turbid that anything deeper than eight inches could not be seen from the surface.
Today, the Dutch water is much clearer. Objects at depths of seven to nine feet can be clearly seen from the surface. As a consequence, sunlight can penetrate better, and that's a key first step to restoration of SAV.
The Europeans pumped enormous amounts of money into clean up projects. The Dutch passed laws forbidding the opening of new factory farms, and encouraging the closure of existing facilities. A strong alliance of animal protection and environmental conservation reversed industrialized cruelty that was responsible for massive point-source nutrient overloads. Other projects targeted sewage processing, industrial wastes, and even the holiest of Holland's cows, the Dutch dairy industry. Strict controls prevented toxins and excess nutrients from entering rivers and estuaries, and pumping projects removed nearly all of the run-off sediments that had fouled the Dutch waters. Shortly after this was accomplished, the submerged aquatic vegetation colonies that had collapsed through previous decades made dramatic recoveries.
And they didn't have to kill any mute swans to do it.
In England, the Thames underwent a similar resuscitation. The river which in the 1960s was so polluted that it caught fire several times, after three decades of devoted work became the cleanest metropolitan estuary in Europe.
Ichthyologists will confirm that sea bass, salmon and flounder are fish species that are very sensitive to pollution. Yet, these species are today found in the Thames, and in good numbers. Mute swans are found there as well.
The British have learned their lesson and are vigilant in keeping their river and its estuary clean. The entire European Community has adopted the "Polluter Pays" principle. Aggressive environmental protection units track down those responsible for environmental damage and haul them into court.
So far, they haven't arrested a single mute swan.
But they have prosecuted farmers, municipalities, and industries that have been remiss in their obligations to protect water quality. Even Thames Water Ltd., a major utility responsible for the river's water management, was dragged in to court a year ago and fined 43,935 British pounds - about $60,000 - because they weren't quick enough to repair a leak. The Crown Court acknowledged that vandals had broken a sewer pipe, but it also found that Thames Water, in taking five hours to get a repair crew to the scene, did not act fast enough to protect the precious river.
Similar stories may be told about France and Denmark, and about Belgium and Germany and Sweden. The European Union has taken a lead in developing techniques - a mix of voluntary, regulatory, incentive and disincentive-based measures to curb the pollution of their waterways. They have taken a technological lead in developing systems for purging toxins, sediments and nutrient overloads out of the water.
They have done a lot of homework, paid an enormous price and achieved a lot of success. European estuaries are today much cleaner than those found in the United States. It would be worth while for those concerned with the future of Chesapeake Bay to review European policy and technological achievements - and then consider how they might be applied on this side of the ocean.
The mute swans of Chesapeake Bay are the offspring of naturalized Americans, just like the vast majority of this country's citizens. They too are the children of immigrants.
They are not invasive. They harm no one. They contribute beauty and grace to our landscapes and our lives. The least we can do in return is to provide them with peace and security while we cooperate in identifying and addressing the real problems that are causing ecological dysfunction in Chesapeake Bay.