My previous blog discussed the relative meanings of the term “overabundance” to various stakeholder groups and touched on what was happening with snow goose populations in North America. What is amazing and what I will show is how nature repeats itself and wildlife management falls into the same repeated traps.
The double-crested cormorant, Phalacrocorax auritus, the main topic of my blog site, survived the onslaught of DDT to come back into the environment after the EPA courageously banned unregulated uses and production of the bioaccumulated insecticide. Cormorants also thrived after they were finally included in later provisions of the Migratory Bird Treaty Act (MBTA), protecting nearly all wild birds from unlimited shooting and feather hunters. In addition to these birds encountering cleaner water and less-toxic prey fish, on the Great Lakes where they breed in the summer, they found fantastically increased food supplies of forage fish because natural predators such as lake trout, Atlantic salmon, and others disappeared due to overfishing and pollution. At about the same time, on their wintering grounds, cormorants stumbled on and exploited a new food source in the form of farmed catfish in the South’s Mississippi Delta region. All this free-for-the-asking food at both ends of their range allowed double-crested cormorants to produce larger numbers of healthier, stronger youngsters and to stay fit and vigorous over the course of the winter for the return flight north.
The snow goose, Chen caerulescens, is a medium-sized white goose that breeds in summer arctic tundra regions in Canada, Alaska, and Russia, and migrates south in a number of fixed flyways. This goose also has a blue version that was once thought of as a different species, but proved to be merely a “morph” of the more common white form. The snow goose suffered from unrestricted hunting, reducing its numbers to about 5,000 until it was protected by the MBTA early in the twentieth century. When their numbers increased to what federal wildlife managers considered acceptable levels hunting seasons were established in 1973.What happened after that closely parallels the progression of cormorant populations.
During their southern migration snow geese once settled on marshes on both coasts to feed on the grasses and their tuberous roots. Much of that is in the past now since many of the coastal marshes are gone or greatly reduced due to commercial and residential development and urban expansion. Ordinarily, as food supplies decrease, so does the wildlife population dependent on that food. The expected decline in snow goose numbers never materialized. What happened? Humans intentionally created an alternate food source: flooded rice fields. Flooding prepares the fields to receive the next planting while at the same time provides aquatic forage for thousands of migrating snow geese. The flooded fields in fact filled with so many birds that the thousands of snow-white birds became an attraction for birdwatchers, naturalists, and the just plain curious. And not unlike the convenience of unguarded catfish ponds in the delta that supported tens of thousands of cormorants, the rice fields bolstered snow goose numbers on both coasts. More food, more birds.
Then there’s the arctic breeding ground. It is postulated that warming climates and higher tundra temperatures created improved breeding conditions resulting in more, stronger, healthier chicks ready for the rigors of a long migration. Better breeding, better birds.
The result of all this improved feeding and breeding is the proclaimed “overabundance” of snow geese. The negative effect is that the geese are literally and figuratively eating themselves out of house and home. Their dining practices of tearing grasses from the ground or marsh bottoms kills the plants, weakens the tundra substrates and increases erosion, allowing ocean tides deeper access into the marshes, virtually drowning them.
The great snow goose flocks have also crowded and pillaged the rice fields making them difficult for growers to manage and have become pests to northern farmers when they descend on corn and grain fields like falling snow, as their common name suggests.
How do wildlife managers control the bird’s numbers? Not an easy question to answer. Several states, including New York, with the help of more flexible federal regulations, have expanded their legal hunting seasons and daily bag limits for snow geese. The problem arises that killing and dressing twenty-five geese a day quickly fills the family freezer. With about a million snow geese using the Atlantic flyway and another three million or so settling in the Rocky Mountain states, plus huge numbers in the other flyways, killing tens or even hundreds of thousands of geese may slow, but not curtail the growth in snow geese numbers. Managers faced some of the same problems in trying to reduce the two million cormorants in North America, but in the case of those birds, they are inedible, so hunting seasons to put meat on the table were never seriously considered.
One measure that was applied to reduce cormorants was the cull, in which paid “technicians” armed with suppressed (silenced) weapons brutally shot thousands of birds, often leaving wounded adults and starving chicks in their wake. The carcasses were then buried or somehow composted. All that violence to reduce cormorant numbers by mere fractions of one percent. And now, with the failure of the expanded hunting seasons, the use of snow goose culling programs is being considered, but again, with the taste for snow goose dinners waning, the slaughtered birds will probably be destined for ignoble composting.
What is the alternate solution to massacring wild birds? Just as the cause of their growth in numbers had multiple roots, the answer to snow goose “overabundance” has multiple remedies. The first of course is to do nothing. If the geese are making their breeding grounds less habitable then it’s reasonable to assume that recruitment (new individuals added to the population) will fall and the species’ reproductive capacity will reach a new reduced level. Another choice is to somehow separate the geese from their food sources during migration. Rice farmers need not flood their fields to the same extent to kill off old growth after the grain harvest. At one time growers burned their fields, but faced criticism for the added air pollution. They then decided to flood the fields instead, and to justify the use of such massive quantities of water and come down on the side of the good guys, flooded adjacent fields to provide additional habitat for migrating snow geese.
So, as the converse to “more food, more birds” and “better breeding, better birds,” wildlife managers can encourage efforts to reduce the food available in the rice fields and let the geese temporarily reduce the productivity of their own breeding grounds.
That way we can tell the “technicians” to put the guns down, stay home, and take the day off.To respond or make a comment click "comment" below or contact me at denniswild@earthlink.net .
No comments:
Post a Comment