GLG 599 Costa Rica Field Ecology 2000
There are approximately 350 species of birds that spend part of their lives in North America and part of their lives in Central and South America. Unlike some birds these species migrate according to seasonal changes and do not remain in the same area year round. Species remaining in the same area year round are referred to as "resident" birds. Those that move are referred to as "migratory" birds. In North America they attract mates, build nest and raise their young. Then come fall they migrate to the warmer climates of Central and South America to live out the winter when food is more abundant. These birds are called neotropical birds. ("neo" refers to the new world, and "tropical" refers to the area between the Tropics of Cancer and the Tropic of Capricorn).
There are many birds that fall in the category of neotropical migrants. These include raptors (bird of prey), shorebirds, waterfowl and songbirds. Many of the familiar birds seen in Ohio during the summer are these birds. Example would include Turkey Vultures, Killdeer, Ruby Throated Hummingbirds, Red Winged Blackbirds, and the many warblers that can be seen in our forests. While many of these birds are still found in large numbers, others are in decline. The populations of birds such as the Grasshopper Sparrow, Dicksickel and Cerulean Warbler have been observed to be in decline for years. The reasons for this decline are many. It includes habitat loss both nesting and wintering sites, habitat fragmentation, and years of exploitation by humans. But there is a strong move to increase conservation for these species, both in the tropics and the states. Cooperation is needed in both locations for this conservation to succeed.
Reasons for Decline
There is not a single factor that is at fault for the decline of migratory birds but the combination of many different ones. For many species the largest contributing factor is the loss of habitat both in wintering and nesting grounds. Within the United States alone we have lost over 90% of both our wetlands and native grasslands. These two types of ecosystems are used by a large number of species to raise their young. In Central and South America habitat is loss due to clear cutting for agriculture. These factors cause species to crowd into smaller and smaller area and increase competition for resources. While natural areas are set aside for wildlife in both nations, this habitat loss also leads to an increase in habitat fragmentation.
Habitat fragmentation is the reduction in the size and dimension of a system into smaller units. Habitat fragmentation often reduces the amount of resources available for a species. It may limit the size of territories, decrease availability of nesting sites or reduce food resources. Habitat fragmentation can be seen more in the United States as areas are set aside as wildlife islands surrounded by cities and towns. Large areas are diced up into smaller pieces with roads bisecting them. In the case of forest fragmentation of the deep woods needed for many warblers is limited. What does increase is the amount of area covered by the edge habitat of the forest. With this increase comes an increase in predators who reside in the edges and can forage farther into the forest interior than before. This edge increase also allows for other species to compete with birds that nest in deeper woods. Of major concern is the increase availability for Brown Head Cowbirds to parasitize nests of other birds especially the woodland warblers.
Historically Cowbird followed the migrating bison herd of North America. Since there was no time to raise young the Cowbird evolved into laying its eggs in the nest of other birds. The parent Cowbirds moved on with the herd leaving the other species to raise their young. The baby Cowbird grows bigger and faster and often forces the underdeveloped step-sibling out of the nest. With the increase in edge space the Cowbirds can travel farther into the fragmented woods than ever before. This allows them access to nests of species they would not have encountered before. With fragmentation Cowbird populations increase (to the point of being considered pest) while other woodland species decline.
Laws in both the United States and Costa Rica are in place to provide protection for migratory birds. In the United States it is illegal of posses any part of a migratory bird, unless it is for educational purposes. There are many areas set aside within the United States that these birds follow on their yearly migration. For those birds that may be hunted (waterfowl and shorebirds) there are hunting seasons and bag limits that have to be observed.
In Costa Rica it is a different story. With only 8%(as of 1989) of its land set aside as natural areas birds still faces challenges on private land. Two of the biggest problems include hunting and the trade of exotic bird for pets. For many hunting has been a mean to provide for ones family. Often any bird bigger than a sparrow can be considered fair game. This especially holds true in the countryside where hunting is an important source of protein. Bag limits and seasons are hard to enforce due to a limited number of people in the country's wildlife service. When hunting is combined with habitat alteration then the impact on populations increases.
Much in the manner that American keep dogs and cats, Costa Ricans keep small songbirds in cages. This is an ingrained part of the Costa Rican culture. Birds like the Scarlet Macaw are considered a status symbol. One can even see wild birds being sold on street corners, even during breeding season. While the trade in parrots and macaws has been virtually eliminated there is still some illegal trade through other countries. There is a licensing system in place for bird owners and catcher but it is believed that only 1/3 of those people actually obtain a license.
The migratory birds are facing many problems in both the United States and in Costa Rica. But there are many program and organizations that are helping with the efforts to conserve these species.
This is by no means a complete list of all the conservation efforts. Instead it is an overview of the variety of methods there are to promote conservation efforts, not only for birds, but for other species as well.
Educating people about a problem is the first step to a solution. The more people understand an issue the more they are likely to concerned and take action. Educating the public can be one of the first steps in developing a conservation mindset in them.
There are many organizations that are interested in migratory bird conservation. Some of the more interesting ones are those that form partnerships between organizations in the United States and their counterparts in Central and South America. One such example is the partnership between Hawk Mountain Sanctuary in Pennsylvania, and Pronatura Veracruz in Veracruz, Mexico. These two groups are interested in conservation of migratory raptors. Nearly the entire population of the world's Broad Winged and Swainson's Hawks migrate through Veracruz every year. Both organizations participate in conducting counts of the migrating birds to keep track of population trends. They also provide educational programs in their communities to increase awareness of these animals. Other partnerships include the National Audubon's Birds in Balance program. School children in both the US and Central America follow the path of migrating songbirds. Through exchange letters they learn more about each other culture using the birds as a common link.
The manner and methods to educate vary but they all share a common goal: to increase awareness about the plight of migratory birds.
One of the products of education is the interest it creates in people to want to see the birds first hand. Birding is quickly becoming a major recreational pastime for Americans. Each year billions of dollars are spent on equipment, lodging and other expenses by birders. There are now bird watching tours, events, and programs being held throughout the US and the world. While this may not seen as important in the United States places like Costa Rica can value from this type of conservation effort. The local community can benefit from revenue brought in by leaving the birds and their habitat alone. By leaving the area in it's natural state the community can benefit economically from it. Ecotoursim in an increasing business that can be used as one method to encourage the conservation of valuable habitat.
Often habitat is destroyed for agriculture. Now there is a form of agriculture that can benefit from both tourism and products grown. Instead of cutting down the forest to grow crops, crops are now being grown in the shade of the forest canopy. One style of growing coffee now being used is to grow the plants in the shade of the rainforests canopy. This coffee, known as "shade coffee", is marketed as an ecologically friendly crop. Since none of the trees or undergrowth is disturbed there is still habitat left for the animals. This way the grower can benefit from both the crop and the positive reputation that this type of farming produces.
The interest in the conservation of migratory birds continues to grow every year. At the same time habitat is lost in both their wintering and nesting grounds faster that it is placed aside for their benefits. As we continue to strive to conserve space for both man, plants and animals we must seek to find a balance point. We must be able to allow people to provide for themselves a sustainable method of living. At the same time we need to see the manner of living chosen also allow for the continuation of the unique lifestyle found in the animal world, the annual migration of thousand of birds between out homes and those in the south.
USGS National Wetlands Research Center, http://www.nwrc.gov/releases/pr99_054.html
US Fish and Wildlife Service, Migratory Songbird Conservation,
US Fish and Wildlife Service
National Audubon Society
Migratory Bird Conservation Society
Hawk Mountain Sanctuary
Stiles, F. Gary and Skutch, Alexander F., A Guide to Birds of Costa Rica, 1989, Cornell University, pp21-51
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