Búsqueda alfabética
Search by Word

Search by Topic

Glossary of Terms >

Migratory species

All around the world there are many species that migrate between different habitats in regular cycles. They are species that have populations which regularly, and predictably, travel long distances across countries and continents. They differ from resident species, which do not migrate within or between ecosystems, countries or continents, and feed and breed locally. In comparison, migratory species travel every year in search of optimum conditions for feeding and breeding during periods of scarcity, drought and cold. The renowned Global Registry of Migratory Species estimates that there are over 5,000 species which move seasonally between different geographic locations to improve their chances for healthy nutrition and a successful reproduction, thus ensuring their survival.

There are several types of species migration: latitudinal migration (from north to south and from south to north), longitudinal migration (from west to east and from east to west), altitudinal migration (from uplands to lowlands and vice versa) and different combinations of the above. Migration occurs through forests - or fragments of forests -, in rivers, and lakes, and in the air. Some species migrate only a few hundred meters per year, as is the case of some insects, while others travel the world, like some species of water fowl and shorebirds that migrate from the Arctic areas to Tierra del Fuego, in southern Argentina. An example of longitudinal migration is intratropical migration, in which species migrate within the tropical zone of a continent or a country, or from one habitat to another.

Some of the better known migratory taxonomic groups are formed by insects (e.g., the monarch butterfly in Mexico), shore birds and bats in the aerial environment, herbivorous mammals of large African savannahs on earth, and whales, sea turtles and marine and freshwater fish in the aquatic environment. Increasingly, modern science applies techniques to learn the migratory routes of these species. Radio-collars (transmitters) monitored by satellites are some of the latest technologies which will help decipher the migratory behavior of species such as birds, fish, turtles, whales, cats and bats.

Environmental Services

A large number of migratory species play key roles in natural ecological processes and, consequently, provide important ecosystem services to humans. Some of these services are pollination of crop flowers, depredation of species that cause pests, seed dissemination, among others. Moreover, the great local abundance of migratory species is an important food source for non-migratory species that inhabit the places where migratory species pass by. The life cycle of these resident species often depends on the seasonal presence of migratory species that serve them as food or prepare the grounds, as is the case of geese from temperate zones which oftentimes have a large impact on local ecosystems.


Many migratory species are currently threatened by human beings and their non-sustainable actions. Because migratory species depend on a variety of habitats in order to meet their needs during their journey through the migration route, they are very vulnerable to the loss and reduction of these habitats. Factors such as changes in land use, alteration of habitats, forest fragmentation, the effects of natural disasters, coastal and rural development, water, air and soil pollution, indiscriminate hunting and trapping, and the current climate change, increasingly threaten the populations of migratory species. Recently, the negative impact that electric transmission cables, certain marine fishing techniques , and wind power turbines have on migratory species populations, especially birds and fish, has also been recognized.

As a result, many of these species are now critically endangered or already in danger of extinction, especially those that make use of wetlands and lakes, lagoons and estuaries during their migration. Often times, these environments have been destroyed at alarming speeds. For example, in various parts of the American tropics, mangroves have disappeared in favor of shrimp farms, causing difficulties for the migratory birds which depend on these habitats during their migration cycles. Similarly, migratory marine species have suffered from pollution of the seas, coastal development and overfishing. Some examples are sea turtles that cannot find beaches for nesting and are harmed by fishing with extensive lines and trawl fishing. Whales and seals are also harmed by indiscriminate hunting or when forced to swim in contaminated waters.

Climate Change

It has been progressively recognized that climate change dramatically affects migratory birds which fly to the tropics before and during the northern hemisphere winter. In fact, the effects of climate change are already starting to be felt with the arrival of these birds to lower latitudes. However, the analysis to determine the rate at which it is happening and how birds respond to this change has only just started. In addition, there are other simultaneous threats, such as changes in land use, loss of habitat, environmental pollution, global warming and changes in rainfall distribution, which also have severe effects on migratory bird populations. Several studies suggest that there are birds that die from the loss of habitats in which they feed when they are en route to the destination where they will spend the temperate winter. Other birds, however, adapt to the new conditions and change food, or even alter their migratory route, incorporating areas and habitats that were not previously part of their itinerary. However, at present, we still know very little about the patterns that are surfacing. It requires a greater effort in scientific research in order to determine the magnitude of the effects of climate change on migratory birds, so as to understand how large flocks react to these changes and how human beings can act in order to ensure their long term survival in a changing world.

Considering that many migratory species move between two or more countries, collaboration in political, legal and institutional spheres between nations is key to ensuring that these species -often of economic, touristic, agricultural, cultural and spiritual interest - can survive in healthy populations and keep connecting ecosystems of different countries and regions. For this reason, on June 23, 1979 the United Nations member countries adopted, in Bonn, Germany, the Convention on the Conservation of Migratory Species of Wild Animals (CMS). This convention, also known as the Bonn Convention, was sponsored by the United Nations Environment Program (UNEP) and came into effect on November 1, 1983. The current body responsible for making decisions within the CMS is the Conference of the Parties (COP), whose parties - the signatory countries - meet every three years.

Convention on the Conservation of Migratory Species of Wild Animals (CMS): Bonn Convention

The objectives of the Bonn Convention are: 1) to conserve those species of wildlife that migrate across national borders by means of: 2) development and implementation of cooperative agreements; 3) prohibition of extractions of threatened species; 4 ) habitat conservation ; and 5) control of other adverse factors. In addition, the Convention seeks to promote cooperation and research to benefit those species. Some of the actions currently being taken within the framework of this international agreement are: 1) to include all countries located on the migratory routes of each species; 2) to conduct research on the status and migration of each species, reviewing it periodically; 3) to conserve, restore and rebuild habitats on the migratory routes, 4) to control and prevent harmful human activities, such as the introduction of exotic species in delicate habitats; and 5) to keep disseminating information and increasing public awareness on these issues.

According to UNEP, to date, more than 100 countries have signed a total of 11 binding agreements to protect various species, including the seals of the northern seas of Europe, North Mediterranean and Black Sea cetaceans, European bats, aquatic birds in Africa, Europe and Asia and Asian sea turtles, among many other species. Although there is abundant information on bird migration thanks to the various monitoring initiatives that exist, there is still much to be learned about the migration of certain groups of vertebrates, fish and insects. For example, it is a known fact that there are large gaps of information on Asian antelopes, bats, some whales and some species of freshwater migratory fish in the tropics. Therefore it is necessary that the different countries cooperate in the scientific research on natural resources in certain areas frequented by migratory species.

As stated by UNEP, the future of these and other migratory species depends on overcoming the current challenges and reducing the threats already mentioned. Cooperation between the CMS signatory members, and between the CMS and other conventions on biodiversity, will be critical to the success in establishing an adequate and durable protection.

As for America, the Western Hemisphere Migratory Species Initiative (WHMSI) was developed in Chile in 2003, with a view to strengthen public/private commitments and partnerships at the regional, national and local levels, as conservation mechanisms. The goal is to jointly contribute to the conservation efforts of American migratory species, the habitats they use in different countries of the Western Hemisphere (the American Continent), the migration routes and the many benefits these provide to society.

Dominican migratory species

At present, in the Dominican Republic, there are many habitats that are considered critical for migratory species that pass through the island of The Hispaniola. Dominican migratory species include bats, birds, whales, sea turtles and tuna fish. Bats of the Molossidae (Tadarida brasiliensis) family migrate from South America (Argentina, Uruguay) to the Greater Antilles in the Caribbean, including the Dominican Republic. The blue whale (Balaenoptera musculus) is one of the whales that visit the island every year. Likewise, Dominican migratory turtles include the green turtle (Chelonia mydas), the hawksbill sea turtle (Eretmochelys imbricata), the loggerhead sea turtle (Caretta caretta) and the leatherback sea turtle (Dermochelys coriacea). In recent times, it has been proven that all these species suffer from changes in land use, pollution, fisheries, and coastal tourism development.

The most conspicuous group of migratory species in the Dominican Republic is that of aquatic birds. In fact, in many areas of the country, even in urban areas of the capital, Santo Domingo, large flocks of migratory birds have been observed. Some studies report up to ten species of migratory birds in the capital, including the small Redstart (Setophaga ruticilla), an insectivorous species from North America. Examples of other migratory birds are the Roseate Tern (Sterna dougallii) and the Arctic Tern (Sterna paradisaea), both coastal aquatic species. Currently, at least 47 species of migratory birds are known to pass through the Jaragua National Park every year. Similarly, it is known that two species of migratory birds pass through the Sierra del Bahoruco National Park.

Laguna Cabral or Rincon Wildlife Refuge

A migratory bird count conducted by volunteers revealed the importance of the Laguna Cabral Wildlife Refuge wetland for birds that migrate towards the Dominican Republic in winter. As of today, at least 117 species of birds have been identified in this wetland, 46 of which are migratory, including a large number of Anatidae (ducks). A few years ago, a specialized committee of volunteers on boats, used the transect method to carry out several surveys of six species of ducks in Laguna Cabral. The maximum number of ducks observed ranged between 20 and 2.500 individuals. In light of these results, it was decided to develop a management plan for the conservation of this lagoon, to favor the permanence of these migratory ducks, among other birds. Training is being programmed for surveillance personnel of this wetland, which has much value for Dominican conservation efforts. In addition, Laguna Cabral was included in the list of Areas of Importance for the Conservation of Birds, due to its importance for migratory birds at the hemispheric level.