Estuario del río Gallegos

The Río Gallegos Estuary is located in the province of Santa Cruz, Argentina in extreme southeastern continental Patagonia. It is oriented west to east, extending nearly forty kilometers from Güer Aike to where the river empties into the Argentine sea (Atlantic Ocean). Although smaller, the Río Chico also empties into the Atlantic and forms an estuary of great importance to bird life due its extensive tidal flats. The Estuary waters are shallow except for the channel located at the river mouth which is some 20 meters in depth. Two kilometers from the river mouth is Deseada Island. The Estuary’s northern bank protects this island of approximately 37 hectares, an important nesting site for various species of sea and shorebirds. The cool coastal climate here has a median temperature of 7.2 degrees centigrade and winds that blow nearly constantly from the west averaging 35 kilometers per hour. The capital city of the province, Río Gallegos, with a population of some 95,796 inhabitants (INDEC, 2010), is located on the Estuary’s south bank.

The WHSRN site comprises two sections with different ownerships: the Provincial Reserve for Migratory Shorebirds (Province of Santa Cruz, Argentina) and the Coastal Urban Reserve (Municipality of Río Gallegos).

The Estuary gives shelter and sustenance to a significant proportion of the world’s population of species such as the Magellanic Plover (Pluvianellus socialis) and the Magellanic Oystercatcher (Haematopus leucopodus), both endemic to southern Patagonia. In addition, it is a site used by large numbers of three other shorebird species: the White-rumped Sandpiper (Calidris fuscicollis), the Red Knot (Calidris canutus), and the Hudsonian Godwit (Limosa haemastica). These three arrive from the northern hemisphere and use the Estuary as a migration stopover during the non-breeding season. It is estimated that the Estuary gives shelter to more than 20,000 Nearctic and Patagonian shorebirds every year.

It is also the habitat of other equally important species such as the Hooded Grebe (Podiceps gallardoi), a vulnerable endemic found almost exclusively in Santa Cruz, and the Austral Canastero (Asthenes anthoides), an insufficiently known endemic living in the neighboring brush land. The breeding colonies of more than 20,000 pairs of seabirds that nest there further enhance the conservation value of the Estuary. Worth noting are the Magellanic Penguin (Spheniscus magellanicus), the Blue-eyed Cormorant (Phalacrocorax atriceps), the Chilean Skua (Stercorarius chilensis), the Dolphin Gull (Leucophaeus scoresbii), and the Kelp Gull (Larus dominicanus). In September, 2005 Birdlife International designated the Río Gallegos Estuary an Important Bird Area (IBA).

Habitat loss and deterioration are among the threats confronting the Coastal Urban Reserve, due primarily to human activities in the coastal zone. The city of Río Gallegos was growing chaotically along the coast, which not only triggered the filling in of ecologically productive areas to build houses, or to be used as urban solid waste dumps, but also the fact that the municipal dump is currently located within the city (adjacent to the Coastal Urban Reserve). These uses not only harmed the natural habitat upon which a great number of birds depended, they also diminished the proportion of natural spaces suitable for recreation and tourist activities. In addition, they changed coastal dynamics affecting the natural processes of erosion and accumulation and thus had a direct impact on the quality of life of the city’s inhabitants. At the present time, the creation of the Reserve has stopped such practices. Now only the lots that had been approved prior to the Reserve’s establishment have continued to be filled in.

Another effect from urban growth in the area is the presence of domestic animals (primarily dogs and horses) on the coast, causing increased disturbance to birds, especially during high tide when they are concentrated in certain areas very close to shore, interrupting their roosting and feeding.

In the Provincial Migratory Bird Reserve, the main threat comes from the oil industry. Crude oil and coal are loaded onto ships at a hydrocarbon port where the Estuary empties into the sea, adjacent to the salt marsh zone. The difficulties posed to navigation by extreme tides, strong winds, and tidal currents in the Estuary and the history of oil tankers running aground because of poor piloting is a clear warning concerning the risks involved. A shipwreck could easily contaminate key bird areas.

In the areas surrounding the Estuary, land has historically been used for cattle raising. During the past few years, significant areas of brush land next to the Provincial Reserve have been cleared and designated for agricultural use and for the establishment of small farms. This implies the loss of buffer zones for the Reserve, an increase in the human presence in the zone, as well as a possible rise in disturbances in zones critical for bird feeding and resting. This is in addition to the permanent presence of illegal fisherman at the site, whose practices directly and indirectly affect the birds, because the estuary is adjacent to the city.

Below is a summary of the most significant accomplishments partners at Río Gallegos have achieved to conserve these wetlands: