versión impresa ISSN 2007-8706
Rev. Mex. Biodiv. vol.82 no.2 México jun. 2011
New and noteworthy waterfowl records at artificial wetlands from Baja California Sur, Mexico
Registros nuevos y sobresalientes de anátidos en humedales artificiales de Baja California Sur, México
Roberto Carmona1*, Víctor Ayala-Pérez1,2 and Antonio Gutiérrez Aguilar3
1 Departamento de Biología Marina. Universidad Autónoma de Baja California Sur. Apartado postal 19-B. 23080 La Paz, Baja California Sur, México. *Correspondent: email@example.com
2 Departamento de Pesquerías y Biología Marina, Centro Interdisciplinario de Ciencias Marinas-IPN. Av. Instituto Politécnico Nacional s/n. Col. Playa Palo de Santa Rita. 23096, La Paz, Baja California Sur, México.
3 Exportadora de Sal, S. A. de C. V., Guerrero Negro, Baja California Sur, México.
Recibido: 18 mayo 2009
Aceptado: 10 agosto 2010
We present 9 recent records of rare waterfowls in Baja California Sur, all of them in artificial wetlands: 3 freshwater sites and 1 concentration area for a saltworks. We present the first records of the Ross's Goose in the state. The remaining 8 species are: Black-bellied Whistling-Duck (breeding), Fulvous Whistling-Duck, Greater White-fronted Goose, Snow Goose, Cackling Goose, Tundra Swan, Mallard and Hooded Merganser. To this list we added an historical compilation of the records of these species in artificial sites of the state. The artificial wetlands are no replacement for their natural counterparts, they are nevertheless an important part of the region's landscape mosaic. As the records of the present work exemplify, this man-made habitat increases the regional species richness, and should be considered as important areas that need to be protected.
Key words: waterfowls, artificial wetlands, Baja California Peninsula.
Presentamos registros recientes de 9 especies de anátidos raros en Baja California Sur, todos ellos realizados en humedales creados por el hombre: 3 sitios dulceacuícolas y 1 área de concentración para la producción de sal. Se incluyen los primeros registros del ganso de Ross (Chen rossii) para el estado. Las 8 especies restantes son: Dendrocygna autumnalis (anidación), D. bicolor, Anser albifrons, Chen caerulesens, Branta hutchinsii, Cygnus columbianus, Anas platyrhynchos y Lophodytes cucullatus. A la lista, agregamos una recopilación histórica de los registros de estas especies en humedales artificiales del estado. Aunque estos sitios no deben sustituir a sus contrapartes naturales, actualmente forman parte del mosaico paisajístico que ofrece la región; adicionalmente, incrementan la riqueza de especies de la región, por lo que es necesario brindarles protección.
Palabras clave: Anatidae, humedales artificiales, península de Baja California.
Even though the avifauna of the Baja California Peninsula is well documented (Wilbur, 1987; Erickson et al., 2001), new records continue to accumulate, especially of migratory species. Most of the peninsula has a dry climate therefore freshwater bodies are scarce (Guzmán et al., 1994). Consequently, there are few studies on the waterfowl species that use freshwater habitats, particularly as compared with the research made in coastal and marine environments.
Recent increase in human population has entailed a reduction of adequate habitat for waterfowl, because these habitats have been used by man to develop agricultural, industrial, or tourist activities (Erwin et al., 1986; Myers et al., 1987). This has caused the displacement and even eradication of the populations of some birds (Llinas and Jiménez, 1997). In contrast, some human modifications of the landscape have benefitted bird communities, compensating to a certain extent for the loss of natural wetlands (Zamora-Orozco et al., 2007).
In the Baja California Peninsula, the creation of artificial wetlands such as saltworks and freshwater bodies (e.g. Exportadora de Sal S.A. de C.V., oxidation ponds and a storage pond for residual waters), has increased the diversity of birds. These environments function as human-made ecosystems, which provide food and shelter for a large number of migratory and resident birds. The effort to study the birds using these artificial water bodies has increased in the last 10 years (Castillo-Guerrero and Carmona, 2001; Danemann et al., 2002; Carmona et al., 2006; Zamora-Orozco et al., 2007).
Important observations of uncommon waterfowls have been carried out in the area, such as: Greater White-fronted Goose (Anser albifrons), Common Goldeneye (Bucephala clangula), Muscovy Duck (Cairina moschata), Black-bellied Whistling Duck (Dendrocygna autumnalis) and its first breeding record, and Greater Scaup (Aythya marila; e.g. Carmona et al., 1999; Erickson et al., 2006).
In this paper, we present records of 9 notable species of waterfowls that use different artificial wetlands of Baja California Sur. Eight of these species are catalogued as uncommon winter visitors (Table I), and 1 is a new record (Ross's Goose, Chen rossi) for Baja California Sur. The data presented, added to information from previous studies, suggest the necessity to preserve these places.
Our records are from 4 localities, 1 saltwater and 3 freshwater artificial wetlands: (1), the first concentration area (area 1) from the Guerrero Negro saltworks (Exportadora de Sal) was originally created by building a dike across a bay of the Ojo de Liebre Lagoon. There is a pumping station in the dike that pumps seawater from the lagoon more or less continuously. Therefore, this area has similar conditions to the lagoon with only slightly higher salinity, but there is no tidal influence (Fig. 1); (2,) Guerrero Negro Oxidation Ponds, (2 oxidation lagoons of 0.5 km2 each one) located southeast of Guerrero Negro town (Fig.1); (3), The Chametla Lagoons (5 oxidation lagoons of 5 hectares each), located southeast of La Paz (Fig.1), where the constant flooding of the adjacent areas has favored the development of grazing lands (c.a. 17 ha) in which different species of birds are seen, and (4), El Centenario tank is located at the south west of La Paz (Fig. 1); this is a pond of waste water storage of El Centenario Town. This tank stores the originating water of the treatment plant that is distributed to the different cultivated fields of the zone and has a capacity of 500 000 m3.
As part of a research program on the utilization of the Ensenada de La Paz and Guerrero Negro by aquatic birds, we performed continuous surveys at these sites. During all surveys we identified the birds using binoculars (10x) and telescopes (15-60x), at a maximum distance of 100 m. The order of the presentation of bird records is based on that proposed by the AOU (1998). With the exception of the Snow Goose, we have photographic evidence for all the other species.
Black-bellied Whistling-Duck (Dendrocygna autumnalis). The Black-bellied Whistling-Duck ranges from the southern United States to northwestern Peru, occupying lakes and shallow freshwater marshes in the tropical and subtropical zones (AOU, 1998). Although the species is generally nonmigratory, the Baja California Peninsula is not part of the Black-bellied Whistling-Duck's historical range (Grinnell, 1928; Wilbur, 1987), although Howell and Webb (1995) reported 1 at San José del Cabo (June, 1999). Since 1999 this species has been sighted several times at the Chametla Lagoons (oxidation ponds; Carmona et al., 1999; Erickson et al., 2001). In September 2004, Sauma et al. (2005) reported the first breeding record of this species in the Chametla lagoons (2 adults and 3 chicks). We observed a second breeding record of this species in the same place in August 2007 (Table I), with the presence of 2 adults and 2 chicks that were swimming together.
Fulvous Whistling-Duck (Dendrocygna bicolor). This species tends to prefer the tropical habitats at the center of the continent (Leopold, 1977; AOU, 1998). It winters on the Pacific coast from southern California (formerly) to Oaxaca, Mexico (Howell and Webb, 1995; AOU, 1998). The Fulvous Whistling-Duck uses shallow waters, swamps, lagoons, and crop fields (Howell and Webb, 1995; AOU, 1998). In the Baja California Peninsula, D. bicolor is a rare species (Howell and Webb, 1995) with no records reported in more than 80 years. Reported specimens were collected in southern Baja California Sur in 1928 (Erickson et al., 2001). We observed this species 3 times at the Chametla Lagoons in December 2005 (Table I).
Greater White-fronted Goose (Anser albifrons). This species is considered a rare or uncommon winter visitor in the Baja California Peninsula (Wilbur, 1987; Howell y Webb, 1995). Its winter distribution range in Mexico is restricted to the coast of Sonora, Sinaloa, Nayarit, and Baja California (Wilbur, 1987; Howell y Webb, 1995), although some records exist for the Pacific coast of the Baja California Peninsula close to Bahía Magdalena (Howell y Webb, 1995). The first record from the southern portion of the peninsula was published by Carmona et al. (1999), and includes 4 records in La Ensenada de La Paz, 3 of them in the Chametla Lagoons. We observed 1 adult (November-December 2009) in the Chametla Lagoon roosting in the water body, and in the borders of this lagoon, and sometimes feeding in company of White-faced Ibis.
Snow Goose (Chen caerulesens). This species regularly winters in the United States and also in northwestern Mexico and Veracruz in eastern Mexico (AOU, 1998). Historically, its major winter abundance in Mexico was in the Colorado River delta, the interior lakes of Chihuahua and Durango, and the north coast of Tamaulipas (Leopold, 1977). It shows affinity for freshwater bodies, swamps, wetlands, cultivated fields, lakes, estuaries, and flooded fields (Howell and Webb, 1995). The Snow Goose was considered an uncommon winter visitor in Baja California Sur by Wilbur (1987). In Baja California Sur, there are 9 records between 1984 and 1999, 3 of them they in artificial wetlands, and most of them from autumn and winter. We added 3 records in the same type of habitats (Table I). In agreement with previous records, the Snow Goose was observed in autumn and winter.
Ross's Goose (Chen rossii). This species is considered rare along the Pacific coast of Mexico, including the Baja California Peninsula (AOU, 1998). The first record of the Ross's Goose on the peninsula was from the Mexicali Valley, where hunters collected some individuals in December 1950January 1951 (Saunders and Saunders, 1981). We observed the first Ross's Goose in Baja California Sur at the Chametla lagoons in November 2004 (Table I). It was seen feeding in pastures near the Chametla lagoons along with some individuals of Cinnamon Teal ducks (A. cyanoptera). Between November 2006 and February 07, we recorded 6 visits of the Ross's Goose at the same location. In addition, we documented another record for the Ross's Goose in Guerrero Negro, Baja California Sur, the bird was also using a man-made habitat (Table I).
Cackling Goose (Branta hutchinsii). This species predominantly winters on the western coast of the USA (Mowbray et al., 2002). Apparently some birds deviate towards the Baja California Peninsula (AOU, 1998). In Baja California Sur, only 3 previous records exist (Erickson et al., 2001). We observed a Cackling Goose at the Chametla Lagoons on 30 October 2001 to 17 December 2002. Another Cackling Goose was observed 3 months after in the same area. It is highly probable that it was the same goose that winters in the region. And again 3 months after this last record, 1 bird was observed after the breeding season. This bird remained all the winter season of this year in the same zone. Another 2 birds were recorded in the same artificial area during the winter of 2006 in company of 1 Ross's Goose. More recently we have 1 record from the Guerrero Negro oxidation ponds (December 2009), where we observed it in company of a Tundra Swan.
Tundra Swan (Cygnus columbianus). In general, in northern Mexico, the Tundra Swan is considered an uncommon winter visitor (Howell y Webb, 1995). In the Baja California Peninsula, this species is cataloged as a rare winter visitor, with only 1 record per locality in Guerrero Negro (1982), La Paz (1950), and San José del Cabo (1968; Wilbur, 1987). We observed an adult of the Tundra Swan in a small oxidation pond of the waste water treatment plant of the Exportadora de Sal in Guerrero Negro; the bird was present between 21 and 24 of December 2009.
Mallard (Anas platyrhynchos). The Mallard is the most abundant duck species in North America (AOU, 1998). However, it was considered an uncommon winter visitor in Baja California Sur by Wilbur (1987) with only a few records for the region. These records include 1 in La Paz in 1972 (Wilbur, 1987), 1 female in San Ignacio in 1986 (Erickson et al., 2001), and 1 for El Centenario Tank in 2001 (Castillo-Guerrero and Carmona 2001). Here we added another record from Baja California Sur and the first record from Guerrero Negro (November 2006; Table I). The Mallard was observed in the Guerrero Negro Oxidation Ponds. It was a male adult that was in company with a group of Northern Pintail.
Hooded Merganser (Lophodytes cucullatus). The Hooded Merganser is the smallest of 3 North American mergansers and the only one restricted to this continent (Dugger et al., 2009). This is an uncommon and rare wintering visitor in the Baja California Peninsula and only a few have been seen in this region (Wilbur, 1987). These records include 1 bird in San Jose del Cabo in February 1860 (Wilbur, 1987), 1 male in Mulegé in December 1992 and 1 female in the same area in February 1999. Here we present the first record in 1 concentration area from the Guerrero Negro Salt work (1 male), in company of a big flock of Lesser Scaup (December 2009; Table I).
The majority of the records we present here are from artificial freshwater wetlands. Because most of their natural equivalents are scarce in this region, and threatened by human activities, (Rodriguez-Estrella et al., 1997), the construction and permanence of artificial wetlands have been beneficial for bird communities. Artificial wetlands seem to have mitigated the loss or reduction of natural wetlands, and are human-made ecosystems used by large numbers of migratory and resident birds (Zamora-Orozco et al., 2007; Castillo-Guerrero and Carmona, 2001). At the moment they are part of the landscape mosaic that the region offers to birds (Castillo-Guerrero and Carmona, 2001), allowing an increase in the number of waterfowl species at the regional level.
Additionally, the artificial sites of Exportadora de Sal have an important role for the overall avian community, in particular for waterfowl species (Carmona and Danemann, 1998). The existence of these sites has led to the settlement of bird communities that have preferences for different halophilic wetland conditions that are hardly present in the natural wetlands of this region (Carmona y Danemann, 1998).
Our observations show that artificial wetlands can be important, at least locally, for waterfowl and landbirds. This man-made habitat is used for feeding and refuge. It is necessary to consider that this type of wetlands should not replace their natural counterparts (Schnack et al., 2000). However, there are cases like those presented here, where the artificial water bodies have a practical use for humans (water treatment and production of salt). Due to artificial wetlands can supply, in part, the functions, values and attributes that characterize the natural ones (Schnack et al., 2000), and can help to compensate for the loss of the natural sites, it is important to consider them as areas than need to be encouraged and protected.
We thank all facilities granted by the staff at the Residual Water Treatment Plant (La Paz), where Abigail Solano was especially helpful. Thanks to the staff of the Aquatic Birds Program at the Universidad Autónoma de Baja California Sur for their support. To Exportadora de Sal S.A. de C.V (ESSA) and all its staff, especially Edmundo Elorduy, Martín Domínguez, Martín García, Ramiro Zaragoza and Fabián Castillo for their logistic support both in the field and in their hosting facility. Reviews by Richard A. Erickson and Melania López Castro were greatly appreciated.
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