Phalacrocorax Brasilianus Research Articles

Long-Term Trends in Population and Community Measures of Colonial-Nesting Waterbirds in Galveston Bay Estuary

-We examined diversity measures of the colonial-nesting waterbird community in Galveston Bay Estuary from 1973-1990 to determine if trends were apparent at three levels of ecological organization (i.e., community, assemblage, and population), each representing a different level of data aggregation. The community was dominated numerically by the Laughing Gull (Larus atricilla), a species with the lowest annual variability. In general, species that exhibited high annual variability also had low mean abundances [e.g., Anhinga (Anhinga anhinga) and Yellowcrowned Night-Heron (Nycticorax violaceus)]. White Ibis (Eudocimus albus) and Sandwich Tern (Sterna sandvicensis) were unusual in that they were both highly variable and abundant. Trend analyses of the abundances of individual species showed that Roseate Spoonbill (Ajaia ajaja), Snowy Egret (Egretta thula), and Black Skimmer (Rynchops niger) declined significantly. Neotropical Cormorant (Phalacrocorax brasilianus) and Sandwich Tern increased significantly, and the remaining 13 species showed no statistical change. A classification analysis identified five species assemblages. Two assemblages increased significantly in abundance, one assemblage decreased significantly, and two assemblages showed no change. At the community level, none of the indices we examined showed a significant change over the 18-year period. We hypothesized that loss of coastal marsh vegetation and the development of favorable feeding conditions outside of Galveston Bay may have caused some of the population changes we identified. Our ability to identify trends was affected by the level of data aggregation. Community measures were less sensitive to change than were assemblage and population-level data. Received 17 November 1997; accepted 24 February 1998.

Fish and wildlife resources in the pantanal wetlands of Brazil and potential disturbances from the release of environmental contaminants

AbstractThe Pantanal is one of the world's largest wetland ecosystems, encompassing 140,000 km2. The region is a breeding ground for waterfowl, and enormous rookeries of storks, herons, egrets, and ibises indicate a vast abundance of birds. The Pantanal is also one of the most important refuges for many of Brazil's threatened or endangered species, such as jaguars, giant anteaters, and swamp deer. The productive web of waters supports an important fishery industry. The Pantanal, with its extraordinary diversity and abundance of wildlife, is a threatened region. Deforestation, expanding agriculture, illegal hunting and fishing, unplanned tourism, and pollution with pesticides have caused a progressive deterioration of the natural environment, placing one of Brazil's most important ecosystems at risk. Gold mining is still common in the northern Pantanal. Along the Cuiabá river are 700 functional gold‐mining dredges. In the town of Poconé, unregulated gold mines have also contaminated the area with mercury, which is used during the processing of gold. Approximately 50% of the fishes from the Cuiabá River and 35% from the Bento Gomes River have mercury levels higher than 0.5 μg/g, which is beyond the international standard for contamination. Fishes from the Paraguay River have levels below 0.5. Birds like Phalacrocorax olivaceus, Aramus guarauna, and Rosthramus sociabilis were also contaminated. No research has been conducted on the fate of pesticides in the Pantanal. However, because of the huge demand for soybean plantations on the upland areas surrounding Pantanal, the application of toxic agricultural chemicals is very common.

Migration and other movements among the lower Paraná River valley wetlands, Argentina, and the south Brazil/Pantanal wetlands

SummaryThe southern portion of South America plays an important role for the conservation of many waterfowl and waders. Migratory movements were, till recently, known only for Arctic or Patagonian species. The only exception was the Southern Pochard Netta peposaca, with a west—east winter migration from the lower Parana River valley to south Brazil coastal wetlands. The banding studies that have been conducted by the Centro de Pesquisas para a Conservação das Aves Silvestres (CEMAVE/IBAMA) since 1980, directly or through agreements with local organizations, showed more details of this migration, plus indications that other aquatic species such as Chilean Flamingo Phoenicopterus chilensis, other duck species, Neotropic Cormorant Phalacrocorax olivaceus and White-faced Plegadis chihi may follow the same pattern. A migration into the same area the Pantanal population of the Wood Stork Mycteria americana was only recently discovered, and other species may also do likewise when the Pantanal is seasonally flooded. The studies of such bird migration or movements between the main South American wetlands are of great importance to understanding their conservation needs, especially when international cooperation among the countries plays a most important role. The region has been suffering human pressures of various types, from land reclamation for pasture and/or agriculture to the operation, in the last 30 years, of big hydroelectric dams which affect the natural flow of rivers or keep flood-plains under water. The impending construction of the Hidrovia Paranà/Paraguay, a large project for heavy river use as a main transportation route, may represent an enormous impact on such rich aquatic habitats, demanding immediate cooperation among the countries involved to mitigate negative effects on the environment. The impact may be similar to what happened in the Mississippi valley early this century. The west-east movements between the Paranà River valley and south Brazil are of special conservation interest, as a nationally threatened species (in Brazil) is involved (the Chilean Flamingo) as well as duck species targeted for the hunting season in the area.

Experimental Infection of Contracaecum multipapillatum (Nematoda: Anisakinae) from Mexico in the Domestic Cat

Juveniles of Contracaecum multipapillatum infected the Mayan cichlid (Cichlasoma urophthalmus) and adults infected the olivaceous cormorant (Phalacrocorax olivaceus) and the great egret (Casmerodius albus) in the coastal lagoon at Celestun, State of Yucatan, Mexico. All are new host records, and, even though the geographic locality record of Mexico for the species has not been published, unidentified but presumably conspecific specimens have been reported from there. When juveniles of C. multipapillatum were fed to a kitten, but not rats, ducks, or chickens, they developed into adults. Measurements and morphological data are provided on the specimens from the kitten. Development of an avian ascaridoid in the intestine of a mammal increases the potential of this widespread species to infect other mammals, including humans.

Pesca associada entre golfinhos e aves marinhas

Along ten years of study of a common dolphin from the brazilian coast, Sotalia brasiliensis Van Beneden, 1874, I could see some occasions of feeding associations of this dolphin with five species of birds, Sula leucogaster (Boddaert, 1783), Fregata magnificens Mathews, 1914, Sterna hirundinacea Lesson, 1831, Larus dominicanus Lichtenstein, 1823 and Phalacrocorax olivaceus Humboldt, 1895. The commonest association observed was between the dolphin and S. leucogaster, and in all the associations was characterized the commensalism, with advantaged to the birds.

Gastrointestinal Helminths of Fish-Eating Birds from Chiloe Island, Chile

Of four species of fish-eating birds from Chiloé Island (Chile), three were infected with eight species of helminths. Tetrabothrius sp. was found in Larus scoresbii. Tetrabothrius cylindraceus, Profilicollis antarcticus, Anomotaenia dominicanus, Stephanoprora denticulata, Capillaria sp. and P. antarcticus were found in Larus dominicanus. Contracaecum rudolphii and Corynosoma sp. infected Phalacrocorax olivaceus. With the exception of S. denticulata, C. rudolphii and Capillaria sp., the above helminths are reported for the first time from Chile.

Food Habits and Organochlorine Contaminants in the Diet of Olivaceous Cormorants in Galveston Bay, Texas

Food Habits and Organochlorine Contaminants in the Diet of Olivaceous Cormorants in Galveston Bay, Texas

Population trends, reproductive success, and organochlorine chemical contaminants in waterbirds nesting in Galveston Bay, Texas.

The effects of environmental contaminants on the reproductive success of olivaceous cormorants (Phalacrocorax olivaceus), laughing gulls (Larus atricilla), and black skimmers (Rhynchops niger) nesting in Galveston Bay, Texas were investigated from 1980 through 1982. Populations of cormorants and gulls have remained stable in recent years, but skimmer numbers may have declined. Cormorants produced 1.9 to 2.8 young per pair in nests that remained active throughout the season. Gull and skimmer reproduction was seriously limited by storms and predation. DDE and polychlorinated biphenyl (PCB) residues in carcasses and eggs generally were below levels associated with chronic poisoning and reproductive problems in most species of birds. Possible exceptions were four black skimmer carcasses with DDE concentrations that ranged from 20 to 92Μg/g and one olivaceous cormorant carcass with 20Μg/g DDE. The generally low levels of dieldrin, chlordane, HCB, toxaphene, and heptachlor epoxide were below those know to affect avian reproduction and survival. Mean DDE residues in cormorant and gull eggs were less than 1.8Μg/g. The mean DDE residue in skimmer eggs was less than 3.3Μg/g; 12% of the skimmer eggs contained at least 12Μg/g DDE, a level known to cause reproductive problems in some avian species. DDE in the eggs of all species declined from 1.5- to 7-fold over the past decade. Polychlorinated biphenyl was detected in all gull and skimmer eggs and in 90% of the cormorant eggs. Residues of PCB in cormorant and skimmer eggs in 1980–82 were lower than in 1970, but the frequency of occurrence in gull eggs increased. Polychlorinated styrenes were recovered in 45% of the cormorant carcasses at levels below 1Μg/g. Eggshell thicknesses in all three species were similar to those of eggshells collected before the widespread use of DDT.

Mercury, Cadmium, Lead, and Selenium in Three Waterbird Species Nesting in Galveston Bay, Texas, USA

-Heavy metal and selenium concentrations were determined in Olivaceous Cormorants (Phalacrocorax olivaceus), Laughing Gulls (Larus atricilla), and Black Skimmers (Rynchops niger) nesting in Galveston Bay, Texas, during 1980-81. Lead was detected at low levels in a small proportion of the liver samples. Mercury was present in all livers sampled, the highest levels being found in cormorants (7.8 ppm) and skimmers (16 ppm). Concentrations were considerably lower than those reported in birds from mercury-contaminated lakes in northern United States and Canada. Cadmium and selenium were detected in 93 and 95% of the kidneys. Cadmium was highest in gulls and skimmers with a maximum value of 16 ppm. Selenium levels were similar among species except for higher concentrations in gulls collected in 1981. Mean concentrations that year were 8.88 ppm, and 6 of 10 samples exceeded 11 ppm-a level associated with impaired reproduction in experimental birds. We found no differences between sexes for mercury, cadmium, or selenium. Differences among colonies in selenium concentrations occurred in gulls.

Bird mortality at a power transmission line in Northeastern Venezuela

A survey of bird casualties resulting from collisions with cables in a section of the Margarita power transmission line at Chacopata Lagoon, northeastern Venezuela, where it runs between two expanses of water, was undertaken on 27 February 1983. A total of 611 birds skulls and freshly killed or crippled birds belonging to 10 species were counted. Brown pelicanus Pelecanus occidentalis, neotropic cormorants Phalacrocorax olivaceus, royal terns Sterna maxima, and black-crowded night-herons Nycticorax nycticorax, listed here in decreasing order of abundance, suffered the heaviest losses. The frequency of collisions with the power line is discussed in function of the species composition in the bird community, the behaviour of the birds, the flight characteristics or flight directions, the familiarity with local features, and the interactions with local fishermen and poachers. Undetermined quantities of casualties resulting from the removal of carcasses by scavengers appear more significant in smaller species, whereas those resulting from the hiding of injured birds seems to be more significant in larger species. Most collisions with the power line apparently occur either at dusk or at dawn. Burying of the cables is considered as the best corrective measure to prevent bird mortality in this case.

Experimental St. Louis encephalitis virus infection of sloths and cormorants.

Experimental infection of 11 Bradypus variegatus and Choloepus hoffmanni sloths with St. Louis encephalitis (SLE) virus produced detectable viremias of seven to 27 (median 13) days duration and maximum titers of 2.7 to 6.5 (median 5.1) log10 median suckling mouse intracranial lethal doses (SMicLD50) per ml. Experimental SLE viremia onset was delayed and maximum titer depressed in two sloths concurrently infected with naturally acquired viruses. SLE viremias in four experimentally inoculated cormorants Phalacrocorax olivaceus were shorter, and of equal or lower titer, than in sloths. Colonized Culex pipiens quinquefasciatus mosquitoes were infected by feeding on sloths circulating at least 4.8 log10 SMicLD50 of SLE virus per ml, and subsequently transmitted the infection to mice and chicks. An uninoculated baby Bradypus became infected by contact transmission from its mother. The antibody response of sloths to SLE virus was slow, being undetectable until several weeks post-inoculation. However, both sloth species developed high and long-lasting neutralizing and hemagglutination-inhibition antibody titers. The complement-fixation antibody response in Bradypus was lower and slower to develop than in Choloepus. Sloths with naturally acquired SLE virus antibody did not become detectably viremic after experimental inoculation. Neither sloths nor cormorants become overly ill from SLE virus infection.

Breeding Biology and Age-Specific Mortality of Olivaceous Cormorants

Breeding Biology and Age-Specific Mortality of Olivaceous Cormorants

Interspecific Association of Olivaceous Cormorants and Roseate Spoonbills

Interspecific Association of Olivaceous Cormorants and Roseate Spoonbills

Vagrancy of Neotropical Cormorant, Egrets, and White-Faced Ibis

Vagrancy of Neotropical Cormorant, Egrets, and White-Faced Ibis