Nycticorax

About: Nycticorax is a research topic. Over the lifetime, 359 publications have been published within this topic receiving 6012 citations.

Impact of water diversions on colonially-nesting waterbirds in the Macquarie Marshes of arid Australia

Abstract: -The building of dams and subsequent diversion of water from the Macquarie River have had a significant impact on the breeding of colonial waterbirds in the Macquarie Marshes, New South Wales, southeastern Australia Annual flows (1978, 1986-1996), measured at Oxley where the Marshes begin, were significantly related to total colony size (number of nests) and sizes of six nesting Ciconiidae (Intermediate Egret Ardea intermedia, Rufous Night Heron Nycticorax caledonicus, Glossy Ibis Plegadisfalcinellus, Straw-necked Ibis Threskiornis spinicollis, Australian White Ibis Threskiornis mollucca and Royal Spoonbill Platalea regia) colonies We used these results and available historical flow data extending back to 1944 to demonstrate the probable impact of water diversions on breeding in these colonial nesting species The impact of Burrendong Dam, opened in 1967, and Windamere Dam, opened in 1984, on the numbers of nests would have been significant Instead of a colony of more than 100,000 nests in 1969, a colony of less than 10,000 probably established Similarly, in 1984, a colony of more than 100,000 could have been established with no water diversions, but in all likelihood the colony was less than 5,000 Generally colony sizes were significantly less (100,000 over 11 years) than would be expected without diversions of water upstream Colony sizes of more than 100,000 nests estimated during the floods of the 1950s are unlikely to occur again Numbers of annual breeding events also declined with water diversions from ten to seven (1963-1973); eight to seven (1974-1984) and eight to five (1985-1995) Received 18 December 1997, accepted 18 May 1998

Current impact of DDE on black-crowned night-herons in the intermountain west

Abstract: Organochlorine contamination was studied in eight black-crowned night-heron (Nycticorax nycticorax) populations nesting in Washington, Oregon, and Nevada in 1978-80. DDE was detected in 220 eggs sampled; eggshell thickness was negatively correlated with residues of DDE and polychlorinated biphenyls (PCB's). Other contaminants were detected in 35% or fewer of the eggs. Except for the two Columbia River colonies in which local DDE contamination was a probable compounding factor, a strong north-south clinal pattern of DDE residues among colonies existed. Southern colonies were most contaminated, and observed productivity was below population maintenance in one colony (Ruby Lake). At DDE levels in eggs above 8 ppm, clutch size and productivity decreased, and the incidence of cracked eggs increased. No evidence of breeding-ground DDE-DDT contamination was found except along the Columbia River. J. WILDL. MANAGE. 48(1):1-13 DDT and its metabolites may have played a role in the decline of blackcrowned night-herons in the northeastern United States (Ohlendorf et al. 1978). For example, Anderson and Hickey (1972) reported 18% shell thinning by 1952 in New Jersey. The use of DDT in the United States was banned in 1972, and by the midto late 1970's, production rates at several locations in eastern North America (Wisconsin, Qu6bec, Rhode Island, and Massachusetts) appeared normal, eggshell thickness was normal or near-normal, and/ or residues of organochlorine pesticides were lower (Hoefler 1980, Tremblay and Ellison 1980, Custer et al. 1983), with the possible exception being Lake Ontario (Price 1977). Similar improvements have been reported for other species, including the osprey (Pandion haliaetus) (Henny 1977, Spitzer et al. 1978). An adult black-crowned night-heron died at Ruby Lake National Wildlife Refuge near Elko, Nev., in 1975-3 years after the DDT ban. Its brain contained 230 ppm DDE and 1.1 ppm DDT (wet weight) (Ohlendorf et al. 1979). Although DDE concentrations in eggs from the northeast were diminishing in the late 1970's, the mortality at Ruby Lake in 1975 led us to suspect that DDE was still a problem for bird populations in the Intermountain West. Most birds nesting in the region are migratory, and many winter in Latin America. We studied two colonies in 1978 and extended our efforts to eight colonies by 1980. This study was designated to (1) determine levels of DDE and other organochlorine residues in black-crowned nightheron eggs; (2) evaluate the most common contaminants in relation to shell thickness and egg breakage; (3) evaluate regional patterns and trends of DDE residues; (4) evaluate DDE in eggs in relation to productivity; (5) evaluate the source of the contaminants; and (6) evaluate residues in herons found dead to determine if pesticides were implicated. National Wildlife Refuge personnel who provided field assistance included S. H. Bouffard, J. E. Cornely, and S. P. ThompJ. Wildl. Manage. 48(1):1984 1 This content downloaded from 40.77.167.80 on Mon, 13 Jun 2016 06:09:49 UTC All use subject to http://about.jstor.org/terms 2 DDE IN BLACK-CROWNED NIGHT-HERONS * Henny et al.

Heavy Metal, Organochlorine Pesticide, and PCB Residues in Eggs and Feathers of Herons Breeding in Northern Italy

Abstract: We report on organochlorine pesticide and PCB concentrations in eggs of the little egret, Egretta garzetta, and the black-crowned night-heron, Nycticorax nycticorax, collected in 1993–1994, and on mercury, cadmium, and lead concentrations in feathers of 20-day-old nestlings collected from the same nests in 1994, from heronries near Pavia, northern Italy. Organochlorine pesticide and PCB residues were lower than those commonly associated with mortality and reduced reproductive success. As population levels of the species studied are not declining, these contaminants appear to have no significant adverse effect on reproduction in the heronries studied. DDE levels have decreased markedly in heron eggs since 1978. However, the presence of both DDT and β-HCH, albeit at low levels, is notable, given that these compounds were banned in Italy in 1978 and 1988, respectively. Relatively high levels of Hg, Cd, and Pb in feathers suggest birds in their colonies are exposed to these contaminants, although both Cd and Pb may relate more to external than to internal contamination.

The Feeding Ecology and Behavior of Five Species of Herons in Southeastern New Jersey

Abstract: Theoretically, if two species resemble each other too closely in their requirements, one will have more efficient methods of using the necessary resources and ultimately will drive the second to extinction (Gause 1934). In recent years many field studies have concentrated on documenting differences in resource use between similar species. Schoener (1974) has reviewed many of these studies. Along the east coast of the United States, south of Long Island, are marshes that support up to eleven species of herons: Great Blue Heron (Ardea herodias), Green Heron (Butorides striatus), Little Blue Heron (Florida caerulea), Cattle Egret (Bubulcus ibis), Great Egret (Casmerodius albus), Snowy Egret (Egretta thula), Louisiana Heron (Hydranassa tricolor), Black-crowned Night Heron (Nycticorax nycticorax), Yellowcrowned Night Heron (Nyctanassa violacea), Least Bittern (Ixobrychus exilis), and American Bittern (Botaurus lentiginosus). The coexistence of these closely related species makes them an interesting group to examine for methods of sharing resources. Meyerriecks (1960, 1962) investigated behavioral differences between many of these species. My study is a quantitative exploration of the ecological and behavioral adaptations by which some of these herons avoid direct competition for food.