Topic
Night heron
About: Night heron is a research topic. Over the lifetime, 189 publications have been published within this topic receiving 2921 citations. The topic is also known as: Night heron.
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TL;DR: Results indicate that the DDTs in eggs would be expected to be associated with adverse effects on the survival of young of both species, particularly the Little Egret.
106 citations
TL;DR: This study is a quantitative exploration of the ecological and behavioral adaptations by which some of these herons avoid direct competition for food.
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.
100 citations
TL;DR: An inverse relationship between the density of mosquitoes and the proportion that successfully obtained blood was indicated, ascribed to the increase in defensive activity displayed by the birds when exposed to increases in mosquito density.
Abstract: A night heron, a green heron, a white ibis, and a cattle egret were individually exposed overnight in 8-ft cages to densities of Culex nigripalpus ranging from 25 to 1,200 per cage. Surviving mosquitoes were examined the following morning and engorgement rates were determined as a measure of effect of antimosquito activity. In addition, the behavior of each bird was recorded for 2-hr periods at three different mosquito densities. Results indicated an inverse relationship between the density of mosquitoes and the proportion that successfully obtained blood. This relationship was ascribed to the increase in defensive activity displayed by the birds (differing in degree according to species) when exposed to increases in mosquito density. The frequency of interrupted feeding (= partial blood meals) was also related to host behavior and mosquito density.
90 citations
TL;DR: A negative correlation existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth.
Abstract: Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial‐nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty‐four black‐crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late‐stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p < 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown‐rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8–52.0 ppm. A negative correlation (r = ‐0.61; p < 0.05) existed between em...
89 citations
TL;DR: Lead levels for all the birds in both Hong Kong and Szechuan were among the highest in the world, and this was attributed to the continued use of leaded gasoline.
Abstract: Several species of herons and egrets frequently nest in colonies in areas where humans also concentrate. Since the birds feed on intermediate-sized fish that themselves concentrate pollutants, they can be used not only to assess the levels of contaminants in avian tissues but as indicators of contaminants in the environment. The concentration of heavy metals and selenium in the breast feathers of fledgling black-crowned night herons Nycticorax nycticorax and Chinese pond herons Ardeola bacchus from the Tu Jing Yan heronry outside Chengdu, Szechuan Province in China; and from fledgling black-crowned night heron, little egret Egretta garzetta, great egret Egretta alba and cattle egret Bubulcus ibis from the Mai Po heronry in Hong Kong, were determined. Breast feathers were also collected from adult great egrets in Hong Kong. Adult great egrets had significantly higher levels of all heavy metals than did young great egrets. There were no significant interspecific differences in metal levels among the young at Szechuan China, except for chromium (pond herons had higher levels). There were significant differences among the young nesting at Hong Kong for all metals examined. Great egrets had lower, and night herons had higher, levels of lead than the other young. Night herons also had the highest levels of cadmium, manganese, and selenium compared to the other young. Great egret chicks had the lowest mercury levels, while little egret had the highest levels. Lead levels for all the birds in both Hong Kong and Szechuan were among the highest in the world, and this was attributed to the continued use of leaded gasoline.
85 citations