Foraging Success of Cattle Egrets, Bubulcus ibis

1973 ◽  
Vol 89 (1) ◽  
pp. 242 ◽  
Author(s):  
James J. Dinsmore
The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Katia Lombardini ◽  
Robert E. Bennetts ◽  
Christophe Tourenq

Abstract We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.


Behaviour ◽  
1982 ◽  
Vol 79 (2-4) ◽  
pp. 212-229 ◽  
Author(s):  
Michael Gochfeld ◽  
Joanna Burger

AbstractIn southern Africa, the commensal foraging cattle egret has a wide variety of potential ungulate species from which to select its hosts. We found that the preferred hosts involved just a few of the available species. We predicted that ultimately the selection of hosts should be adapted to maximize egret foraging success. Selection is hierarchical with birds first choosing a general area in which one or more host species may be present. They then choose a host herd, and finally select an individual which they accompany as long as its actions are suitable and prey items are disturbed. The decision process remains flexible. Egrets freely switch hosts moving from one cow or wildebeest to another. We found the predicted correlation between egret and host walking rate (steps/min.), and also that feeding success was related to number of egret steps. We looked for evidence that egrets would select species and individuals that allowed them to move at the optimum rate for foraging. We found egrets achieving maximum success at walking rates between 10 and 30 steps per minute. When hosts moved more slowly or more quickly, feeding success was low, and egrets switched hosts more frequently. We censused wild animals in game parks and domestic animals on farms, and found a similar overall abundance (individuals/km). Wild animal herds provided fewer suitable hosts (individuals moving at the optimal rate for the egrets). We conclude that there are three components to host selection. Hosts must be available in adequate numbers and must be easy to locate. They must be suitable in terms of providing egrets with good foraging situations. They must be reliable in terms of remaining in the same general area day after day and in terms of consistent rates of locomotion. Although wildebeest, zebras, and buffalo fit one or two of the criteria, cattle fulfill all three. We speculate that the widespread increase in cattle farming in the past century may have facilitated the world wide population explosion of the cattle egret.


2019 ◽  
Author(s):  
Raymond C. Telfair II
Keyword(s):  

Author(s):  
Gus Mills ◽  
Margaret Mills

This book demonstrates how cheetahs are adapted to arid savannahs like the southern Kalahari, and makes comparisons with other areas, especially the Serengeti. Topics dealt with are: demography and genetic status; feeding ecology, i.e. methods used for studying diet, diets of different demographic groups, individual diet specializations of females, prey selection, the impact of cheetah predation on prey populations, activity regimes and distances travelled per day, hunting behaviour, foraging success and energetics; interspecific competition; spatial ecology; reproductive success and the mating system; and conservation. The major findings show that cheetahs are well adapted to arid ecosystems and are water independent. Cheetah density in the study area was stable at 0.7/100 km2 and the population was genetically diverse. Important prey were steenbok and springbok for females with cubs, gemsbok, and adult ostrich for coalition males, and steenbok, springhares, and hares for single animals. Cheetahs had a density-dependent regulatory effect on steenbok and springbok populations. Females with large cubs had the highest overall food intake. Cheetahs, especially males, were often active at night, and competition with other large carnivores, both by exploitation and interference, was slight. Although predation on small cubs was severe, cub survival to adolescence was six times higher than in the Serengeti. There was no difference in reproductive success between single and coalition males. The conservation priority for cheetahs should be to maintain protected areas over a spectrum of landscapes to allow ecological processes, of which the cheetah is an integral part, to proceed unhindered.


2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Elijah Abakpa Adegbe ◽  
Oluwaseyi Oluwabukola Babajide ◽  
Lois Riyo Maina ◽  
Shola Elijah Adeniji

Abstract Background Heavy metal accumulation in the ecosystem constitutes a potential toxic effect which is hazardous to human health. Increasing environmental pollution has necessitated the use of cattle egrets to evaluate the levels of heavy metal contamination, to establish their use in biomonitoring of heavy metals and to provide data for monitoring pollution in the environment. Results The present study assessed the utilization of Bubulcus ibis in monitoring pollution in five abattoirs, namely Agege, Bariga, Kara, Itire and Idi-Araba, all situated in Lagos State. The concentration of five (5) heavy metals, cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) was determined in the liver, muscle and feather of Bubulcus ibis using the atomic absorption spectrophotometer. The trend of metal accumulation was in the order: Zn > Cu > Pb > Cd > Ni for all the sampled tissues. The mean tissue concentrations of the metals were significantly different (p < 0.05) among the sites. The highest levels of metal concentration were reported in the liver in all the locations. Mean concentration of Cd in Kara (0.003 ± 0.00058) was significantly (p < 0.05) higher than those found at Agege (0.0013 ± 0.00058) and Idi-Araba (0.001 ± 0.001). A significant difference (p < 0.05) was also observed between the mean concentrations of Cu in Bariga (0.01 ± 0.001) and Idi-Araba (0.003 ± 0.001). Conclusion All the studied heavy metals were present in the liver, muscle and feathers of the cattle egrets. The contamination levels were ascertained from the study which indicated that cattle egrets are useful in biomonitoring studies and the generated data will serve as baseline data which could be compared with data from other locations for monitoring heavy metal pollution.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kylie Owen ◽  
Kentaro Saeki ◽  
Joseph D. Warren ◽  
Alessandro Bocconcelli ◽  
David N. Wiley ◽  
...  

AbstractFinding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.


Ecology ◽  
2011 ◽  
Vol 92 (6) ◽  
pp. 1258-1270 ◽  
Author(s):  
Michele Thums ◽  
Corey J. A. Bradshaw ◽  
Mark A. Hindell

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