Dietary Segregation of Four Ardeid Species Breeding in Anzali International Wetland, Northern Iran

Ashoori, Abbas; Moradi, H Varasteh; Rezaiee, Hamid Reza; Mahiny, Abdolrassoul Salman

doi:10.1675/063.040.0409

Cited by 5 publications

(6 citation statements)

References 20 publications

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“…2013, Ashoori et al . 2017), and thus showing a different trophic ecology from the other target species. Also, the diversity of feeding habitats where adults obatin food for their chicks was wider than for the other target species, supporting the descriptions of Rafael‐Garrido (2003).…”

Section: Discussionmentioning

confidence: 99%

Unravelling diet composition and niche segregation of colonial waterbirds in a Mediterranean wetland using stable isotopes

Antón‐Tello

Britto

Gil‐Delgado

et al. 2021

Ibis

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Rice fields and waterbirds are an example of a synergy that can occur between agriculture and conservation. This connection is especially relevant during the farming period, when nesting waterbirds need to obtain resources to cover their energy requirements and those of their chicks in rice fields. However, new farming techniques may potentially put fulfilling this role at risk. Studies on how species use rice fields to feed during this critical period are essential to understand waterbird population dynamics and to optimize conservation measures. At present, several species of colonial birds in l’Albufera de València (Spain) that depend on trophic resources available in rice fields have decling populations and decreases in productivity. We therefore assessed trophic niche segregation in the diet of chicks of a waterbird community composed of seven species through stable isotope analyses of carbon (δ13C) and nitrogen (δ15N) obtained from chick blood and tissue samples of potential prey. According to trophic niche widths, chicks of Black‐headed Gull Chroicocephalus ridibundus and Gull‐billed Tern Gelochelidon nilotica showed a similar diet, although Gull‐billed Tern had a major trophic specialization. The Western Cattle Egret Bubulcus ibis fed its chicks in a wider range of different habitats, with organisms located at the base of the food chain and with a greater importance of terrestrial prey than other species. Conversely, the Glossy Ibis Plegadis falcinellus had a more differentiated diet, mostly in freshwater habitats and mainly consuming odonates. Grey Heron Ardea cinerea, Little Egret Egretta garzetta and Squacco Heron Ardeola ralloides showed overlap between their niches, largely explained by the presence and abundance of cyprinid fish and odonates in their diets. Our results suggest a less important role than expected of Red‐swamp Crayfish Procambarus clarkii, and a more important role of odonates despite being a less energy‐rich prey. In conclusion, the diet of generalistic species of waterbirds in this study suggests that their trophic niches can overlap when relative prey abundance is high.

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Section: Discussionmentioning

confidence: 99%

Unravelling diet composition and niche segregation of colonial waterbirds in a Mediterranean wetland using stable isotopes

Antón‐Tello

Britto

Gil‐Delgado

et al. 2021

Ibis

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“…While the nestling diets of the two species showed partial niche overlap, there were striking dietary differences in exploiting food resources. There is general agreement that insects make up the most important dietary component for Cattle Egret nestlings (Siegfried 1971;Fogarty and Hetrick 1973;Ashoori et al 2017). Most of the studies carried out to date show that the diet of Little Egret nestlings is mainly composed of fish (Zhou et al 2000(Zhou et al , 2003Ashoori et al 2017).…”

Section: Discussionmentioning

confidence: 99%

“…There is general agreement that insects make up the most important dietary component for Cattle Egret nestlings (Siegfried 1971;Fogarty and Hetrick 1973;Ashoori et al 2017). Most of the studies carried out to date show that the diet of Little Egret nestlings is mainly composed of fish (Zhou et al 2000(Zhou et al , 2003Ashoori et al 2017). Our sample size of only 5 Little Egret nestlings would normally be considered too small to give a stand-alone result-65.7% fish in the present study-but the close agreement with other studies quoted, and the fact that not a single fish was included in our sample of more than 1500 food items for Cattle Egret nestlings, indicating that our results reflect a real difference in nestling diet of the two species.…”

Section: Discussionmentioning

confidence: 99%

“…Our sample size of only 5 Little Egret nestlings would normally be considered too small to give a stand-alone result-65.7% fish in the present study-but the close agreement with other studies quoted, and the fact that not a single fish was included in our sample of more than 1500 food items for Cattle Egret nestlings, indicating that our results reflect a real difference in nestling diet of the two species. One adaptive explanation for the dietary difference is that it allows resource partitioning between the two egrets, thereby increasing individual fitness through reducing interspecies competition (Ashoori et al 2017;Nicolaus et al 2019). In addition, Little Egrets examined in the present study preyed on larger mean biomasses of the food items than Cattle Egrets.…”

Section: Discussionmentioning

confidence: 99%

“…Competitive interactions are known to be stronger between closely related sympatric ardeid species (Bolton et al 2019). There have been numerous studies on niche partitioning between ardeid species, but most of them have only investigated the diets of various herons (e.g., Trexler et al 1994;Salazar et al 2005;Boyle et al 2012;Choi et al 2016;Ashoori et al 2017). And there were a few studies on nest site selection (Jenni 1969;McCrimmon 1978;Burger 1979;Parejo et al 1999;Metallaoui et al 2020) and temporal separation between species within heron colonies (Weber 1975;Burger 1978;Ashkenazi and Yom-Tov 1997).…”

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Three-dimensional niche partitioning between two colonially nesting ardeid species in central China

Jiang

et al. 2021

Avian Res

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Background Interspecific competition is known to be strongest between those species that are both closely related and sympatric. Egrets are colonially nesting wetland birds that often overlap and can therefore be expected to compete in roosting and nesting habitat as well as in diet. According to the niche partitioning hypothesis, it is to be expected that these similar species would show differentiation in at least one of the main niche dimensions to reduce competition. We tested niche partitioning between the colonially nesting Little Egret (Egretta garzetta) and Cattle Egret (Bubulcus ibis) in temporal, spatial and trophic dimensions. Methods Field study was conducted in three mixed egret colonies in Yangxian County, southwest Shaanxi Province, central China. For each nest colony we recorded its spatial location, the height of nesting trees and of nests, the height of roosting trees and of roosting individuals within the trees. We determined the first egg-laying and first hatching dates of the two species. Craw dissection of storm-killed egret nestlings was used to measure the diet. Six transects were surveyed to study foraging habitat selection. Results We found that hatching time of Little Egrets peaked earlier (by about 1 month) than that of Cattle Egrets. Cattle Egrets nested and roosted higher than Little Egrets. The foraging habitats used by Little Egrets were dominated by river banks (73.49%), followed by paddy fields (13.25%) and reservoirs (10.84%), whereas Cattle Egret foraging sites were characterized by grasslands (44.44%), paddy fields (33.33%) and river banks (22.22%). Little Egrets consumed more fishes (65.66%) and Odonata larvae (13.69%) than Cattle Egrets, while Cattle Egrets were found feeding mainly on Coleoptera (29.69%) and Orthoptera (23.29%). Little Egrets preyed on larger mean biomasses of food items than Cattle Egrets. Conclusions Our results confirm the niche partitioning hypothesis as a mechanism for coexistence among ecologically similar species. In two coexisting egret species, niche partitioning is multidimensional, such that the two coexistent species occupy differing ecological space based on all three temporal, spatial and trophic niche dimensions.

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Spatio-temporal variability of ichthyophagous bird assemblage around western Mediterranean open-sea cage fish farms

Aguado‐Giménez

Eguía-Martínez

Cerezo-Valverde

et al. 2018

Marine Environmental Research

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Dietary Segregation of Four Ardeid Species Breeding in Anzali International Wetland, Northern Iran

Cited by 5 publications

References 20 publications

Unravelling diet composition and niche segregation of colonial waterbirds in a Mediterranean wetland using stable isotopes

Unravelling diet composition and niche segregation of colonial waterbirds in a Mediterranean wetland using stable isotopes

Three-dimensional niche partitioning between two colonially nesting ardeid species in central China

Spatio-temporal variability of ichthyophagous bird assemblage around western Mediterranean open-sea cage fish farms

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