Grey Heron (<i>Ardea cinerea</i>) Expansion Promotes the Persistence of Mixed-Species Heron Colonies

Mashiko, Miyuki; Toquenaga, Yukihiko

doi:10.1675/063.037.0403

Cited by 4 publications

(4 citation statements)

References 28 publications

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“…We considered the total abundance of herons and egrets. The five species in the study area have overlapping ecological niches; they forage in farmlands and often share colonies (Mashiko & Toquenaga, 2014). In addition, the number of herons and egrets is related to the abandonment of farmland and taxon diversity and can therefore be used as an indicator of species richness on farmlands (Katayama, Mashiko, Koshida, & Yamaura, 2021;Katayama et al, 2019;Koshida & Katayama, 2018).…”

Section: Discussionmentioning

confidence: 99%

Distance sampling with vehicle-mounted cameras for the estimation of farmland bird abundance over a wide area

Kumada

Fukasawa

Yoshioka

et al. 2023

Preprint

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Agricultural birds are declining due to farmland abandonment and agricultural intensification, and monitoring approaches, including efficient survey methods, are crucial for the development of effective conservation strategies. Roadside surveys (RS), especially those using vehicle-mounted video cameras, can be used to efficiently search for targets; however, they are limited by the unknown detection range. Distance sampling (DS), in which animal density or abundance is estimated from the distance between the observer and the detected individual, can provide a complimentary approach to address this limitation of RS. We developed a DS model robust to location uncertainty based on video-based RS. We integrated location errors determined by an independent field test using RS and unmanned aerial vehicles (UAVs) into a stochastic DS model. We estimated the abundance of herons and egrets in farmlands in and around the evacuation zone of the Fukushima Daiichi nuclear power plant accident by combining RS and DS. The video-based RS covered 7,031 km of roads and 24.41 km2 of farmlands. All herons and egrets were observed around the evacuation zone and none were detected in the zone. The predicted abundance of herons and egrets differed substantially between areas inside (0.0158 ± 0.0174/km2) and outside of the zone (4.62 ± 5.41/km2). Integrating location uncertainty into the DS model did not affect predicted heron and egret population densities (4.62 ± 5.41 vs. 4.66 ± 5.45/km2, with or without integrating location uncertainty, respectively). Accordingly, our survey method combining RS and DS is robust to location uncertainty. The study system (i.e., herons and egrets in farmlands) and the inability of location error to exceed the size of one farmland separated by levees may contribute to the accuracy of RS in this study. Synthesis and Applications: Combining RS with vehicle-mounted cameras and DS considering location uncertainty is widely applicable to open land species and can improve the efficiency of monitoring. When large location errors are expected by conventional approaches, DS models incorporating location uncertainty determined by RS and UAVs could be effective for abundance estimation over wide areas.

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Section: Discussionmentioning

confidence: 99%

Distance sampling with vehicle-mounted cameras for the estimation of farmland bird abundance over a wide area

Kumada

Fukasawa

Yoshioka

et al. 2023

Preprint

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“…Different heron and egret species have different individual site fidelity levels (Melvin et al ), while different species can have a different effect on the persistence of a colony over the years. Mashiko and Toquenaga () showed that the presence of grey herons increased the persistence of the colonies in Ibaraki prefecture. Furthermore, the grey heron population in the region has increased significantly in the last decade, with its distribution limited to only one colony up until 1999 (Mashiko and Toquenaga ).…”

Section: Discussionmentioning

confidence: 99%

“…Mashiko and Toquenaga () showed that the presence of grey herons increased the persistence of the colonies in Ibaraki prefecture. Furthermore, the grey heron population in the region has increased significantly in the last decade, with its distribution limited to only one colony up until 1999 (Mashiko and Toquenaga ). We found that colony site fidelity levels and the grey heron population were highly correlated (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Six species of herons and egrets settle their annual mixed‐species colonies across the study area from late February to mid May. The grey heron, the species not present in the study area until the mid 1990s (Mashiko and Toquenaga ), is the first species to arrive at the breeding locations, followed by the great egret, little egret E. garzetta and black‐crowned night heron Nycticorax nycticorax . Finally, the intermediate egret E. intermedia and cattle egret Bubulcus ibis , the migrant species, arrive by early May.…”

Section: Methodsmentioning

confidence: 99%

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Balance between site fidelity and habitat preferences in colony site selection by herons and egrets

Carrasco

Toquenaga

Mashiko

2017

Journal of Avian Biology

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Habitat selection in avian species is a hierarchical process driven by different factors acting at multiple scales. Habitat preferences and site fidelity are two main factors affecting how colonial birds choose their breeding locations. Although these two factors affect how colonial species choose their habitats, previous studies have only focused on one factor at a time to explain the distribution of species at regional scales. Here we used 28 yr of colony location data of herons and egrets around Ibaraki prefecture in Japan in order to analyze the relative importance of habitat preferences and colony site fidelity for selecting breeding locations. We used Landsat satellite images together with a ground survey-based map to create land-use maps for past years and determine the habitats surrounding the herons and egrets colonies. Combining the estimated colony site fidelity with the habitat data, we used a random forest algorithm to create habitat selection models, which allowed us to analyze the changes in the importance of those factors over the years. We found high levels of colony site fidelity for each year of study, with its relative importance as a predictor for explaining colony distribution increasing drastically in the most recent five years. The increase in collective site fidelity could have been caused by recent changes in the population size of grey herons Ardea cinerea, a key species for colony establishment. We observed a balance between habitat preferences and colony site fidelity: habitat preferences were a more powerful predictor of colony distribution until 2008, when colony site fidelity levels were lower. Considering changes in the relative importance of these factors can lead to a better understanding of the habitat selection process and help to analyze bird species' responses to environmental changes.

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Range expansion of nesting Squacco Heron Ardeola ralloides and Black-crowned Night Heron Nycticorax nycticorax in the Sahara

Bouzid

Chedad

Samraoui

et al. 2023

Wetlands Ecol Manage

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Grey Heron (Ardea cinerea) Expansion Promotes the Persistence of Mixed-Species Heron Colonies

Cited by 4 publications

References 28 publications

Distance sampling with vehicle-mounted cameras for the estimation of farmland bird abundance over a wide area

Distance sampling with vehicle-mounted cameras for the estimation of farmland bird abundance over a wide area

Balance between site fidelity and habitat preferences in colony site selection by herons and egrets

Range expansion of nesting Squacco Heron Ardeola ralloides and Black-crowned Night Heron Nycticorax nycticorax in the Sahara

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