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Gravel bars can be critical for biodiversity conservation: a case study on scaly-sided Merganser in South china.

Zeng Q, Shi L, Wen L, Chen J, Duo H, Lei G - PLoS ONE (2015)

Bottom Line: We then built habitat suitability models (Generalized Linear Models-GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability.We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser.Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting.

View Article: PubMed Central - PubMed

Affiliation: School of Nature Conservation, Beijing Forestry University, Beijing, 100083, China.

ABSTRACT
Gravel bars are characteristic components of river landscapes and are increasingly recognized as key sites for many waterbirds, though detailed studies on the ecological function of gravel bars for waterbirds are rare. In this study, we surveyed the endangered Scaly-sided Merganser Mergus squamatus along a 40 km river section of Yuan River, in Central China, for three consecutive winters. We derived the landscape metrics of river gravel bars from geo-rectified fine resolution (0.6 m) aerial image data. We then built habitat suitability models (Generalized Linear Models-GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability. We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser. Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting. Therefore, maintaining the exposure of gravel bars in regulated rivers during the low water period in winter might be the key for the conservation of the endangered species. These findings have important implications for understanding behavioral evolution and distribution of the species and for delineating between habitats of different quality for conservation and management.

No MeSH data available.


Related in: MedlinePlus

Distribution of Scaly-sided Merganser flocks and gravel bar patches in the 36 km river section of the lower Yuanjiang River.The red dots indicate 127 Scaly-sided Merganser flocks recorded over three winters.Green points represent houses along the river within a 50 m buffer zone. Areas in dark grey are gravel bars in river and area in light grey are islands.
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pone.0127387.g002: Distribution of Scaly-sided Merganser flocks and gravel bar patches in the 36 km river section of the lower Yuanjiang River.The red dots indicate 127 Scaly-sided Merganser flocks recorded over three winters.Green points represent houses along the river within a 50 m buffer zone. Areas in dark grey are gravel bars in river and area in light grey are islands.

Mentions: At each survey, we travelled along the 36 km long river course by boat, and used binoculars (8×42) to identify and locate Scaly-sided Merganser, and then mapped the Scaly-sided Mergansers using a GPS (Fig 2). Each survey lasted for four hours (09:00–13:00). During the survey, we kept our boat in the middle of the river to minimize disturbance to birds, and also to ensure that we had a full view of the river section. Distances of less than 10 m between individuals were defined as a flock (i.e. identified as a single occurrence point in mapping). To avoid repeat counting, only birds not flying, e.g. the ducks resting on land or foraging in water were counted. All field surveys were conducted on clear days, avoiding snowy, rainy, or strong windy days, to ensure the quality of the field survey data.


Gravel bars can be critical for biodiversity conservation: a case study on scaly-sided Merganser in South china.

Zeng Q, Shi L, Wen L, Chen J, Duo H, Lei G - PLoS ONE (2015)

Distribution of Scaly-sided Merganser flocks and gravel bar patches in the 36 km river section of the lower Yuanjiang River.The red dots indicate 127 Scaly-sided Merganser flocks recorded over three winters.Green points represent houses along the river within a 50 m buffer zone. Areas in dark grey are gravel bars in river and area in light grey are islands.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440824&req=5

pone.0127387.g002: Distribution of Scaly-sided Merganser flocks and gravel bar patches in the 36 km river section of the lower Yuanjiang River.The red dots indicate 127 Scaly-sided Merganser flocks recorded over three winters.Green points represent houses along the river within a 50 m buffer zone. Areas in dark grey are gravel bars in river and area in light grey are islands.
Mentions: At each survey, we travelled along the 36 km long river course by boat, and used binoculars (8×42) to identify and locate Scaly-sided Merganser, and then mapped the Scaly-sided Mergansers using a GPS (Fig 2). Each survey lasted for four hours (09:00–13:00). During the survey, we kept our boat in the middle of the river to minimize disturbance to birds, and also to ensure that we had a full view of the river section. Distances of less than 10 m between individuals were defined as a flock (i.e. identified as a single occurrence point in mapping). To avoid repeat counting, only birds not flying, e.g. the ducks resting on land or foraging in water were counted. All field surveys were conducted on clear days, avoiding snowy, rainy, or strong windy days, to ensure the quality of the field survey data.

Bottom Line: We then built habitat suitability models (Generalized Linear Models-GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability.We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser.Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting.

View Article: PubMed Central - PubMed

Affiliation: School of Nature Conservation, Beijing Forestry University, Beijing, 100083, China.

ABSTRACT
Gravel bars are characteristic components of river landscapes and are increasingly recognized as key sites for many waterbirds, though detailed studies on the ecological function of gravel bars for waterbirds are rare. In this study, we surveyed the endangered Scaly-sided Merganser Mergus squamatus along a 40 km river section of Yuan River, in Central China, for three consecutive winters. We derived the landscape metrics of river gravel bars from geo-rectified fine resolution (0.6 m) aerial image data. We then built habitat suitability models (Generalized Linear Models-GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability. We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser. Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting. Therefore, maintaining the exposure of gravel bars in regulated rivers during the low water period in winter might be the key for the conservation of the endangered species. These findings have important implications for understanding behavioral evolution and distribution of the species and for delineating between habitats of different quality for conservation and management.

No MeSH data available.


Related in: MedlinePlus