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Providing evidence to improve practice

Individual study: Increasing food availability for hooded cranes Grus monacha by reducing water buffalo grazing and trampling of sea-bulrush Scirpus mariqueter in Chongming Dongtan National Nature Reserve, Shanghai, China

Published source details

Choi C.Y., Cai Y. & Ruan Y. (2010) Wintering ecology of hooded cranes at Chongming Dongtan. Unpublished report to the Conservation Leadership Programme


In Chongming Dongtan National Nature Reserve (31°25' – 31°38'N, 121°50' – 122°05'E) in the municipality of Shanghai, eastern China, grazing and trampling by domestic water buffalo affects the growth of sea-bulrush Scirpus mariqueter, the main food resource of locally wintering hooded cranes Grus monacha. Policy has been introduced to restrict buffalo grazing to areas without sea-bulrush during the period when cranes are present. This study investigated the impact of excluding buffalo, using cages, on the growth of sea-bulrush during the period when cranes are absent.

In May 2008, to analyse the impact of buffalo grazing on sea-bulrush over the summer, six wooden exclusion cages measuring 1 m × 1 m were constructed.

In October 2008, before the return of cranes, sea-bulrush samples were taken in and around exclusion cages. One cage was damaged by buffaloes, and was excluded from subsequent analyses. Ten shoots were randomly selected for height measurement from within 0.5 m × 0.5 m quadrats placed inside and outside the remaining five cages. The average dry mass of corms was also measured, but owing to the low number of corms collected, only three cages were included in the analysis.

The average shoot height of sea-bulrush within exclusion cages was significantly higher than in quadrats outside cages for all five undamaged cages.

The average dry mass of corms in exclusion cages was also significantly higher than that outside cages (41.3 g versus 36.7 g; n = 3 cages).

The authors suggest that the higher corm mass and shoot height of sea-bulrush observed in exclusion cages would improve the availability of food for cranes if buffalo were prevented from grazing on sea-bulrush all year round.


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