Abstract
Investigations of day and night abundance and foraging activity of several shorebird and waterfowl species in the western Jade Bay had previously shown that their abundance did not differ between day and night but the proportion actively foraging was significantly higher at night, especially in surface feeders, such as plovers, Dunlins, Common Redshanks, Pied Avocets, Shelducks and Mallards. Foraging activity patterns in shorebirds are greatly affected by the behaviour and availability of their benthic prey, but quantitative data on day-night activity of intertidal invertebrates are scarce. Therefore in this study we determined activity patterns and availability of benthic prey species (i) by different sampling methods and (ii) by visual observations of macrozoobenthic organisms during day and night from April to June 2004. Sampling showed that the abundance and biomass of macrozoobenthic organisms was similar during both day and night. But visual observations showed significantly greater numbers of the polychaetesHediste diversicolor andHeteromastus filiformis at the surface by night than by day suggesting that polychaetes may be more available to shorebirds at night. In addition two sampling methods, the generally used corer and the sediment-plane (described byDesholm et al. 1998) were compared for their ability to determine the vertical distribution of benthic organisms. Sediment-plane samples showed a significantly higher abundance of vertically mobile polychaetes in the uppermost layer than the core samples. This indicates that the sediment-plane is a better and more accurate means of recording the density of benthos communities in the uppermost sediment layers than the corer, because the polychaetes are not able to escape into deeper mud. However, the best method for determining the availability of macrozoobenthic prey for surface feeding birds would appear to be direct observation of surface activity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
