Gudrun Hilgerloh¹ & Peter R. Evans²

1Forschungszentrum Terramare, Schleusenstrasse 1, D-26382 Wilhelmshaven, Germany, e-mail g.hilgerloh@ucc.ie; ²Department of Biological Sciences, University of Durham, Science Laboratories, South Road, Durham DH1 3LE, UK, e-mail P.R.Evans@Durham.ac.uk

Hilgerloh, G. & Evans, P.R. 1999. Predation by birds on tidal flats. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban: 2293. Johannesburg: BirdLife South Africa.

In the view of marine biologists, top predators on tidal flats, especially birds, have only moderate impacts on their benthic invertebrate prey, not even causing local extinctions of prey populations. They have suggested that this results from restricted (tidal) availability of the invertebrates; from density-dependent choice of prey; from cropping of body parts, e.g. siphons, that can regenerate (instead of always killing prey); and from predation by birds on intermediate predators, such as crabs and errant polychaetes, as well as on the sedentary benthic invertebrates. In reality, the trophic and other interactions are even more complicated, as this symposium will show. The five papers explore how the behaviour and population ecology of benthic invertebrates affect, and are affected by, the behaviour and population densities of their bird predators. Novel findings are reviewed from estuarine, marine tidal flat habitats, where many bird species prey upon either a limited or a wide range, respectively, of invertebrates; from studies of nocturnal foraging; from investigations of the effects of trematode parasites on invertebrate behaviour and, subsequently, on the behaviour of the birds that ingest them; and from modelling of the effects of predation by birds on populations of mussels Mytilus edulis.