Estimate of removal rate of nereis-virens polychaeta nereidae from an intertidal mudflat by gulls larus-spp

The feeding behavior of herring gulls (Larus argentatus), ringed-billed gulls (L. delawarensis) and great black-backed gulls (L. marinus) on an intertidal mudflat in Maine, USA, was investigated. Remains of fish, mussels, crabs, insects, and the polychaete Nereis virens were recovered from gull feces. Forty-three percent of the fecal samples contained N. virens jaws, setae, or both. A comparison of jaws from fecal material and from worms collected from the natural community demonstrates that gulls preferentially preyed upon larger worms. Feeding was largely confined to 3 h around low tide, and birds fed mostly in the low intertidal and below mean low water where the largest worms were located. Individual birds remained on the flat for a mean of 28.0 min and consumed a mean of 19.2 worms per visit. It was calculated that gulls remove a mean of 808 large N. virens from the flat per tide from June to October, representing an estimated 0.04% of the standing crop of large N. virens.