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Providing evidence to improve practice

Individual study: The effects of different gull deterents on ring-billed gull Larus delawarensis breeding

Published source details

Maxson S.J., Mortensen S.A., Goodermote D.L. & Lapp C.S. (1996) Success and failure of ring-billed gull deterrents at common tern and piping plover colonies in Minnesota. Colonial Waterbirds, 242-247

This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Reduce inter-specific competition for nest sites of ground nesting seabirds by removing competitor species Bird Conservation

A replicated study in the summers of 1992-5 at four lake sites in Minnesota, USA (Maxson et al. 1996), found that coloured nylon string or monofilament line strung between electric fence posts (2 m apart, 0.8 m above ground) were effective at preventing ring-billed gulls Larus delawarensis from breeding (and so out-competing common terns Sterna hirundo) at small or new colonies (with 60-70 gulls abandoning two sites after erection of strings and destruction of several nests). However, strings were not effective at larger, denser colonies (even when the distance between wires was reduced to 1.2 m), unless placed in a grid structure (and some gulls still nested at the site). A combination of chicken wire at ground level and wires 1 m apart visible wires above ground was not effective at the large colony it was tested at. Adding monofilament line to this structure did not deter gulls but several Caspian terns S. caspia (a non-target species) became entangled in some of the monofilament wires.