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Providing evidence to improve practice

Individual study: The efficacy of exclosures in preventing predation of piping plover Charadrius melodus nests, northeastern Massachusetts, USA

Published source details

Rimmer D.W. & Deblinger R.D. (1990) Use of predator exclosures to protect piping plover nests. Journal of Field Ornithology, 61, 217-223

Summary

The piping plover Charadrius melodus is an endangered, small, ground-nesting shorebird. In 1986, while studying a breeding population of piping plovers on a beach in Massachusetts, USA, it was observed that predation by mammals and birds was severely limiting nesting success. It was decided to test a wire mesh exclosure designed to protect piping plover nests.

Between 1986-1989, 26 piping plover Charadrius melodus nests were selected to trial the efficacy of a predator exclosure design at a coastal breeding site in northeastern Massachusetts, USA. In the same area, 24 nests, unprotected by exclosures, were selected as controls. A triangular exclosure of 5 cm diameter wire mesh, with a 30.5 m perimeter and black twine in parallel rows over the top was designed to surround a nest and exclude mammalian and avian predators. Piping plover adults and chicks were able to move freely through the mesh and their behaviour appeared normal.

Monitoring was undertaken to assess hatching success of protected and unprotected nests.

Of the protected nests 92% (24/26) successfully hatched one or more eggs. Only 25% (6/24) of unprotected nests hatched, with most losses (94%, 17/18) the result of predation.

During the study it became apparent that piping plover chicks hatching earlier in the breeding season had, in general, a much higher survival rate. Chicks hatching before 1 July had a 79% (78/99) survival rate compared to a 26% (4/15) survival for chicks hatching after 1 July. Most adult plovers return to their breeding areas in Massachusetts in March and April. At this time, beach use by humans is relatively low. However, beaches become more crowded as it gets warmer, typically reaching a peak towards the latter part of the plover breeding season in June and July. Most plover chicks fledge by early July, but nest loss from predation often stimulates re-nesting, resulting in young, vulnerable chicks on crowded, disturbed beaches that fledge (if they survive), later in the season than usual.

This study indicated that protection of early nests with an exclosure can reduce re-nesting and enhance chick survival.


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