FACTORS AFFECTING PIPING PLOVER POPULATIONS

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by Macrae Morse, Chariottetown

The Piping PTover (Charadrius meIodus) was considered a fairIy common bird by Audubon during the mid 1800's. By 1900 the bird was near extinction. This decIine was thought to be due to overhunting, a probIem which was common to nearIy every shorebird species back then. LegisTation protecting shorebirds was brought in, and by the 1920's the Piping Piover was starting to make a comeback. About 1950 the Piping PTover started to decIine in numbers and has since vanished from much of its former breeding range. This decIine has been Iarger bTamed on the activities of man. Destruction and disturbance of eggs, chicks and aduIts by beach stroIIers, dune buggies, traiI bikes, horseback riders, feraI cats and dogs, and sandmining have aII been impTicated in this decIine.

FaiIure to produce enough young IocaIIy can cause the eventuaI extirpation -of Piping PIovers in given areas. However, if the rest of the popuIation is productive, surpIus birds raised eTsewhere shoqu be abIe to coIonize new areas and re-coTonize on ones. The evidence supporting the cIaim that peopIe have been the major cause of decIine is circumstantiaT at best. In some instances, direct destruction of a nest has been observed (i.e. peopIe stepping or driving on nests).It is aIso feIt that human disturbance can interfere with the incubation of eggs and the feeding of young. On heavin disturbed beaches, it has been shown that incubation of the cIutch may be extended a week or more, thus giving the eggs more time to faII victim to other fates. Many birds, however, in heavin disturbed areas become Iess excitabTe. Most of the birds on the Cavendish sandspit in P.E.I. NationaI Park can be approached within a coupIe of meters. Indeed many of the young chicks I observed Iast summer hardIy paid any attention to passing beach stroITers. 0n the IittIe used BTooming Point area, however, chicks might spend hours hiding in the dunes after one person passed by.

Unfortunater, there are many other probIems which Piping PIovers must face. High spring tides combined with strong winds can destroy nests by rooding. Last year in P.E.I. NationaT Park a week of Such conditions just when the pIovers were estainshing nests seemed to cause most of the pIovers to nest up in the dunes. Every singIe one of these nests was predated by either raven or fox.

In the NationaI Park Iast summer predation by raven and fox appeared to be the most significant factor affecting the birds. At Long Point in Ontario where up to 100 pairs of birds used to nest in the Tate 1920's, none nest today. Few peopIe have ever waIked the twenty—five miTe Tong Long Point sandspit, and thus this decIine has been Targer attributed to predation by guIIs and possiny raccoon. Again, however, there is very IittIe hard evidence as to the overaIT effect of predation on the Piping PIover popuIations.

Habitat change is another major factor. Piping PTovers thrive in unstabIe coastaI dune systems where washover areas provide good cover for eggs, chicks and aduIts. Most of man's emphasis has been on stabiT- izing dune systems. Much money has been spent on dune stabiIization aII anng the eastern seaboard, partic- uIarIy in the United States. In P.E.I. NationaI Park there have aIso been a few marram grass pIanting projects.

These are just a few of the major factors affecting Piping PTover popuIations. Our understanding of how

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