Semipalmated Plover Nesting on the Oregon Coast

NOTES

SEMIPALMATED PLOVER NESTING ON THE OREGON COAST

CAROLE E. HALLE'Fr, BRUCE R. CASLER, and MARK A. STERN, Oregon NaturalHeritage Program, The NatureConservancy, 1205 NW 25th Ave., Portland, Oregon 97210

In the PacificNorthwest, the SemipalmatedPlover (Charadrius seraipalmatus) is primarilya migrant,occurring in flocksalong the coastduring spring migration from mid-April to mid-May and in fall migrationfrom July through September.Peak numbersoccur in late April and late July. Occasionalsmall flocks of non-breeding birds remain through the summer (Paulson1993) and may be found in suitable habitatin coastaland inland British Columbia, Washington, and Oregon (H. B. Nehls pers.comm.). The species'breeding range, encompassing the North Americanarctic and subarctic(Paulson 1993), extendssouth locally in BritishColumbia to the Queen CharlotteIslands, Iona Islandnear Vancouver,and Le BlancLake inland(Campbell et al. 1990). Southof thisrange, four nestshave been recorded from coastalWashing- ton and the interior of Oregon. The first SemipalmatedPlover nest recordedin Oregonwas found at StinkingLake on MalheurNational Wildlife Refuge, Harney Co., in 1987 (Iveyet al. 1988). Ivey and Baars(1990) reporteda secondnest from Malheur NationalWildlife Refuge, at Harney Lake, in 1989. Two successfulnests were foundalong the Pacificcoast at OceanShores, Grays Harbor County, Washing- ton in 1973 (Morris1974). Birdshave been observedsubsequently at thesesites, but no additionalnests have been found(Nehls pers. comm.) Here we reportthe firstand seconddocumented Semipalmated Plover nests along the Oregon coast. On 6 June 1993, while conductingsurveys for Snowy Plovers (Charadrius alexandrinus) on the south dredge spoil of the Coos Bay North Spit, Coos Co., Caslerand Hallett observedan adultfemale Semipalmated Plover incubating a nest. An adultmale SemipalmatedPlover was flickingbits of shelltoward the incubating bird, which tuckedthem arounditself, apparently adding to the nest bowl'slining. After watchingthe birdsfor severalminutes we approachedand found a nestheavily linedwith shellfragments and containingthree darklymottled eggs. When the eggs were "floated"to determinetheir stageof development,all three sankand lay fiat on the bottom of the container,indicating that they were new (Haysand LeCroy 1971). Both adultSemipalmated Plovers were highlyvocal and did vigorousbroken-wing and tail-draggingdisplays while we were near the nest. On 8 June,the nestcontained four eggs measuring 32.6 + 0.8 mm x 24.4 _+0.4 mm (Figure1). Again,both adults were presentand activelydefended the nestarea. Only three eggsremained in the nest on 26 June; the fourth was lostto unknown causes.The eggshatched on 30 June and 1 July. We saw the broodregularly throughlate July, and at leasttwo of the threechicks fledged, as we sawthe juveniles flyingin earlyAugust. On 18 May 1994, we founda secondnest approximately 150 metersfrom the 1993 nest location.Three of the four eggshatched on 8 and 9 June 1994; the remainingegg was infertile. We useda circularwalk-in nest trap to captureand band bothadults with an aluminumU.S. Fishand Wildlife Service band on theirright leg and two of three chickson their left leg (Figures2 and 3). Althoughwe did not observethis broodregularly, on 9 July we saw a bandedfledgling Semipalmated Ploverwith a flockof about20 adultSemipalmated Plovers on the CoosBay North Spit. On 28 June1994, we sawan adultSemipalmated Plover making a nestscrape approximately15 metersfrom the 1994 nest,and on 1 Julya pairof Semipalmated Ploverswas copulatingnear thisscrape. The male was unbanded;we couldnot tell if

Western Birds 26:161-164, 1995 161 NOTES the femalewas banded.Subsequent searches of the area did not revealsuccessful nesting. The presenceof the unbandedmale suggeststhat at least three Semipal- mated Ploverswere engagedin breedingat this site in 1994. Both SemipalmatedPlover nests and the nest scrapewere locatedon top of low shell-coveredrises. The nestbowls were heavilylined with shellfragments and, while readilydistinguishable from the sparselylined Snowy Plover nests nearby, could be confusedwith Killdeer(Charadrius vociferus) nests, which are alsoheavily lined. The SemipaimatedPlover eggs were smallerthan Killdeereggs and much darker and more heavilymottled than Snowy Plovereggs. When approached,unlike the SnowyPlovers, which typicallyskulked away from the nest before displaying.the SemipaimatedPlovers tended to call while standing closeto their nests.Both membersof the pairswere observedincubating. Both adult Semipaimated Ploversassociated with the 1993 nest stayedwith the chicks until fledging.The 1994 broodwas not observedregularly, so it is not clear if both adults tendedthe brood.Broods in bothyears used the samestretch of beachalong the bay east of the southdredge spoil. In addition,the 1994 brood usedan area surrounding the dredgespoil and recentlycleared of vegetation. At 124 ø 19' 45" N, 43 ø 21' 30" W, the SemipaimatedPlover nestsat Coos Bay are the southernmostknown for this speciesalong the Pacificcoast. The Semipal- mated Ploversused nestinghabitat similar to that of Snowy Plovers,as have all nestingSemipalmated Plovers detected to date in Oregon and Washington.The discoveryof successfulnests in 1993 and 1994 and apparentnest attempt in 1994 suggestthis area may be usedintermittently, if not regularly,by a smallnumber of

Figure 1. SemipaimatedPlover nest at Coos Bay, Coos County, Oregon, 8 June 1993.

,Photo by Bruce Casler

162 NOTES

Figure 2. One- or two-day-oldSemipalmated Plover chicks at Coos Bay, Coos County, Oregon, 9 June 1994. Photo l•y Bruce Casler

Figure3. Adult male SemipalmatedPlover at Coos Bay, Coos County,Oregon, 9 June 1994.

Photo l•y Bruce Casler

163 NOTES nestingSemipalmated Plovers. Birders should watch for evidenceof Semipalmated Ploversnesting to documentfurther the extentto whichthis speciesnests in the Pacific Northwest. Theseobservations were madeduring Snowy Plover surveys supported in part by the OregonDepartment of Fishand Wildlife and the Coos Bay District of the Bureau of Land Management.

LITERATURE CITED

Campbell,R. W., Dawe,N. K., McTaggart-Cowan,I., Cooper, J. M., Kaiser,G. W., and McNall, M. C. E. 1990. The Birdsof BritishColumbia, vol. 2. Royal Br. ColumbiaMus., Victoria. Hays,H., and LeCroy,M. 1971. Fieldcriteria for determiningincubation stage in eggsof the CommonTern. Wilson Bull. 83:425-429. Ivey,G., andBaars, C. 1990. A secondSemipalmated Plover nest in Oregon.Ore. Birds 16:207-208 IveyG., Fothergill,K., and Yates-Mills,K. 1988. A SemipalmatedPlover nest in Oregon.W. Birds19:35-36 Morris,J. 1974. Breedingrecord for the SemipalmatedPlover at Ocean Shores, Washington.W. Birds5:22. Paulson,D. 1993. Shorebirdsof the PacificNorthwest. Univ. of Wash. Press, Seattle.

Accepted17 April 1993

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