512 SHORT COMMUNICATIONS

aging in Downy Woodpeckers.Anim. Behav. 32: WAITE, T. A. 1987b. Dominance-specific vigilance 16-22. in the Tufted Titmouse: effects of social context. WAITE, T. A. 1987a. Vigilance in the White-Breasted Condor 89:932-935. Nuthatch: effectsof dominance and sociality. Auk 104: 429-434.

The Condor 90:512-513 0 The CooperOrnithological Society 1988

NOTES FROM CLARION ISLAND’

WILLIAM T. EVERETT Department of Birds and Mammals, San Diego Natural History Museum, P.O. Box 1390, San Diego, CA 92112

Key words: Clarion Island; RevillagigedoIslands; cunicularia)were seen.As recently as 1953 Brattstrom Townsends’ Shearwater; Clarion Wren; Clarion Island and Howell (1956) describedthem as “common every- Dove; island endemics;green sea turtles;feral pigs. where.” The following species,previously unrecorded from Clarion (seeJehl During the course of a fishing trip in January 1986 I and Parkes 1982).I, were observeddur- was able to spend several days at Isla Clarion, the ing my stay: one Great Egret (Casmerodiusalbus), one westernmostof Las Islas Revillagigedos,located about Osprey (Pandion haliaetus), three American Kestrels 400 nautical miles southwestof Cabo San Lucas, Baja (Falco sparverius),one American Coot (Fulica amer- California, . Our party was in the vicinity of icana), one LesserYellowlegs (Tringajlavipes), and six the island from 16 to 18 January. The commander of Laughing Gulls (Larus atricilla). the Mexican Navy garrison on the island graciously Shortly after establishment of the weather station, allowed me to come ashore, and for 2 days I explored domestic pigs and hares were released as a source of much of the highland portion of the island. food; both have multiplied and now occur everywhere The garrison was establishedin 1979 to support a from the shorelineto the highestelevations. Residents weather station at Bahia Sulphur, on the south side of estimate pig numbers at 800 to 1,000. Evidence of the island. The settlement consists of a building for rooting and destructionof vegetation was widespread, living quarters,a nearby electric generatingplant, and especiallyon the western half of the island. Chickens an approximately 500-m aircraft runway parallel to the and goatswere also released,but the chickensremain beacheast of Bahia Sulphur. The garrisonconsisted of in the immediate vicinity of the settlementand no live 11 men. goatswere seen. According to one of the residents,an There were numerousunoccupied burrows in several extensive fire in 1984 burned the western two-thirds areasof the highlands,where earlier visitors had found of the island. This may account for the low, grassy Townsend’s Shearwaters,P@nus auricularis(Antho- vegetation I encountered over most of the island, in ny 1900, M. E. McLellan 1926, Jehl 1982). At least contrast to the extensive dense vine-covered 200 Masked Boobies(S&a dactylatra)were nestingon () describedby Anthony (1898) and Townsend the ground at several sites, but I saw no eggs. Red- (1890). footed Boobies(S. sula) were nestingon sparsebushes Harvesting by humans and predation by pigs may in several colonies near the eastern end of the island; reduce the small population of green sea turtles (Che- most nests had one egg.At least 800 active nests were lonia mydas)which nest at Bahia Sulphur (Awbrey et counted. al. 1984). Ground-nesting birds such as Townsend’s I saw the endemic Clarion Wren (Troglodytestan- Shearwaterand Masked Booby are especially vulner- neri) most often in areas around and just east of the able to predation by pigs. Massive reduction of veae- garrisonbuilding. Up to 20 individuals-werenoted. No tation by the fire and rooting by pigs has dramatic&y more than 20 endemic Clarion Island Mourning Doves reduced habitat for the endemic landbird fauna. (Zenaida macrouraclarionensis) were seen du&g my LITERATURE CITED explorations. For both endemics, this appearsto be a substantial reduction in numbers from the previous ANTHONY, A. W. 1898. Avifauna of the Revillagi- characterizationas “abundant” (Townsend 1890, An- gedo Islands. Auk 15:311-318. thony 1898).No more than 10 BurrowingOwls (Athene ANTHONY, A. W. 1900. Nesting habits of the Pacific coast speciesof the genus Pa&us. Auk 17:247- 252. I Received 16 October 1987. Final acceptance27 AWBREY, F. T., S. LEATHERWOOD, E. D. MITCHELL, AND January 1988. W. ROGERS. 1984. Nesting greensea turtles (Che- SHORT COMMUNICATIONS 513

lonia mydas)on Isla Clarion, Islas Revillagigedos, MCLELLAN,M. E. 1926. Expedition to the Revilla- Mexico. Bull. South. Calif. Acad. Sci. 83(2):69- gigedoIslands, Mexico, in 1925. VI. The birds and 15. mammals. Proc. Calif. Acad. Sci., 4th Ser. 15:297- BRATTSTROM,B. H., AND T. R. HOWELL. 1956. The 322. birds of the , Mexico. Con- TOWNSEND,C. H. 1890. Birds from the coasts of dor 58107-120. western North America and adjacent islands, col- JEHL,J. R., JR. 1982. The biology and taxonomy of lectedin 1888-89, with descriptionsofnew species. Townsend’s Shearwater.Le Gerfaut 72: 121-l 35. Proc. U.S. Natl. Mus. 13:131-142. JEHL,J. R., JR., AND K. C. PARKES. 1982. The status of the avifauna of the RevillagigedoIslands, Mex- ico. Wilson Bull. 94: 1-19.

TheCondor90:513-514 0 The CooperOrnithological Society 1988

EVIDENCE FOR INTRASPECIFIC BROOD PARASITISM IN THE ’

JAROSLAVPICMAN AND JEAN-CLAUDE BELLES-ISLES~ Department ofBiology, Universityof Ottawa, 30 SomersetE., Ottawa, Ontario KIN 6N5, Canada

Key words: Intraspecificbrood parasitism; House The final clutch laid in this nest consistedof seveneggs Wren;first evidence. and of these six young fledged. Second, in 1986 in the Bog we recorded a casewhere the first eggwas laid on Most avian brood parasites reproduce by laying eggs 22 June, and 4 days later (on 26 June) the nest con- in nests of other species (e.g., Hamilton and Orians tained six eggs. The further breeding history of this 1965, Payne 1977). but some mav lay in nests of con- nest is not known. Third. in one House Wren nest that specifics.-Intraspecificbrood parasitism has been re- was under observation in the Bog, six eggswere laid ported for over 50 speciesofbirds, mostly ducks(Yom- between 16 June and 19 June 1987. This nest suc- Tov 1980).For passerines,however, intraspecificbrood cessfully fledged all six young. Since passerinesnor- parasitism has been reported far less frequently, al- mally lay only one eggper day, the appearanceof more though several well-documented cases do exist (see than one eggper day can be used as evidence for para- Yom-Tov et al. 1974, Manwell and Baker 1975). In sitic laying (see Yom-Tov 1980). this note we provide the first evidence for intraspecific Case 4-Appearance of a new egg after completion brood parasitism in a small, cavity-nesting passerine, of the clutch.In May/June 1986, we observed the ir- the House Wren, Troglodytesaedon. regular appearanceof an egg in a House Wren nest Between 1984 and 1987 we conducteda study of the located in the Bog. In this nest seven eggswere laid House Wren breedingecology in Presqu’ille Provincial between 20 and 26 May. During the next visit on 31 Park (hereafter the Park) and in the Mer Bleue Bog May the nest still contained seven eggs.However, on (hereafter the Bog) near Ottawa, Ontario (description 2 June, we discovered a new egg near the entrance of of thesestudy sitescan be found elsewhere;Belles-Isles the nest box. This nest eventually fledgedseven young. and Picman 1986a, Belles-Isles 1987). In the 4 years The irregular time interval between laying of the sev- of this study we have made observationson a total of enth eggand the last egg,along with an unusuallocation 123 nestsand obtained evidencefor five probable cases of the last egg at the box entrance away from the nest (about 4% of the total) of intraspecific parasitic egg depression,strongly suggestthat the last egg was laid laying. Becausewe could find no previous reports of by a parasitic female. intraspecific brood parasitism for this species,below Case 5-Abnormally large clutch.On 25 June 1987, we provide a description of these cases. in one of the boxes used for breeding by House Wrens CasesI, 2, and 3-Appearance of two eggsper day. in the Bog, we found a clutch consistingof nine eggs. First, late in June 1985, we found a nest in the Park, Most House Wrens in our study areas, however, laid where three eggswere laid in two consecutive days. between four and seven eggs(for 1984 to 1987 mean clutch size * 99% CI = 6.1 ? 0.2: n = 123). The abnormally large clutch in this casethus suggestspara- sitic laying by another female. ’ Received 28 October 1987. Final acceptance4 Jan- The five above cases provide strong evidence for uary 1988. intraspecific nest parasitism in the House Wren, al- 2 Present address: Departement de Biologie, Uni- though this mode of reproduction appearsto be infre- versite Laval, St. Foy, Quebec GlK 7P4, Canada. quent (about 4%) in our wren populations. However,