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SHORT COMMUNICATIONS 97

nesting success of cavity-nesting in high el- RAPHAEL,M.G.AND M. WHITE. 1984. Use of snags evation forest drainages. Auk 108:405±418. by cavity-nesting birds in the Sierra Nevada. LOMBARDO, M. P. 1988. Evidence of intraspeci®c Wildlife Monographs, no. 86. brood in the Tree . Wilson Bul- ROMAGNANO, L., A. S. HOFFENBERG, AND H. W. POWER. letin 100:126±128. 1990. Intraspeci®c brood parasitism in the Euro- MEEK, S. B., R. J. ROBERTSON, AND P. T. B OAG. 1994. pean Starling. Wilson Bulletin 102:279±291. Extrapair paternity and intraspeci®c brood para- SANDELL,M.I.AND M. DIEMER. 1999. Intraspeci®c sitism in Eastern revealed by DNA ®n- brood parasitism: a strategy for ¯oating females gerprinting. Auk 111:739±744. in the European Starling. Behaviour 57: MOORE, W. S. 1995. Northern Flicker (Colaptes au- 197±202. ratus). The Birds of , no. 166. SEMEL,B.AND P. W. S HERMAN. 2001. Intraspeci®c par- MOORE,W.S.AND W. D. KOENIG. 1986. Comparative asitism and -site competition in Wood . reproductive success of Yellow-shafted, Red- Animal Behaviour 61:787±803. shafted, and ¯ickers across a hybrid zone. SHERMAN, A. 1910. At the sign of the Northern Flicker. Auk 103:42±51. Wilson Bulletin 22:135±171. PETRIE,M.AND A. P. MOLLER. 1991. Laying in WIEBE, K. L. 2002. First reported case of classical others' : intraspeci®c brood parasitism in polyandry in a North American woodpecker, the birds. Trends in & 6:315±320. Northern Flicker. Wilson Bulletin 114:401±403. PICMAN,J.AND J.-C. BELLES-ISLES. 1988. Evidence for WIEBE, K. L. 2003. Delayed timing as a strategy to intraspeci®c brood parasitism in the . avoid nest-site competition: testing a model using Condor 90:513±514. data from starlings and ¯ickers. Oikos 100:291± PINXTEN, R., O. HANOTTE,M.EENS,R.F.VERHEYEN, 298. A. A. DHONDT, AND T. B URKE. 1993. Extra-pair WINKLER, H., D. A. CHRISTIE, AND D. NURNEY. 1995. paternity and intraspeci®c brood parasitism in the Woodpeckers: a guide to the woodpeckers of the European Starling, Sturnus vulgaris: evidence world. Houghton Mif¯in, Boston, . from DNA ®ngerprinting. Animal Behaviour 45: YOM-TOV, Y. 1980. Intraspeci®c nest parasitism in 795±809. birds. Biological Reviews of the Cambridge Phil- POÈ YSAÈ , H. 1999. Conspeci®c nest parasitism is asso- osophical Society 55:93±108. ciated with inequality in nest risk in the ZINK, A. G. 2000. The evolution of intraspeci®c brood Common (Bucephala clangula). Be- parasitism in birds and . American Natu- havioral Ecology 10:533±540. ralist 155:395±405.

Wilson Bulletin, 116(1), 2004, pp. 97±101

Common Pairs Rear Four-Chick Broods

Steven T. A. Timmermans,1,2 G. Eoin Craigie,1 and Kathy E. Jones1

ABSTRACT.ÐCommon (Gavia immer) nor- ation, or a combination of these factors. Received 8 mally lay a single of two eggs each breeding July 2003, accepted 24 March 2004. season. They occasionally lay one- or three- clutch- es, and rarely, four-egg clutches. Participants of the Canadian Lakes Loon Survey provided seven indepen- dent observations of loon pairs rearing four-chick Supernumerary broods, either as a result of broods. Photographic evidence con®rmed two separate nest parasitism by unrelated conspeci®cs, su- instances of adult loon pairs at Anglin Lake, Saskatch- pernumerary clutches, or post-hatch brood ewan, and Kasshabog Lake, , exhibiting paren- amalgamation, are relatively common among tal behavior toward a four-chick brood. Occurrence of (Storer and Nuechterlein 1992, Cullen four-chick broods may be the result of supernumerary et al. 1999, Muller and Storer 1999, Stout and clutches, nest parasitism, post-hatch brood amalgam- Nuechterlein 1999, Stedman 2000) and water- (Afton and Paulus 1992:90, table 3±21; Sayler 1992). However, there are few docu- 1 Studies , P.O. Box 160, Port Rowan, ON N0E 1M0, Canada. mented instances of supernumerary broods in 2 Corresponding author; e-mail: loons (Barr et al. 2000), including the most [email protected] widely studied , the 98 THE WILSON BULLETIN • Vol. 116, No. 1, March 2004

(Gavia immer; McIntyre 1988:30, McNicholl length with dark gray down ), small 1993). young (1/3 to 2/3 adult length with light Common Loons are large, long-lived wa- brown-gray or mottled-gray down feathers) or terbirds that normally lay a single clutch of large young (2/3 adult length or longer with a two eggs each breeding season, although oc- full coat of light and dark gray feathers). Al- casionally they will lay one or, even less fre- though not part of the survey protocol, CLLS quently, three-egg clutches (Peck and James participants often found loon nests during sur- 1983, Croskery 1991, McIntyre and Barr veys and recorded clutch sizes. Periodically, 1997). The frequency of three-egg clutches re- participants also provided photographic re- ported for Common Loons is low and ranges cords of observations during surveys. These from 0.5% (Campbell et al. 1990) to 0.8% records provided the basis for results reported (Peck and James 1983, McIntyre 1988:table here. 2±5). Clutches containing four eggs are rare, but have been noted several times (Nelson RESULTS AND DISCUSSION 1983, Peck and James 1983, Zicus et al. 1983, Since the initiation of the CLLS in 1981, McNicholl 1993). To our knowledge, there is participants have reported 6 of 687 (0.87%) no con®rmed record of Common Loons rear- loon nests containing three-egg clutches and ing four-chick broods. In this paper we report no four-egg clutches. CLLS participants re- seven instances of Common Loon adults ac- ported 45 of 6021 (0.75%) Common Loon companying and rearing four-chick broods, pairs with supernumerary broods (Ͼ2 chicks), two of these con®rmed by photographic re- which is similar to values that others have re- cords. ported for this species (see above). In ®ve sep- arate instances, CLLS participants provided METHODS written evidence of four-chick Common Loon Data were gathered by volunteer partici- broods: two on Shepherd Lake, Ontario (44Њ pants of the Canadian Lakes Loon Survey 39Ј N, 81Њ 7Ј W) during 1983 and 1984; one (CLLS), who monitored Common Loon on Oak Lake, Ontario (44Њ 36Ј N, 77Њ 55Ј W) breeding pairs on lakes, rivers, and bays during 1984; and two on the Mactaquac River, throughout Canada. Participants selected their New Brunswick (46Њ 01Ј N, 66Њ 58Ј W) during own water body or portion of a water body to 1988 and 1993. Participants also provided survey breeding loons and recorded observa- photographic evidence of two separate in- tions of breeding pairs at least once during stances of Common Loon pairs accompanied each of three time periods: nesting (early June by four-chick broods. The ®rst photograph to mid-July), hatching and early brooding was taken on 14 July 1999 at Anglin Lake, (early to late July), and pre-¯edging (mid-Au- Saskatchewan (53Њ 44Ј N, 105Њ 56Ј W; Fig. gust to mid-September). All surveys lasted a 1A). This group of birds was observed inter- minimum of 2 hr and often were supplement- mittently from 14 July to 17 August 1999. ed by incidental observations. During each CLLS participants estimated these chicks to survey, observers recorded the date, survey be 3 weeks of age on 14 July, and adults ex- method (e.g., from a single point on shore, hibited feeding behavior toward all four walking along shoreline, or from a boat or ca- chicks. noe), maximum number of adult loons ob- Photographic evidence was also secured at served (including paired loons), maximum Kasshabog Lake, Ontario (44Њ 38Ј N, 77Њ 57Ј number of mated loon pairs present, and max- W; Fig. 1B, C), where a Common Loon pair imum number and age of young. The was observed attending four chicks from 21 CLLS survey protocol instructed volunteers to July to 30 September 2001. CLLS participants classify chicks as downy young (Ͻ1/3 adult estimated this four-chick brood to be 3 weeks

FIG. 1. Photographs of two different pairs of adult Common Loons with four-chick broods: (A) Anglin Lake, Saskatchewan, Canada, 14 July 1999 (photograph by W. R. and E. V. Hoffman), and (B and C) Kasshabog Lake, Ontario, Canada, July 2001 and August 2001, respectively (photographs by P. Grisson). SHORT COMMUNICATIONS 99 100 THE WILSON BULLETIN • Vol. 116, No. 1, March 2004 of age on 21 July, and adults exhibited feeding on a lake by the CLLS. Concentrations of loon behavior toward all four chicks. Observations pairs on Anglin Lake were high on 14 July later that summer showed that one of these 1999, when 36 separate Common Loon pairs chicks was smaller than the other three, and were observed. Size and behavioral differenc- often it was observed farther away from the es in the brood photographed at Kasshabog adults than the other chicks (Fig. 1C). Lake also suggested brood amalgamation. In- Occurrence of four-chick broods in Com- tensive monitoring and/or genetic evidence mon Loons may be the result of supernumer- are required to determine de®nitively whether ary clutches, nest parasitism, post-hatch brood supernumerary broods in Common Loons re- amalgamation, or a combination of these fac- sult from supernumerary clutches, nest para- tors (Nelson 1983, Zicus et al. 1983, Belant sitism, or post-hatch brood amalgamation. and Olson 1991, McNicholl 1993). Both Nel- son (1983) and Zicus et al. (1983) discounted ACKNOWLEDGMENTS the occurrence of four-egg clutches as a result We thank J. F. Barr, C. A. Paszkowski, and an anon- of nest parasitism, suggesting that nest para- ymous reviewer for their helpful and critical reviews, sitism was unlikely due to aggressive territory and we also thank S. S. Badzinski and J. D. Mc- defense exhibited by breeding loons. Four-egg Cracken who provided comments on an earlier draft clutches have been documented twice for of this manuscript. We gratefully acknowledge Cana- Red-throated Loons (Gavia stellata); in both dian Lakes Loon Survey participants, whose survey efforts and support made this publication possible. instances two different females were observed laying eggs in the same nest (Barr et al. 2000). LITERATURE CITED Supernumerary clutches have been document- ed several times for Common Loons (see AFTON,A.D.AND S. L. PAULUS. 1992. Incubation and McNicholl 1993). However, there are only brood care. Pages 62±108 in The ecology and management of breeding waterfowl (B. D. J. Batt, two con®rmed reports of supernumerary A. D. Afton, M. G. Anderson, C. D. Ankney, D. clutches hatching successfully in Common H. Johnson, J. A. Kadlec, and G. L. Krapu, Eds.). Loons; McIntyre (1988) found two three-egg University of Press, Minneapolis. clutch nests on two different lakes, and later BARR, J. F., C. EBERL, AND J. W. MCINTYRE. 2000. Red- observed a brood of three young on each of throated Loon (Gavia stellata). The Birds of North these same lakes. America, no. 513. Adult loons may adopt chicks if the young BELANT,J.L.AND J. F. OLSON. 1991. Chick fostering by Common Loons, Gavia immer. Canadian become separated from their natal parents due Field-Naturalist 105:406±407. to inclement weather (Strong and Bissonette CAMPBELL, R. W., N. K. DAWE,I.MCTAGGART-COWAN, 1989), human disturbance (Robertson and J. M. COOPER,G.W.KAISER, AND M. C. E. Flood 1980, Clay and Clay 1997), or parental MCNALL. 1990. The birds of British Columbia, abandonment (Gingras and Paszkowski 1999). vol. 1. Royal British Columbia Museum, Victoria, Persistent wind and wave action can separate British Columbia, Canada and Environment Can- ada, Canadian Wildlife Service, Ottawa, Ontario, loon chicks from their natal parents (Sjolander Canada. and Agren 1976). On Anglin Lake in 1999, CLAY,D.AND H. CLAY. 1997. Reproductive success of poor weather conditions occurred from 30 the Common Loon, Gavia immer, on a small ol- June through 6 July, and a severe hailstorm igotrophic lake in eastern Canada. Canadian Field- occurred on 12 July (W. R. Hoffman and E. Naturalist 111:586±590. V. Hoffman pers. comm.). Thus, weather con- CROSKERY, P. R. 1991. Common Loon, Gavia immer, nesting success and young survival in northwest- ditions existed that could have resulted in ern Ontario. Canadian Field-Naturalist 105:45±48. chicks becoming separated from their natal CULLEN, S. A., J. R. JEHL,JR., AND G. L. NUECHTER- parents and then being adopted by one of sev- LEIN. 1999. Eared ( nigricollis). eral other breeding pairs on Anglin Lake. The Birds of North America, no. 433. Post-hatch brood amalgamation can also GINGRAS,B.A.AND C. A. PASZKOWSKI. 1999. Breeding occur when brood densities in breeding areas patterns of Common Loons on lakes with three are high (Afton and Paulus 1992). Anglin different ®sh assemblages in north-central Alberta. Canadian Journal of 77:600±609. Lake (1,500 ha) consistently had the highest MCINTYRE, J. W. 1988. The Common Loon: spirit of annual number of breeding loon pairs record- northern lakes. University of Minnesota Press, ed (mean of 38 pairs/ from 1996 to 2002) Minneapolis. SHORT COMMUNICATIONS 101

MCINTYRE,J.W.AND J. F. BARR. 1997. Common Loon ecology and management of breeding waterfowl (Gavia immer). The Birds of North America, no. (B. D. J. Batt, A. D. Afton, M. G. Anderson, C. 313. D. Ankney, D. H. Johnson, J. A. Kadlec, and G. MCNICHOLL, M. K. 1993. Supernumerary clutches of L. Krapu, Eds.). University of Minnesota Press, Common Loons, Gavia immer, in Ontario. Cana- Minneapolis. dian Field-Naturalist 107:356±358. SJOLANDER,S.AND G. AGREN. 1976. Reproductive be- MULLER,M.J.AND R. W. STORER. 1999. Pied-billed havior of the Yellow-billed Loon, Gavia adamsii. Grebe (Podilymbus podiceps). The Birds of North Condor 78:454±463. America, no. 410. STEDMAN, S. J. 2000. (Podiceps auri- tus). The Birds of North America, no. 505. NELSON, D. H. 1983. A Common Loon nest from containing four eggs. Wilson Bulletin STORER,R.W.AND G. L. NUECHTERLEIN. 1992. Western Grebe (Aechmophorus occidentalis) and Clark's 95:672±673. Grebe (Aechmophorus clarkii). The Birds of PECK,G.K.AND R. D. JAMES. 1983. Breeding birds of North America, no. 26. Ontario: nidiology and distribution, vol. 1: non- STOUT,B.E.AND G. L. NUECHTERLEIN. 1999. Red- . Royal Ontario Museum Life Sciences necked Grebe (Podiceps grisenga). The Birds of Miscellaneous Publication, Toronto, Canada. North America, no. 465. ROBERTSON,R.J.AND N. J. FLOOD. 1980. Effects of STRONG,P.I.V.AND J. A. BISSONETTE. 1989. Feeding recreational use of shorelines on breeding bird and chick-rearing areas of Common Loons. Jour- populations. Canadian Field-Naturalist 94:131± nal of Wildlife Management 53:72±76. 138. ZICUS, M. C., R. H. HIER, AND S. J. MAXSON. 1983. A SAYLER, R. D. 1992. Ecology and evolution of brood Common Loon nest from Minnesota containing parasitism in waterfowl. Pages 290±322 in The four eggs. Wilson Bulletin 95:671±672.

Wilson Bulletin, 116(1), 2004, pp. 101±103

A Possible Foraging Association between White and White-nosed

Susan D. Booth-Binczik,1,3,4 Gerald A. Binczik,2 and Ronald F. Labisky1

ABSTRACT.ÐSome species of birds commonly et al. 1983, Thiollay and Jullien 1998), and forage by following other and capturing prey Double-toothed Kites (Harpagus bidentatus) ¯ushed by the movements of the latter. Here we de- associate with several species of scribe a possible foraging association between White Hawks (Leucopternis albicollis) and white-nosed co- (e.g., Fontaine 1980, Egler 1991). There are atis (Nasua narica) in Tikal National Park, Guatemala. occasional reports of other Eastern and West- The frequency of association varied seasonally, per- ern hemisphere raptors that appear to forage haps due to differences in availability of , the in association with a variety of mammalian hawks' main prey. Received 28 January 2003, accept- carnivores, although prey capture has been ob- ed 26 March 2004. served only rarely (e.g., Sliwa 1994, Silveira et al. 1997). Here, we describe a possible association be- Many species of birds habitually forage by tween White Hawks (Leucopternis albicollis) capturing prey ¯ushed by other animals. For and an omnivorous , the white-nosed instance, Barred Forest-Falcons (Micrastur (Nasua narica), in the lowland tropical ru®collis) frequently follow army (Willis forest of Tikal National Park, Guatemala. White Hawks, which prey primarily on 1 Dept. of Wildlife Ecology and Conservation, Univ. and lizards (Draheim et al. in press), have of , Gainesville, FL 32611, USA. been documented following monkeys in Costa 2 Dept. of Zoology, Univ. of Florida, Gainesville, FL Rica (Boinski and Scott 1988) and French 32611, USA. 3 Current address: 450 Paradise Ln., Bronson, FL Guiana (Thiollay and Jullien 1998, Zhang and 32621, USA. Wang 2000). White-nosed coatis are diurnal 4 Corresponding author; e-mail: [email protected] procyonids; their diet consists primarily of