J. Field Ornithol., 69(3):364-375 ADULT BROOD PARASITES FEEDING NESTLINGS AND FLEDGLINGS OF THEIR OWN SPECIES: A REVIEW JANICEC. LORENZANAAND SPENCER G. SEALY Departmentof Zoology Universityof Manitoba Winnipeg,Manitoba R3T 2N2 Canada Abstract.--We summarized 40 reports of nine speciesof brood parasitesfeeding young of their own species.These observationssuggest that the propensityto provisionyoung hasnot been lost entirely in brood parasitesdespite the belief that brood parasiticadults abandon their offspringat the time of laying.The hypothesisthat speciesthat participatein courtship feeding are more likely to provisionyoung was not supported:provisioning of young has been observedin two speciesof brood parasitesthat do not courtshipfeed. The function of this provisioningis unknown, but we suggestit may be: (1) a non-adaptivevestigial behavior or (2) an adaptation to ensure adequatecare of parasiticyoung. The former is more likely the case.Further studiesare required to determinewhether parasiticadults commonly feed their genetic offspring. ADULTOS DE AVES PARAS•TICASALIMENTANDO PICHONES Y VOLANTONES DE SU PROPIA ESPECIE: UNA REVISION Sinopsis.--Resumimos40 informes de nueve especiesde avesparasiticas que alimenaron a pichonesde su propia especie.Las observacionessugieren que la propensividadde alimentar a los pichonesno ha sido totalmente perdida en las avesparasiticas, no empecea la creencia de que los parasiticosabandonan su progenie al momento de poner los huevos.La hipttesis de que las especiesque participan en cortejo de alimentacitn, son milspropensas a alimentar los pichonesno tuvo apoyo.Las observacionesde alimentacitn a pichonesse han hecho en dos especiesparasiticas cuyo cortejo no incluye la alimentacitn de la pareja. La funcitn de proveer alimento se desconoce.No obstante,sugerimos que pueda ser: 1) una conducta vestigialno adaptativa,o 2) una adaptacitn parc asegurarel cuidado adecuadode los pi- chonesparasiticos. E1 61timo parece ser la causamgts probable. Se necesitanestudios mils detaliados parc determinar si los adultos de especiesparasiticas alimentan a sus pichones comfnmente. Arian brood parasitism is a reproductive strategy that has evolved in 1% of all bird species.Obligate brood parasiteslay all of their eggsin nests of other speciesand are believed to provide no parental care to their offspring. They leave the incubation of their eggs and feeding of their offspringto hostsand do not normally participatein thesebehaviors (Payne1977). Interestingly,it hascome to our attentionthat somebrood parasiteshave been observedfeeding young of their own species.We reviewedthe literature and compiled observationsof this behavior (1) to determine which parasitic species have been observed provisioning young; (2) to determine how frequentlythis behaviorhas been described in the literature; (3) to describe the nature of the observations (i.e., the sex of the provisioner,whether nestlingsor fledglings are involved,and duration of the feeding); and (4) to identify the possiblefunction of this behavior. TREATMENT OF RECORDS Publishedobservations were mainly anecdotalbecause it wasnot known in any casewhether the provisioningadults were the genetic parents of 364 Vol.69, No..• BroodParasites Feeding Young [365 the young that were fed. Care must be taken when interpreting the ap- parent feeding of a young bird becausesome observers may havemistook it for feeding of an adult female, which occursduring courtshipfeeding. We determined, therefore, which speciesalso are known to practicecourt- ship feeding becausewe wanted to determine whether the records of provisioninginvolved only these species.Species that courtship feed may be more predisposedto feedingyoung (Bensonand Serventy1957). If the provisioningof young is an extensionof courtshipfeeding, then only maleswould be expected to perform this behaviorbecause only they feed females.Common namesof specieswere usedthroughout the paper (sci- entific namesin Appendix); taxonomyfollows Sibley and Monroe (1990). OBSERVATIONS OF PROVISIONING OF YOUNG BY BROOD PARASITES Feeding of young brood parasitesby individuals of the same species has been reported at least 40 times (Table 1). This behavior has been observedin at leastnine parasiticspecies from the familiesCuculidae and Fringillidae (Tribe Icterini), and has been reported most often in Pallid (n = 9) and Dideric (n = 11) Cuckoos (Table 1). Other authors have made only a general statementthat the followingparasites feed young of their own species,but did not provide details of the observations:Pied Cuckoo (Ali and Ripley 1969), Fan-tailed Cuckoo (Friedmann 1968), Shining Bronze-cuckoo(Oliver 1955), Dideric Cuckoo (Mackworth-Praed and Grant 1970, Roberts 1958), Channel-billed Cuckoo (Friedmann 1968), and cuckoosin general (Chisholm 1956, Fletcher 1915). Including these observations,provisioning of young by a brood parasite has been recorded in at least 12 parasiticspecies. Ten of these speciesalso court- ship feed. Thus, "parental" feeding has been observedin two speciesthat do not courtshipfeed: Asian Koel and Brown-headedCowbird (Table 2). Speciesthat courtshipfeed are not more likely to provisionyoung (Fisher exact test, one-tailed, P > 0.05). Five reportsinvolved nestlings and 38 involvedfledglings (three reports involvedboth nestlingsand fledglings).Most authorsdid not report the sex of the individual that fed the young, but in those caseswhere birds were sexed,provisioners included males (n = 7), females(n = 6), a pair of adults (n = 3), and one group of adults of both sexes.A pair wasnot assumedto be male and female. Some adult parasiteswere observedfeed- ing more than one parasiticyoung (Baird 1945, Merritt 1956). Some observationswere made over several days (J. A. Fletcher 1915, L. R. Fletcher 1925, Hanscombe 1915, Hare 1915, Hume in Fulton 1904, Kik- kawa and Dwyer 1962, Van Someren 1956, Walton 1903); however,be- cause the individuals were not banded, their identities were not known. McCracken (1984) "believed" a male Bronzed Cowbird fed one of three cowbird fledglings that was in its company,but the evidence was insufficient to include in Table 1. The following records were also ex- cluded from our review becausethey were criticized: (1) Cheeseman (1890) and (2) Fulton (1910) were criticized by Friedmann (1949), (3) Graham (1940) by Watsonand Bull (1950), (4) Hartlaub (in Friedmann 366] J. C. Lorenzanaand S.G. Sealy j. FieldOrnithol. Summer 1998 TABLE1. Feeding of parasiticnestlings or fledglingsby an adult of the same species. Known or suspected Parasitespecies host speciesa Comments Reference Great Spotted Artamussp. (s) adult fed fledgling North 1912 Cuckoo Great Spotted U adult fed "juvenile" Mundy and Cook Cuckoo 1977 CommonCuckoo U 57fed recentfledgling Browne 1886 Common Cuckoo U adult fed fledgling Kelin 1911 Common Cuckoo Meadow-pipit(k) more than one observation Bannerman and of adult feeding cuckoo Lodge 1955:132 during nestlingand fledg- ling stages Common Cuckoo U adult fed young Palmer in Bannerman and Lodge 1955: 132 Pallid Cuckoo U adult fed young (2 reports) Campbell 1900 Pallid Cuckoo Artamus sp. (s) adult fed fledgling North 1912 Pallid Cuckoo U pair of cuckoosassisted host Hanscombe1915 daily in feeding fledgling Pallid Cuckoo U adult fed "well-grown Jackson1949 young" Pallid Cuckoo U adult twice fed young Learmonth 1949 Pallid Cuckoo U adult cuckoofed fledgling Cooper 1958 Pallid Cuckoo U adult fed fledgling; another Kikkawaand Dwyer adult fed a different fiedg- 1962 ling repeatedlyduring one period of observation Pallid Cuckoo U feedingyoung or courtship Fleming1979 feedingof immature 57 Pallid Cuckoo White-browed 57fed fledgling Ambrose1987 Scrubwren (k) Pallid Cuckoo or Yellow-rumped adult fed nestling Howe 1905 Shining Bronze- Thornbill (k) cuckoo Shining Bronze- Grey Gerygone adult fed nearly full grown Hursthouse1944 cuckoo (s) cuckoo Klaas's Cuckoo u adult fed young (4 reports), Moreau and Moreau one young not able to fly 1939 Klaas's Cuckoo adult fed young (3 reports) Van Someren 1939 Klaas's Cuckoo adult fed fledgling Moreau 1944 Klaas's Cuckoo observationsof c•sfeeding Van Someren 1956 nestlingsand fledglingson separateoccasions Klaas's Cuckoo c• fed 2 youngrepeatedly for Baird 1945 15 min African Emerald c• fed young Millar 1943 Cuckoo Dideric Cuckoo sparrow pair fed fledglingdaily for a Hare 1915 (Passersp.) (k) week or more Dideric Guckoo Village Weaver captive5? fed captivefiedg- Millar 1926 (s) ling; c• fed samefledgling through cage bars Dideric Cuckoo 8 fed young or courtship Moreau 1944 feeding Vol. 69, No. 3 BroodParasites Feeding Young [367 TABLE 1. Continued. Known or suspected Parasitespecies host species• Comments Reference Dideric Cuckoo U feeding young or courtship Bannerman in Mo- feeding reau 1944 Dideric Cuckoo U c• fed "well-grown"young Friedmann 1948 or courtshipfeeding Dideric Cuckoo U c• fed young or courtship Maclaren 1952 feeding observed10 times in 6 min Dideric Cuckoo U on severalseparate occa- Maclaren 1953 sions, different adults fed different young recently able to fly Dideric Cuckoo U c• fed fully fledgedyoung Symonsin Friedmann 1956 Dideric Cuckoo U adultsfed fledglingson sev- Smith 1957 eral occasions Dideric Cuckoo U c• fed young Thomas 1960 Dideric Cuckoo U adult fed fledgling Ottow and Duve 1965 Asian Koel U on severalseparate occa- Hume in Fulton 1904 sions, different adults fed different young Brown-headed Rose-breasted 9 fed nestlingdaily Bonwell 1895 Cowbird Grosbeak (k) Brown-headed Common Yellow- 9 fed cowbirdat nestling Walton 1903:219