Eastern Wood-Pewee Attempts to Feed Killdeer Chicks

j. Field Ornithol.,61(2):214-216

EASTERN WOOD-PEWEE ATTEMPTS TO FEED KILLDEER CHICKS

ABBY N. POWELL Departmentof Fisheriesand Wildlife Universityof Minnesota 1980 Folwell Avenue St. Paul, Minnesota 55108 USA

Abstract.--In July 1988, a wild Eastern Wood-Pewee (Contopusvirens) was observed attemptingto feed two captiveKilldeer (Charadriusvociferus) chicks throughout one day. The Killdeer were in an open air pen closeto a forestedge. This was an unusualadoption, involvingan altricialspecies feeding precocial young. Apparently vocalizations of the Killdeer chickswere enoughto elicit a feeding responsein the adult pewee.

INDIVIDUO DE CONTOPUS VIRENS INTENTA ALIMENTAR PICHONE$ DE CHARADRIUS VOCIFERUS Sinopsis.--En julio de 1988 un individuo de Contopusvirens fue observado,a lo largo de un dla, tratar de alimentar dos pichonescautivos de Charadriusvociferus. Los polluelosse encontrabanen una jaula al aire libre cercanaal borde de un bosque.Aparentemente la vocalizaci6nde los pichonesfue lo que estimulola alimentaci6npor parte del ave adulta. Adoption or feedingof unrelated young by conspecificsappears to be fairly commonin bothaltricial and precocialbird species(Bowman 1983, Flemming 1987, Hayes et al. 1985, Hitchcockand Mararchi 1985, How- itz 1986, Welty and Baptista 1989). However, observationsof natural interspecificadoptions, not theresult of nestparasitism, are limited (Abra- ham 1978, Breiehagen1984, Rowleyand Chapman 1986, Southern1952, Welty and Baptista1989). I foundno recordsof natural adoptionsmixing parentand youngof altricial and precocialspecies. This paper documents the attempted feeding of Killdeer (Charadriusvociferus) chicks by an Eastern Wood-Pewee(Contopus virens) adult. This is an exampleof a specieswith altricial youngattempting to feedprecocial chicks, which are never fed by their natural parents. The observationsite was locatedon High Island (45ø45'N, 85ø40'W), Charlevoix County, in northeasternLake Michigan. As part of another studyI constructeda pen for captiverearing youngKilldeer. The enclosure was 8.2 x 8.2 m, and evenlydivided into four 4.1 x 4.1 m sections.The pen was constructedwith plasticmesh attached to 1 m high wood lath, and was openat the top. It was locatedon openbeach adjacent to a mixed hardwood-coniferous forest. On 14 Jul. 1988, at 0830 two one-day-oldKilldeer chickswere placed for the first time in the southeastsection of the pen. Four 10-day-old Killdeer chicksalready occupiedthe northeastsection of the pen. All of the chickswere observedfrom a blind placed2 m from the outsideof the pen. Bothof the day-oldchicks continuously gave distress calls in response to their first day in captivitywithout their parents.The older chicksdid not give distresscalls. At 0923 an Eastern Wood-Pewee appearedand perchedon the edge

214 Vol.61, No. 2 Wood-PeweeFeeds Young Killdeer [215 of the southeasternpen section.The pewee carried a large moth in its bill, and called with a "peweer" vocalization.After 30 s on the perch, the peweeflew down into the pen with the moth. It fluttereddirectly in front of one of the Killdeer chicks and thrust the moth toward the chick's beak. The Killdeer chick flinched, but did not run or crouch and freeze. The pewee attemptedto feed the chick four more times before finally eating the moth itself. From 0927 to 0931 the pewee was observedhovering and gleaning from a branch 10 m from the pen. After it succeededin catchinga small insectit returned to the pen. This time the pewee made 13 attemptsto feedthe youngKilldeer. It occasionallyperched on the pen corneradjacent to the 10-day-old chicks,but it never lookeddown at them. The older Killdeer chicksresponded to the pewee'spresence by crouchingand freez- ing. The youngKilldeer were neverobserved taking food from the pewee. When I left the blind at 1030 the peweewas still present.I returnedto the blind at 1200 and 1430. On both occasionsa peweewas perchedon the pen's edge or in nearby bushes.On subsequentdays peweeswere heardcalling from trees50 m from the pen, but were neverseen in contact with the chicksagain. The feedingof youngby parentbirds is thoughtto be controlledby an integrationof environmentalstimuli and the hormonalstate of the bird (Emlen and Miller 1969, Holcomb 1979). The primary environmental cuesthat elicit feedingbehavior vary among species.Visual and tactile cuesstimulate feeding behavior in birds that have exposed,open nests (Schuchmann1983). Acousticcues are important in somehole nesting species(Haartman 1953). In thiscase the EasternWood-Pewee was most likely hormonallyprimed to feedchicks. The Killdeer distresscalls, given in responseto separationfrom their parents,provided an auditorystimulus to the pewee.Although the Killdeer chicksnever acceptedfood from the peweethey continuedto call. The peweeattempted to feed the Killdeer chicksthe entire period that the distresscalls were given, but stopped after the chicksno longervocalized. Despite the fact that Killdeer chicks are very dissimilar to pewee young in appearanceand behavior, the auditorystimulus of their callsproduced a strongfeeding response in the adult pewee.

ACKNOWLEDGMENTS

The captiverearing study was funded in 1988 by the Universityof MinnesotaAgricultural ExperimentStation, the Bailey Trust Fund, and the James W. Wilkie Fund for Natural History. I thank F. J. Cuthbert,L. F. Baptista,E. H. Burtt, Jr. and an anonymousreferee for their commentson this manuscript.

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