784 Short Communications [Auk, Vol. 99 STINSON,C. H. 1976. On the recognitionof off- VEHERENCAMP,S. L. 1977. Relativefecundity and springby raptors.Raptor Res. 10: 30-32. parental effort in communallynesting Anis (Cro- --. 1977. Familiallongevity in Ospreys.Bird- tophagasulcirostris). Science 197: 403-405. Banding 48: 72-73. Received18 January1982, accepted6 May 1982. WILSON,E. O. 1975. Sociobiology.Cambridge, Massachusetts,Belnap Press. Notes on the Breedingof the Chestnut-belliedHeron (Agamiaagami) in Venezuela CRISTINA RAMO AND BENJAMIN BUSTO UniversidadNacional Experimental de losLlanos Occidentales, Ezequiel Zamora, Guanare,Estado Portuguesa, Venezuela Althoughsome information on the breedingof the This small colony (80 breeding pairs) was about 75 Chestnut-bellied Heron (Agamia agami) in other m from a much larger heronry (2,000pairs) that con- countrieshas been published (Michener et al. 1964, tained the following breeding species:Great Egret Haverschmidt 1968, J. Hancock and H. Elliot 1978), (Casmerodiusalbus), Snowy Egret (Egretta thula), Lit- no previousbreeding records have been reportedfor tle Blue Heron (Floridacaerulea), Cattle Egret, and Venezuela. On 26 July 1980, we located three nests Bare-facedIbis. Michener et al. (1964)found a colony of this heron, eachwith two nestlings,in a seasonal of Agamiaagami with about 12 nests in Veracruz, marsh surroundedby forest closeto the village of M•xico near somenests of Great Egretsand Anhin- Santa Rosa, Estado Barinas. The surface area of the gas (Anhingaanhinga). marsh was about 2 ha, and its depth was 60 cm. The On 9 August the young Chestnut-belliedHerons vegetationwas dominatedby Rhandiaaculeata (Ru- were able to climb into the branches of their nest biac.), a shrubabout 3 m high, and by Thaliagenic- bushes, and on 18 September they were completely ulata (Maranth.),a typicalmarsh perennial. A num- feathered and found in the canopy of the bushes. ber of small trees under 6 m tall were sparsely Our last visit to the colonywas on 23 September,at distributed over the marsh. The nests were found in which time we were not able to find any Agamia a smallarea containingR. aculeataand were approx- agami.Therefore, the period of nestingat this site in imately 1.5-2 m above the water level. Venezuelawas from June to September,the time of At our secondvisit on 31 July, we discoveredsix maximum annual rainfall in this area. nests, eachwith two downy chicks.There were nine We thank BetsyTrent Thomasfor translatingthis adults in the immediate area. In later observations note into English. at the same site, we found no more nests or nest- lings, and thus we believe that there were but six LITERATURE CITED breeding pairs. Each nest was placed in a separate HANCOCk(,J., & H. ELLIOT. 1978. The herons of the bush. world. New York, Harper and Row. In this sameheronry we alsofound activenests of HAVERSCHMIDT, F. 1968. Birds of Surinam. Lon- Black-crownedNight-Herons (Nycticoraxnycticor- don, Oliver and Boyd. ax), Yellow-crownedNight-Herons (Nyctanassavio- MICHENER,M. C., J. S. WES•(E,& R. B. CLAPP. 1964. lacea), Boat-billed Herons (Cochleariuscochlearius), A breeding colony of Agami Herons in Vera- and Bare-facedIbis (Phimosusinfuscatus). When the cruz. Condor 66: 77-78. Chestnut-bellied Herons abandoned the colony, it wasoccupied by breedingCattle Egrets (Bubulcus ibis). Received8 February1982, accepted18 May 1982. Nesting by One-year-oldBlack-crowned Night Heronson Hope Island, Rhode Island THOMASW. CVSTER1 AND WILLIAM E. DAviS, JR.2 •U.S. Fishand Wildlife Service, Patuxent Wildlife Research Center, Laurel, Maryland 20708 USA, and ZBostonUniversity, College of BasicStudies, 871 CommonwealthAvenue, Boston, Massachusetts02215 USA Therehave been few consistentreports concerning mature night heronsof the genusNycticorax. One- the frequencyand successof nestingattempts by ira- year-old Black-crownedNight Herons (Nycticorax October1982] ShortCommunications 785 • 4 o• 3 • • 2 = • 1 •'-•z o 2-yr-old male -'--]1-yr-old female • neitheradult lOO 80 õ 60 20 10 15 21 I 5 10 Day of Incubation Day of Nestling Period Fig. 1. Percentagetime on the nest and number of nest reliefsby a 1-yr-old femaleand 2-yr-old male Black-crownedNight Heron during the incubation and nestling period. nycticorax)mated to 2-yr-old or olderbirds built nests number 352004,Osborn and Custer 1978)on 30 May, and incubatedeggs in the wild (Gross1923). In a 9 June, and 19 June 1979. The blind was set up on captive colony,many 1-yr-old pairs of night herons 10 May 1979in an areawhere nestswere not being courted and built nests, and one pair successfully studied for reproductivesuccess. From 1 to 24 June raisedfour young (Noble and Wurm 1942).One pair 1979, a time-lapse Canon 814 super-8 movie camera of 1-yr-old night heronslaid eggsbut did not pro- set to take one photographevery minute recorded duceyoung in a captivecolony at PatuxentWildlife diurnal incubationand broodingbehavior of a mixed- ResearchCenter (H. Ohlendorf pers. comm.). Breed- agepair of youngnight heronsnesting near the blind. ing among1-yr-old birds of the closelyrelated Nan- A clock was attached below the nest so that the time keen Night Heron (Nycticoraxcaledonicus) is appar- of each exposedframe was recorded.The film was ently common (Braithwaite and Clayton 1976). In analyzedwith a KodakEktagraphic MFS-8 projector. contrast, in a 3-yr study of a colony of about 350 Heronswere agedby plumagecoloration (Gross 1923, Black-crownedNight Heron pairs on Long Island, Palmer1962) and sexedby cranialplume length (No- New York, no l~yr-old breederswere observed(Al- ble et al. 1938). The criteria for age and sex identi- len and Mangels1940). fication appear to be adequate, becauseplumage col- While involved in studies of environmental con- oration of known-age birds in the Patuxent colony taminants and successin night herons (TC) and of was consistentwith the categoriesidentified by Gross heron vocalizations (WD), we had the opportunity (1923) and Palmer (1962) (J. $pann pers. comm.) and to observetwo instancesof nestingby 1-yr-oldnight plume length was longer in malesthan femalesin 52 herons. We report here the first documentationof a pairs, the samein 3 pairs, and shorterin only 1 pair 1-yr-old mated pair breedingin the wild, alongwith in a night heron colonyat GreatNeck, Long Island, more detailed observations of the incubation behav- New York (Noble et al. 1938). Also, cranial plumes ior and nestingsuccess of a 1- and 2-yr-old mated were significantlylonger in male than female night pair. heronsin the Patuxentcolony (J. Spann pers. comm.). Nesting behavior of Black-crownedNight Herons On 30 May 1981 a pair of 1-yr-old night herons was recorded from an observation blind within the with eggswas observedand photographedfrom the Hope Island, Rhode Island heron colony (colony blind. Neither individual had cranial plumes. Nest- 786 ShortCommunications [Auk, Vol. 99 lings of 2-5 days of age were observedin this nest 1979 (Custer in prep.) are as follows: first clutch 7 on 19 June. Becauseour emphasiswas on the mixed- April, medianclutch 25 April, lastclutch 4 June.These age pair, we did not determine the exactnumber of results support earlier studies of night herons eggsor young producedin this nest. This is the first (Braithwaiteand Clayton 1976,Gross 1923) and co- documentationof a 1-yr-old mated pair of Black- lonialnesting seabirds (Ryder 1980) that revealedthat crowned Night Herons nesting in the wild. Mixed- younger individuals nest later in the seasonthan older age breeding pairs have been observedin the wild ones. (Gross1923), but 1-yr-old mated pairs have been ob- We do not know the frequencyof 1-yr-oldnesting servedonly in captivity (Noble and Wurm 1942). on Hope Island in 1979, but we suspectthat it was A secondpair, observedfrom the blind and re- not rare. The two instanceswe observed1-yr-old cordedon film, consistedof a 1-yr-old female and night heronsnesting were in an areawhere only a 2-yr-old male.Both of thesebirds had cranialplumes. smallfraction (less than 1%) of the colonycould be The cranial plumes of the 1-yr-old bird were about observed. two-thirds the length of those of the 2-yr-old, and, We thankLorrae Fuentes and James Myers for as- on that basis, we suspectthat the youngerbird was sistancein the field; DeniseClearwater for analysis the female.Two of the threeeggs in this nesthatched, of the film; and R. Michael Erwin, Donald Mc- and the nestlingssurvived to at least 12 days of age. Crimmon, Harry Ohlendorf, and JamesSpann for The mixed-age pair was filmed from 1-24 June, a reviewing the manuscript. period that included the last 12 days of incubation and 12 days after hatching of the first egg (Fig. 1). LXTERATUaE CITEV During that time, there were 5 days with no nest ALLE•, R. P., & F. P. MaWgELS. 1940. Studies of exchanges,14 with 1 exchange,2 with 2 exchanges, thenesting behavior of theBlack-crowned Night 2 with 3 exchanges,and 1 with 4. Infrequent nest Heron. Proc. Linnean Soc. New York. Nos. 50- exchangesobserved in our study are consistentwith 51: 1-28. observationsmade while studying heron vocaliza- BR•IT•IwaITE, L. W., & M. CLa¾TO•. 1976. Breed- tions from blinds in this and anothercolony (W. Da- ing of the NankeenNight Heron Nycticoraxca- vis pers. obs.). Lowe (1954) reported that nest ex- ledonicuswhile in juvenileplumage. Ibis 118:584- changes occurred every 4-6 h in the Grey Heron 586. (Ardeacinerea). In contrast,Milstein et al. (1970)found incubation spellsgreater than 9 h. In the Patuxent GRoss,A. O. 1923. The Black-crownedNight Her- on (Nycticoraxnycticorax naevius ) of SandyNeck. colony, a male night heron incubatedfor 5 consec- Auk 40: 1-30, 191-214. utive days following the escapeof the female. The Kus•ILa•, J. A. 1976. Feedingrhythm in nestling female was recaptured, and the nest was successful White Ibis. Wilson Bull. 88: 656-658. (J. Spann pers. comm.). We suspectthat the long 1981. Resourceuse strategiesof wading periods of incubation and brooding by each adult birds.