The Condor 90538-545 0 The Cooper Ornithological Society 1988

THE USE OF COURT OBJECTS BY LAWES’ ’

S. G. PRUETT-JONES AND M. A. PRUETT-JONES~ Department of Biology C-016, Universityof California, San Diego, La Jolla, CA 92093

Abstract. Males of Lawes Parotia (Parotia lawesii), a lek-breedingbird of paradise, collectedobjects at their terrestrialdisplay courts. These included shed snake skin, mammal scats,chalk, mammal fur, feathers,and bonefragments. The objectswere not usedby males in their courtshipdisplay but wererubbed on the displayperch and may have had indirect effectson display.Females searched for and tookthe objectswhen visiting courts, and males stolethem from eachother and placedthem at their own courts.Experiments showed that objectswere removed quickly by females,usually within 24 hr, and oncetaken, they were not broughtback. Females only took objectsduring the nestingseason, and we suspectthat femalesused the shedsnake skin as nest-liningmaterial and ate the chalk as a mineral supplement.Collection of the items was not relatedto mating successin malesbut may have influencedfemale visitations. Key words: Lawes ’ Parotia; of paradise; court objects;display objects;mating be- havior;Papua .

INTRODUCTION METHODS The purpose of this paper is to describe an un- The data presentedhere were gathered as part of usual behavior in Lawes’ Parotia (Parotia law- a long-term study of lek evolution in P. lawesii esii), a montane speciesof bird of paradise (Par- (Pruett-Jones 1985). Fieldwork was conducted adisaeidae). Males collected natural objects in on Mount Missim, Morobe Province, from Au- the forest and placed them at their terrestrial gust to December 1980, and August 198 1 to De- court sites. This behavior is similar to the col- cember 1983 (see Pruett-Jones and Pruett-Jones lection of display ornaments by male 1982, 1986). We worked on an area composed (Marshall 1954, Gilliard 1969, Cooper and For- of primary, montane rainforest approximately shaw 1977, Diamond 1986) except that in P. 1,000 ha in size, from 1,300 to 2,200 m altitude. lawesii, males did not use the objects in display This area encompassedthe entire altitudinal range and each type of item was removed by females. of adult male P. lawesii on Mount Missim and Collection of the objects by females was restrict- between 25 and 32 males held courtson the study ed to the breeding season and we believe they area each year. In this population, the majority were important in reproduction. of courts were spatially clumped at lek sites but Lawes’ Parotia occurs in montane, rainforest approximately one-third of the males each year habitats from 1,000 to 2,200 m altitude in east- displayed solitarily (Beehler and Pruett-Jones em Papua New Guinea (Gilliard 1969, Schodde 1983, Pruett-Jones 1985). A total of 144 and McKean 1973, Beehler et al. 1986). The were individually color-banded on the study area. is almost totally frugivorous (Beehler Each season from 198 1 to 1983 was divided 1983, Beehler and Pruett-Jones 1983, Pratt and into regular sampling periods of 3 weeks (198 1) Stiles 1985) feeding on canopy and subcanopy and 2 weeks (1982, 1983). Courts were active for fruits. Males display terrestrially at court sites up to 10 months a year, yielding a total of 49 which they clear and actively clean, maintain, sampling periods over the three seasons.During and defend from other males (Schodde and Ma- each period, all courts were checked for activity’ son 1974, Beehler and Pruett-Jones 1983). Males and the presence of objects. A total of 21, 23, mate promiscuously and do not assist females and 20 courts were monitored in 1981, 1982, with parental duties (Pruett-Jones 1985). and 1983, respectively. Use of the items by males and response to I Received3 August1987. Final acceptance13 April objects by conspecifics were quantified during 1988. * Presentaddress for both authors:Department of behavioral samples from hides set near courts. Ecologyand Evolution, The University of Chicago, Samples were 4.0 to 5.5 hr in length, conducted Chicago,IL 60637. throughout daylight hours, and most or all males

[5381 COURT OBJECTS BY LAWES ’ PAROTIA 539 in the population were sampled each period. We 1986, a sample of chalk was collected from a report data from 920 behavior samples (total of court and sent to a commercial laboratory for 4,424 hr) on 19, 23, and 22 adult males during spectroscopic analysis of trace elements. The 1981, 1982, and 1983, respectively. The data analysis technique used was inductively coupled from one of the males studied in 198 1 were de- plasma-atomic emission spectrometry (methods leted in the analysis of mating successdue to 43.292-43.296 and 4.AOl-3.A04, Official Meth- insufficient sampling of that individual, ods of Analysis, 14th Edition, 1984, and 1st Sup- For analysis, we calculated three measures of plement, 1984, AOAC, Arlington, Virginia). the collection of objects by males: (1) the pro- portion of sample periods during which males RESULTS had objects at their courts, (2) the proportion of The courts of P. lawesii consistedof cleared areas behavior samplesduring which males brought in on the forest floor and ranged in size from 0.5 items, and (3) the actual rate of collection (ob- to 20.0 mZ. Each court was cleared and main- jects/ 10 hr of observation). These variables were tained by only one male and individual males strongly intercorrelated (P < 0.005 in each cleared from one to five courts (in our use of the regression). term court, we are referring to the single or mul- During behavior samples we placed various tiple sites that an individual male used for dis- objects at courts to determine any preferencesby play). The court itself, but not the surrounding males for color or type. We offered blue, green, forest, was aggressively defended against con- red, white, and yellow fruits known not to be specificmales. Courts were cleared only under a eaten by P. lawesii, fruits identified as part of the suitable display perch which was a horizontal or species’ diet, flowers, and white lichen. slanting branch or vine, usually 1 to 3 cm in At a central lek we conducted experimental diameter, and approximately 0.5 m above the offerings of objects to quantify rates of disap- court. During the breeding season,males cleared pearance. For each offering, the objects were all debris, e.g., leaves, bark, twigs, fungi, small placed at all active courts (nine in 1982, six in stones, etc., off their court each time it was vis- 1983) at 06:30 on day 1. Then the courts were ited. Males also pulled leaves from small saplings checked,and the number of objectsrecorded three at the court. Males did not clear away the objects times, at lO:OO, 14:00, and 17:30, that day and discussedhere. All display interactions and mat- then four times on day 2. In the snake-skin ex- ings took place at the court. periment, courts were also checked on day 3. Two offerings of snake skin were conducted, OCCURRENCE AND SEASONALITY OF from 20-22 October 1982 and from 25-26 Jan- OBJECT USE uary 1983. Four small pieces, each approxi- Several kinds of objectswere recorded (Table 1). mately 16 x 8 mm in size, were placed at each Shed snake skin and mammal scats were most court. Becausemales quickly tore the snake skin common, followed by chalk, fur, feathers, and into smaller pieces, we counted the number of bone fragments. Other objects seen at least once, whole piecesand whole-piece equivalents (an es- but not regularly observed, were small rootlets, timate of the number of pieces represented by snail shells, and piecesof clear plastic wrapping. the many smaller pieces). The offering of mam- We did not identify the snake skin to species, mal scatswas conducted from 22-23 November but skins of large pythons were the most fre- 1983. The scatsoffered were found in the forest quently seen. Most mammal scats were 5 to 7 at den sites of opossums(Phalanger vestitusand mm in diameter and 35 to 40 mm long, com- P. orientalis) and were of the same type and size posed of compacted plant material and insect found at courts naturally. Three scats, each parts, and thought to be those of opossums(Pha- marked with a small white dot, were placed at langer sp., Pseudocheirussp). Scatsof forest wal- each court. Two experiments with standard labies (Thylogale bruijni and Dorcopsulus van- chalkboard chalk were conducted, from 27-29 heurni) were infrequently observedat courts. The November 1982 and from 28-29 November chalk was collected by males as small pieces, 1983. Three pieces of chalk, broken into small about 10 mm across,from landslides in the forest pieces 5 to 8 mm on each side, were placed at with exposedmineral veins. The fur appeared to each court. be either shed fur or actual remains (skin with During additional work on the study area in fur attached) of small mammals. The feathers 540 S. G. PRUETT-JONES AND M. A. PRUETT-JONES

TABLE 1. Presenceof objects at courts.’

Periodsduring which courtshad objects2 Active courtswhere objects were found ’ All periods Breedin season All periods Breedin season n (W n(h)% n (W n ($ 0) Total 49 675 491 Any object 33 (67.4) z: (92.6) 201 (29.9) 171 (35.0) Snake skin 31 (63.3) 23 (85.2) 93 (13.8) 74 (15.1) Mammal scat 30 (61.2) 24 (88.9) 120 (17.8) 99 (20.2) Chalk 17 (34.7) 14 (51.8) 37 (5.5) 33 (6.7) Fur 7 (14.3) 7 (25.9) 9 (1.3) 9 (1.8) Feathers 3 (6.1) 3 (11.1) 3 (0.4) 3 (0.6) Bone 1 (2.0) 1 (3.7) 1 (0.2) 1 (0.2) ’ Data from 1981, 1982, and 1983 combined. * Courtswere checked during 49 samplingperiods overall and 27 periodsduring the time of matingseach year. Thus, during 31 (63.3%) periods, at leastone court of thosechecked had snakeskin present. ’ ’ Consideringeach court separatelyeach period, there was a total of 675 courtschecked for objects,491 during the time of matings.As objects wereremoved quickly from courtsby conspecifics,it is unlikely that they wereever countedtwice in successiveperiods.

were small and colored (not from P. law&i). The bone fragmentswere piecesofjawbone from small mammals. IOO- Concentrations (ppm) of trace elements of the chalk sample that was analyzed were as follows: .; 80. Ca-270, P-182, Mg-237, Na-4512, Al- 2 60. 10 ~35.4, Ba--35.4, Fe-29.3, Sr--35.4, B- tl ~35.4, Cu-1.32, Zn--1.27, Mn-d0.88, Cr- a 40. u x35.4. K 20. Only adult males collected the items; on the three occasions when immature males main- tained courts, they did not bring in objects.Most, but not all, males collected objects. Individual males had objects at their courts on an average of 29.9% of the occasions that we visited the court over the entire year, 35.0% during the breeding season (September to February; Table 1). During all 3 years combined only four (6% of total numer) males were never seen to have objects at their courts or to bring them in during t;0-J 40 - behavior samples. Both solitary and grouped 2 period of mating males collected objects at the same frequency. 0 30. al Our data on year-round seasonality of activity s at courts and use of objects is most complete for ;; 20. the period April 1982 to March 1983 (Fig. 1). z c 10. Some courtswere active throughout the year (Fig. h lA), with individual males active for an average E 0 - of 24 weeks. With the exception of the early sea- ii *4O’ 24 7 215 19 2 1630 13 27 II 25 8 22 6 20 3 173, 14 28 14 28 son, from April to June and then again in August, AMJ J A SONDJ FM males collected objects throughout the period of FIGURE 1. Seasonalityof court activity (A), occur- court activity (Fig. IB). renceof objectsat courts(B), and the removal ofobjects The retrieval of objects by females was re- by females (C). The data for Figure 1A and 1B were stricted to the nesting period (Fig. 1C). In late gatheredduring regularcourt checksand those for Fig- ure 1C during behavior samples.In Figure 1C, intervals August, before matings started, females did not with no data points representperiods during which no take objectsdespite the fact that some courts had behavior sampleswere conducted.The time period was them. Females were observedtaking objectsfrom April 1982 to March 1983. COURT OBJECTS BY LAWES’ PAROTIA 541

TABLE 2. Collection of objects by residents and removal by conspecificmales and females.’

Number of behavior samples’ The residentmale Femalestook at least Conspecificmales took retrievedobiects one obiect at leastone obiect n % n % n %

Any object 206 22.4 181 19.7 103 11.2 Snake skin 119 12.9 139 15.1 :66 7.2

MammalChalk scat 869 9.41.0 308 0.93.3 1 ::; Other objects (combined) 21 2.3 16 1.7 6 0.6 ’ ’ Data from 1981, 1982, and 1983 combmed. 2Atotal of 920 behavior sampleswas conducted,percentages were calculated with referenceto this value. courts during approximately one-fifth of all be- Males rearrangedthe location of objectsat their havior samples (Table 2). court throughoutthe day. Objects were not placed Comparable data to that in Figure 1C for the in any regular fashion or in one particular area 1983 seasonalso indicated that females did not but they were generally placed towards the center take objects prior to the nesting season. During of the court and in clear view from the display June, July, and August 1983 an average of 2 1% perch. The objects were never hidden and the (range = O-60%) of active courts had objects but males did not eat them. For males that main- during only one of 17 behavior samples was a tained more than one court, the objects were female seen to collect items from a court. invariably placed at the site used most often for display. USE OF OBJECTSBY MALES AND Objects were not always present at courts (Ta- RESPONSEOF CONSPECIFICS bles 1, 2) but visitors behaved as if they were Males that were more active at their courts col- searching for them. Visitors dropped from the lected more objects. There was a significant, pos- display perch to the court and then hopped back itive correlation between attendance of the court and forth with their head downwards scanning by males (proportion of time during behavior the surface. If an object was present, the visitor samples that males were present at their court) invariably took it. Both males and females vis- and the rate of collection of objects (n = 63, r = ited courts when the resident was present as well 0.490, P = 0.001). On arrival at the court with as when the resident was absent. If the resident objects, males typically rubbed them along the was absent, the visitors went directly to the court, display perch and the vertical, bare saplings be- collected whatever objects were there, and left fore placing them on the court. The objects were immediately. Banded females were observed to held at the end of the male’s bill and then me- return repeatedly to a given site to retrieve all thodically rubbed up and down the perch or sap- available snake skin if a large amount was pres- ling. Rubbing behavior became more frequent ent. When in attendance, the resident male im- and intense if the male brought in several items mediately chased females away if the females at once, e.g., several pieces of snake skin. Males tried to land on the surface of the court as if to rubbed snake skin along their perch for as long steal the objects. Visiting males were usually as 20 min. The rubbing behavior was not, how- chasedaway whether or not they appeared to be ever, an actual display; males neither picked up trying to steal objects. When conspecific males the objects during interactions with females, nor did take objects they would lly to their own area in any way obvious to observers tried to draw and rub and arrange the objects as described the attention of females to the objects. above. The section of the display perch directly above the court was often smoother and shinier than the remainder of the branch of vine. We could EXPERIMENTAL OFFERINGS not detect whether the rubbing of objects made Of the items placed at courts during behavior the perch more visible or left an odor, except samples, all inedible fruits, regardless of color, with respect to the chalk. Chalk marks-wide, were either tossed off the courts as soon as the white streaks along the perch-were noticeable male arrived or, in a few cases,ignored. No pos- from 10 to 15 m away. itive responses(rubbing along the display perch) 542 S. G. PRUETT-JONES AND M. A. PRUETT-JONES

declined rapidly during the morning of the first day and then more slowly during the afternoon and on the second day (Fig. 2). More than half of the snake skin and mammal scatswere taken within 4 hr of their placement at courts. By the end of the second day, only 10 to 15% of the original number of objects remained. The lek where experimentswere conductedwas more than 1 km from the nearest lek and over 500 m from the nearest solitary court. Males did not make interlek visits and the male displaying solitarily was seen at the study lek only once during the 1982 season. Thus, reduction in the total number of objects at the lek during the ex- periment was due to loss through females taking the objects,not from outside males stealingthem. The number of objects never increased between court checksand there was no evidencethat males retrieved natural objects during the time of the &I6 l experiment. g 15 C z . In 12 8 COURT OBJECTS AND MATING ; 9 SUCCESS OF MALES . . . z 6 . Elsewhere (Pruett-Jones 1985; Pruett-Jones and t 3 . Pruett-Jones,unpubl.) we presentdata on mating 2 . successof males and female choice in P. lawesii. 10 ~..,.,.,, 1000 1730 1000 1730 1000 All males received female visitors, but not all 0630 1400 0630 1400 0630 males mated. During 1981, 1982, and 1983 re- Day I Day2 Day3 spectively, 7 of 18 (38.9%), 7 of 23 (30.4%) and FIGURE 2. Removal by females of objects offered 9 of 22 (40.9%) males obtained matings. For 198 1 at P. lawesii courts: A. Number of whole pieces, or to 1983 combined, successful(mating at least equivalents, of shed snake skin (four pieces placed at once) males (n = 24) averaged a collection rate each of nine courts); B. Mammal scats (three scats placedat each of six courts);and C. Chalk (three pieces of 0.8 objects/l0 hr of observation (SD = 0.5, placedat eachof six courts).See Methods for additional range = O-1.7). The mean rate of collection for details. unsuccessful(nonmating) males (n = 39) was 0.6 objects/l0 hr of observation (SD = 0.5, range = were seen. The edible fruits were eaten (five of O-l .5; differencesnot significant, Mann-Whitney 25 fruits offered at eight courts), tossed off the U = 560, Z = - 1.32, P > 0.10). One of the four court (19 of 25), or in one case, ignored. The males that was never observed to collect objects flowers and lichens were also tossedoff the court. did successfully mate. The collection of court Snail shells were tossed off at one court and ig- objectscorrelated with the length offemale visits, nored at another. With respect to these same but not with the rate of female visitation or the items, females showed a response only to the mating successof males (Table 3). The rate of edible fruit (one female ate one fruit). None of female visitation, the length of female visits, and the items were taken by females or by conspecific the mating successof males were each intercor- males. related with each other (Pruett-Jones and Pruett- The results of the snake skin, mammal scat, Jones, unpubl.). and chalk experiments are illustrated in Figure Six nest-site locations of P. lawesii were found 2. The double experiments with snake skin and during this study and work by T. K. Pratt be- chalk each yielded similar results, and with re- tween 1978 and 1980 (pers. comm.). Due to the spect to both objects we report the results from height and inaccessibility of the nests, we could only one offering. The number of items present not verify whether females placed court objects COURT OBJECTS BY LAWES’ PAROTIA 543

TABLE 3. Correlations between measuresof collection of objects by males and female visitations and mating success.1

% sample % behawor Rate of periods’ SXIlpkS’ collection’ I P I P r P

Rate of female visitation (females/hr of observation) 0.189 0.152 0.246 0.052 0.215 0.090 Mean length of female visits (min) 0.246 0.066 0.354 0.005 0.262 0.041 Mating successof male (matings/ 10 hr of observation) 0.078 0.559 0.022 0.863 0.023 0.860

’ ’ Basedon the combineddata from 18, 23, and 22 malesstudies in 1981, 1982, and 1983, respectively.Ps < 0.05 are underlined. i The proportionof sampleperiods males were observed to have objectsat thar courts. ’ The proportionof behavior samplesduring which maleswere seen to bnng in objects. 4 The rate of collection(objects/l0 hr of observation). at or near their nests. The nesting biology of P. Use of snake skin by other birds is also known; lawesii remains sparsely known. most, if not all, speciesof Myiarchus flycatchers in the New World use it as nest-lining material (Skutch 1960; Bent 1963; Lanyon 1978, 1982) DISCUSSION and it may be common in other as Accounts and descriptions of courts of P. lawesii well (Bent 1963). from other areas in Papua New Guinea are pro- The chalk and mammal scatsare probably eat- vided in Gilliard (1969) Schodde and McKean en by females as sourcesof nutrients. The pri- (1973) Schoddeand Mason (1974) and Cooper mary inorganic minerals in eggshellsare calcium, and Forshaw (1977). These authors made no magnesium, phosphorus, iron, and sulphur mention of objects at the courts. B. Bacchusre- (Romanoff and Romanoff 1949). The sample of ported (pers.comm.) shedsnake skin at the courts chalk that was analyzed had substantial concen- of P. lawesii on Crater Mountain in Eastern trations of four of thesefive minerals. Given that Highlands Province. We suspect this behavior as much as 75% of the mineral, particularly cal- will be shown to be common in other populations cium, content of eggscomes from a bird’s diet as well. (Comar and Driggers 1949), eating the chalk could Becausemales do not derive benefits from the certainly benefit females during egg production. objectsthemselves, it seemsclear that males col- Females supplementingtheir breeding seasondiet lect them for females. Moreover, given that the with sources of calcium, e.g., bones, is known removal of objects by females is restricted to the from other passerines (Payne 1972, MacLean period of mating and nesting, we believe that all 1974) and may be widespread. In this regard, it objects were used in some context related to re- is interesting to note that the shellsof land snails, production. We suspect that females used the another possible source of calcium, were fairly shed snake skin as nest-lining material. The re- common in the forest on Mount Missim but were peated and frequent visits of some females to only rarely found at the males’ court sites. De- courts to collect snake skin when large amounts spite its potential importance, however, chalk were offered suggestedto us that they were taking was relatively rare at courts compared with snake it somewhere,perhaps a nest, and then returning skin and mammal scats (Table l), presumably for more. We were, however, unable to locate a either becauseit is rare in the forest or has less nest which could be observed or closely exam- importance than we have hypothesized. Females ined and cannot confirm this. Hartert (19 10, cit- could get bones, and thus calcium, from the scats ed in Gilliard 1969) provides a description of a of the predatory marsupials (e.g., Dasyurus al- nest of P. lawesii but there was no mention of bopunctatus),but males were not seen to collect snake skin. such scats. The ParadiseRiflebird (Ptilorisparadiseus) and With respect to the mammal scats, an inter- Queen Victoria’s Riflebird ( victoriae), esting possibility is that the females placed them relatives of Parotia lawesii endemic to Australia, around their nest as an antipredator device. are known to use shed snake skin as nest lining. Opossums and other arboreal marsupials would Campbell (1974) provides a photograph of a nest be among the most significant predators on eggs. of P. paradiseuswith what appearsto be an entire If individual opossums avoid areas where they shed skin encircling the upper rim of the nest. detect markings of others, then scats around a 544 S. G. PRUETT-JONES AND M. A. PRUETT-JONES nest or along the branch leading to a nest might intermediate stagesin which males first collected reduce marsupial traffic there. objectsunrelated to bower construction. It is pos- Irrespective of the specific use of the objects sible that the collection of court objects in P. by females,it appearsthat the items provide some lawesiirepresents such an intermediate stage.The benefit to females. The benefit could be relatively important difference between the collection of minor, as if snake skin is used as nest lining, or court objects and the use of bower decorations potentially important, if chalk is used as a min- is that for bowerbirds, the decorations appear to eral supplement. The most important question be the focus of male-male competition and fe- is whether the presence of objects at a male’s male choice(Borgia 1985, Borgiaand Gore 1986). court influences the female’s choice of a mate. This is not the case in P. lawesii, the indirect The data presentedhere suggestnot. The collec- aspects of court objects and matings notwith- tion of objects did not correlate with the relative standing. Some other differences are that bower mating successof males (Table 3). In one sense, decorations are not taken by females, male bow- it is this lack of correlation that is intriguing, if erbirds show strong color preferences in which objects do in fact benefit females. Perhaps the items they collect, and in some casesthe deco- benefit is not so great as to generate an initial rations are incorporated into the males’ displays linking between the objects and preferencesfor (Gilliard 1969; Diamond 1982, 1986; Pruett- mates. There may be an indirect relationship be- Jones and Pruett-Jones 1985). tween matings and objects, however, given that Our observations have raised a number of im- the objects appear to influence the length of fe- portant questions which will require experimen- male visitations (Table 3) which itself is corre- tation with captive birds to answer. For example, lated with male mating success(Pruett-Jones and if female P. lawesiiwill breed in captivity it would Pruett-Jones, unpubl.). This indirect benefit to be interesting to offer them snake skin to see if males-increasing their exposure to females- it is incorporated into their nest. Also, females may explain why males collect the objects at all could be offered chalk and/or eggshellsto see if if it doesnot increasetheir probability of mating. they will, in fact, eat theseitems. Although much It is possiblethat the collection of objects orig- of our discussion is speculative, we believe the inated in ancestral P. lawesii populations which objects will be shown to be important with re- were presumably monogamous and exhibited bi- spectto nesting biology of females. Assuming so, parental care (Gilliard 1969, Schodde 1976). If, this behavior will add yet another dimension to in the ancestral speciesof P. lawesii, shed snake the diversity of mating patterns in lek-breeding skin, mammal scats,and chalk were used in nest- birds of paradise and another intriguing similar- ing or as nutrients, both males and females may ity between birds of paradise and bowerbirds. have collected them. In the course of evolution of a promiscuous mating system, indirect ben- efits to males may have been sufficient for the ACKNOWLEDGMENTS behavior to be retained. Thane K. Pratt and Gunter Ziesler first observed the Males may rub the objectson the display perch use of court objects in this population of P. lawesii. to make the perch smoother or to increase its We are grateful for their communication and unpub- visibility or conspicuousness.In the instances lished observations.Our work was generouslyfunded where males marked their perch with chalk, the by National GeographicSociety, New York Zoological Society, Chem-tronics Inc. and Dan Brimm, Papua perch was much more noticeable (at least to us). New Guinea Biological Foundation, Frank M. Chap- If the objects have parasites on them, rubbing man Memorial Fund, Joseph Henry Fund, Flora and may also reduce the level of parasites. Males Fauna Preservation Society, Carl Koford Memorial probably tear the snake skin into smaller pieces Fund, and Harry Hoogstraal. The work during 1986 to lessen the possibility that a single female can was supportedby NSF Grant BSR 84 16000. We wish to thank our field assistantsand A. Allison, B. Beehler, easily take it all. J. Diamond, A. Safford, H. Sakulas,the staff at Wau The collection of court objects by P. lawesii is EcologyInstitute and Museum of Vertebrate Zoology, similar to the collection of bower decorations in and the PapuaNew Guineans,Diro, Herean, Iling. and bowerbirds in that both behaviors involve ma- Buka for assistance,support, and discussions.J. Brad- bury, R. Payne, F. Pitelka, and R. Schodde imoroved nipulation of objects by males that display ter- the paper with their comments and criticisms -and S. restrially. Gilliard (1963, 1969) suggestedthat Rohwer alerted us to important references.This paper the evolution of bower building arose through is contribution 12 of Ecology ResearchAssociates. COURT OBJECTS BY LAWES’ PAROTIA 545

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