Cultural Diversification in the Flight Call of the Ringneck Parrot in Western Australia ’

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The Condor 102:905-910 Q The CooperOrnithological Society 2MM

CULTURAL DIVERSIFICATION IN THE FLIGHT CALL OF THE RINGNECK PARROT IN WESTERN AUSTRALIA ’

MYRON C. BAKER Department of Biology, Colorado State University,Fort Collins, CO 80523, e-mail: [email protected]

Abstract. I investigated geographic variation in a ties, the Twenty-eight Parrot (B. z. semitorquatus)oc- parrot vocalization to obtain an understandingof cul- cupies the southwestern comer of WA, whereas the tural population differentiation and exchange-between nominate Port Lincoln Parrot (B. z. zonarius)occupies hvbridizing taxa. The flight calls of Rinaneck Parrots the south central portion of WA and extends eastward (Barnard& zonarius) w&e tape record:d in Western into South Australia (Higgens 1999). In a broad zone Australia within and outside the zone of overlap and of overlap and hybridization, including the Perth area hybridization between the Port Lincoln (B. z. zonarius) and a portion of the wheatbelt region of WA, these and Twenty-eight (B. z. semitorquatus)subspecies. two forms occur together with obvious hybrids and Measured variablesdistinguished the Twenty-eight call backcross phenotypes (Serventy and Whittell 1962, from those in the overlap populations.Although birds Fisher 1970). In the zone of overlap and hybridization in typical Twenty-eight plumage were present in the within 50 km of Perth, I identified visually the char- overlap zone, no Twenty-eight flight calls were found, acteristic plumage phenotypes of both B. z. semitor- suggesting convergence by immigrants. Populations quatus (hereafter semitorquatus)and B. z. zonarius within the hybrid zone also were acoustically differ- (hereafter zonarius) as well as various intermediate entiated as dialects associatedwith roosting areas.Ob- plumages suggestinghybridization. servationson the social behavior of the birds indicated Naturalists had noticed previously that the “call that this call functions in coordination of movements notes” of semitorquatusand zonarius sound different of the mated pair. Roost-specific dialects might aid (Serventy and Whittell 1962), and field guidesmention pairs in finding each other in the event of separation it as well (Pizzey 1980). Thus, my first objective was during the day’s foraging activity. to describe differences in these calls of birds in the semitorquatusdistribution compared to those in the Key words: Bamardius zonarius, dialects, &ht Perth area overlap zone. My second objective was to call, hybrid zone, RingneckParrot, social behavior. determine whether the populationsexhibited vocal dialects within the overlap zone. Although parrots are widely known to be vocal leam- ers, field studies of acoustic signals of this group are METHODS rare. Dialects, a frequent consequenceof vocal leam- ing, have been describedin a large number of songbird STUDY AREAS species (oscine passerines),yet of the 332 parrot spe- From 1 March through 30 May 1999, I tape-recorded cies world-wide (Forshaw 1977), in only one case has vocalizations of the Ringneck Parrot at five sites in documentation of vocal dialects been published Western Australia (Fig. 1). In Perth, I recorded in (Wright 1996). Dialects in two other parrot speciesare Kings Park, adjacent to the Swan River, and in Bold implied in verbal descriptionsby Nottebohm and Not- Park, 4.8 km northwest of Kings Park. Recordings tebohm (1969) and Saunders(1983). The cultural dif- were also made along a 2-km segment of the Helena ferentiation represented by dialects in learned com- Valley Road adjacent to Gooseberry Hill National munication signalsraises questions about how the geo- Park, 21 km west and slightly north of Kings Park, graphic differences are established and what, if any, and in Yanchep National Park, 50 km north and slight- functional significancemight be attributedto such cul- ly west of Kings Park. These four sites will be referred tural markers (Baker and Cunningham 1985). to as the Perth area sites. A fifth recording site was I studied geographic variation in a vocalization of along Donnelly Road and Kevill Road West near Mar- the Ringneck Parrot, Bamardius zonarius, in Western garet River, approximately 225 km south and some- Australia (WA). A morphologically distinct subspe- what west of Kings Park. The Perth area sites lie within the hybrid zone, whereas the Margaret River site includes only semitorquatus. i Received 15 February 2000. Accepted 19 July I also examined a few calls recorded near Green- 2000. bushes,WA, 90 km east of Margaret River in the sem-

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TABLE 1. Comparison of flight calls (_Zf SE) of Ringneck Parrots in the Perth area (n = 16) and at Margaret River (n = 17). Tabled values are measurementstaken on seven acoustic variables. Significant overall heterogeneity was found between locations,and all pairwise comparisonsfor each variable were significantlydifferent.

Variable Perth Area Margaret River 1st note frequency range (Hz) 1,243 ? 110 677 t 34 1st note mid-frequency (Hz) 2,604 2 49 2,175 2 23 1st note duration (set) 0.119 ? 0.006 0.142 t 0.007 Interval between notes (set) 0.056 t 0.004 0.129 2 0.006 2nd note frequency range (Hz) 618 t 44 279 2 38 2nd note mid-frequency (Hz) 2,841 ? 33 2,275 2 26 2nd note duration (set) 0.136 5 0.004 0.161 + 0.003

itorquatus range (J. Hutchinson, pers. comm.), and trails aided my mobility and undergrowth was often near Alice Springs, Northern Territory, east of the hy- sparseenough to allow easy passage.Sometimes such brid zone within the range of zonan’us. Neither the a pair would be alone for an hour or more as they Greenbushesnor Alice Springs sampleswere adequate moved about foraging and perching, but eventually for statisticalanalyses. they would join a small number of others for a time, PLUMAGE VARIATIONS and then the group would break up. At the roosting area in the late afternoon, many birds accumulated, B. z. zonarius is bright green with a black head, bluing on the cheeks, a bright yellow collar (hence “ring- spentthe night, and ranged outward from the roost area neck”), and a sharply demarked bright-yellow belly. the next morning. B. z. semitorquatus differs in being all-green below The most common call recorded was termed the and possessing a bright-red frontal band above the flight call because it was produced mainly when one beak. This red band is sometimesreduced or absentin bird of a pair took flight and emitted this call while females. Intermediate plumages in the hybrid zone the other bird followed, itself often calling as well. were most noticeable in the differing amountsof yel- Sometimesa bird continueduttering the flight call after low/green feathering in the belly and in the amounts it landed and was answered by the following bird as of red feathering in the frontal band (Higgens 1999). it joined the first. The same call was given whether All three classesof plumage were seen in all the Perth the birds took flight spontaneously(no obvious cause) area recording sites. or if disturbedby human, dog, or automobile and took BEHAVIOR AND VOCALIZATIONS flight as a result. This call has been referred to by others as a contact call, flight call, or alarm call (For- The fundamental year-round social unit of the Ring- shaw 1964, Pizzey 1980, Higgens 1999). My obser- neck Parrot is the mated pair (Immelmann 1968, Fisher 1970). The pair travels and forages together,but com- vations suggestedthat this call is a within-pair signal monly consortswith small numbers of conspecificsin employed in coordinating movements and indicating loose and fluid groupings during the day. In the non- location if separated,as suggestedalso by the obser- breeding season, for the areas in which I conducted vations of Immelmann (1968). Random sampling of my study, ringnecks usually assembled in traditional calls for measurementand inclusion in statisticalanal- roosting areas in the late afternoon. During the day, I ysis insured that calls of mated pairs were not both was able to follow pairs for considerabletime, espe- included in the sample, except intentionally to illus- cially in Kings Park and Bold Park where numerous trate convergence.

TABLE 2. Comparison of flight calls of Ringneck Parrots recorded at four sites (n = 10 birds each site) in the Perth area. Tabled values are means _t SE of measurementstaken on seven acoustic variables. Significant overall heterogeneity was found among populations,and pairwise comparisons”revealed significant differences between sites for individual variables.

Variable Kings Park (KP) Bold Park (BP) Helena Valley (HV) Yanchep(YA) 1st note frequency range (Hz) 1,378 + 81 1,101 ? 78 926 ? 93 866 ” 57 1st note mid-frequency (Hz) 2,651 2 29 2,699 ? 47 2,822 ? 70 2,654 2 43 1st note duration (set) 0.092 ? 0.004 0.080 t 0.003 0.106 f 0.003 0.142 5 0.003 Interval between notes (set) 0.041 t 0.003 0.059 2 0.004 0.050 * 0.003 0.072 t 0.006 2nd note freq. range (Hz) 699 2 43 585 ? 35 605 2 25 528 ? 35 2nd note mid-frequency (Hz) 2,963 2 34 2,875 ? 22 2,884 t 34 2,882 ? 23 2nd note duration (set) 0.125 2 0.002 0.117 ? 0.006 0.133 ? 0.004 0.136 ? 0.004

aSignificant differences between samples for: 1st note frequency range: KP-BP, KP-HV, BP-YA; 1st note mid-frequency: KP-HV, HV-YA; 1st note duratmn: KP-HV, KP-YA, BP-HV, BP-YA, HV-YA; Interval between notes: K&-BP, KP-YA, HV-YA; 2nd note frequency range: KP-BP, KF-YA; 2nd note mid-frequency: KP-BP, KP-YA; 2nd note duration: BP-HV, BP-YA. SHORT COMMUNICATIONS 907

of the major pair, but not all individuals possessthis introductory note. Therefore, all measurementsused in statisticalanalyses were made on the two major notes. This resulted in seven variables: the frequency range, mid-frequency, and duration of each of the two notes, and the interval between them. Multivariate analysis of variance (MANOVA, Harris 1975) was applied to v the seven variables. Pairwise comparisonsamong populations were made for each variable separately by Fisher’s LSD, which adjusts for the experimentwise T error rate (Carmer and Swanson 1973).

RESULTS Audible propertiesof the flight call were easily distin- guishedbetween the Perth area ringnecks and those of semitorquatusat Margaret River (Fig. 2, 3). Record- ings of ringnecks made at Greenbushes,WA, within the distributionof semitorquatus,also closely followed the structureof those recorded at Margaret River (Fig.

HV 3, bird A). The different-sounding call of semitorquatus is readily discriminatedby ear and does not require instrumentalanalysis for identification by an observer. I spent several hundred hours recording birds of a number of different species in these populations and heard several thousandRingneck Parrot flight calls. I never heard a semitorquatusflight call in the Perth area l’remantle or a zonarius flight call in the Margaret River population. Unpublished sonograms (Rex Buckingham, Bird Observers Club of Australia) of flight calls recorded from ringnecks near Alice Springs, Northern Territory, east of the overlap zone, are similar to ringneck calls from the Perth area. FIGURE 1. Sampling locations of Ringneck Parrot To examine the statisticaldifferences in the acoustic vocalizations in Western Australia. Sites within the features of the Perth area birds compared to Margaret zone of overlap and hybridization of Barnardius zon- River semitorquatus,I randomly selected four calls arius zonarius and B. z. semitorquatusare: KP (Kings from each of the four Perth area locations to represent Park), BP (Bold Park), HV (Helena Valley), YA (Yan- a group (n = 16) to compare to all the calls recorded chep). Site MR (Margaret River) is west of the overlap at Margaret River (n = 17; Table 1). Comparing the zone and comprisesonly B. z. semitorquatus. Margaret River birds to those of the Perth area for the set of seven variables by MANOVA, the two samples were significantly different (Wilks’ lambda = 0.12, P RECORDINGAND SPECTROGRAPHICANALYSES < 0.001). Multiple comparisonstests (Fisher’s LSD) Vocalizations were recorded on a Marantz cassette showed that all seven measuredfeatures of these calls deck (PMD 201) at a tape speed of 4.8 cm secl em- differed between the two samples. ploying a Sennheisermicrophone (model ME62) and In the Perth area samples,I visually identified, and amplifier mounted in a 45cm diameter parabolic re- in some cases recorded, birds presenting the full red flector. Spectrographicanalyses were conducted with frontal band and green belly of semitorquatus.There Kay Elemetrics MultiSpeech and RealTime Spectro- also was an abundanceof typical zonarius plumages gram operating on a computer configured with an au- as well as those birds with hybrid plumage features. dio card and software. Analog-to-digital conversion There were, however, no cases of flight calls that cor- was 16 bit with a 44.1 kHz sampling rate. Spectro- respondedto the acousticfeatures of the Margaret Riv- grams were producedwith a 512 point (126 Hz) trans- er birds. form and Hamming analysis window. Measurements Microgeographic variation occurred in the flight of frequency and time characteristicsof the call were calls in the Perth area samples.I randomly selected 10 made on the computer screen using the cursor-gener- calls from each of the four Perth area recording sites. ated values. Only one call per bird was used in the MANOVA results on these samnles revealed sianifi- analysis. cant heterogeneity among populations for all seven acousticvariables (Wilks’ lambda = 0.04, P < 0.001; STATISTICALANALYSES Table 2). Pairwise comparisons(Fisher ’s LSD) among All flight calls have two different major notes that oc- populations showed consistent differentiation of the cur as a pair. These pairs of notes are most often pro- flight call variables, suggesting that each population duced in strings of variable number and at variable could be referred to as a different dialect. In addition rates of delivery. In some populations, a brief note to the mensuralfeatures of the flight calls, certain pop- occurs in front of and nearly attachedto the first note ulations differed in the general shapesof the notes and 908 SHORT COMMUNICATIONS

KingsPark 1ooms 5

B 0 -II-

Bold Park

0 III FIGURE 2. Sound spectrogramsof flight calls representativeof Ringneck Parrots in the Perth area samples. Brackets on the abscissa enclose different individuals. Included are examples from birds from the Yanchep population that were in B. Z. semitorquatusplumage, the plumage typical of Margaret River ringnecks. Also included are the calls of a mated pair (Rings Park, A and B), indicating convergent features that may imply individual recognition.

in the presence or absence of the introductory note ner of Western Australia (Serventy and Whittell 1962). (Fig. 2). A period of aridity isolated this population and differentiation occurred over time. These events were fol- DISCUSSION lowed by moistening of the environment and a second The flight calls of B. z. semitorquatusat Margaret Riv- spreadof Bamardius into Western Australia. Thus en- er and Greenbushesdiffer from those of birds in the sued secondarycontact leading to the existing zone of Perth area samples, the latter comprising individuals overlap and hybridization (Serventy and Whittell in B. z. zonariusplumage, semitorquatusplumage, and 1962, Fisher 1970). hybrids of these two morphs. In addition, there are Although it is clear that more samples are needed population differences in acousticfeatures of the flight from the entire range of B. zonarius, the data are suf- calls among the four samplesfrom the Perth area, each ficient to raise several questions for further study. sample location correspondingto a major roosting as- Why, for example, do all the birds in the zone of hy- semblage. bridization, at least in the Perth area sites I sampled, The Margaret River birds are all phenotypically possess relatively similar acoustic features distinctly semitorquatus,as are other populationsof the extreme different from those of semitorquatus?One possibility southwestarea (Fisher 1970). They are thought to de- is that upon secondary contact, and since then, rela- rive from a late Pliocene or early Pleistoceneinvasion tively small numbers of semitorquatusdispersed into from the Bassianregion of easternAustralia acrossthe more dense populations of zonarius and altered their southernedge of the continent into the southwestcor- vocalizationsto convergeon the local acousticfeatures SHORT COMMUNICATIONS 909

Margaret River 1 OOms

A 1I I I I

FIGURE 3. Sound spectrogramsof flight calls representative of Ringneck Parrots of Margaret River B. z. semitorquatus.Bird A, lower right, is from a recording of B. z_.semitorquatus made by John Hutchinson 90 km east of Margaret River near Greenbushes,Western Australia. of the flight call encounteredthere. The characteristic are mostly restricted to stream-beds (Seddon 1972). flight call of semitorquatusis lost from the hybrid zone Therefore, the moist and heavily forested habitat of even though morphotypesof the subspeciesare present semitorquatusmay inhibit a westward movement of in substantialnumbers. There may be several contrib- zonarius,but the prevalence of the rich food resources uting factors to such a model of one-way cultural ex- of cereal crops in the wheatbelt may attract semitor- change and extinction of the semitorquatusform of the quatuseastward into the dryer habitat. flight call in the zone of overlap. First, there may be In addition, a south-to-northdispersal corridor along a semi-permeablehabitat barrier that inhibits zonarius the Swan Coastal Plain for semitorquatusapparently from entering the range of semitorquatusbut not vise exists as a consequenceof the jarrah, marri, and tuart versa. The western border of the hybrid zone corre- (E. gomphocephala)forest tree species. Tuart, for ex- spondsto a belt of jarrah (Eucaplytusmarginata) for- ample, is limited to the Swan Coastal Plain and ex- est mixed with marri (E. calophylla), which has been tends from the Vasse district deep in the distribution implicated in limiting the westward spreadof a number of semitorquatusto its limits at approximately Yan- of bird species (Serventy and Whittell 1962). To the chep in the north (Seddon 1972). Together with jarrah west and south is increasingly moist habitat and, cor- and marri in the Swan Coastal Plain, these forest spe- respondingly, an increasing prevalence of the tall for- cies may provide a passageway.This mix of eucalypts ests of karri (E. diversicolor). East of the jarrah belt is well represented in Kings Park and in Bold Park the habitat is more Savannah-like,and following the areas, for example. clearing of native vegetation has been turned over to A second issue involves the advantagesfor an im- farming, thus constituting the western wheatbelt of migrant to adopt the flight call features of the local Australia. Here, trees of the southwesteucalypt forests area. A possible advantageof flight call convergence 910 SHORT COMMUNICATIONS in local populations, and the consequentgeographic inson and the Bird Observers Club of Australia for differentiation, can be hypothesized by consideration allowing me access to Ringneck Parrot recordings. of the use of the flight call in relation to the social Thanks also to the three reviewers of the manuscript structureof these birds. Parrotsare typically long-lived for their advice. with long-term pair bonds, pairs remaining together year round (Saunders 1983, Rowley 1990), and peren- LITERATURE CITED nial pair bonds in long-lived birds translateinto higher BAKER,M. C., AND M. A. CUNNINGHAM.1985. The reproductive success(Rowley 1983). In Ringneck Par- biology of bird song dialects. Behav. Brain Sci. 8: rots, the flight call is the most frequent call produced 85-133. and is performed in the context of coordinatingmove- CARMER,S. G., AND M. R. SWANSON. 1973. An eval- ments and maintaining pair contact. Birds converge to uation of ten pairwise multiple comparisonspro- a night roosting area from which they range out in the ceduresby Monte Carlo methods.J. Am. Stat. As- morning. In and near the general roosting area are nest soc. 68:66-74. sites of some of the pairs, as I judged by occasionally FISHER,C. D. 1970. Geographic variation and evolu- seeing pairs linger in the vicinity of and enter such tion in the Australian ringneck parrots (Barnar- cavities. All my recording sites were based upon roost- &us). Ph.D. diss., Univ. Michigan, Ann Arbor, ing aggregationswhere I could record birds congre- MI. gating in the late afternoon and dispersing from the FORSHAW,J. M. 1964. The parrots of Australia. Avi- area in the mornings. Movements to and from such culture Magazine 70:59-68. roost areaswere gradual, which sometimesallowed me FORSHAW,J. M. 1977. Parrots of the world. T E H. to follow pairs and record flight calls when given. Publications,Neptune, NJ. This general description of roosting congregations HARRIS,R. J. 1975. A primer of multivariate statistics. and daily movementsof pairs suggestsa possiblefunc- Academic Press, New York. tion of the locale-specific features of the call. If the HIGGENS,P J. [ED.]. 1999. Handbook of Australian, members of a pair are faithful to a roosting locale but New Zealand and Antarctic birds. Vol. 4: Parrots become separatedduring the day and lose contactwith to Dollarbird. Oxford Univ. Press. Melbourne. each other while ranging out from the roost area, then IMMELMANN,K. 1968. Australian parakeets.A. Ziem- following a roost-specific flight call back to the even- sen Verlag, Wittemberg, Germany. ing aggregation would enable the pair to regain con- NOTTEBOHM.E. AND M. NO~TEBOHM.1969. The carrots tact. Upon reaching the roosting location there may be of Bush Bush. Anim. Kingdom 72: 19-23. I a traditional place where the pair spendsthe night, or PIZZEY,G. 1980. A field guide to the birds of Australia. they may be able to locate one another from specific Collins, Sydney. and convergent flight call features that are shared by ROWLEY,I. 1983. Re-mating in birds, p. 331-360. In the pair (e.g., Fig. 2, birds A and B; Saunders 1983). I? Bateson [ED.], Mate choice. Cambridge Univ. Thus, the roost-specific properties (dialect) of flight Press, Cambridge. calls could provide an acoustic map, probably operat- ROWLEY,I. 1990. Behavioural ecology of the Galah ing in concert with landmarks, which enable a pair to Eolophus roseicapillusin the wheatbelt of West- regain their association. ern Australia. Surrey Beatty and Sons, Chipping Norton, Australia. I thank Bob Black and Mike Johnson for making SAUNDERS,D. A. 1983. Vocal repertoire and individual my sabbatical stay at the University of Western Aus- vocal recognition in the short-billed white-tailed tralia possible. Win Bailey, Dale Roberts, Jean Ban- black cockatoo, Calyptorhynchusfunereus latiros- ning, Kerry Knott, Brenda Loney, Wally Gibb, and tris Carnabv. Aust. Wildl. Res. 10:527-536. Bert and Barbara Main were more helpful than I had SEDDON,G. 1972. Sense of place: a response to an a right to expect, and their friendship remains a high environment, the Swan Coastal Plain, Western point of my year. Bob Black gave me accessto com- Australia. Univ. Western Australia Press, Perth. puting equipment and provided considerablehelp and SERVENTY,D. L., AND H. M. WHITTELL.1962. Birds of discussion. Helpful advice was received from Ian Western Australia. PattersonBrokensha, Perth. Rowley and Mike and Leslie Brooker. Susanand Rog- WRIGHT,T E 1996. Regional dialects in the contact er Davis were generoushosts and guides at Margaret call of a parrot. Proc. R. Sot. Lond. B 263:867- River. I also appreciatethe cooperationof John Hutch- 872.