VOL. 16 (2) JUNE 1995 49

AUSTRALIAN WATCHER 1995, 16, 49-57

Great and Spotted nucha/is and C. maculata (Ptilonorhynchidae) Sympatric and Interacting at Each Other's Bowers

by CLIFFORD B. FRITH!, DAWN W. FRITH1 and MARNIE McCULLOUGH2

1'Prionodura', P.O. Box 581, Malanda, Queensland 4885 2 'Bruslee', P.O. Charters Towers, Queensland 4820

Summary An area of sympatry between bower-attending Great and Spotted Bowerbirds Ch/amydera nucha/is and C. maculata (Ptilonorhynchidae) in northern Queensland is described. Great Bowerbirds maintained bowers within little more than a kilometre of riverine vegetation and Spotted Bowerbirds mostly beyond this and in more arid habitat. The two species meet where the two favoured habitats abut and thus do so linearly either side of the major river system of the study area. The two closest pairs of bowers of each species were 1020 m and 1200 m apart. Spotted Bowerbirds visited bowers of, and displayed to, Great Bowerbirds, and the latter species visited bowers of the former. Photographic evidence is presented. Mean nearest-neighbour distance of 10 active Spotted bowers was 870 m (range 645-1170 m) and of nine bowers was 1370 m (range 825-1920 m). Introduction Records of sympatry between congeneric species of polygynous and bower-building bowerbird species (Ptilonorhynchidae) are few . The few records of sympatry between congeneric Australian bowerbird species involve only odd vagrant individuals within the peripheral range of another. In the case of polygynously breeding bowerbird species, sympatry of bower-attending congeneric males is unknown. Instances of sympatry are of interest as they may provide opportunities to examine the function of bower form, the influence of sympatry upon bower structures and upon the behaviour and reproduction of individuals and populations of bird taxa involved (Gilliard 1969, Frith 1970, Schodde & McKean 1973). The few such records are therefore briefly reviewed here. Gilliard (1969) observed two individual Yellow-breasted Bowerbirds Chlamydera lauterbachi visit an active bower of a Fawn-breasted Bowerbird C. cerviniventris at Aiome on the Ramu River in northern Papua . One of the Yellow-breasted was seen to tear aggressively at the bower and to display to a female Fawn­ breasted Bowerbird. Bailey (1992) also noted sympatry in these two species on the Ramu River. It is probable these two bowerbirds are sympatrically breeding congeneric species in the Ramu River valley, but a bower of the former remains to be found there. These two bowerbirds have also both been recorded in the Aiyura Valley, Papua New Guinea, at c. 1700 rn above sea level (Doyle et al. 1981). Frith (1970) cited historical records of apparent sympatry between the otherwise mostly altitudinally isolated New Guinea Streaked Bowerbird Amblyomis subalaris and Macgregor's Bowerbird A. macgregoriae. The reliabilty of these data was questioned (LeCroy 1971, Bell 1972), but Schodde & McKean (1973) then reported the two species together in some areas and described a specimen suggestive of hybridisation between them. A second probable specimen between these two species was discovered as the present paper went to press (CBF & DWF unpubl. data). Roberts (1975) recorded a single Great Bowerbird C. nuchalis 'in open eucalypts along Portland Roads Road', an area of Cape York Peninsula, Queensland, where AUSTRALIAN 50 FRITH, FRITH & McCULLOUGH BIRD WATCHER

Figure 1. Map of continental showing approximate distributional range of Great and Spotted Bowerbirds, the black area indicating where they overlap (after Blakers et al. 1984).

Fawn-breasted Bowerbirds reside. A Great Bowerbird was seen on 6 June 1983, several kilometres inland of Portland Roads, where Fawn-breasted Bowerbirds were common (Ray Pierce pers. comm.). A single vagrant Great Bowerbird was seen on 27 May 1987 at Trephina Gorge, N.T., where the C. guttata is a common resident; a recent cylone may have been responsible for the presence of this lone Great Bowerbird (Graham & Graham 1990). CBF and DWF have seen a Great Bowerbird near the Heathlands National Park ranger's residence in an area where the Fawn-breasted Bowerbird is resident (Irtgram 1993). The Great Bowerbird is by far the most extensively distributed bowerbird in Australia, being found throughout most of the tropics north of 20 os and a little to the south in the east. The C. maculata inhabits much of central New South Wales and Queensland north to the Townsville area in the east, and westward across Queensland to just into the Northern Territory. In the extreme north of its eastern and central Queensland range, non-breeding Spotted Bowerbirds have been reported within the range of the Great Bowerbird (Figure 1). For details of distributions and habitats of these bowerbirds see Gilliard (1969), Cooper & Forshaw (1977) and Blakers et al. (1984). The two species are geographical representatives of the Chlamydera superspecies. Defining points at which the Great and Spotted Bowerbirds most closely meet or replace each other in tropical Queensland has long interested ornithologists (Gilbert 1844 in Chisholm 1945, Elsey 1856 in Macdonald & Colston 1966, Marshall 1954). Parker (1968) reported them as sympatric, having seen a single Great Bowerbird at 'Glendower', on the Flinders River, near Hughenden, Queensland, where the Spotted Bowerbird was moderately common in riverine forest and adjacent woodland. In northern Queensland Andree Griffin (in litt.) observed a vagrant Great Bowerbird at Paluma, within the clearing in upland rainforest atop the Seaview Range occupied by the village, on 12 April 1989, and a vagrant Spotted Bowerbird there on 5 June 1993. Both birds were out of their species' known range and habitat. VOL. 16 (2) JUNE 1995 Great and Spotted Bowerbirds Sharing Bowers 51

N t 13

2 1 5 3 0 10 7 9 4 8 6 12

------'\:c.\\c.e

kilometres

Figure 2. Map showing area of sympatry between Great and Spotted Bowerbirds to south­ south-east of Charters Towers, north Queensland. Numbers = Spotted Bowerbird bowers; letters = Great Bowerbird bowers; square = location of homestead buildings. The extensive areas lacking bower plots were not searched. Note Spotted bower 9 replaced bower 8, and bower 15 was replaced by Great bower D.

Blakers et al. (1984) presented maps of plotted sightings of both Great and Spotted Bowerbirds, indicating both to be present over a band of tropical Queensland some 600 km in length and 100 km broad, west-north-west of Proserpine and Mackay and extending to the Northern Territory border (Figure 1). These records apparently involved non-breeding (i.e. no bowers or nests reported) Great Bowerbirds at the extreme south of the species' range and into the range of the Spotted Bowerbird. There have been no records of breeding populations of any two congeneric bowerbird species being truly sympatric, that is with active bowers of both species within the same area.

Methods In an attempt to discover an area of sympatry between the Great and Spotted Bowerbirds, CBF and DWF drove south-east from Charters Towers, Queensland, 20 °05 'S, 146 °16 'E (where the Great Bowerbird is common), to 'Cardigan' and 'Warrawee' stations on the Burdekin River c. 43 km from Charters Towers in September 1984. Here they found only Great Bowerbirds and their bowers. They then travelled to 'Bruslee', c. 100 km south-south-east of Charters Towers, where they first met MM who informed them that although all bowers she knew of on the McCullough property were of Spotted Bowerbirds, she had once seen a Great Bowerbird in the area. MM subsequently located a Great Bowerbird's bower (Figure 2, bower F) on the west bank of the Cape River. In September 1987 MM saw a Spotted Bowerbird visit this Great Bowerbird bower, where it spent two minutes within the avenue examining decorations before the calls of the returning Great Bowerbird caused it to leave. AUSTRALIAN 52 FRITH, FRITH & McCULLOUGH BIRD WATCHER

As a result ofMM's latter observation, CBF and DWF made visits to 'Bruslee' during September­ November 1988, March-April and September 1989, July and September 1990 and August-September 1991. An extensive area of the property to either side of the normally dry Cape River bed, and immediately about and to the west of the homestead about the dry bed of Dish Creek, was searched for bowerbirds and their bowers. Twenty-seven Spotted Bowerbirds were captured near bowers and banded with metal bands (Australian Bird Banding Scheme) and 19 of them also with plastic colour bands. Three Great Bowerbirds were caught and metal-banded before release. Habitat away from the influence of tall dense riverine woodland on the Cape River was low open woodland dominated by and eucalypts Yiith vine thickets where the Spotted Bowerbird was found nesting (Frith & Frith 1990). The understorey of this open woodland was dominated by Currant Bush Carissa lanceolata, beneath which most bowers of both species were found . Canvas hides were erected near several bowers, notably Spotted bowers 5, 10 and 12 and Great bowers A and F (Figure 2) and observations/photographs made at various times.

Results We located and plotted 16 active bowers of the Spotted and nine of the Great Bowerbird (Figure 2). Although nine of the Spotted Bowerbird bowers were typical of the species in being almost, if not exclusively, of grass stems with their broad avenue floor at or almost at ground level (Plate 13, front cover), four were grass­ stem structures with modest to most substantial stick foundations to the lower outer walls with an avenue floor conspicuously above ground level (Plate 14). A minimum of nine concurrently active Spotted Bowerbird bowers was found in an area of little more than 7 km2 • The locations of all active Spotted and Oreat Bowerbird bowers are indicated in Figure 2 as a result of plotting them onto high­ quality aerial photographs. It should be noted that Spotted Bowerbird bower 9 replaced bower 8 in consecutive seasons, and that bower 15 was replaced by Great Bowerbird bower D in the 1991 season. No two Spotted Bowerbird bowers in the homestead area were more than 1.2 km apart, most being (1 km apart, and the mean nearest-neighbour distance of 10 was 870 m (range 645-1170 m). From hides near bowers, we witnessed a few instances of bower destruction and decoration theft, although we did not make systematic watches for this behaviour. We consider it likely that males at bowers in our study area could hear each other call as, at least under favourable conditions, in many cases we could ourselves do so. Although we did not search for bowers to the east and west of those Great Bowerbird bowers found either side of the Cape River, we note that the mean nearest-neighbour distance of the nine active Great Bowerbird bowers we did plot (Figure 2) was 1370 m (range 825-1920 m). Active Great Bowerbird bower A was found to be 1200 m from active Spotted Bowerbird bower 12 (Figure 2). During hide watches at bower A, we saw the previously colour-banded, crested and presumed male Great Bowerbird owner, an uncrested immature-plumaged and presumed male Great Bowerbird, and three or four, presumed male, Spotted Bowerbirds regularly frequent the structure, bring sticks, grass stems and decorations to it and paint its inner walls. Spotted Bowerbirds displayed both to conspecifics and to Great Bowerbirds (see Plate 16). This bower was typical of the Great Bowerbird except that its inner walls were substantially 'lined' with grass stems (Plate 17). Both the Great Bowerbird owner and several Spotted Bowerbirds added grass to the inner avenue walls. Interestingly, the male Great Bowerbird owning bower A appeared quite content to watch Spotted Bowerbirds attend and build/decorate/paint his bower or to be displayed to by one or more of them whilst himself maintaining his structure. The only time the male Great was seen to resent the presence of the Spotteds was when he was displaying to a conspecific visitor (presumed female), when he attempted to chase them off between his courtship posturings. While the bower-owning Great VOL. 16 (2) JUNE 1995 Great and Spotted Bowerbirds Sharing Bowers 53

An adult, presumed male, Spotted Bowerbird in bower 5 (see Figure 2). Note that this bower has substantial outside wall bases of sticks with grass stems within them and that the avenue floor is above ground level (see text). Plate 14 Photo: C. & D. Frith

A presumed adult male Great Bowerbird visiting, and adding material to, Spotted Bowerbird bower 12 (see Figure 2). Plate 15 Photo: C. & D. Frith An adult, presumed male, Spotted Bowerbird courting the presumed male Great Bowerbird owner of bower A (see Figure 2). Note grass-stem lining to this bower was seen to be placed there by birds of both species. Plate 16 Photo: C. & D. Frith Bowerbird displayed to a conspecific, one or more Spotted Bowerbirds showed intense interest by standing near the displaying male Great Bowerbird to watch closely (Plate 17). A Spotted Bowerbird occasionally joined the courting male Great in his 'peripheral display' (ofWarham 1962) run around the bower. We did not see a Great Bowerbird display to a Spotted but did see one in, and adding material to, Spotted Bowerbird bower 12 (Plate 15). Spotted Bowerbirds were seen to attend, build and display at Great Bowerbird bowers B and C (see Figure 2) where they were also mist­ netted and banded before release. Spotted Bowerbird bower 14 was attended during the 1988-1993 seasons, when 1020 m from active Great Bowerbird bower B, but was defunct in the following season when Great Bowerbird bower C was found, 210 m distant, to be attended by a Great Bowerbird owner and at least one Spotted Bowerbird visitor. Great Bowerbird bower B was located 1920 m from the nearest known active Spotted Bowerbird bower during the 1993 season, when Spotted Bowerbirds were seen to attend the former bower in its owner's absence. A bower of a Spotted Bowerbird (bower 15, Figure 2) found to be on the west bank of the Cape River in 1989 and 1990 was structurally remarkable. This bower, although constructed of )90% grass stems, was extremely narrow between the inner walls, was as long as the longest Great Bowerbird bower we have seen (c. 1 m), and had the floor of either end of the bower avenue approximately 15 em above ground. Thus, whilst consisting of materials typical of Spotted Bowerbirds' bowers, the size, shape and form of this structure were typical of Great Bowerbirds' bowers. Unfortunately this bower was beneath the centre of an extensive, dense and low berry bush that prevented close examination or photography. In 1991 the bower at this site VOL. 16 (2) JUNE 1995 Great and Spotted Bowerbirds Sharing Bowers 55

A presumed adult male Great Bowerbird (centre) courtship-displaying to a conspecific standing inside bower A (see Figure 2) as an adult, presumed male, Spotted Bowerbird (foreground) watches events intensely. Plate 17 Photo: C. & D. Frith proved, however, to be built exclusively of sticks and to be attended by a Great Bowerbird (bower D) and to remain so to the 1993 season.

Discussion · Some stick component to Spotted Bowerbirds' bowers may be found (Gilliard 1969, Chaffer 1984, Borgia & Mueller 1992, our pers. obs.), particularly at the outer base AUSTRALIAN 56 FRITH, FRITH & McCULLOUGH BIRD WATCHER of the avenue walls, and is possibly indicative of a bower of younger, or less experienced, males. In view of the sympatry in this area it is possible that males might be influenced by bowers of the sympatric congeneric species. Collias & Collias (1984) discussed the fact that the type of nest materials that young birds are raised with determines the type of materials the birds select for nest-building later in life. Presumably, then, the bowers young male bowerbirds frequent could influence the way they construct their own bowers. Chaffer & Waterhouse (1987) and Neville (1988) reported a unique instance of a male Spotted Bowerbird spending several years completely outside the normal range of its species, at Tuggerah near Gosford, N.S.W., where Satin Bowerbirds Ptilonorhynchus violaceus were common. This Spotted Bowerbird built a substantial bower of 'fine sticks, casuarina needles and grass stems' and decorated it with numerous blue objects. Male Spotted Bowerbirds do not normally use blue objects as bower decoration, whereas Satin Bowerbirds typically do (Gilliard 1969, Cooper & Forshaw 1977, Borgia & Gore 1986). Thus, this misplaced Spotted Bowerbird's bower appeared to exhibit the influence of another bowerbird species with respect to materials, construction and decorations. It is well established that it requires considerable experience gained at bowers of older males for Satin Bowerbirds to aquire the skills necessary to construct a high­ quality bower that will impress females (Borgia 1985). There is no doubt that, at least in the , females do choose to mate with males exhibiting a better­ quality bower and more numerous blue decorations, and presumably thereby influence males in their bower building and choice of decorations (Borgia 1985, Borgia & Gore 1986). Our observations of bowers of sympatric Great and Spotted Bowerbirds, and those of a misplaced male Spotted Bowerbird within the range of Satin Bowerbirds (Chaffer & Waterhouse 1987, Neville 1988), indicate that inter-male influence upon bower form and decoration exists. This was apparent here in Spotted Bowerbird bower 15 (which, although of grass stems, was the size and shape of a Great Bowerbird bower) and in Spotted Bowerbird bowers _[including those near to (bower 16) and distant from (bower 2) Great Bowerbird bowers] that were predominantly of sticks with avenues narrower than those typical of their species. Decoration stealing and bower destruction between rival males were found to be much less common in a Spotted Bowerbird population than in a Satin Bowerbird one (Borgia 1985, Borgia & Mueller 1992). This was attributed to the larger inter-bower distances between Spotted Bowerbirds' bowers recorded by Borgia & Mueller (1992) who thought these also prevented the males from hearing one another's calls from their bowers. The 11 bowers of Spotted Bowerbirds about the 'Bruslee' homestead were, however, at a density twice that of the most densely distributed (mean nearest­ neighbour distance of just under 2 km) of 12 bowers in south-central Queensland (Borgia & Mueller 1992). Thus, rates of decoration stealing and bower destruction between rival male Spotted Bowerbirds may vary between populations. During this study Great and Spotted Bowerbirds were found to be sympatric at each other's bowers over a narrow north-south linear zone immediately to the west of the Cape River (Figure 2) and probably were also sympatric to the east of that river. In view of the extent of overlap in distribution of the two species (Figure 1), it is likely that other such areas of true sympatry exist in tropical Queensland.

Acknowledgements We thank Bob, Annette and Brian McCullough for making this study possible by providing much appreciated help, interest and hospitality in numerous ways. VOL. 16 (2) JUNE 1995 Great and Spotted Bowerbirds Sharing Bowers 57

References Bailey, S.F. (1992), 'Bird observations in lowland Madang Province', Muruk 5, 111-135. Bell, H.L. (1972), 'Altitudinal distribution of bowerbirds of the genus ', Emu 72, 34. Blakers, M., Davies, S.J.J.F. & Reilly, P.N. (1984), The Atlas ofAustralian Birds, Melborne University Press, Melbourne. Borgia, G. (1985), 'Bower quality, number of decorations and mating success of male Satin Bowerbirds (Ptilonorhynchus violaceus): an experimental analysis', Anim. Behav. 33, 266-271. --& Gore, M.A. (1986), 'Feather stealing in the Satin Bowerbird (Ptilonorhynchus violaceus): male competition and the quality of display', Anim. Behav. 34, 727-738. --& Mueller, V. (1992), 'Bower destruction, decoration stealing and female choice in the Spotted Bowerbird Chlamydera maculata', Emu 92, 11-18. Chaffer, N. (1984), In Quest of Bowerbirds, Rigby, Adelaide. --& Waterhouse, J.D. (1987), 'A new coastal record of the Spotted Bowerbird in New South Wales', Aust. Birds 21, 58-59. Chisholm, A.H. (1945), 'Birds of the Gilbert Diary. Part 2', Emu 44, 183-200. Collias, N.E. & Collias, E. C. (1984), Nest Building and Bird Behaviour, Princeton University Press, Princeton. Cooper, W.T. & Forshaw, J.M. (1977), Birds of Paradise and Bower Birds, Collins, Sydney. Doyle, G., Doyle, D., Stringer, M., Fabb, C., Sanderson, C., Foreman, V. & Marten, H. (1981), Birds of the Aiyura Valley, Department of Education, Papua New Guinea, Port Moresby. Frith, C.B. (1970), 'Sympatry of Amblyornis subalaris and A. macgregoriae in New Guinea' , Emu 70, 196-197. --& Frith, D.W. (1990), 'Notes on the nesting biology of the Spotted Bowerbird Chlamydera maculata (Ptilonorhynchidae)', Aust. Bird Watcher 13, 218-225. Gilliard, E.T. (1969), Birds of Paradise and Bower Birds, Weidenfeld & Nicolson, London. Graham, H. & Graham, D. (1990), 'A Great Bowerbird near Alice Springs, Northern Territory', Aust. Bird Watcher 13, 263. Ingram, G. (1993), 'Birds recorded on the Cape York Peninsula Scientific Expedition' , Cape York Peninsula Scientific Expedition Wet Season 1992 Report, vol. 2, 271-275, Royal Geographical Society of Queensland, Brisbane. LeCroy, M.K. (1971), 'Sympatry in bowerbirds of genus Amblyornis', Emu 71, 143. Macdonald, J.D. & Colston, P.R. (1966), 'J.R. Elsey and his bird observations on Gregory's overland expedition, Australia, 1856', Emu 65, 255-278. Marshall, A.L. (1954), Bower-birds -Their Displays and Breeding Cycles, Clarendon Press, Oxford. Neville, B. (1988), 'The strange case of Billy Bowerbird', Geo 10, 73-79. Parker, S. A. (1968), 'An instance of apparent sympatry between the Great Bowerbird and the Spotted Bowerbird', Emu 68, 222. Roberts, G. J. (1975), 'Additional species from the Iron Range area of Cape York Peninsula', Aust. Bird Watcher 6, 127-128. Schodde, R. & McKean, J.L. (1973), 'Distribution, and of the gardener bowerbirds Amblyornis spp. in eastern New Guinea with descriptions of two new subspecies', Emu 73, 51-60. Warham, J. (1962), 'Field notes on Australian bower-birds and cat-birds', Emu 62, 1-30. Received 18 October 1994 • Correction: In Frith et al. (1994, Aust. Bird Watcher 15, 314-319) the photographs for Plates 55 and 57 were accidentally transposed during the printing process.

Addendum: See also Borgia (1995), Emu 95, 1-12.