AUSTRALIAN 6 WATCHER

AUSTRALIAN BIRD WATCHER 1989, 13, 6-19

Miscellaneous Notes on the cerviniventris and C. lauterbachi (Ptilonorhynchidae) in Papua New Guinea

by C.B. FRITH and D.W. FRITH 'Prionodura', Paluma via Townsville, Queensland 4816

Summary Nests, a nestling and three bowers of the Fawn-breasted Chlamydera cerviniventris are described, and observations of parental nest attendance reported. Nests, eggs and bowers of Lauterbach's Bowerbird C. lauterbachi are described and observations of male and female behaviours at a bower reported. First descriptions of nestling, fledgling and juvenile Lauterbach's Bowerbird are given. The location of nests relative to bowers and seasonality of nesting of the Fawn-breasted and Lauterbach's Bowerbirds are reviewed.

Introduction The four or five Chlamydera bowerbird species (Ptilonorhynchidae) are unlike the other fourteen, forest-dwelling, species in that they inhabit only open drier habitats of riverine forests, open woodlands, grasslands and adjacent forest edges (Donaghey et al. 1985). They are all members of the 'avenue' bower building group but differ from and Ptilonorhynchus species, in which males are brightly coloured, by being dull and cryptically sexually monomorphic or very nearly so (Gilliard 1969). Least known of the Chlamydera species are Lauterbach's Bowerbird C. lauterbachi endemic to central and north-eastern New Guinea, and the Fawn-breasted Bowerbird C. cerviniventris of north-western Cape York Peninsula, Australia, and coastal central and eastern New Guinea and the eastern Vogelkop (Cooper & Forshaw 1W7) . Other than descriptions of bowers, some male displays and nest and eggs, little is known of nesting habits and nest dispersion relative to bower locations in Lauterbach's and Fawn-breasted Bowerbirds (Peckover 1969, Cooper & Forshaw 1W7). It is commonly assumed that males are promiscuous, and females alone attend the nest (Gilliard 1969, Peckover 1969, Cooper & Forshaw 1W7, Diamond 1982, 1986) but no direct evidence of this is available. During 3 to 5 December 1985 we examined bowers and nests of the Fawn-breasted Bowerbird in a previously unknown location, in the Lai River valley (Frith 1987) . During a brief trip to Baiyer River Sanctuary, Western Highlands Province, Papua New Guinea in November 1W7 we examined three active bowers and one active nest of Lauterbach's Bowerbird. We returned in November 1985 and spent 52 hours observing an active bower and 12.5 hours photographing a presumed female at her nest and egg; and examined several nestling, fledgling and juvenile specimens in the Baiyer River Sanctuary and Papua New Guinea National Museum collections. Our observations include new facts which add to the limited knowledge of these .

Results Fawn-breasted Bowerbird Observations of this bowerbird were made at Ruti Cattle Station on the Lai River, Jirni Valley, Western Highlands Province, Papua New Guinea, during 3 to 5 December 1985. Three active bowers and one active and two disused nests were examined within 1.5 kilometres of Ruti Homestead. VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 7

Nest 1 was 1300 mm above ground in a 2.25 m tall, well-foliaged sapling located in grassland approximately 250 m from the rainforest edge (see Plate 6a) and 400 m from the nearest known bower (#1). At midday on 3 December 1985 this nest contained a tail-less nestling with flight feathers in pin, a wing length of 48 mm, and the bird's first (inner) primary 30 mm entirely in pin. Its eyes were open. Tawny-grey down was conspicuous on crown and body, the bill was black with an obvious white egg tooth, and the gape a dull dark white. Breast and flank feathers were in pin but were clearly seen to be dark fawn in colour through the sheaths. Mouth colour was bright orange-yellow, and skin dark flesh. Nestling weight was greater than 50 grams, the maximum of the scales available at the time. At 1200 hours on 4 December nestling wing length was 56 mm, the first (inner) primary 35 mm entirely in pin, and skull plus bill length, or total head length (THL) 40.3 mm. At midday on 5 December wing length was 61 mm and first primary 40 mm long, entirely in pin. Observations of parental care were made at nest 1 on 4 December from 0700 to 1200 and 1400 to 1700 h from a hide 15 m distant, using 8 x 30 binoculars. We gained the distinct impression that only one parent, assumed to be female, attended the nest. The same few routes to and from the nest were repeatedly used and at no time was there any suggestion of two birds in the area, notwithstanding the open country and good visibility about the nest tree (see Plate 6a). The parent was present (in nest tree, on nest rim, or brooding) for only 10.6 % of the eight hour watch. The only three brooding bouts (0.4 per hour) averaged 2 minutes 34 seconds in length. Twenty-one feeding visits (2.6 per hour; mean duration 57 seconds) were made to the nest. During twelve feeding visits the nestling meal could not be identified; three meals consisted of a fruit, and six were of insects of which three were caterpillars. All meals were carried in the bill, not regurgitated to the nestling. All nestling faecal sacs were swallowed by the parent; one sac examined contained remains of several beetles. Empty nests 2 and 3 were located in grassland adjacent to the rainforest edge, 20 m and 80 m respectively from active bower #1 which was located just 4 m from the grassland into the rainforest edge. Nest 2 was a recently disused nest of the current season and nest 3 older and perhaps of the previous season. All nests were in small, isolated, well-foliaged trees within the grassland, the nests being built into near-vertical forks of branches. Table 1 presents measurements of all three nests. Sticks of the foundations of these nests measured up to 450 mm in length and 5 mm in diameter, and extended up to 300 mm outward and beyond the outer nest rim. A substantial symmetrical cup nest of tendrils is built into the stick foundation and a discrete nest­ cup lining of fine twiglets and vine tendrils within that (see plate 6b). The first two bowers examined were consistent with Peckover's (1969) observations in having their central avenue orientated within 30° of east-west, being at 255 o and 290° for bowers 1 and 2 respectively; bower 3 being approximately at 225° (R.D. Mackay pers. comm.). Bower 2 was unusual in having only one stick platform, at its eastern (110°) end of the avenue and this decorated with 35 round green fruits 10 to 21 mm in diameter. Peckover, however, stated that with very few exceptions bowers are decorated on the west platform, and did not note that any of his 85 examined bowers lacked one platform. In addition, bower 2 also lacked sticks on the ground to the north of the avenue wall and this area had, moreover, been meticuously cleared of all debris down to the black soil. Other than this anomaly the two Jimi Valley bowers were typically laid out and decorated, and were of dimensions within recorded extremes for the species. Sticks of the outer avenue walls measured up to 3.5 mm in diameter. AUSTRALIAN 8 FRITH & FRITH BIRD WATCHER

Sticks of the inner avenue walls were very much finer but there was no hair-like rootlet fibres lining the extreme inner wall as observed in bowers belonging to Lauterbach's Bowerbirds.

Lauterbach's Bowerbird Observations were made in and about Baiyer River Sanctuary, where local people call the species 'Takagul'. Nest 1 was 2 m high in a well-foliaged small tree in grassland of an old native garden 50 m from an active bower. This unmeasured nest contained one egg, measuring 38.5 x T7.3 mm and weighing 14.5 g on 5 November 1fJ77. Chaffer (1949) provided a fine plate of a similar nest and egg. Nest 2 was found on 22 November 1985, within 200 m of the above, still-active, bower in a sparse clump of Helianthus shrubs intermixed with and surrounded by tall blady grass within native gardens. This nest was built between near-vertical fork stems of a Helianthus. It consisted of a sparse and rather haphazard foundation of sticks, up to 500 mm long and 5 mm diameter (predominantly c. 300 mm long and (3 mm diameter) supporting a neat compact cup of fine twigs and vine tendrils 1.5 to 0.6 mm diameter and up to c. 200 mm long (Plate 7c). The tendril-lined cup was strong, but could be seen through in places. Some foundation sticks extended up beside the nest rim and above it as much as 140 mm. Some of these sticks extended out away from the outer cup rim up to 280 mm. Foundation sticks were dry and pale grey, whereas the cup was of moister dark brown tendrils. Measurements appear in Table 1. This nest contained one egg measuring 39.9 x Tl.O mm and weighing 14.7 g. During the 12.5 hours that CBF spent photographing incubation activity at this nest (see Cover Plate) from a hide, the distinct impression was gained that only one bird, assumed to be female, was involved. Nest 3 was found on I December 1985 in a small clump of Acalypha mixed with Helianthus shrubs, amidst native gardens, within less than 200 m of a disused bower which locals knew to be in use some weeks earlier. This nest, built between three vertical fork stems of Acalypha, was similar to nest 2 but smaller (see Table 1) and with much sparser and Jess substantial stick foundation. Foundation sticks about the upper nest extended up to 170 mm out beyond the rim. The nest contained one egg measuring 37.8 x Tl.O mm and weighing I4.6 g. From 0800 h on 30 November I985, 47 minutes were spent watching a presumed female, at a different nest from the above, in company with her single fledged young. The latter was about two-thirds parent size with nearly fully grown wings and tail, but was dull overall with darker-looking head, duller yellow breast and conspicuous upper-breast streaking (see nestling, fledgling and juvenile plumage descriptions below). These two birds moved about trees bordering open grassy areas very close to bower I, the fledgling often following the adult from tree to tree. The open country enabled us to watch continuous activity of both birds, and to satisfy ourselves that only the one parent attended the young, notwithstanding the frequent presence of several conspecifics in the area. During the 47 minutes the parent fed the young at least six times, five times with fruits and once an unidentified meal. On 1 December 1985, from 0720 h, 85 minutes were spent similarly watching parent and young, during which at least two fruit and two unidentified meals were fed. All meals were carried in the bill. Often the parent was watched feeding herself in fruiting trees, where most picked fruit was immediately swallowed in situ, but occasionally a fruit was picked and taken to a nearby perch to swallow. VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 9

Fawn-breasted Bowerbird. (a) Site of nest 1 indicated by left hand of DWF; Ruti Cattle Station, Jimi Valley, Papua New Guinea. Note rainforest edge beyond grassland. (b) Nest 2, with nest cup lining of fine twiglets (right) lifted from the stick foundation (left). Plate 6 Photos: C. & D. Frith

Table 1 Measurements (mm) of three Lai River Chlamydera cerviniventris and two Baiyer River C. lauterbachi nests Nest Height External Internal Cup Total # above ground cup diameter cup diameter depth nest depth* c. cerviniventris 1 1300 135 104 50 240 2 1000 133 103 50 500 3 1200 145 115 52 190 c. lauterbachi 2 1350 116 45 210 3 1400 135 100 55 210 *Total nest depth: from highest point of rim to bottom of stick foundation. AUSTRALIAN 10 FRITH & FRITH BIRD WATCHER

The three bowers examined were all just into and beneath the edge of a remnant rainforest patch or an 'island' of shrubs, vines, ferns and blady grasses in the vicinity of the banks of the Trauna River within Baiyer Sanctuary grounds. The bowers were between approximately 0.5 and 1 kilometre apart. Orientation of the central bower avenue was 165, 210 and 270°. In size, shape and decoration these bowers were similar to those previously described (Gilliard 1969, Cooper & Forshaw 1fJ77). The large spherical blue fruits typically used as decoration additional to stones on these bowers (see Plate 7a) were those of Elaeocarpus spheridus.

Observations from a previously long-established hide of local construction of vegetation 6 m from bower 1 were made for 52 hours during periods 4-10 November, 19 November-1 December and 8-9 December 1985, mostly between 0700 and 1030 h. It is noteworthy that an active bower has been known to be in use within a few metres of the observed bower for at least eight years (R.D. Mackay pers comrn.). We found the male at this, and another, bower as shy and wary as any of the eight other bowerbird species we have observed at bowers; and certainly much more so than its congenerics. By 8 November our daily observations showed that birds behaved normally at bowers and appeared unaware of us.

Bower painting of inner avenue walls by the male was observed often between 22 November and 9 December inclusive and, in addition to numerous briefer bouts, five bouts were timed to last between 10 and 13 minutes, the male standing in the central avenue intensely applying 'paint' to the finer textured inside wall sticks in the manner described by Bell (1967) . Most painting, and all of the longer bouts, was performed between 0730 and 0840 h. Viewed from directly above, the painted areas of the inner finer bower sticks are clearly discernible as a darker area (Plate 7a).

Of numerous observations of male display in the presence of a presumed female several were particularly interesting in their behavioural content and it is, therefore, worth recording these in detail. The total period of each hide observation follows the date in parentheses.

8.11.1985 (0715-0935 h). At 0820 a presumed female hopped down to bower and into central avenue, and male then hopped down to behind north-west avenue wall giving soft grating calls whilst hopping up and down on the spot; he then passed through the south-western bower cross-passageway to about tum and present his nape in the crest-presentation posture (Plate 7b) of Gilliard (1959), Warham (1962) and Cooper & Forshaw (1fJ77) whilst repeatedly picking up and putting down small decoration fruits (predominantly one of the only three red ones), and jerking his head sharply up and down (Plate 7b). In a higher intensity form of this display the male brought his head further round, toward his tail, as the tail was brought toward the head and partly fanned as depicted in Cooper's 'tail-fanning' sketch (Cooper & Forshaw 1fJ77: 293). This display lasted approximately two minutes before both birds flew off in apparent alarm at 0832. At 0920 a presumed female entered bower and stood within the central avenue, and the male hopped down to the ground to the north-west of the bower and gave several soft grating notes followed by plaintive low notes before performing the crest-presentation posture at the south-western cross-passageway. During this display he held a pebble, then a stone, in his bill whilst simultaneously flicking his tongue in and out and producing soft call notes. After approximately a minute the female left the bower, followed by the male. VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 11

(a)

(b)

(c)

Lauterbach's Bowerbird. (a) Bower viewed from directly above showing central avenue (centre), end walls Oeft & right) and stone, pebble, and spherical fruit decorations. Note dark painted walls of inner central avenue. Central avenue orientation 210 ° (to left) by 30° (to right). (b) Male in crest-presentation display with Elaeocarpus fruit in bill, direct­ ed at female standing inside central avenue (tail visible at left). (c) Nest 2 with nest cup lining of fine twigs and vine tendrils (right) lifted from the stick foundation (left). Plate 7 Photos: C. & D. Frith AUSTRALIAN 12 FRITH & FRITH BIRD WATCHER

19.11.1985 (0715-0923 h). Male about the bower before 0855 but produced little vocalisation, and none at all for at least 30 minutes before the arrival of a presumed female which entered the central avenue at 0855 and sat perfectly still, with drooped wings, except for head movements. One minute later male slowly and silently hopped down through adjacent vegetation to the ground to the north-west of the bower and then produced soft low churring vocalisations as he approached and hopped into the south-west cross-passageway to perform the crest-presentation pose accompanied by sharp 'reptilian' jerking head movements, mouth gaping, and waggling of his tongue. During this display he often briefly picked up a large blue Elaeocarpus decoration fruit, but only rarely faced the female, to expose the bright orange interior of his open mouth, whilst giving a churring call note. Occasionally he moved out of her sight to the north-west side of the central avenue wall, whilst giving soft calls, before re­ entering the south-west cross-passageway to perform crest-presentation. This display continued for 4.5 minutes before the male ran around the bower, in a clockwise direction, to enter the north-west bower entrance behind the motionless female and mount her and mate with fully open flapping wings. He then suddenly flew up to above the bower and the female sat within the central avenue for a further 45 seconds before flying off. The male then continued for two minutes to regularly repeat a sharp loud chit call note above the bower, in marked contrast to his very soft and low calls during display. 20.11.1985 (0700-1030 h). At 0823 presumed bower owner above bower giving short harsh call notes whilst two additional conspecifics giving scolding notes close by, and by 0839 birds vigorously chasing one another about immediate area. At 0841 a bird hopped quietly into bower central avenue and vigorously tore out inner, painted, avenue wall sticks by their bases. At 0844 a second bird, presumably the bower owner, flew rapidly into bower and chased off the marauder, and then perched close by to give repeated loud scold notes. At 1006 this bird entered the central avenue and carried out repairs to avenue walls until 1015, when he flew away.

22.11.1985 (0700-1115 h) . At 0926 a presumed female entered central avenue and a male immediately came to the ground by bower and commenced soft vocalisations only to fly off at 09TI. He returned to the south-west end of central avenue at 0934 and directed an open-mouth gaping display at female, followed by crest-presentation posture with a fruit held in his bill. He again flew off at 0938, to displace an approaching conspecific. At 0940 male returned to south-west end of central avenue to give gaping~ mouth display immediately followed by crest-presentation displays until 0943 when he hopped to north-east end of the avenue and flew off. At 0951 male returned to south-west end of avenue for two minutes and then flew off to displace a conspecific calling softly close by, where he remained and called softly himself as the female became restless in the bower and picked at avenue sticks before departing at 1017 (51 minutes after entering the bower avenue) to perch a few metres away. At 1035 female returned and entered central avenue, but this time faced north-east end of bower. At 1036 two males simultaneously hopped down to bower area, one to crest-presentation display at south-west end (the female's tail end) of avenue as other male made for north-east end only to be then vigorously chased off by the male that had commenced display. At 1039 a male hopped down to the bower giving soft calls and went to south-west end of avenue, the female's tail end, and performed crest-presentation posture to the female's rear end before hopping away at 1044 apparently distracted by the presence of several conspecifics in the immediate area. At 1105 male again entered south-west end of bower and performed mouth gaping and crest-presentation displays at the female, which now faced south-west, until 1110 VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 13 when he picked up a blue Elaeocarpus fruit in his bill and hopped around the bower to the north-east entrance, entered the central avenue and mounted the crouching female very briefly before flying up. The female then vigorously shook her wings several times and flew off, after 36 minutes wait in the bower. 27.11.1985 (0730-1045 h). At 0740 male arrived and commenced painting walls of central avenue, then removed unwanted fallen leaves and rearranged bower decorations until 0756 when he left. At 0911 a male entered central avenue and tore out sticks of inner walls until leaving at 0915. At 0958 male returned with a small grey pebble and carefully dropped it onto his chosen location among other decorations in south-west cross­ passageway from a perch on an immediately adjacent vertical sapling stem some 30 em above. He then hopped down and into the central avenue and repaired damage to inner walls and rearranged decorations until 1010, when he left. Morphology Gilliard (1969) stated that the first-year plumage of Lauterbach's Bowerbird is 'apparently much like adults but generally more pallid yellow'; Cooper & Forshaw (1fJ77) give the immature plumage as 'undescribed'. As we were able to examine study skins of two nestlings, three fledglings, two juveniles, and a freshly dead nestling in the Baiyer River Sanctuary and Papua New Guinea National Museum collections, we give here the first detailed descriptions and measurements (Table 2) of same, and compare them with some adult specimens in the collections.

Table 2 Measurements (mm) of Chlamydera lauterbachi specimens in the Baiyer River Sanctuary and Papua New Guinea Museum collections

Specimen# Date Location Wing Tail THL Culmen Tarsus Nestlings: BRS 2256 7.11.76 Iki Valley 88 24 46.5 21.4 BRS 2265 20. 4.76 Trauna Valley 91 28 42 .4 18.0 33.6 Fresh 21.11.85 Trauna Valley 87 24 42 .2 20.4 33.7 Fledglings: BRS 2282 17.11.76 Tambima P.P. 109 49 47.0 24.3 37.0 BRS 5320 16. 9.84 Trauna Valley 111 57 48.8 24.4 37.0 PNGM 14429 Kumberata, B.R. 111 58 48.6 21.7 36.9 Juveniles: BRS 2302 20. 4.76 Trauna Valley 128 106 56.0 27.3 36.8 PNGM 12988 Baiyer River 130 54.6 27.7 35.2 Adults: PNGM, mean of 4 specimens 131 108 57.6 28.7 37.6 Note: THL = total head length all immature specimens unsexed, except male BRS 5320 all dates are those birds died as captives

Plumage descriptions: Nestlings 2256 & 2265 are about fledgling age and are so similar that one description will serve them both. Crown with pale rusty down being replaced with pin feathers, and some pale streaked feathers (as in 5320, see below). Lores and ear coverts in pin or just out. Chin, throat, breast, abdomen and flanks soft off-white downy feathering with some fine greyish tipping and edges of those of upper breast (but nothing like the extent of 5320) and pale fine brown-grey tipping to flank feathers giving scalloped appearance. Sides of neck bare. Mantle and back feathers are rufous-grey, and very AUSTRALIAN 14 FRITH & FRITH BIRD WATCHER

soft, with whitish central shafts and adjacent vanes - giving streaked appearance. Rump feathers soft, downy and rust-rufous in colour. Tail and wing feathers as in 5320. Bill in all nestling/fledglings is blackish-brown.

Fresh dead nestling (Plate 8). Down on head brownish-grey, being replaced by feathers bursting from pin. Very similar in colouration to 5320 on wings, back, tail, and underparts. Very yellow trailing edges to primaries and secondaries of under-wing, and olive-yellow leading edges to primaries and secondaries on the upper-wing. In general appearance this freshly dead bird is slightly more yellow throughout than the preserved nestlings and fledglings. Skin is dark flesh in colour. Bill, blackish-brown with obvious white egg tooth. Iris, dark grey-brown. Mouth, bright orange-yellow. Legs, grey-flesh.

Fledgling 2282. The crown, ear-covert and lore feathers attained are like those of adults but are less olive and more yellow. The crown feathers, however, have obvious white-yellow central shafts and vanes. Chin, throat and nape with off-white down feathers tipped and edged dark grey. Breast, flanks and abdomen a soft downy plumage of dirty white feathers tipped dark grey to give scalloped appearance. Back with soft brown-grey feathers with whitish central shafts and hint only of lighter tips to them, unlike well-scalloped adult feathering. Upper tail coverts like adults' but white tips to feathers much more extensive down feather length. Tail feathers more brown and less blackish than adults' with pale buff fine edging to outer edges (broader on inner vane) and small huffish tips. Wing much like adults' but primaries and secondaries lighter and the white tips to secondaries and spotting on coverts less white, more greyish to buff. Fledgling 5320, male. Crown plumage colour much as adults' but feathers with obvious white-yellow central shafts and adjacent vane, giving streaked appearance. Lores and ear coverts like adults'. Chin and throat soft downy off-white feathering with grey edging and/or tipping giving a mottled look. Upper breast similar but with heavier and darker grey edging. Feathers of breast, flanks, and abdomen downy soft and off-white (with pale and dull yellow wash in middle of abdomen) and finely tipped grey to give scalloped appearance - more so on breast and flanks than lower abdomen and under­ tail. Back with soft dark grey feathers, washed with olive, have whitish central shafts and adjacent vanes to give streaked look. Only slightest hint of paler feather tips to back- unlike obvious ones in adults. Upper tail coverts like adults but with more extensive white tips and more down feathering. Tail feathers like adults' but more olive and yellow influence and slightly less black than adults; white tipping and edging similar to adults but less pure white, more yellowish or huffish. Wings very similar to adult but little more olive and brown than the blacker of adult primaries and secondaries. White spotting duller, more huffish, and less obvious; but same distribution. Fledgling 14429 has soft downy plumage of underparts, off-white with grey edging to feathers of breast and flanks giving scalloped appearance. Vague band on upper chest of more pointed feathers edged grey-brown giving streaked appearance. Throat feathers downy off-white. Ear coverts whitish-yellow spindly feathers with dark edges. Crown olive-brown, less yellow-olive than adults (and juvenile 12988) and feathers with whitish centrals, giving streaked appearance. Juvenile 2302. This bird (Plate 8) is very similar indeed to adult BRS 5204 (see Plate 8), which has a wing length of 133, tail of 110 and THL of 57.2, but is smaller. Above it has less conspicuous light scalloping, or crescent edging, to the mantle feathering but does have this on the lower back. The white tipping to the wing coverts, tertials VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 15

and secondaries is a dirtier white and less extensive than in adults, likewise on the tail. Upper tail coverts same as adults in colour and spotting. Crown, !ores, ear coverts and throat as in adults. Breast and underparts as in adult but yellow of abdomen slightly duller, and a dirtier yellow. Flank barring like adult. Under-wing a dirtier yellow­ buff, and slightly darker, than adults'. Tail tips, as in other lighter markings, are smaller and more huffish than in whiter adults.

(a)

(b)

Lauterbach's Bowerbird. Dorsal (a) and ventral (b) views of freshly dead nestling, juvenile specimen 2302 and adult specimen 2504 (largest bird). See text. Plate 8 Photos: C. & D. Frith AUSTRALIAN 16 FRITH & FRITH BIRD WATCHER

Juvenile PNGM 12988. Basically similar to plumage of adult specimen PNGM 2fJ775 but upper wing feathers slightly darker making contrast with white tips greater. Crown very slightly darker. As a result of an examination of two adult female and one adult male skins from Minj, Wahgi River, collected between 12-17 November 1950 and two adult male skins from Menebe, 8 miles east, Mt Hagen Range, Sepik-Wahgi Divide, Central Highlands, Papua New Guinea collected between 19-21 October 1946 all by Fred Shaw-Mayer, we were able to look for plumage sexual dimorphism. As all five skins are of the subspecies C. l. unifonnis and are October and November birds in a 'worn' state, on a 'very fresh, fresh, worn, very worn' scale of plumage wear, a worthwhile comparison could be made. We found the crown feathering of the three males to extend slightly more onto the nape and to be conspicuously brighter, more glossy, and more olive yellow than the duller, more matt and olive, crown of the females. Of five skins of this subspecies reliably sexed in the American Museum of Natural History collections, kindly examined by Mary LeCroy, the three males also have slightly more extensive crown feathering than the females, and all of the same colour. Of the two females one has a crown the same olive-yellow as the males and the other has a duller crown that may, however, be the result of its very worn plumage. Clearly, more reliably sexed specimens in fresh or similar worn plumage are required but it would seem probable that the male Lauterbach's Bowerbird has a distinctly more yellow, and slightly more extensive, crown colour than the female.

Discussion Fawn-breasted Bowerbird Harrison & Frith (1970) reported that Shaw-Mayer collected a female with her nest and egg, the latter measuring 40.4 x 27.6 mm, on 6 January 1941. Several authors refer to the female Fawn-breasted Bowerbird nest-building, incubating and raising young alone (Gilliard 1963, Peckover 1969, Cooper & Forshaw 1977). This is almost certainly the case, and is supported by our limited observations at one nest, but conclusive evidence has yet to be obtained. Such evidence has, however, recently been obtained by us for the congeneric Chlamydera nucha/is (C. & D. Frith in prep.), the first such evidence for any member of the genus. In view of the single nestling's wing, first primary, and total head length, state of plumage attainment, and weight of over 50 g, we assess its age to have been approximately 10 to 11 days on 3 December 1985, in view of similar measurements obtained from known-age nestling Great Bowerbirds (C. & D. Frith in prep.). For a single bowerbird nestling of this age the parent's small percentage of time spent at the nest, very low number of brooding bouts per hour and their short duration, and the number and short duration of feeding visits per hour support the conclusion, and direct observations, that only a single parent attended the nest and nestling (Donaghey 1981, Frith & Frith 1985). Our measurements of three Jimi Valley nests and their heights above·ground are smaller than the approximate measurements given by Peckover (1969) for Port Moresby nests. In addition to our record of a nest with a nestling 10-11 days old on 3 December, Rand (1942a) reported a nest with a half-grown nestling on 15 December. Three dissected adults were found to be in breeding condition in September and one in December, and a nestling was found on 30 November (Rand 1942b, Gilliard 1969). Shaw-Mayer (in Harrison & Frith 1970) collected an egg on 6 January. Cooper (in Cooper & Forshaw 1977) found a nest with an egg on 25 September. Menzies (1976) VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 17

first noted a nest under construction on 28 January. On 23 February he saw an egg which hatched on 28 February and the subsequent nestling fledged at 0745 h on 20 March, after 21 to 22 days in the nest. Nestlings of unknown age were found in the Baiyer River Sanctuary area in November and April, fledglings during September and November, and a juvenile in April (see Table 2). From available data it can, thus, be stated that the species is known to breed and nest in New Guinea during September to March and possibly April inclusive. Peckover (1969) wrote 'Nesting activity has been observed during all months of the year except April' but it is not clear if he was referring to personal observations and he presented no supporting data or reference. With respect to the location of nests relative to an active male bower or bowers Peckover (1969) stated that 'nesting trees found to date have been well clear of the bower site, at least 150 m distant'. Firstly, we would consider 150 m no great distance from an active bower in a species that is described as having a bower density, in savannah, of one per 340 square metres to less than one per square kilometre, or of approximately 500 m or more apart (Peckover 1969, Peckover & Filewood 1976). Secondly, the three nests we found were 20, 80 and 400 m distant from the nearest known active bower. H. L. Bell (in litt. 22.6.1979) informed us that he found an active nest within 40 m of an active bower (see below). Warham (1962) reported a nest of the Great Bowerbird c. 50 m from an active bower and stated that Chlamydera maculata nests are 'not very far from the bower'. Vellenga (1980), writing ofthe Ptilonorhynchus violaceus, noted 'No nests were located close to a bower, the nearest being c. 200 m distant' but we note that the two dominant male bowers in her study area were 3 km apart, and that the only plotted nest on her map of a c. 12 km2 area is shown immediately adjacent to an alpha male's bower. We have found active nests of Great Bowerbird, Satin Bowerbird, Tooth-billed Bowerbird Scenopoeetes dentirostris and Prionodura newtoniana within 50 m of active bowers (C. & D. Frith and C. Frith in prep.) and therefore find vague statements concerning the location of bowerbird nests relative to bowers as 'well distant from bower' or 'far from bower' (Schodde 1976) as misleading and lacking justification. Indeed, we believe it may be true that female bowerbirds habitually nest relatively close to the bower of the male of their choice to protect the investment made by them in selecting him. Our observations and those of Donaghey (1981) and Pruett-Jones & Pruett-Jones (1983) support the possibility of this suggestion.

Lauterbach's Bowerbird The nest of this species is very similar to that of the Fawn-breasted Bowerbird in general construction, materials and measurements except that the nest-cup lining is courser, being of fine twiglets and vine tendrils with no fine rootlets or fibres. Our measurements of nest height and structures are generally in accord with those of Chaffer (1949) and Gilliard (1969). The three eggs that we measured were smaller than the only previous measurement of 43 x 28 mm (sic) by Iredale (in Chaffer 1949) and misleadingly given as 43.0 x 28.0 mm by Forshaw (in Cooper & Forshaw 1977); and the weights we give are the first recorded for the species. Three recorded female adult weights of this species (Mayr & Gilliard 1954, Gilliard & LeCroy 1966) result in a mean weight of 101.3 g and a mean of our three egg weights is 14.6 g. Thus the mean egg weight represents 14.4% of the mean female weight; and of course the fresh egg weight would be heavier and the percentage of female body weight even greater (Frith & Frith 1985). This proportionate egg weight in relation to body weight is considerably higher than 10.2% for female nesting Satin Bowerbird (Donaghey 1981) and is high for a of Lauterbach's Bowerbird body weight, and is thus further suggestive of the female only attending the nest. AUSTRALIAN 18 FRITH & FRITH BIRD WATCHER

Observations of activity of a presumed female incubating at her nest over 12.5 hours by CBF gave the clear impression of a single bird in attendance. The bird at the nest was extremely shy and wary and males at their bowers were more wary than any other bowerbird species studied by us, including all congeneric species. Our nesting data add the months of October to December inclusive to those of January, April, July and September for the Wahgi Valley (Gilliard 1969). Bulmer (in Gilliard 1969), however, offered a reward to locals for nests shown to him during the period April 1955 to March 1956 on the nearby northern watershed of Mt Hagen but was only shown active nests during August to January inclusive, suggesting a possible seasonality in the area. Diamond (1972) noted a female with enlarged ovaries in the second half of June 1965. Gilliard (1969) concluded from his and Bulmer's data that the species breeds throughout the year, which is cbviously true of New Guinea populations as a whole. Bower painting is as important an element of male bower activity as in any other avenue bower building species, if not more so. Apparently critical elements of male courtship display to a female within the bower avenue are the holding of a fruit in the bill, and the crest-presentation posture (Plate 7b) previously described by Diczbalis (1974) and Cooper & Forshaw (1977). Similar to near-identical postures are performed (also with a decoration held in the bill), by all congeneric species (Warham 1962; Gilliard 1959, 1963, 1969; Cooper & Forshaw 1977; Veselovsky 1978) and the Satin Bowerbird (see plates in Vellenga 1970 and Pruett-Jones & Pruett-Jones 1983). Gilliard (1959) pointed out that the 'crest-presentation' posture of the crestless male Fawn-breasted Bowerbird represents a vestigial display posture the origin of which is actual crest-presentation as is still to be seen in the Great and Spotted Bowerbirds. Clearly, Lauterbach's Bowerbird is also performing an evolutionary vestigial posture when performing 'crest-presentation'. As the crestless species C. cerviniventris and C. lauterbachi construct more complex bowers than do the crested species C. nuchalis and C. maculata, Gilliard (1959) made the important observation that this represents further evidence of the 'transferral effect' which he first observed in members of the bowerbird genus Amblyomis, in which species with bright crests build simpler bowers and species with smaller or no crest build respectively more complex bowers. Diamond (1982) suggested that this phenomenon in the genus Chlamydera has evolved one step further because 'male C. cerviniventris compensates (for his lack of a crest) by holding a sprig of green berries in his bill during the display'. This is, however, a gross over­ simplification of the situation as all Chlamydera species perform the crest-presentation pose with or without a decoration held in the bill. To support Diamond's suggestion to any degree it would have to be demonstrated that crestless species hold a decoration in the bill significantly more often than do crested species during the crest-presentation posture. The continuous occupation of the central bower avenue by a female for 36 and 51 minutes, including periods of male absence, before copulation, suggests a considerable persistence in soliciting fertilisation by a chosen male. Our observations of rival males entering the bower of another to destroy the central avenue walls, to be chased off by the owner on occasions, provide the first evidence of male competitive interactions (bower destruction or decoration theft) in this species. Such behaviour is documented for the Fawn-breasted Bowerbird (Peckover 1969), Great Bowerbird (S. Garnett in litt. & C. Frith pers. obs.), Satin Bowerbird (Borgia 1986, Diamond 1986, Donaghey 1981, C. Frith pers. obs.), Macgregor's Bowerbird Amblyomis macgregoriae (Pruett-Jones & Pruett-Jones 1983), Golden and Tooth-billed Bowerbird (pers. obs., C. Frith in prep. & D. Frith in prep.) and the Sericulus chrysocephalus (Threlfo 1984). VOL. 13 (1) MARCH 1989 Notes on Bowerbirds in Papua New Guinea 19

Acknowledgements We sincerely thank Roy and Margaret Mackay for much help, hospitality and the opportunity and means to visit the Jimi Valley; and Jim and Flossie Gentle for kind hospitality there. We also thank Mary LeCroy for kindly examining American Museum of Natural History specimens for us.

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