Observations of birds feeding in a fruiting Planchonella

During a visit to Ambua Lodge, near Tari (Southern Highlands Province) at c.2200m, we observed several species of birds feeding in a fruiting Planchonella sp. (Sapotaceae) tree was observed. It stood near the top of a steep sided valley and was c.20m tall with a large spreading canopy with sparse foliage that allowed clear views of feeding birds. The fruits were about 10mm in diameter and grew singly on short stalks amongst the leaves. Birds were only recorded feeding on ripe fruits which were distinguished from the unripe green fruits y being black with soft flesh. They usually contained two elongated seeds. Other Planchonella sp trees in the same area of forest were also in fruit and Short-tailed Paradigalla Paradigalla brevicauda and Superb Bird of Paradise Lophorina superba were noted feeding in them.

We first found the tree on 9 October 1987. Over the following three days (10 – 12 October 1987) we watched this Planchonella tree for a total of 465 minutes (7.75 hours) spread over five periods: 10 Oct: 14:30-16:00; 11 Oct 09:30-12:15, 16:45-18:00; 12 Oct 07:15-08:15, 09:30-10:45). The shortest observation period was 60 minutes and the longest 165 minutes. We observed the tree from a convenient vantage point, less than 20m from the trunk and which allowed us to view most of the canopy. We used 10x and 8x binoculars.

Over the four days seven species were observed feeding in the tree, including a minimum of nine individuals of five species of birds of paradise. No birds were present in the tree for 289 minutes of the observation periods (62% of the total observation time). Periods of no bird activity coincided with overcast, cooler and windier conditions, particularly when the wind was strong enough to move the branches. During the remaining 176 minutes five species of birds were recorded feeding in the tree. Most activity was noted in sunny and calm conditions (11 Oct 10:00-11:25 14 feeding records; 12 Oct 09:39-10:30 9 feeding records) and in the early evening (11 Oct 16:47-17:54 15 feeding records).

During our first cursory observation, at 15:20 on 9 October 1987, two species of bird of paradise, a female Blue Bird of Paradise Paradisaea rudolphi and two Short-tailed Paradigalla, considered to be an adult and a juvenile (Hicks & Hicks 1988), were seen feeding in the tree but not subsequently recorded in the tree.

A party of four Buff-faced Scrub-Wrens Sericornis perspicillatus was seen on three occasions, moving noisily through the tree, foraging along the smaller branches and twigs and amongst epiphytes. They were present for less than five minutes each time and were not seen to feed on the fruit or any part of the fruit.

The remaining four species were all recorded feeding on the Planchonella fruit. White-breasted Fruit-Doves Ptilinopus rivoli, never more than one male and one female at a time, were present in the tree for 124 minutes. They spent very little time actively feeding, mostly perching still in leaf shade. A solitary male was present on two occasions, spending 44 minutes in the tree, but was seen to take only one fruit. A solitary female also made two visits, both times overlapping with the single male, and was seen to take four fruits, three of them in a nine minute period. This species ingested the fruits whole.

Three species of bird of paradise visited the tree to feed (other than the two species only recorded during our first brief visit mentioned above). In total they spent much less time in the tree in the tree than the fruit-doves, only coming to this Planchonella tree to feed, but they took more fruits.

A female Lawes’ Parotia Parotia lawesii spent 10 minutes in the tree, two visits lasting seven and three minutes respectively, both on the same morning, In this time it fed on 11 fruits. The bird pulled each fruit from the tree using its bill and then held the fruit against a branch while it tore strips from the fruit with its bill.

Superb Birds of Paradise, never more than one male or one female at any one time were present on the tree for 20 minutes and took 17 fruits. A male made four visits to the tree during the two morning observation periods, no visit exceeding four minutes. A female also made four visits, all during the evening observation period, so never overlapping with the male. Both male and female birds foraged throughout the canopy of the tree in a ‘tit-like’ manner, often hanging upside down to reach fruit. As well as the fruit, a male Superb Bird of Paradise was noted feeding on a grub which it had extracted from the bark of the tree. It probably obtained other food items this way as it was observed foraging alon branches and among epiphytes on other occasions.

Loria’s Birds of Paradise Cnemophilus loriae were present in the tree for 30 minutes and took 20 fruits, which were ingested whole. Only one female was present at any one time. A solitary female mad six visits to the tree, feeding on the fruits on each visit except one when it was in the tree for less than a minute. The average length of a feeding visit was 2.25 minutes and the average number of fruit taken per visit was 1.5. A solitary male made three visits to the tree while for one five minute period, two males and one female were present. Males ate the fruit on each visit. The average length of a feeding visit was 2.66 minutes amd the average number of fruit taken per visit was 1.2. Male(s) and female were only present together on the tree for six minutes.

As far as we know Planchonella sp has not previously been recorded as a food plant of birds of paradise or fruit-doves (Rand & Gilliard 1967, Gilliard 1968) although the seeds have been recorded in Dwarf Cassowary Casuarius bennetti droppings (Pratt 1983).

In the lowlands of PNG flocks of fruit-doves, sometimes numbering 50 – 100 birds are found in fruiting trees often feeding in a frenzy. At most, only two birds were present in this tree and only occasionally took a fruit. This may indicate that Planchonella is not a favoured food source of fruit-doves but will be taken to supplement the diet or that fewer frugivores at this altitude both in terms of species, e.g. only one species of fruit-dove c.f. six at sea-level, and individuals means less competition for a food source which possibly leds to less frenetic activity.

Two species, Lawes’ Parotia and Blue Bird of Paradise, were at the limits of their altitude range and had not previously been recorded in the grounds of Ambua Lodge, at c.2200m, although both were known to occur lower in the Tari Basin (Finch 1987).

Voucher specimen at UPNG is Hicks & Hicks #5. We would like to thank Paul Katik of the National Herbarium,Lae, for identifying the plant and Helen Fortune Hopkins for her helpful criticisms of earlier drafts.

Beehler, B.M, T.K.Pratt & D.A.Zimmerman. 1986. Birds of New Guinea. Princeton University Press.

Finch, B.W. 1987. The Birds of Ambua and Tari District – a Trans-Niugini Tours guide to the birds in the vicinity of Ambua Lodge (with additional notes by C.Frith, D.Frith and N.Gardner). 2^nd Edition. Trans-Niugini Tours.
Gilliard, E.T. 1969. Birds of Paradise  and Bowerbirds. London. Weidenfeld and Nicolson.
Hicks, R.K. & J.H. Hicks. 1988. Feeding Observations of Short-tailed Paradigalla. Muruk 3: 14
Pratt, T.K. 1982. Diet of Dwarf Cassowary Casuarius bennetti picticollis at Wau, Papua New Guinea. Emu 82: 283-285.
Rand, A.L. and E.T.Gilliard. 1967 Handbook of New Guinea Birds. London. Weidenfeld And Nicolson.

First published in Muruk 3(1): 10-11, co-authored with Jenny H. Hicks.