Trees for Birds: 1. Ficus benjamina (Waringin, Weeping Fig)

Ficus benjamina, commonly known as Waringin or Weeping Fig, is a tree that attracts large number of birds whenever it produces figs (above, tree on right). Scientifically known as syconium, the fig is the enlargement of a stem tip that becomes hollow and fleshy. Within this cavity are the tiny flowers – male, female and gall-flowers (which are sterile female flowers). The pollination of the flowers is undertaken by tiny fig wasps. A developing fig attracts female wasps that are covered with pollen after emerging from another fig. These wasps enter the fig via the small opening at the bottom. As this opening is covered with tightly overlapping scales at this stage of development, the wasps have to force their way inside. In doing so they may lose a wing or a leg. Once inside the fig, they seek out gall-flowers to lay their eggs. The wasps then die.

[left: trans-section of F. benjamina fig showing fruits; right: longi-section of F. religiosa showing gall flowers after the fig wasps had chewed their way out]

In the process of laying the eggs, the wasps pass on the pollen to the female flowers. In time these female flowers develop into tiny fruits. Figs are thus false fruits as the true fruits are found inside the figs.

The ripening of the fig is timed with the hatching of the wasps’ eggs and the maturity of the male flowers. The emerging young wasps bite their way out of the gall flowers. The male wasps will mate with the female and then die. The female wasps seek out the opening, which by now is enlarged due to the ripening of the fig. However, as they move out of the fig, they will by covered with pollen shed by the male flowers found around the fig entrance.

The emerged female wasps immediately seek out other figs of the same species to repeat the process.

Each species of fig has its corresponding species of fig wasp and they depend on each other for their existence. Without the fig plant, the wasp cannot multiply. And without the wasp the fig plant cannot form seeds and can only propagate through vegetative means like cuttings and marcots.

The tree attracts hordes of birds that feed on these succulent figs every few months when the tree flowers and fruits. These figs contain starch, sugars, minerals and some proteins and fats. The presence of fig wasps inside the figs, this of course depends on the stage of the ripening fig, provide extra proteins to the birds

Depending on whether the birds are frugiverous (fruit eating) or insectivorous (insect eating), they are attracted to the tree and the insects the ripening figs attract. Yet other species of birds, especially raptors, are attracted to the swarm of birds feeding in the tree.

However, this was not recognised earlier when local birdwatchers started observing birds attracted to the F. benjamina growing at the summit of the Bukit Timah Hill (top) LINK. They listed all birds seen in and around the vicinity of the tree, rather than separating them into frugiferous, insectivorous, etc. Wildlife consultant Subaraj Rajathurai pointed this out and separated the different categories of birds seen around the tree, including those that had no interest in the figging tree LINK. A revamped list, updated by subsequent observations, gives a total of 43 species – see list below. Whether the birds were there for the figs (32 spp.), insects (10 spp.) or for the leaves to line their nests (1 sp.), are specified. To each documentation is attached the author/s responsible for the record. The full details of authorship is given below under References. Here, the links to the posts are provided.

As a fantastic bird tree, F. benjamina should be encouraged to attract birds to the urban environment. However, because the roots are invasive, causing damage to pavements, drains, etc., they are not commonly seen in urban areas. Birds spread the seeds onto branches of trees where they germinate, and if allowed to develop further, their roots can hinder the healthy growth of the host trees as well as damage the areas around LINK. In large parks and sites away from built-up areas, mature F. benjamina can still be found.

Below is a list of birds that are attracted to the figs, insects or nesting material of F. benjamina, citing sources that can be verified under “References” below.

Barbets: Blue-eared Barbet: fruit (Amar-Singh, 2014b); Coppersmith Barbet: fruit (Amar-Singh, 2010r); Gold-whiskered Barbet: fruit (Amar-Sing, 2010y); Lineated Barbet: fruit (Yong, 2006; Amar-Singh, 2010r); Red-crowned Barbet: fruit (Wee, J. et al., 2008).
Bee-eater: Blue-throated Bee-eater: insect (Yong, 2006).
Bluebird: Asian Fairy Bluebird: fruit (Yong, 2006).
Bulbuls: Ashy Bulbul: fruit (Subaraj, 2006); Black-crested Bulbul: fruit (Yong, 2006); Black-headed Bulbul: fruit (Amar-Singh, 2010e); Cream-vented Bulbul: fruit (Yong, 2006); Red-eyed Bulbul: fruit (Yong, 2006); Yellow-vented Bulbul: fruit (Bucknill & Chasen, 1990; Wee & Chan, 2006; Redzian & Chua, 2009; Amar-Singh, 2010r); nest-material (leaves) (Wee, 2006n).
Doves: Emerald Dove: ?fruit (Amar-Singh, 2010r); Zebra Dove: ?fruit (Amar-Singh, 2010r).
Drongo: Greater Racket-tailed Drongo: insect (Yong, 2006).
Flowerpeckers: Plain Flowerpecker: fruit (Amar-Singh, 2013m); Thick-billed Flowerpecker: fruit (Amar-Singh, 2013m).
Flycatchers: Asian Paradise Flycatcher: insect (Yong, 2006); Yellow-rumped Flycatcher: insect (Wee & Chan, 2006; Yong, 2006).
Green-pigeons: Pink-necked Green-pigeon: fruit (Amar-Singh, 2010r); Thick-billed Green-pigeon: fruit (Yong, 2006; G., 2009a; Amar-Singh, 2013m); Yellow-vented Green-pigeon: fruit (Amar-Singh, 2013m).
Hornbills: Great Hornbill: fruit – Yong (2006); Oriental Pied Hornbill: fruit (G. & Lumb, 2010); Rhinoceros Hornbill: fruit (Yong, 2006).
Ioras: Common Iora: insect (Amar-Singh, 2010r).
Leafbirds: Blue-winged Leafbird: fruit (Yong, 2006); Greater Green Leafbird: fruit (Yong, 2006; Amar-Singh, 2011w); Lesser Green Leafbird: fruit (Yong, 2006).
Mynas: Common Myna: ?fruit (Amar-Singh, 2010r); Hill Myna: fruit (Yong, 2006); Javan Myna: fruit (Wee & Chan, 2006; Yong, 2006).
Orioles: Black-naped Oriole: fruit (G., 2009b; Yong, 2006; Amar-Singh, 2010r).
Shrikes: Tiger Shrike: insect (Subaraj, 2006).
Starlings: Asian Glossy Starling: fruit (Wee & Chan, 2006; Yong, 2006).
Sunbirds: Brown-throated Sunbird: fruit (Subaraj, 2006); Crimson Sunbird: insect (Subaraj, 2006).
Tailorbird: Dark-necked Tailorbird: insect (Subaraj, 2006).
Thrushes: Blue Rock Thrush: fruit (Amar-Singh, 2010r).
Trillers: Pied Triller: insect (Amar-Singh, 2010r).
Warblers: Arctic Warbler: insect (Subaraj, 2006); Eastern Crowned Warbler: insect (Yong, 2006).

Credit: YC Wee (text, figs) & YM Chan (image of fig tree).

References:
Amar-Singh, H. S. S., 2010r. Birds and fruiting Ficus benjamina in Ipoh, Malaysia LINK.
Amar-Singh, H. S. S., 2010y. Gold-whiskered barbet feeding on fruits and call LINK.
Amar-Singh, H. S. S., 2011w. Juvenile greater green leafbird feeding on Ficus benjamina LINK.
Amar-Singh, H. S. S., 2013m. Birds feeding in a Ficus benjamina tree LINK.
Amar-Singh, H. S. S., 2014b. Blue-eared Barbet and Ficus benjamina figs. LINK.
Bucknill, J.A.S. & F.N. Chasen (1990). Birds of Singapore and South-east Asia. Graham Brash, Singapore. 247 pp.
G., Mark, 2009a. Thick-billed green-pigeons feasting on figs LINK.
G., Mark, 2009b. Juvenile black-naped oriole eating figs LINK.
G., Mark & K. Lumb, 2010. Oriental pied hornbills at Singapore’s Chinese Garden LINK.
Redzian, A. R. & Mark Chua, 2009. Yellow-vented bulbul swallows figs LINK.
Subaraj, R., 2006. The fig tree at Bukit Timah: 2. Comments by R. Subaraj LINK.
Wee, Johnny, Y. M. Chan & Y. C. Wee, 2008. Portrait of a bird: Red-crowned barbet LINK.
Wee, Y. C., 2006n. Anatomy of a nest: Yellow-vented bulbul LINK.
Wee, Y. C. & M. Chan, 2006. The fig tree at Upper Seletar LINK.
Yong, D. L. 2006. The fig tree at Bukit Timah: 1. Efforts at documentation LINK.