In gardening for birds LINK, many plants can be grown to attract the avian fauna. Of these, figs (Ficus spp.) are among the best. A fruiting fig tree can attract hordes of birds that usually results in a feeding frenzy.
Figs are a group of plants that have their tiny flowers (male, female and gall-flowers) set inside fleshy figs (below right: long-section F. religiosa fig; note holes in the few gall-flowers where the wasps emerged). Pollination is by tiny fig-wasps and each species of fig is closely associated with its specific wasp species. Both the fig and the wasp depend on each other for their mutual survival and one cannot reproduce without the other.
The wasp enters the developing fig via its opening at the opposite end of the stalk. The entrance is tight and the wasp needs to force its way in, often losing a wing or a leg in the process. Once inside, it lays its eggs in the gall-flowers. In the process the wasp, covered with pollen from an earlier fig, pollinates the female flowers to subsequently die. When the fig ripens, the eggs of the wasps would have developed into adult wasps. Mating of the wasps takes place inside the fig, with the male dying shortly after. The female escapes from the fig via the opening, whose scales that seal the entrance would have by then loosened to make this possible.
The male flowers, usually found near the entrance of the fig, shed their pollen onto the escaping female wasps. These wasps then seek out other trees of the same species and force their entry into the developing figs to repeat the cycle.
There are about 600 species of figs consisting of climbers, shrubs and trees throughout the tropics. Some of these trees are stranglers, in the sense that their seeds germinate on the branch of a host tree to develop aerial roots that eventually grow round the host’s trunk. And as these roots thicken and coalesce, they prevent the host from growing in girth. In time, the host dies and the fig takes over, its mass of coalescing roots function as the “trunk” of the fig tree.
The list below gives a few of the commoner species that we recommend for use in a bird garden.
1. Benjamin fig or waringin (Ficus benjamina) is a large tree with a wide overhanging crown (top left). This is a strangling fig and not recommended for small gardens as the roots are very invasive. The old tree at the top of the Bukit Timah Nature Reserve used to be frequented by birdwatchers whenever it produced a crop of figs. Yong Ding Li documented a total of 29 species of birds found in and around the tree in September 2006 LINK.
Similarly in Peninsular Malaysia, Dato’ Dr Amar-Singh HSS listed Pink-necked Green Pigeon (Treron vernans), Black-naped Oriole (Oriolus chinensis), Asian Glossy Starling (Aplonis panayensis), Yellow Vented Bulbul (Pycnonotus goiavier), Coppersmith Barbet (Megalaima haemacephala), Lineated Barbet (Megalaima lineata), Blue Rock Thrush (Monticola solitarius), Common Iora (Aegithina tiphia) and Pied Triller (Lalage nigra) feeding in such a tree in May 2010 LINK.
2. Bodh-tree (F. religiosa) is another large fig tree that attracts numerous birds during its figging periods LINK (above left). This is again a strangler and not recommended for small gardens.
3. Sea fig (F. superba) is a coastal strangler, again not recommended for small to medium-sized gardens (above right). This is a large tree with large leaves. Figs are somewhat rounded, each with a long stalk. They ripen white or pale yellow to pink and finally purple. They are set in bunches along twigs and branches.
4. Yellow-stem fig (F. fistulosa) is a tree that can reach a height of 15 metres. It is not a strangling fig and thus not invasive. It can be considered for medium-sized gardens. The figs here are borne in bunches along the trunk and larger branches. A 2003 study on the feeding behaviour of birds listed a total of 15 species that visited this tree as well as the shrub listed below LINK.
5. White-leaved fig (F. grassularioide) is a shrub that is commonly found in secondary vegetation (see #4).
6. Climbing fig (F. villosa) has densely hairy leaves. It grows up nearby tree trunks to reach the light in secondary growth. Figs are pear-shaped with a protruding opening. They ripen orange. See this LINK.
(Image of white-leafed fig by Angie Ng; that of F. benjamina by M Chan; others by YC Wee)