Coxen's Fig-parrot Cyclopsitta diophthalma coxeni Recovery Plan 2001-2005

Coxen's Fig-Parrot Recovery Team
© The State of Queensland, Environmental Protection Agency, 2001

5. Ecology

5.1 Life history

The life history and ecology of Coxen's fig-parrot are largely unknown. Information is pieced together from incidental sightings and, where appropriate and possible, extrapolated from knowledge of the other subspecies. Holmes (1990, 1994a, 1995) summarises knowledge currently available.

Coxen's fig-parrot is a cryptic species. Most observations are of single birds or pairs feeding in fruiting trees or flying above the forest canopy. However, it is easy to overlook small, green birds living high among the foliage of canopy trees (Forshaw 1981). Even when the birds are known to be present in a tree, they can be impossible to detect (Norris 1964). To compound this problem, Coxen's fig-parrots feed quietly, moving swiftly and silently along the branches (Brenan 1924, Waller in Chisholm 1924, Irby 1930). Often they are only detected by the continual stream of fruit debris, the unwanted pulp of figs, falling to the ground (Chisholm 1924). The soft chattering of feeding red-browed fig-parrots (Bourke and Austin 1947) has not been described for Coxen's fig-parrots.

Individual fruiting trees may form important habitat components, especially during the breeding season. On the Sarabah Range, a rusty fig Ficus rubiginosa was visited for at least a week in September 1982, and a deciduous fig F. superba for three successive days in January of both 1982 and 1983. A Moreton Bay fig F. macrophylla in the Conondale Ranges was visited in October and November of successive years (Holmes 1990). Recent anecdotal evidence from the Bundaberg area in Queensland may indicate regular usage of individual trees until the fruit reserves are exhausted (Gynther et al. 1998).

Although Holmes (1990) suggests Coxen's fig-parrots are seasonal, altitudinal migrants, this may be an artefact of habitat decline and an assumption incorrectly based on the limited number of reported sightings. Whether any such movements occur is presumably determined by the local availability of food. Where food resources are capable of supporting a subpopulation throughout the year, altitudinal migrations appear to be reduced or absent (I. Gynther pers. comm.).

In some highland areas, birds may move to progressively higher altitudes from August to February following the wave of ripening fruit through the rainforests (Holmes 1995). All sightings in the Sarabah Range occurred during this period (Holmes 1990). As summer wanes, the wave of ripening fig and other fruit retreats to the lowlands from March to about October and the fig-parrots may follow. Lowland figs, which produce some fruit all year, have a winter fruiting peak (Storey 1994, S. Horton pers. comm., L. Jessup pers. comm.). At this time, fig-parrots may travel in search of food in small flocks (Holmes 1990). The largest 'winter' flock sighted in the past 25 years contained seven birds (Holmes 1990). During summer, the birds may occur more regularly in pairs.

The home range size of fig-parrots during either breeding or non-breeding seasons is unknown. Red-browed and Marshall's fig-parrots habitually form communal overnight roosts of up to 200 birds in particular trees (Bourke and Austin 1947, Forshaw 1969, 1981, Holmes 1995). Communal roosting is not known for Coxen's fig-parrot but Holmes (1995) speculates that it may once have occurred. Furthermore, he suggests that if the population is now so low that communal roosting is precluded, the loss of social interaction and consequent ability to locate food sources may be a contributing factor to the subspecies' apparent ongoing decline.

5.2 Food

Fig-parrots are omnivorous. They feed mainly on seeds of near ripe or ripe fruits of native figs, and/or insect larvae, which may include the fig wasp (Forshaw 1981, Romer and Spittall 1994, Pizzey and Knight 1997).

Favoured species are the Moreton Bay fig Ficus macrophylla and green-leaved strangler fig F. watkinsiana, but other species also eaten include rusty fig F. rubiginosa, white fig F. virens, small-leaved fig F. obliqua, cluster fig F. racemosa, the sandpaper figs F. coronata, F. opposita and F. fraseri and deciduous fig F. superba (Holmes 1990, Gynther et al. 1998, I. Gynther pers. comm.).

Native fruits also probably eaten are sour cherry Syzygium corynanthum, blue quandong Elaeocarpus grandis and bolly gum Litsea reticulata (Benfer in Chisholm 1924, Irby 1930, Holmes 1990). Other likely food sources include other lilly-pillies (Syzygium spp., Acmena spp.) and red ash Alphitonia excelsa (Holmes 1990). Silky oak Grevillea robusta nectar is reportedly eaten as well (Irby 1930). Consumption of lichens may supply a source of zinc (Romer and Spittall 1994).

Coxen's fig-parrot is also known to feed on exotic plants. These include edible fig F. carica, cotoneaster Cotoneaster lacteus and queen palm Syagrus romanzoffiana in gardens (Holmes 1990, Gynther et al. 1998), and loquat Eriobotrya japonica on farmland (Forshaw 1969). Such introduced species may be used when native food is in short supply (Holmes 1990).

5.3 Nest and eggs

Coxen's fig-parrots, like their related subspecies, are thought to nest in high trees usually within or near the edge of rainforest, although there are a few unconfirmed records from eucalypts some distance away. Like those of their northern counterparts, the nest chamber is excavated on the underside of a dead or decaying limb or trunk in a living or dead tree (Holmes 1995, Pizzey and Knight 1997, J. Young pers. Comm.). Nest construction is thought to begin in August (Gynther 1996a, J. Young pers. comm.) and breeding occurs from October to December or January (Holmes 1990, 1995). The normal clutch size is probably two (Holmes 1995, Pizzey and Knight 1997). Incubation and fledging details are unknown for Coxen's fig-parrot but, in captivity, red-browed fig-parrots incubate clutches for approximately 20-24 days and their young fledge after about 36-42 days (Romer and Spittall 1994).

5.4 Predators

Although no published information is available, predators of Coxen's fig-parrot are expected to include the brown goshawk Accipiter fasciatus, grey goshawk A. novaehollandiae, collared sparrowhawk A. cirrocephalus, sooty owl Tyto tenebricosa and southern boobook Ninox novaeseelandiae (J. Young pers. comm.).