The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. II. Breeding behaviour and diet

Abstract

Little is known of the breeding behaviour of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso (FRTBC), a large, iconic forest cockatoo, endemic to the south-west corner of Western Australia, currently listed as Vulnerable under the State Western Australian Wildlife Conservation Act and under the Commonwealth Environment Protection and Biodiversity Conservation Act. In this paper, we provide details of breeding behaviour of FRTBC based on observations throughout the year over 17 years, together with observations of diet and feeding behaviour over the same period. FRTBC are monogamous hollow-nesters. Breeding was recorded in all months, with peaks in autumn-winter (April– June) and spring (August–October), with few records in January and February. Breeding also varied between years, with little breeding in 1999, 2001 and 2008, but many observations in 2006 and 2009. Breeding occurred at times of fruiting of either of the principal feed trees, Jarrah Eucalyptus marginata or Marri Corymbia calophylla, so it does not depend solely on one or the other of these species. Courtship displays were noted at all times of the day, from before dawn at roost sites to dusk. In total, 205 breeding events were recorded, of which 69 (93%) of 72 nests had breeding confirmed on a second visit. Use of particular nest hollows varied considerably, with some used only once and some up to seven times. Only one egg is laid, which the female incubates for 29 to 31 days, before a nestling hatches weighing between 27 and 32 g. The female remains in the hollow during incubation and only leaves for a short period in the evening to be fed by the male, usually at dusk. The chicks are brooded for up to 10 days, after which the female leaves the nest between dawn and dusk. Pairs of birds appear to recognise each other by calls, not responding to calls by others in the area. Chicks only respond when the parent is heard. Chicks are fully feathered at 48 days. Fledgling success was estimated at 60%. Juveniles remain dependent on the adults 18 months to 2 years. Thirty-seven chicks were banded between 1997 and 2011. Juvenile-immature birds moved on average less than 3 km from their natal tree and older birds were observed moving up to 19 km. This suggests that FRTBC are generally sedentary. Immature birds took up to three times as long as their parents to open Jarrah or Marri nuts and eat the seeds. In recent years there has been an interesting change in foraging behaviour of birds in the northern Darling Range (adjacent to the Perth metropolitan area) with the FRTBC discovering and using a new food source, the introduced Cape Lilac Melia azedarach, and this species is of growing importance as food in the Perth region. In combination, the data on breeding biology and diet highlight the importance of identifying recruitment rates and food availability in managing populations of FRTBC.

Successional changes in feeding activity by threatened cockatoos in revegetated mine sites

“…Marri fruit availability can vary significantly from year to year because the trees may flower heavily only every 3-4 years and the seeds are released 2-2.5 years after flowering (Seddon 1972;Powell 1990), suggesting that periods of low fruit availability are likely to occur. Thus, at a landscape scale, cockatoos shift between feeding on marri and jarrah according to what is fruiting (Johnstone et al 2013b), which may account for the higher feeding activity on jarrah observed in unmined forest in an earlier study at NBG (Biggs et al 2011). Second, young trees in revegetated areas are unlikely to provide the large fruit crops that older trees in unmined forest can.…”

“…First, the frequency of flowering and, consequently, fruiting events may differ between revegetation and unmined forest. Cockatoos opportunistically feed on marri and jarrah trees that have large fruit crops following prolific flowering events (Johnstone et al 2013b). Marri fruit availability can vary significantly from year to year because the trees may flower heavily only every 3-4 years and the seeds are released 2-2.5 years after flowering (Seddon 1972;Powell 1990), suggesting that periods of low fruit availability are likely to occur.…”

“…Floristics were recorded as the number of species present known to be food plants of the three study species (Table 1), on the basis of Saunders (1974aSaunders ( , 1974bSaunders ( , 1980, Johnstone and Storr (1998), Johnstone and Kirkby (1999), Johnstone et al (2013b) and Lee et al (2013a). To quantify vegetation structure, we measured canopy cover, canopy height and understorey height, and counted stem densities of plant species that are a common food resource for black cockatoos (Banksia spp., Hakea spp., marri and jarrah; Table 1).…”

“…Habitat loss is a major threat to the survival of the three black cockatoos endemic to south-western Australia (the forest red-tailed black cockatoo (Calyptorhynchus banksii naso; FRTBC), Carnaby's cockatoo (Calyptorhynchus latirostris; CBC), and Baudin's cockatoo (Calyptorhynchus baudinii; BBC) (Chapman 2008;Garnett et al 2011;Department of Environment 2012;Johnstone et al 2013aJohnstone et al , 2013b. All three species of cockatoo are listed as threatened under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, whereas CBC and BBC are classified as Endangered in the IUCN Red List (Birdlife International 2013a.…”

A thirteen‐year study on the impact of a severe canker disease of Corymbia calophylla, a keystone tree in Mediterranean‐type forests

“…These include the costs associated with lost honey and pollen production, tree removal, loss of wildlife habitats and food resources, including that of the threatened Carnaby's black cockatoo (Calyptorhynchus latirostris Carnaby), Baudin's (Calyptorhynchus baudinii Lear) and Forest red-tailed black cockatoo (Calyptorhynchus banksia naso Gould; Johnstone & Kirkby, 1999;Lee, Finn, & Calver, 2013), conservation of roadside verges, the loss of amenity values such as shade, and the control of salinity and erosion by reforestation (Shearer, 1992). These include the costs associated with lost honey and pollen production, tree removal, loss of wildlife habitats and food resources, including that of the threatened Carnaby's black cockatoo (Calyptorhynchus latirostris Carnaby), Baudin's (Calyptorhynchus baudinii Lear) and Forest red-tailed black cockatoo (Calyptorhynchus banksia naso Gould; Johnstone & Kirkby, 1999;Lee, Finn, & Calver, 2013), conservation of roadside verges, the loss of amenity values such as shade, and the control of salinity and erosion by reforestation (Shearer, 1992).…”