Ecology of black cockatoos at a mine-site in the eastern jarrah-marri forest, western Australia.

Abstract

Three threatened black cockatoos inhabit the Jarrah Eucalyptus marginata-Marri Corymbia calophylla forest of southwestern Australia: Baudin’s Cockatoo Calyptorhynchus baudinii, Carnaby’s Cockatoo C. latirostris, and Forest Redtailed Black Cockatoo C. banksii naso [FRTBC]. Their local ecology in relation to anthropogenic disturbance is poorly known, hampering effective conservation management. Therefore we studied their group size, site occupancy patterns, habitat use, and food plants at a mine-site and its surrounds in the eastern forest over three years. FRTBC showed similar group sizes and occupancy across seasons, suggesting year-round residency and no marked seasonality in movements and grouping patterns. In contrast, Carnaby’s Cockatoos were up to twice as abundant in spring and summer, indicating migrating or transient flocks and some year-round residents. Few Baudin’s Cockatoos were present in summer, but their abundance increased at other times. All three cockatoos were observed in modified or humanmade habitats such as mine-site rehabilitation, farm paddocks, and pine plantations. Carnaby’s Cockatoos used the broadest habitat range. We documented feeding on 16 plant species, with Carnaby’s Cockatoos eating at least 10. Examination of feeding residues as well as observations of behaviour were essential to obtain a complete picture of feeding. Current mine-site rehabilitation protocols provide food for all three black cockatoos within a decade and should continue to do so long-term if Marri is maintained in the seed mix. However, because climate change scenarios predict declining rainfall over much of southwestern Australia, the plant species used to revegetate mine-sites and other landscapes may need to be reconsidered. For areas that do not specify restoring a jarrah forest landscape, the selective use of exotic or non-endemic flora better adapted to lower rainfall conditions may be an option.

Forest specialist species in the urban landscape: Do different levels of urbanization affect the movements of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso)?

“…As recently as the 1980s RTBC's were considered a rare and seasonal (May to November) visitor to the eastern SCP (Johnstone et al 2018), however, in 2019 the annual Birdlife Australia Great Cocky Count recorded 3499 birds on the highly urbanized coastal plain, a six-fold increase from 601 birds counted in 2014 (Peck et al 2019). Forest clearing is suggested as contributing to increased numbers on the plain, as the species' distribution is predominantly associated with jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forests, as is the presence of native and non-native food species such as cape lilac (Melia azedarah) (Johnstone et al 2013, Lee et al 2013, Johnstone et.al. 2018).…”

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

“…Lee et al (2013aLee et al ( , 2013b observed that black cockatoos used revegetation for feeding, but not roosting, perhaps because of the small size and open canopy of overstorey trees in intermediate-aged revegetation. Cockatoos prefer to roost in taller trees with wider canopies (Johnstone and Kirkby 2008).…”

“…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).…”

“…We sought to address these knowledge gaps by comparing the results of Lee et al (2010Lee et al ( , 2013aLee et al ( , 2013b to additional data on feeding activity by black cockatoos in revegetated areas and unmined forest at two other mine sites in the jarrah forest, namely, the Huntly mine of Alcoa of Australia Ltd (hereafter AA) and the Boddington Bauxite Mine of BHP Billiton Worsley Alumina (hereafter BBM). We tested whether there are successional patterns in cockatoo feeding activity in revegetation aged from 4 to 23 years, by documenting (1) structural and floristic variation in vegetation across mine sites and revegetation ages, (2) differences in cockatoo feeding activity across mine sites and revegetation ages on the basis of feeding residues and (3) any edge effect reflecting preferential use of vegetation at the interior or exterior of revegetated mine pits.…”

“…They come to resemble unmined forest more closely as the vegetation ages, a canopy of eucalypts forms and fire and silvicultural treatments are applied (Koch and Hobbs 2007). Lee et al (2010Lee et al ( , 2013aLee et al ( , 2013b used feeding residues (e.g. chewed eucalypt fruits) to document the use of 7-14-year-old revegetated mine pits by black cockatoos at the large, open-cut Newmont Boddington Gold mine (NBG) in the jarrah forest near Boddington, Western Australia.…”