Pine as Fast Food: Foraging Ecology of an Endangered Cockatoo in a Forestry Landscape

William D Stock,Jackson Parker,Hugh Finn,Ken Dods,Claudia Mettke-Hofmann

doi:10.1371/journal.pone.0061145

Abstract

Pine plantations near Perth, Western Australia have provided an important food source for endangered Carnaby’s Cockatoos (Calyptorhynchus latirostris) since the 1940s. Plans to harvest these plantations without re-planting will remove this food source by 2031 or earlier. To assess the impact of pine removal, we studied the ecological association between Carnaby’s Cockatoos and pine using behavioural, nutritional, and phenological data. Pine plantations provided high densities of seed (158 025 seeds ha−1) over a large area (c. 15 000 ha). Carnaby’s Cockatoos fed throughout these plantations and removed almost the entire annual crop of pine cones. Peak cockatoo abundance coincided with pine seed maturation. Pine seed had energy and protein contents equivalent to native food sources and, critically, is available in summer when breeding pairs have young offspring to feed. This strong and enduring ecological association clearly suggests that removing pine will have a significant impact on this endangered species unless restoration strategies, to establish alternative food sources, are implemented.

Highlights

Carnaby’s Cockatoo (Calyptorhynchus latirostris) is a threatened avifauna endemic to southwestern Australia that has declined by more than 50% over the last half-century [1,2]
In the Perth metropolitan region, for example, 5974 ha of native vegetation were cleared between 1998 and 2004 [19]. These losses add to historical losses for agriculture, industry, and housing, with the Swan Coastal Plain around Perth retaining less than 30% of its original native vegetation cover [19]
Nitrogen was more variable with an average of 9.0% across all species and the pines had nearly 45% less protein than the high N seeds of the Proteaceae (Banksia and Hakea spp.) Protein in pine seeds is more similar to other native species of the Myrtaceae (Eucalyptus and Corymbia spp.) and Fabaceae (Acacia spp.)

Summary

Introduction

Carnaby’s Cockatoo (Calyptorhynchus latirostris) is a threatened avifauna endemic to southwestern Australia that has declined by more than 50% over the last half-century [1,2]. Carnaby’s Cockatoos feed on a range of foods on the Swan Coastal Plain, including seeds and flowers of proteaceous shrubs and myrtaceous trees within remnant heath and woodland habitats, as well seeds of plantation pine (Pinus spp.) [8,9,10,11,12,13,14,15]. Remaining native bushland is under pressure from regular arson fires, plant pathogens such as Phytopthora cinnamomi (dieback), climate change, and other stressors [20,21] These factors make the loss of feeding habitat on the Swan Coastal Plain an important conservation concern for Carnaby’s Cockatoos and emphasise the need to conserve natural and anthropogenic food sources wherever possible [6,7,8]

Objectives

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Results

Conclusion