The glossy black-cockatoo

Watch a small flock settle into a stand of she-oaks and the surprise is how quietly, how unhurriedly, they go about it. A big, smoky-brown cockatoo, panels of dull red flashing in the tail, sidles along a branch, takes a woody cone in one foot, and works it bill-first, splitting the hard case to prise the seeds out one at a time. An awkward, fiddly way to make a meal — and that is the point. The glossy black-cockatoo has taken on a food so tedious to extract that scarcely any other bird bothers, and by bothering it has claimed that food almost entirely to itself. You can read the evidence on the ground: beneath a favoured feed tree lies a litter of chewed, shredded cones, the unmistakable wreckage of a glossy black at dinner.

That is the specialist’s logic. Survive on what almost nothing else will touch and you escape the competition. But a living this inefficient comes with a bill attached, and for the cockatoo the bill is doubled. Feeding is only half of it.

Like so many of the gum forest’s tenants, the glossy black-cockatoo cannot breed without a large hollow in an old tree, and it is fussy even about that: a big hollow in a big old trunk, nothing less, and then raising, as a rule, a single slow-growing chick at a time. So the bird is pinned between two resources, and neither can be hurried. A she-oak takes years to mature and bear cones; fungi, termites, fire and rot excavate a hollow fit for a cockatoo over a century or more, and nothing conjures it back on any human timescale. Two resources, one bird, two ways to lose it.

Clear the she-oaks and it starves. Fell the old hollow-bearing veterans and it cannot nest. Do both, as land-clearing tends to do at once, and the bird goes. It turns up only where a stretch of woodland still holds both its dependencies together, the feed trees and the nest trees, and it is among the first birds to drop out when either is thinned, long before the woodland looks obviously broken. A stand can be green and loud and apparently healthy and still be quietly failing the cockatoo, because the old hollow trees can go out of it without the green changing at all. The bird is a living audit of how intact the country really is.

Set it beside the koala, its neighbour under the same canopy, and each sharpens the other. The koala stakes everything on the eucalypt leaf and on having enough feed trees joined closely enough to move between safely; it uses no hollow at all. The glossy black stakes itself on she-oak seed and on the century-old hollow, and worries less about connection than about whether both those slow things survive side by side. Different needs, the same forest, the same blunt conclusion. You keep the animal only by keeping the slow-built system its life is staked on.

A warming, fire-prone century bears on both halves of the bargain at once. Too-frequent or too-severe fire kills old hollow-bearing trees outright, and nothing can replace them within a bird’s lifetime, while the same fires and the same clearing eat into the she-oak stands it feeds on. The south-eastern subspecies is now listed Vulnerable, and it is not hard to see why. An animal that needs the seed and the hollow together has given the modern landscape two easy ways to undo it.

And yet where the woodland still stands whole, there they are, working the cones tree by patient tree, dropping their shredded ledger on the ground: a slow bird making a slow living in a forest that, for now, is still keeping its old trees.