Parrots: The Animal Answer Guide

10. Human Problems (from a parrot’s viewpoint)

169 Are any parrots endangered? We had been climbing steadily for an hour, zigzagging across the steep slope. Our objective was the top of a cliff on which nine pairs of Red-andgreen Macaws (Ara chloropterus) nested. The landholder had arranged for his brother to act as my guide, and a couple of children had come along for the ride. My tortoise-like advance contrasted starkly with the hare-like progress of the children. They nimbly negotiated the worst parts of the climb, rubber thongs apparently no disadvantage. On reaching the summit, I had to clutch at the sparse vegetation and steady myself. I was standing on a small area of level ground atop a vertiginous cliff. I made a slow turn and marveled at the unbroken expanse of vegetation in all directions. I knew people eked out a living in this country, but from my present vantage point it appeared an untouched wilderness. The scene was markedly different from what I had witnessed only a few hundred kilometers south. Flying into Barrieras two days earlier, my aircraft window had framed a view of orderly fields and pivot irrigators. Much of the vegetation surrounding this agricultural center in Brazil’s Bahia State had been cleared for soybean production . My thoughts were interrupted by a tug on my sleeve—the children had located a pair of macaws on the cliff. The birds were perched in one of the potholes used for nesting, though it was too early in the season for breeding to be underway. My guide explained they had once climbed down to these nests to retrieve the young; now they preferred to show the birds to tourists. As the landowner later explained, he had been “absent from nature, but now he was present in nature.” Parrots are one of the most threatened groups of birds in the world, with Chapter 10 Human Problems (from a parrot’s viewpoint) 170 Parrots: The Animal Answer Guide 27% of species listed as threatened. An additional 12% of species are of conservation concern. Parrots have a number of attributes that make them especially vulnerable to extinction. First, many parrots are large-bodied and slow-breeding. In these species, adults live for a long time but produce relatively few young. This sometimes delicate balance between mortality and fecundity can be easily disrupted by small alterations to nest success and survival rates. Second, numerous parrots have small populations or restricted ranges. Populations of large-bodied species may be small because a substantial area of habitat is required to sustain an individual, while parrots of all sizes can have small populations when they are restricted to small areas (e.g., islands). Small populations are more likely to be wiped out by catastrophic events than are large populations. Third, the slow life history of some parrots means they are ill-equipped to recover from any reduction in population size. The longer a population remains small, the greater its risk of extinction. Finally, nearly all parrots rely on cavities for nesting, and some have specialized diets. Specialization on a resource makes a species vulnerable to changes in the abundance or distribution of that resource. Loss of habitat continues to pose a risk to the world’s parrots. Around half of the world’s tropical forests have been cleared, and much of what remains is degraded or fragmented. Some of the most important countries for parrot conservation have the worst recent land-clearing records (e.g., Australia, Brazil, Indonesia, Mexico) or are experiencing increased rates of deforestation (e.g., New Guinea, Solomon Islands). In southeastern Brazil , >90% of the Atlantic rainforest has been cleared, with remaining areas existing as isolated fragments. Several parrots are endemic to this area, including the endangered Red-browed Amazon (Amazona rhodocorytha) and vulnerable Blue-throated Parakeet (Pyrrhura cruentata). In Australia, more than 50% of the vegetation outside the arid zone has been cleared for agriculture, with >500,000 hectares cleared each year between 1990 and 2000. This clearing has been a major factor in the decline of species such as Carnaby’s Cockatoo (Calyptorhynchus latirostris) and the Swift Parrot (Lathamus discolor). A recent study tracking changes in forest cover in Papua New Guinea found that 15% of tropical forests had been cleared between 1972 and 2002, with deforestation rates of between 1–18% recorded for individual bioregions. Much of this deforestation occurred in lowland forests, though high clearing rates were also recorded in forests adjoining subalpine grasslands. Worryingly, these forest types are poorly represented...