Differential extinction of forest species following forest fragmentation raises the questions of which populations are most prone to disappeaq and why. Hence we studied an 86–hectare woodland in west Java, the Bogor Botanical Garden (BBG), that became isolated when suwounding woodland was destroyed 50 years ago. Out of 62 bird species breeding in the BBG during 1932–1952, 20 had disappeared by 1980–1985, four were close to extinction, and five more had declined noticeably. The two main variables that identifl extinction‐prone populations in the BBG are 1) small initial population size in the BBG and 2) rareness or absence in the surrounding counttyside. Although the BBG retained wooded habitat, it is evidently too small to retain self‐sustaining populations of many woodland bird species. Small populations at high risk of extinction for stochastic reasons are doomed to disappear permanently unless subsidized by re‐colonization from the surroundings Thus, a too‐small reserve cannot function as a distributional island but comes to mirror the species composition of its surroundings More such case studies documenting species losses from small habitat fragments are required to demonstrate to nonbiologists the need for reserves large enough to support self‐sustaining populations.
Geophagy, the ingestion of soil, has been reported for birds and other animals from many regions, but its functions remain debated. We report geophagy for the first time for New Guinea birds: four or five parrot species, two or three pigeon species, one hornbill species, one crow species and possibly one cassowary species. These species ate soil at an area of bare ground created by a landslide on a steep mountain slope. Parrots visited the site in the early morning, pigeons in the late afternoon, flying in from considerable distances. All 11 of these species are frugivores. In the vicinity, we recorded 133 other bird species (including 37 other frugivore species) that were not observed to visit the site. Within each taxonomic group of frugivores, those practising geophagy tended to be the largest species of their guild. To test hypotheses regarding the functions of geophagy, we carried out chemical and physical analyses of soil samples from the site. The ingested soil was much too fine‐grained to be useful as grit; it contained only modest levels of all 14 minerals analysed; it lacked buffering capacity; and there was no evidence that it protected against diarrhoea. Instead, the soil's high measured cation‐exchange capacity, high content of cation‐binding minerals and binding of large quantities of tannic acid and quinine suggest a different hypothesis: that geophagy in this case served to bind poisonous and/or bitter‐tasting secondary compounds in ingested fruits and seeds. Geophagy thus represents one weapon in the escalating biological warfare between plants and animal consumers‐an evolutionary arms race at which parrots excel. We discuss five unsolved problems posed by geophagy.
During the course of a recent compilation of information concerning the natural history of Sulawesi, Indonesia, it became apparent that there were no recent records of the endemic Caerulean paradise‐flycatcher Eutrichomyias rowleyi and few of the endemic species of the fish family Adrianichthyidae. Efforts were made to confirm the continued existence of these animals but without success, and while it is impossible to be certain, we suggest that these species, and perhaps others from their communities, may be extinct or iritically endangered It is of great concern that none of the species discussed has ever been mentioned in the IUCNRed Data books, and it is suggested that further species in the endemic‐rich area ofWallacea may also have become extinct in the last few decades.
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