Abstract
AbstractNominally protected areas in Papua are under threat from encroachment, logging and hunting. The northern cassowary Casuarius unappendiculatus is the largest frugivore of the lowland rainforest of New Guinea and is endemic to this region, and therefore it is an important conservation target and a potential flagship species. We investigated effects of habitat degradation on the species by means of distance sampling surveys of 58 line transects across five distinct habitats, from primary forest to forest gardens. Estimated cassowary densities ranged from 14.1 (95% CI 9.2–21.4) birds km−2 in primary forest to 1.4 (95% CI 0.4–5.6) birds km−2 in forest garden. Density estimates were intermediate in unlogged but hunted natural forest and in > 30 year-old secondary forest, and considerably lower in recently logged (< 3 years) forest. Cassowary abundance was positively correlated with canopy cover and with tree height and diameter, and negatively correlated with hunting traps and human trails. In generalized linear models cassowary abundance was best explained by the number of fruiting trees and potential water sources. The results suggest that although the northern cassowary is moderately tolerant of intermediate disturbance it is relatively intolerant of heavy disturbance such as intensive logging. To secure the populations of northern cassowary and of other large animal species in Papua, forest degradation needs to be addressed by enforcing regulations in existing protection forest and/or establishing new protected areas, such as wildlife reserves.
Highlights
The rainforest of New Guinea is recognized as one of the last remaining wilderness areas but rapid developmentReceived 1 April 2013
Results varied among habitat types, the highest being 14.1 individuals km−2 in primary forest and the lowest 1.4 individuals km−2 in forest garden
Our density estimate for the northern cassowary (3.9 adults km−2) is higher than that inferred from the BirdLife International (2013) data for this species (c. 0.01– 0.05 adult birds km−2 across its global range)
Summary
The rainforest of New Guinea is recognized as one of the last remaining wilderness areas but rapid developmentReceived 1 April 2013. As in other parts of the tropics, local extinction of forest avifauna following forest fragmentation and extensive forest clearing is to be expected (Kattan et al, 1994; Castelletta et al, 2000; Waltert et al, 2004) Large forest birds such as cassowaries (Casuarius spp.) are likely to disappear if their habitat is disturbed, as their persistence may depend on factors such as the presence of fruiting trees and water sources (Bentrupperbäumer, 1997). Cassowaries are flightless, obligate frugivores and as such they require abundant fruit on the forest floor, a resource that is in short supply or absent in logged or converted forest Their long-term viability probably depends on the preservation of sufficiently large tracts of forest (Moore, 2003). Cassowaries are sought by hunters because of their large body size, and in some areas they are under considerable pressure from hunting (Mack & West, 2005; Pangau-Adam & Noske, 2010)
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