Strategic Planning for Species Conservation: A Handbook - IUCN

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Strategic Planning for Species Conservation 5.3.6 Threat analysis This section attempts to diagnose the processes threatening the species. The aim is to accurately and comprehensively identify the primary threats to species persistence. If the wrong threats are identified, proposed Actions may fail to halt or reverse population declines. Identification of threats therefore needs to be a thorough process, subject to peerreview wherever possible, involving critical analysis of the best available data. The threat analysis process also needs to be participatory, recognising where appropriate how threats vary spatially and temporally across the species’ geographic range. To the extent possible, data on the evidence that particular factors act as threats should be collated for each population. A threat is any factor that causes either a substantial decline in the numbers of individuals or a substantial contraction of the geographic range. Some common threats to species include direct exploitation, habitat destruction and modification, competition for resources with people or human-associated species (e.g., domestic animals), interactions with exotic species, disease organisms, and climate change. Threats may already be in operation (e.g., continued conversion of Bornean orang-utan (Pongo pygmaeus) habitat from natural forest to oil palm plantations), or they may be anticipated (e.g., possible destruction of southern sea otter habitat by an oil spill). It is important to distinguish threats from the natural processes that limit population size and distribution. For example, in large intact ecosystems cheetah numbers and distribution are strongly influenced by lion (Panthera leo) predation (Durant 1998). However, this is a natural process which maintains low cheetah density but does not cause population decline. Lion predation should not, therefore, be considered a threat to cheetah populations under such circumstances. Likewise, brown bear populations in high-altitude habitats of southern Asia are not threatened by low natural food abundance, even though this causes extremely low reproductive rates and hence low population growth. The threat to these populations is human-caused mortality in an environment that provides a minimal sustainable offtake (Nawaz, Swenson, and Zakaria 2008). Conversely, brown bears in the Gobi desert appear to be suffering from increased desertification, which is indeed a real environmental threat. For many species, it will also be helpful to distinguish proximate and ultimate threats to wild populations. Proximate (direct) threats are immediate causes of population decline, usually acting on birth or death rates. Proximate threats are often anthropogenic (e.g., conversion of habitat to cultivation or hunting for bushmeat), but may occasionally involve interactions between native species that formerly coexisted (e.g., unusually high rates of parasitism or predation). Ultimate (indirect) threats are the root causes (also sometimes referred to as underlying drivers) of proximate (direct) threats, and are almost always anthropogenic. For example, conversion of, say, forest to cultivation (a proximate threat) may be driven by human population growth, poverty, or people’s inability to realize economic benefits by sustainable use of uncultivated areas (all ultimate threats). Similarly, unusually high rates of predation by an indigenous predator (a proximate threat) may occur where prey movements are constrained by fencing (Van Dyk and Slotow 2003), where habitat has been modified or fragmented by people (Hedges and Tyson 2002), or where the introduction of exotic prey species has allowed predators to reach unusually high population densities (Novaro and Walker 2005; Roemer, Donlan, and Courchamp 2002). In these examples, the impact of natural predators has been elevated by human activities: hence, while the predator may represent the proximate threat, the ultimate threats are anthropogenic. 33
34 5. Status Review This distinction of proximate and ultimate threats is important. First, the distinction may help to guide Actions (see Chapter 8). Sometimes it may be appropriate to address proximate threats directly (e.g., reducing illegal offtake through anti-poaching patrols), but proximate threats may also be alleviated by addressing their ultimate causes (e.g., increasing local people’s food security to reduce reliance on bushmeat). Second, factors that act as proximate threats may in some cases be components of functioning ecosystems worth conserving in their own right. Examples would be the predation and parasitism processes mentioned above. In these cases it will usually be more appropriate, for long-term biodiversity conservation, to tackle the ultimate threat (e.g., by reversing habitat fragmentation or dismantling fences) than the proximate threat (e.g., through intensive control of an indigenous predator). We admit, however, that sometimes the line between proximate and ultimate threats is blurred. It may be useful to be aware that the Red List Unit of the IUCN Species Programme has recently revised the Red List classification scheme of direct threats into a set of 11 major threats, most of which are anthropogenic, but some of which are not (IUCN/CMP 2006). Details on each of these categories can be accessed online at http:// conservationmeasures.org/CMP/IUCN/browse.cfm?TaxID=DirectThreats (accessed 26 July 2008). It would not, however, be useful to constrain the definition of threats to those categorized by the Red List. The purpose of conducting a threat analysis as part of a Status Review is to guide conservation action by identifying which threats need to be mitigated, and this is likely to require a much more detailed characterization of threatening processes than can be achieved within the Red List definitions. In conducting threat analyses, it is important to avoid extrapolating too much from data on a single population, since threats often vary from place to place. For example, accidental capture in snares caused a major decline in the African wild dog population of Lower Zambezi National Park, Zambia, and was considered an important threat to several other populations, but was seldom or never observed in another set of wild dog study populations (Woodroffe et al. 2007a). 5.3.6.1 Diagnosing ongoing threats Identifying threats correctly is critical to ensuring that the correct measures are taken to reverse species declines. Caughley and Gunn (1996) provide a detailed review of approaches to the diagnosis of factors that cause population declines. They suggest that, after confirmation that a species is in decline, diagnosis of the causes should follow four steps: (a) study the species’ natural history to provide insights into likely causes of decline; (b) list all conceivable agents of decline; Photo 5.2 A Sherpa man with a Blood pheasant (Ithaginis cruentus) in Arun Valley, Nepal IUCN Photo Library © Jeffrey McNeely
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IUCN, International Union for Conse
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Strategic Planning for Species Conservation: A Handbook - IUCN

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