Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.

Biodiversity hotspots for conservation priorities

Recent extinction rates are 100 to 1000 times their pre-human levels in well-known, but taxonomically diverse groups from widely different environments. If all species currently deemed "threatened" become extinct in the next century, then future extinction rates will be 10 times recent rates. Some threatened species will survive the century, but many species not now threatened will succumb. Regions rich in species found only within them (endemics) dominate the global patterns of extinction. Although new technology provides details of habitat losses, estimates of future extinctions are hampered by our limited knowledge of which areas are rich in endemics.

https://science.sciencemag.org/content/sci/269/5222/347.full.pdf

The future of biodiversity.

The accelerating and potentially catastrophic loss of biotic diversity is unlike other environmental threats because it is irreversible. Given the rapid loss of biodiversity and limited resources available to address environmental issues, we must set priorities for our efforts to conserve biological resources. Because biodiversity is by no means evenly distributed, some areas are far richer than others in overall diversity and endemism. Furthermore, many of the richest areas also happen to be under the most severe threat. Over the next few decades, focusing conservation efforts on areas with the greatest concentrations of biodiversity and the highest likelihood of losing significant portions of that biodiversity will achieve maximum impact for conservation investment. By focusing on these high-priority areas we are not suggesting that other less diverse, less threatened areas should be written off, only that the high-biodiversity areas receive priority attention. Of the three different priority setting approaches we have used, we will discuss two in some detail: biodiversity hotspots and major tropical wilderness areas. A third approach, megadiversity countries, represents a country-based method intended mainly to better market biodiversity conservation in the world’s top 17 countries for species diversity and endemism (Mittermeier et al. 1997). All three of these approaches are based on five fundamental premises:

Biodiversity Hotspots and Major Tropical Wilderness Areas: Approaches to Setting Conservation Priorities

https://www.wur.nl/upload_mm/b/3/8/94e7760f-3dca-4cc1-8365-018832a8d729_Persistent%20negative%20effects%20of%20pesticides%20Geiger%20et%20al%202010.pdf

Persistent negative effects of pesticides on biodiversity and biological control potential on European farmland

Biodiversity hotspots have a prominent role in conservation biology(1-9), but it remains controversial to what extent different types of hotspot are congruent(4,10-14). Previous studies were unable to provide a general answer because they used a single biodiversity index, were geographically restricted, compared areas of unequal size or did not quantitatively compare hotspot types(1-10,12-22). Here we use a new global database on the breeding distribution of all known extant bird species to test for congruence across three types of hotspot. We demonstrate that hotspots of species richness, threat and endemism do not show the same geographical distribution. Only 2.5% of hotspot areas are common to all three aspects of diversity, with over 80% of hotspots being idiosyncratic. More generally, there is a surprisingly low overall congruence of biodiversity indices, with any one index explaining less than 24% of variation in the other indices. These results suggest that, even within a single taxonomic class, different mechanisms are responsible for the origin and maintenance of different aspects of diversity. Consequently, the different types of hotspots also vary greatly in their utility as conservation tools.

Global hotspots of species richness are not congruent with endemism or threat

Purpose and design in counting birds census errors territory mapping methods line transects point contacts catching and marking counting individual species counting colonial flocking and nesting birds distribution studies description and measurement of bird habitat chapter summaries and points to consider.

Bird Census Techniques

This is an important document prepared by ICBP. Based on worldwide studies, it states that because much of the world's threatened biodiversity can be found in comparatively small areas, protection of these areas would ensure the survival of a disproportionately high variety of species. Birds are good indicators of these key areas, and analysis of distribution has revealed that species of restricted range tend to occur together, in Endemic Bird Areas (EBAs). The survey identifies some 221 EBAs, with most (76 percent) occurring in the tropics. The report concludes that as these same areas are generally also very important for other species, the future of all EBAs is critical for global biodiversity conservation.

Putting biodiversity on the map: priority areas for global conservation.

Bibby, C.J. 1999. Making the most of birds as environmental indicators. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 70 (1): 81–88. Never previously has there been such an opportunity for biologists to inform and advise environmental decision-makers. Ornithologists have a special contribution to make because of the extent and quality of the information available to us. This paper focuses on environmental indicators—the process by which complex information about the environment can be encapsulated in some simply understood measures. This paper reviews the properties of effective indicators and the contribution that ornithology can currently make. Attention is given to globally threatened species, common bird monitoring schemes, summarising trend data from many species and to spatial questions about the distribution of biodiversity.

Making the most of birds as environmental indicators

Most recent extinctions of birds have been caused by habitat loss or by human or introduced predators and have been on islands. Local losses of species in habitat patches are particularly prevalent amongst various specialist feeders and species occurring in small numbers. Future candidates for global extinction are hard to pick from lists of species with indicators of susceptibility. Population modelling should help, but data are generally lacking. A review of threatened birds in the Americas shows that declines and rarity are often inferred from habitat loss and infrequent records, in the absence of quantitative data. The most threatened species often occur in very few places, where their future is likely to be determined. Safeguarding protected areas within centres of endemism offers a pragmatic response for a high proportion of globally threatened birds and probably other taxa as well.

Colin J. Bibby

Papers

Bird Census Techniques

Putting biodiversity on the map: priority areas for global conservation.

Making the most of birds as environmental indicators

Recent past and future extinctions in birds

Selecting Areas for Conservation