No abstract

Over the past few decades, land-use and climate change have led to substantial range contractions and species extinctions. Even more dramatic changes to global land cover are projected for this century. We used the Millennium Ecosystem Assessment scenarios to evaluate the exposure of all 8,750 land bird species to projected land-cover changes due to climate and land-use change. For this first baseline assessment, we assumed stationary geographic ranges that may overestimate actual losses in geographic range. Even under environmentally benign scenarios, at least 400 species are projected to suffer >50% range reductions by the year 2050 (over 900 by the year 2100). Although expected climate change effects at high latitudes are significant, species most at risk are predominantly narrow-ranged and endemic to the tropics, where projected range contractions are driven by anthropogenic land conversions. Most of these species are currently not recognized as imperiled. The causes, magnitude and geographic patterns of potential range loss vary across socioeconomic scenarios, but all scenarios (even the most environmentally benign ones) result in large declines of many species. Whereas climate change will severely affect biodiversity, in the near future, land-use change in tropical countries may lead to yet greater species loss. A vastly expanded reserve network in the tropics, coupled with more ambitious goals to reduce climate change, will be needed to minimize global extinctions.

Oil palm is one of the world's most rapidly expanding equatorial crops. The two largest oil palm-producing countries-Indonesia and Malaysia-are located in Southeast Asia, a region with numerous endemic, forest-dwelling species. Oil palm producers have asserted that forests are not being cleared to grow oil palm. Our analysis of land-cover data compiled by the United Nations Food and Agriculture Organization suggests that during the period 1990-2005, 55%-59% of oil palm expansion in Malaysia, and at least 56% of that in Indonesia occurred at the expense of forests. Using data on bird and butterfly diversity in Malaysia's forests and croplands, we argue that conversion of either primary or secondary (logged) forests to oil palm may result in significant biodiversity losses, whereas conversion of pre-existing cropland (rubber) to oil palm results in fewer losses. To safeguard the biodiversity in oil palmproducing countries, more fine-scale and spatially explicit data on land-use change need to be collected and analyzed to determine the extent and nature of any further conversion of forests to oil palm; secondary forests should be protected against conversion to oil palm; and any future expansion of oil palm agriculture should be restricted to pre-existing cropland or degraded habitats.

To manage and conserve biodiversity, one must know what is being lost, where, and why, as well as which remedies are likely to be most effective. Metabarcoding technology can characterise the species compositions of mass samples of eukaryotes or of environmental DNA. Here, we validate metabarcoding by testing it against three high-quality standard data sets that were collected in Malaysia (tropical), China (subtropical) and the United Kingdom (temperate) and that comprised 55,813 arthropod and bird specimens identified to species level with the expenditure of 2,505 person-hours of taxonomic expertise. The metabarcode and standard data sets exhibit statistically correlated alpha-and beta-diversities, and the two data sets produce similar policy conclusions for two conservation applications: restoration ecology and systematic conservation planning. Compared with standard biodiversity data sets, metabarcoded samples are taxonomically more comprehensive, many times quicker to produce, less reliant on taxonomic expertise and auditable by third parties, which is essential for dispute resolution.

Many of the world's migratory animals are in decline. This essay explores the unique scientific and political challenges of protecting migratory species while they are still common.

Abst:act. N~st predation ~as ?een suggested as an important cause of the decline of breeding popula~rons o~m~gratory so~gbirds m s~all wo?dlots in eastern North America. I tested this hypothesis by pla~mg artificial ne~ts WI~h fresh quail eggs m forests of different sizes in Maryland and Tennessee. Predation rates were higher_m small woodlots than in large tracts. Predation was especially intense in woodlots near suburban neighborhoods compared to woodlots in isolated rural areas. Experimental ope~-cup nes~~ were more vulnerable to predators when placed on the ground vs. 1-2m above ground. In eithe! position thes~ open-cup nests were more vulnerable to predators than experimental cavity nests. Smce most species ?f migratory s~mgbirds construct open-cup nests, and several species place them near the ground, migratory songbirds should be strongly affected by higher predation rates in small forest tracts.

No abstract

Geographic distribution data for endangered species in the United States were used to locate "hot spots" of threatened biodiversity. The hot spots for different species groups rarely overlap, except where anthropogenic activities reduce natural habitat in centers of endemism. Conserving endangered plant species maximizes the incidental protection of all other species groups. The presence of endangered birds and herptiles, however, provides a more sensitive indication of overall endangered biodiversity within any region. The amount of land that needs to be managed to protect currently endangered and threatened species in the United States is a relatively small proportion of the land mass.