Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.

Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world’s vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species

The origins of South America's domestic alpaca and llama remain controversial due to hybridization, near extirpation during the Spanish conquest and di¤culties in archaeological interpretation. Traditionally, the ancestry of both forms is attributed to the guanaco, while the vicu·a is assumed never to have been domesticated. Recent research has, however, linked the alpaca to the vicu·a, dating domestication to 6000^7000 years before present in the Peruvian Andes. Here, we examine in detail the genetic relationships between the South American camelids in order to determine the origins of the domestic forms, using mitochondrial (mt) and microsatellite DNA. MtDNA analysis places 80% of llama and alpaca sequences in the guanaco lineage, with those possessing vicu·a mtDNA being nearly all alpaca or alpaca^vicu·a hybrids. We also examined four microsatellites in wild known-provenance vicu·a and guanaco, including two loci with non-overlapping allele size ranges in the wild species. In contrast to the mtDNA, these markers show high genetic similarity between alpaca and vicu·a, and between llama and guanaco, although bidirectional hybridization is also revealed. Finally, combined marker analysis on a subset of samples con¢rms the microsatellite interpretation and suggests that the alpaca is descended from the vicu·a, and should be reclassi¢ed as Vicugna pacos. This result has major implications for the future management of wild and domestic camelids in South America.

Guanacos (Lama guanicoe) are the largest native Artiodactyl in South America and the most widely distributed. In arid Patagonia, densities are low and negatively related to domestic sheep numbers in space and time consistent with interspecific competition theory. Although guanacos and domestic sheep have been described as intermediate feeders sharing food resources, no studies have been conducted to compare their diets in sympatric conditions and explore whether the potential exists for direct interspecific competition. We assessed the diet of both species across 9 different sites and 2 seasons by microhistological analysis of fecal samples. We found that (1) guanacos and sheep are generalist herbivores feeding on a wide range of plant species; (2) both are intermediate feeders able to include both monocotyledoneous and dicotyledoneous plants in their diet; (3) both are able to change their diets seasonally; and (4) food niche overlap is high, particularly in summer when food resources are more scarce than in spring. We conclude that the potential for competition between guanacos and sheep is high and could have played a major role in the demise of guanacos. Consequently, current management practices focused on maximizing sheep numbers are not compatible with the recovery of guanaco populations.

Guanacos (Lama guanicoe) are the only wild ungulate species widely distributed across the Patagonian steppe and have undergone a precipitous population decline since the introduction of domestic sheep (Ovis aries) 100 years ago. There has been speculation that sheep ranching may have played a major role in guanaco population decline after monopolising the most productive land because of competition for forage plants. Our aim in this work was to estimate guanaco abundance and account for its variation across nine different sites, two seasons and two years. We conducted over 100 ground surveys of both guanacos and sheep and estimated the availability of the preferred plant species both animal species might select in their diet. We found that (1) sheep densities were up to 23 times higher than guanaco densities in sympatric conditions, (2) at a protected site without sheep, guanaco density was one order of magnitude higher than at the rest of the sites, (3) across nine different sites, sheep densities alone accounted for around 60% of the variation in guanaco abundance, (4) guanaco densities were negatively related to both total plant cover and availability of the preferred plant species in their diet, which were both positively associated with sheep density, and (5) within-site changes in guanaco densities between seasons and years were negatively related to changes in sheep densities. Our results are consistent with predictions on interspecific competition for food resources, although we cannot rule out possible effects of other human-related activities influencing guanaco abundance. We conclude that sheep compete with guanacos for forage in arid Patagonia.

Elephant seals breed in Patagonia (Peninsula Valdes, Argentina) from late August to early November, reaching peak numbers during the first week in October. Observations of this population over the past ten years yielded similar results. Eighty percent of the pups were born by 2 October. Most (96%) of 663 females marked during three breeding seasons gave birth to a pup. Females stayed on land a mean of 28 d, gave birth 6 d after arrival, nursed their pups for 22 d, and copulated a mean of 2.5 times 20 d after parturition and 2 d before departure. Copulations peaked during the third week in October. Males spent 57-80 d on land fasting and defending harems of up to 134 females (median 11-13 females, depending on year). Most (96%) marked females that gave birth (n = 636) also weaned their pups successfully. Pup sex ratio was unity. Harems were smaller and breeding occurred about three weeks earlier in Patagonia than in other colonies. Thermal conditions, day length and food availability may explain clines in the timing of breeding events between populations, Other parameters of the breeding season for the expanding Patagonia colony are similar to those for declining southern elephant seal populations elsewhere.

We conducted focal observations of territorial guanacos, a highly polygynous and social mammal, to compare time budgets between sexes and test the hypothesis that the differences in reproductive interests are associated with differential group size effects on male and female time allocation patterns. In addition, we used group instantaneous sampling to test the hypothesis that grouping improves detection capacity through increased collective vigilance. We fit GLM to assess how group size and group composition (i.e., presence or absence of calves) affected individual time allocation of males and females, and collective vigilance. As expected from differences in reproductive interests, males in family groups devoted more time to scan the surroundings and less to feeding activities compared to females. Both sexes benefited from grouping by reducing the time invested in vigilance and increased foraging effort, according to predation risk theory, but the factors affecting time allocation differed between males and females. Group size effects were significant when females were at less than five body‐lengths from their nearest neighbour, suggesting that grouping benefits arise when females are close to each other. Female time budgets were also affected by season, topography and vegetation structure. In contrast to our expectation, males reduced the time invested in vigilance as the number of females in the group increased, supporting the predation risk theory rather the intrasexual competition hypothesis. The presence of calves was associated with an increase in male individual vigilance; and vegetation type also affected the intensity of the group size effect over male time allocation. In closed habitats, collective vigilance increased with the number of adults but decreased with the number of calves present. Although male and female guanacos differed in their time allocation patterns, our results support the hypothesis that both sexes perceive significant antipredator benefits of group living.

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