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"Trimble, Morgan"
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Savanna elephant numbers are only a quarter of their expected values
2017
Savannas once constituted the range of many species that human encroachment has now reduced to a fraction of their former distribution. Many survive only in protected areas. Poaching reduces the savanna elephant, even where protected, likely to the detriment of savanna ecosystems. While resources go into estimating elephant populations, an ecological benchmark by which to assess counts is lacking. Knowing how many elephants there are and how many poachers kill is important, but on their own, such data lack context. We collated savanna elephant count data from 73 protected areas across the continent estimated to hold ~50% of Africa’s elephants and extracted densities from 18 broadly stable population time series. We modeled these densities using primary productivity, water availability, and an index of poaching as predictors. We then used the model to predict stable densities given current conditions and poaching for all 73 populations. Next, to generate ecological benchmarks, we predicted such densities for a scenario of zero poaching. Where historical data are available, they corroborate or exceed benchmarks. According to recent counts, collectively, the 73 savanna elephant populations are at 75% of the size predicted based on current conditions and poaching levels. However, populations are at <25% of ecological benchmarks given a scenario of zero poaching (~967,000)—a total deficit of ~730,000 elephants. Populations in 30% of the 73 protected areas were <5% of their benchmarks, and the median current density as a percentage of ecological benchmark across protected areas was just 13%. The ecological context provided by these benchmark values, in conjunction with ongoing census projects, allow efficient targeting of conservation efforts.
Journal Article
Conserving Africa’s wildlife and wildlands through the COVID-19 crisis and beyond
2020
The SARS-CoV-2 virus and COVID-19 illness are driving a global crisis. Governments have responded by restricting human movement, which has reduced economic activity. These changes may benefit biodiversity conservation in some ways, but in Africa, we contend that the net conservation impacts of COVID-19 will be strongly negative. Here, we describe how the crisis creates a perfect storm of reduced funding, restrictions on the operations of conservation agencies, and elevated human threats to nature. We identify the immediate steps necessary to address these challenges and support ongoing conservation efforts. We then highlight systemic flaws in contemporary conservation and identify opportunities to restructure for greater resilience. Finally, we emphasize the critical importance of conserving habitat and regulating unsafe wildlife trade practices to reduce the risk of future pandemics.
In Africa, COVID-19 has created a perfect storm of reduced funding, restrictions on the operations of conservation agencies, and elevated human threats to nature. This Perspective discusses solutions to move beyond this immediate crisis.
Journal Article
Over 80% of Africa's savannah conservation land is failing or deteriorating according to lions as an indicator species
by
Loveridge, Andrew
,
Western, Guy
,
Lindsey, Peter
in
Africa
,
African lion
,
area‐based conservation
2022
Calls to increase the global area under protection for conservation assume existing conservation areas are effective but, without adequate investment, they may not be. We collected survey data from expert respondents on perceived budgets, management, and threats for 516 protected areas and community conservation areas in savannah Africa to create a ConservationArea Performance Index. Combining this index with an indicative biodiversity outcome—population status of African lion, Panthera leo—we found that 82% of the sampled area was in a state of failure or deterioration, with only 10% in a state of success or recovery. A large proportion of succeeding or recovering conservation areas received external support through collaborative management partnerships. That Africa’s current conservation area network—the foundation of conservation efforts—is crumbling complicates proposed strategies to protect additional land. We contend that investing in the effective management of existing conservation areas— potentially through well-structured collaborative management partnerships— should be prioritized urgently.
Journal Article
Species Inequality in Scientific Study
by
TRIMBLE, MORGAN J.
,
VAN AARDE, RUDI J.
in
Africa, Southern
,
Amphibians
,
Animal, plant and microbial ecology
2010
Some conservationists argue for a focused effort to protect the most critically endangered species, and others suggest a large-scale endeavor to safeguard common species across large areas. Similar arguments are applicable to the distribution of scientific effort among species. Should conservation scientists focus research efforts on threatened species, common species, or do all species deserve equal attention? We assessed the scientific equity among 1909 mammals, birds, reptiles, and amphibians of southern Africa by relating the number of papers written about each species to their status on the International Union for Conservation of Nature Red List. Threatened large mammals and reptiles had more papers written about them than their nonthreatened counterparts, whereas threatened small mammals and amphibians received less attention than nonthreatened species. Threatened birds received an intermediate amount of attention in the scientific literature. Thus, threat status appears to drive scientific effort among some animal groups, whereas other factors (e.g., pest management and commercial interest) appear to dictate scientific investment in particular species of other groups. Furthermore, the scientific investment per species differed greatly between groups--the mean number of papers per threatened large mammal eclipsed that of threatened reptiles, birds, small mammals, and amphibians by 2.6-, 15-, 216-, and more than 500-fold, respectively. Thus, in the eyes of science, all species are not created equal. A few species commanded a great proportion of scientific attention, whereas for many species information that might inform conservation is virtually nonexistent.
Journal Article
Geographical and taxonomic biases in research on biodiversity in human-modified landscapes
2012
Biodiversity persistence in human-modified landscapes is crucial for conservation and maintaining ecosystem services. Studies of biodiversity in landscapes where humans live, work, and extract resources could support defensible policy-making to manage land-use. Yet, research should cover relevant regions, and biases in study topics should not lead to gaps in the evidence base. We systematically reviewed the literature of biogeography in human-modified landscapes published in eight eminent biogeography, conservation, and ecology journals to assess geographical bias among biomes and geopolitical regions and taxonomic bias among species groups. We compared research output per biome to area, biome type, species richness, proportion of transformed land, and the ratio of transformed to protected land. We also compared research output per geopolitical region to area, proportion of transformed land, the ratio of transformed to protected land, and human population density. Research output was distributed unequally among biomes, geopolitical regions, and species groups. Biome type was a clear factor in research bias, and forest biomes were the subject of 87% of papers, while species richness was not generally associated with bias. Conservation in human-modified landscapes is most important in regions with low protected area coverage, high land conversion, and high pressure from human populations, yet the distribution of published papers did not generally reflect these threats. Seventy-five percent of studies focused on the Americas and Europe, while Africa and Asia were critically understudied. Taxonomically, plants and invertebrates were the most studied groups; however, research output was not correlated with species richness per group. Protected areas alone will not conserve biodiversity in the long term. Thus, a strong biogeographical evidence base is required to support policies for biodiversity maintenance on human-modified land. Under-studied regions and species groups deserve further research to elucidate what, where, and how biodiversity persists in human-modified landscapes to inform conservation policy and enhance efficacy.
Journal Article
Supporting conservation with biodiversity research in sub-Saharan Africa's human-modified landscapes
by
Trimble, Morgan J
,
van Aarde, Rudi J
in
Animal and plant ecology
,
Animal, plant and microbial ecology
,
Applied ecology
2014
Protected areas (PAs) cover 12 % of terrestrial sub-Saharan Africa. However, given the inherent inadequacies of these PAs to cater for all species in conjunction with the effects of climate change and human pressures on PAs, the future of biodiversity depends heavily on the 88 % of land that is unprotected. The study of biodiversity patterns and the processes that maintain them in human-modified landscapes can provide a valuable evidence base to support science-based policy-making that seeks to make land outside of PAs as amenable as possible for biodiversity persistence. We discuss the literature on biodiversity in sub-Saharan Africa’s human-modified landscapes as it relates to four broad ecosystem categorizations (i.e. rangelands, tropical forest, the Cape Floristic Region, and the urban and rural built environment) within which we expect similar patterns of biodiversity persistence in relation to specific human land uses and land management actions. Available research demonstrates the potential contribution of biodiversity conservation in human-modified landscapes within all four ecosystem types and goes some way towards providing general conclusions that could support policy-making. Nonetheless, conservation success in human-modified landscapes is hampered by constraints requiring further scientific investment, e.g. deficiencies in the available research, uncertainties regarding implementation strategies, and difficulties of coexisting with biodiversity. However, information currently available can and should support efforts at individual, community, provincial, national, and international levels to support biodiversity conservation in human-modified landscapes.
Journal Article
Decline of birds in a human modified coastal dune forest landscape in South Africa
2011
Previous studies demonstrate that old-growth forest remnants and vegetation regenerating after anthropogenic disturbance provide habitat for birds in a human modified coastal dune forest landscape in northern KwaZulu-Natal, South Africa. However, occurrence does not ensure persistence. Based on a 13-year monitoring database we calculated population trends for 37 bird species and general trends in overall bird density in different vegetation types. We evaluated species’ characteristics as covariates of population trend and assessed changes in rainfall and proportional area and survey coverage per vegetation type. 76% of species assessed have declined, 57% significantly so at an average rate of 13.9% per year. Overall, bird density has fallen at 12.2% per year across old-growth forest and woody regenerating vegetation types. Changes in proportional area and coverage per vegetation type may partly explain trends for a few species but are unlikely to account for most. Below average rainfall may have contributed to bird declines. However, other possibilities warrant further investigation. Species with larger range extents tended to decline more sharply than did others, and these species may be responding to environmental changes on a broader geographical scale. Our results cast doubt on the future persistence of birds in this human modified landscape. More research is needed to elucidate the mechanisms driving population decline in the study area and to investigate whether the declines identified here are more widespread across the region and perhaps the continent.
Journal Article
Age determination by back length for African savanna elephants : extending age assessment techniques for aerial-based surveys
by
Nørgaard, Camilla F.
,
van Aarde, Rudi J.
,
Ferreira, Sam M.
in
Aerial surveys
,
Age composition
,
Age determination
2011
Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerialbased surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to 27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables.
Journal Article
Fences are More than an Issue of Aesthetics
2010
Licht and colleagues (BioScience 60: 147–153) identify South Africa’s pioneering efforts to reintroduce top predators to small, fenced protected areas as a conservation model America might be wise to follow. However, South African success at large predator reintroduction is largely the result of ubiquitous fencing that generally prevents predator conflict with people and livestock (see Gusset et al. 2008).
Journal Article