Biology subjects

Johnson, T. F.

Publications and source records attributed to Johnson, T. F..

3 recordsLinked to original sources

bioRxiv2022

CaPTrends: A global database of Carnivoran Population Trends

MotivationPopulation trend information is an Essential Biodiversity Variable for monitoring change in biodiversity over time. Here, we present a global dataset of 1122 population trends describing changes in abundance over time in large mammals from the Order Carnivora - some of the worlds most charismatic and functionally important fauna. Main types of variables includedKey data fields for each record: species, coordinates, trend timeframe, methods of data collection and analysis, and population timeseries or summarised trend value. Population trend values are reported using quantitative metrics in 75% of records that collectively represent more than 6500 population estimates. The remaining records qualitatively describe population change (e.g. increase). Spatial location and grainRecords represent locations across the globe (latitude: -51.0 to 80.0; longitude: -166.0 to 166.0) with more trends found within the northern temperate zone. Time period and grainRecords span from 1726 to 2017, with 92% of trends starting after 1950. Major taxa and level of measurementWe conducted a semi-systematic search for population trend data in 87 species from four families in the order Carnivora: Canidae, Felidae, Hyaenidae and Ursidae. We compiled data for 50 of the 87 species. Software format.csv

ecology↗

bioRxiv2021

Socioeconomics drive population change in the world's largest carnivores

Land-use1,2 and climate change3-5 have been linked to wildlife population declines, but the role of socioeconomic factors in driving declines, and promoting population recoveries, remains relatively unexplored despite its likely importance. Here, we evaluate a comprehensive array of potential drivers of population changes observed in some of the worlds most charismatic species - large mammalian carnivores. Our results reveal a strong role of human socioeconomic development, which we find has a greater impact on population change than habitat loss and climate change. Increases in socioeconomic development are linked to sharp population declines but, importantly, once development is high, carnivore populations have the potential to recover. These links between human development and wildlife population health highlight the challenges ahead to achieve the different UN Sustainable development goals.

ecology↗

bioRxiv2021

Density of Pied Crows Corvus albus in two of South Africa's protected areas

In recent decades, the pied crow Corvus albus population has grown in southern Africa, and this may have had impacts on other species. Conservationists and land managers may question the degree of threat posed by pied crows to other species, but a scarcity of ecological information on pied crows limits evidence-based decision-making. Using a distance density function we provide initial pied crow density estimates of 0.24 crows km-2 (0.12-0.5; 95% CI) and 0.18 crows km-2 (0.07-0.45; 95% CI) in two protected areas in the Northern Cape Province of South Africa. We infer that pied crow density is negatively associated with the normalised difference vegetation index (NVDI).

ecology↗