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opencc-zeroAug 2020View details →

Artificial night light helps account for observer bias in citizen science monitoring of an expanding large mammal population

1. The integration of citizen scientists into ecological research is transforming how, where, and when data are collected, and expanding the potential scales of ecological studies. Citizen-science projects can provide numerous benefits for participants, while educating and connecting professionals with lay audiences, potentially increasing acceptance of conservation and management actions. However, for all the benefits, collection of citizen-science data is often biased towards areas that are easily accessible (e.g. developments and roadways), and thus data are usually affected by issues typical of opportunistic surveys (e.g. uneven sampling effort). These areas are usually illuminated by artificial light at night (ALAN), a dynamic sensory stimulus that alters the perceptual world for both humans and wildlife. 2. Our goal was to test whether satellite-based measures of ALAN could improve our understanding of the detection process of citizen scientist-reported sightings of a large mammal. 3. We collected observations of American black bears (Ursus americanus; n = 1,315) outside their primary range in Minnesota, USA, as part of a study to gauge population expansion. Participants from the public provided sighting locations of bears on a website. We used an occupancy modelling framework to determine how well ALAN accounted for observer metrics when compared to other commonly used metrics (e.g. housing density). 4. Citizen scientists reported 17% of bear sightings were under artificially-lit conditions and monthly ALAN estimates did the best job accounting for spatial bias in detection of all observations, based on AIC values and effect sizes (β ^ = 0.81, 0.71 – 0.90 95% CI). Bear detection increased with elevated illuminance; relative abundance was positively associated with natural cover, closer proximity to primary bear range and lower road density. Although the highest counts of bear sightings occurred in the highly illuminated suburbs of the Minneapolis-St. Paul metropolitan region, we estimated substantially higher bear abundance in another region with plentiful natural cover and low ALAN (up to 275% increased predicted relative abundance) where observations were sparse. 5. We demonstrate the importance of considering ALAN radiance when analyzing citizen scientist-collected data, and we highlight the ways that ALAN data provides a dynamic snapshot of human activity. 31-Jul-2020

opencc-zeroDec 2016View details →

Data from: Climatic variation modulates the indirect effects of large herbivores on small-mammal habitat use

Large mammalian herbivores (LMH) strongly shape the composition and architecture of plant communities. A growing literature shows that negative direct effects of LMH on vegetation frequently propagate to suppress the abundance of smaller consumers. Indirect effects of LMH on the behaviour of these consumers, however, have received comparatively little attention despite their potential ecological significance. We sought to understand (i) how LMH indirectly shape small-mammal habitat use by altering the density and distribution of understorey plants; (ii) how these effects vary with climatic context (here, seasonality in rainfall); and (iii) the extent to which behavioural responses of small mammals are contingent upon small-mammal density. We tested the effects of a diverse LMH community on small-mammal habitat use using 4 years of spatially explicit small-mammal trapping and vegetation data from the UHURU Experiment, a replicated set of LMH exclosures in semi-arid Kenyan savanna. Small-mammal habitat use was positively associated with tree density and negatively associated with bare (unvegetated) patches in all plots and seasons. In the presence of LMH, and especially during the dry season, small mammals consistently selected tree cover and avoided bare patches. In contrast, when LMH were excluded, small mammals were weakly associated with tree cover and did not avoid bare patches as strongly. These behavioural responses of small mammals were largely unaffected by changes in small-mammal density associated with LMH exclusion. Our results show that LMH indirectly affect small-mammal behaviour, and that these effects are influenced by climate and can arise via density-independent mechanisms. This raises the possibility that anthropogenic LMH declines might interact with changing patterns of rainfall to alter small-mammal distribution and behaviour, independent of numerical responses by small mammals to these perturbations. For example, increased rainfall in East Africa (as predicted in many recent climate-model simulations) may relax constraints on small-mammal distribution where LMH are rare or absent, whereas increased aridity and/or drought frequency may tighten them.

opencc-by-4.0Oct 2023View details →

FSC-certified forest management benefits large mammals compared to non-FSC

Data for:  Zwerts, J.A., Sterck, E.H.M., Verweij, P.A. et al. FSC-certified forest management benefits large mammals compared to non-FSC. Nature 628, 563–568 (2024). https://doi.org/10.1038/s41586-024-07257-8 Abstract Over a quarter of the world's tropical forests are exploited for timber. This has extensive impacts on biodiversity and ecosystems, primarily through the creation of roads which facilitates hunting for wildlife over extensive areas. Forest management certification schemes such as the Forest Stewardship Council (FSC) are expected to mitigate impacts on biodiversity but to date very little is known about the effectiveness of FSC certification due to research design challenges, predominantly due to limited sample sizes. Here we provide this evidence by using 1.3 million camera trap photos of 55 mammal species in 14 logging concessions in Western Equatorial Africa. We observed higher mammal encounter rates in FSC-certified than in non-FSC logging concessions. The effect was most pronounced for species weighing over 10 kg, and for species of high conservation priority such as the Critically Endangered forest elephant and western lowland gorilla. Across the whole mammal community, non-FSC concessions contained proportionally more rodents and other small species than FSC-certified concessions. Our findings provide convincing data that FSC-certified forest management is less damaging to the mammal community than non-FSC forest management. This study provides strong evidence that FSC-certified forest management, or equivalently stringent requirements and controlling mechanisms, should become the norm for timber extraction to avoid half-empty forests dominated by rodents and other small species.           Data collection We set up arrays of camera traps from 2018 to 2021 in 14 logging concessions owned by 11 different companies (5 FSC and 6 non-FSC) in Gabon and the Republic of Congo. Seven FSC-certified concessions were each paired to the closest non-FSC concession that was similar in terms of terrain and forest type1. All concessions are situated in a matrix of connected forests. Within each pair of concessions, camera traps (Bushnell Trophy Cam HD for pairs 1 - 6 and Browning 2018 Spec Ops Advantage for pair 7) were deployed simultaneously to account for seasonal differences, for two to three months. There was one exception where Covid restrictions obliged the cameras to remain in place for longer. Camera trap grid locations within each pair of concessions were chosen based on similarity between potential drivers of mammal abundance, including distance to settlements, roads, rivers, protected areas, elevation and time since logging (2-10 years before our study), although some camera grids overlapped older logging blocks. Camera traps were set out in systematic, one-kilometre spaced grids with a random start point. Upon reaching the predetermined GPS locations, the first potential installation location was used where cameras had at least 4 metres of visibility. This ensured that each grid was representative of environmental heterogeneity: i.e. not specifically targeting nor ignoring trails or other landscape elements that could influence detection2. The one-kilometre inter-camera distance exceeds most species' home range sizes to avoid spatial autocorrelation. Neither were species expected to migrate within the sampling duration of the study. Between 28 to 36 cameras were deployed in each concession, totalling up to 474 camera traps, distributed over 474 km2. Cameras were installed at a height of 30 cm to enable observations of mammals of all sizes while ensuring that each camera had at least four metres visibility in front of it. Cameras were programmed to take bursts of three photos to maximize the chance of detection and to take a photo every 12 hours for correct calculation of active days in the event of a defect before the end of the deployment period. For each camera, we recorded whether there was an elephant path skidder trail, small wildlife trail, or none of the above within each camera's field of view. We also visually estimated forest visibility (0-10m / 11-20m / >20m), slope (0-5° / 5-20° / >20°), presence of fruiting trees within 30 m and presence of small water courses within 50 m. When approaching each predefined camera point, we counted cartridges, snares and hunting camps from 500 m before the camera up to its location. Various field teams were employed in different sites and hence there may be some influence interobserver bias of hunting observations between sites. Photo processing and data analysis Camera trap efforts yielded 1,278,853 photos, including 645,165 photos with animals. All photos were annotated in the program Wild.ID, version 1.0.1. We identified animals up to the species level if photo quality permitted and otherwise designated the species as 'indet'3. As reliable species identification of small mammals is difficult, they were grouped into squirrels, rats and mice and shrews. Rare observations of humans, birds, bats, reptiles and domestic dogs were excluded from the analyses. Observations of the same species that were at least 10 minutes apart were considered as separate detections. We assessed the influence of this threshold by calculating the number of detections for intervals of 10, 30, 60 and 1440 minutes, which all yielded similar numbers of observations. When multiple animals were observed, the number of individuals was determined by taking the highest number of individuals in a photo within the 10-minute threshold. Sampling effort was defined as the number of camera days minus down time due to malfunctioning cameras or obstruction of vision by vegetation.  Mammal behaviour may be different in hunted concessions, as mammals may be shyer for non-natural objects like camera traps, which would in turn negatively affect their probability of detection. If this dynamic indeed existed, this shyness was assumed to fade over time with habituation to the materials, resulting in an increase of observations over time. We tested for an interaction between certification status and the number of observations over time using a linear model with a log transformed number of observations for the first 65 days of all deployments, as that was the shortest concession deployment period, ensuring that all concessions were equally represented, but did not find that FSC certification was related to a trend in observations over time. We recognize however that other factors may exist that may have influenced detection probability, such as movement rates, which may be affected by hunting. For each species for each concession, we calculated encounter rate, weighted by group size, as the number of observations divided by the sampling effort and we reported all findings using the metric "Observations / day". Encounter rate was calculated for all species combined, per weight class, per taxonomic group, per IUCN Red List category and within taxonomic groups for large versus small forest antelopes, carnivores, primates and pangolins. Body weight of each species was determined by taking the mean across sexes3. Taxonomic groups Hyracoidea and Tubulidentata were excluded from the taxonomic analysis due to low sample sizes. Shrews were included as rodents in the taxonomy analysis even though they are formally not, because they are difficult to distinguish from mice. We consider this acceptable given that shrews are functionally very similar to rodents in the light of this study. Lastly, to study the impact of certification on total estimated faunal biomass, the encounter rate of each species was multiplied by its average weight divided by the sampling effort. To assess whether encounter rates varied between FSC and non-FSC concessions, we quantified the means of the paired concessions using linear mixed-effects models with concession pairs, concessions and cameras as random effects, whereby cameras were nested within concessions within concession pairs, in a multi-level random effect structure. We allowed the means of concession pairs to vary between weight class, taxonomic group and IUCN Red List category if supported by model selection. We tested whether potential drivers of mammal abundance were important using a model-selection approach based on minimization of Bayesian Information Criterion (BIC) values. We found that the inclusion of geographic covariates did not substantially improve the model for weight classes, taxonomic groups and IUCN categories. Only for all mammals pooled together , the inclusion of elevation and distance to rivers resulted in slightly improved models, but differences were negligible and did not support strong evidence for a significant influence of these covariates4.  Quadratic geographic covariate terms and camera trap site covariates did not result in better models. Post hoc comparisons were multivariate t adjusted. We used two-sided Wilcoxon signed-rank tests for all other analyses. Statistical analyses were performed in R version 4.2.2.   References <ol> <li>Grantham, H. S. et al. Spatial priorities for conserving the most intact biodiverse forests within Central Africa. Environmental Research Letters 15, 0940b5 (2020).</li> <li>Zwerts, J. A. et al. Methods for wildlife monitoring in tropical forests: Comparing human observations, camera traps, and passive acoustic sensors. Conserv Sci Pract 3, e568 (2021).</li> <li>Kingdon, J. The Kingdon field guide to African mammals. (Bloomsbury Publishing, 2015).</li> <li>Anderson, D. R. Model based inference in the life sciences: a primer on evidence. vol. 31 (Springer, 2008).</li> </ol>

opencc-zeroDec 2021View details →

An ecoregion-based approach to restoring the world's intact large mammal assemblages

Assemblages of large mammal species play a disproportionate role in the structure and composition of natural habitats. Loss of these assemblages destabilizes natural systems, while their recovery can restore ecological integrity. Here we take an ecoregion-based approach to identify landscapes that retain their historically present large mammal assemblages, and map ecoregions where reintroduction of 1–3 species could restore intact assemblages. Intact mammal assemblages occur across more than one-third of the 730 terrestrial ecoregions where large mammals were historically present, and 22% of these ecoregions retain complete assemblages across >20% of the ecoregion area. Twenty species, if reintroduced or allowed to recolonize through improved connectivity, can trigger restoration of complete assemblages over 54% of the terrestrial realm (11,116,000 km2). Each of these species have at least two large, intact habitat areas (>10,000 km2) in a given ecoregion. Timely integration of recovery efforts for large mammals strengthens area-based targets being considered under the Convention on Biological Diversity.

opencc-zeroOct 2022View details →

Does artificial feeding impact neonate growth rates in a large free-ranging mammal?

Variation and disparity in resource access between individuals in an animal population require attention within human-dominated landscapes where artificial selection processes may be at work. Independent, recreational human-wildlife feeding interactions constitute an increasingly prevalent yet understudied food resource for birds and mammals living in our cities, but only a limited number of risk-taking individuals may access it. Using urban fallow deer as our model species, we hypothesised that if these interactions result in positive effects for the engaging individual, e.g. increased milk quality and yield, then this would result in the increased growth rates of their offspring. Alternatively, if these individuals were prioritising investing time in engagement with humans, resulting in decreased maternal care, then this would result in slower growth rates in offspring. We found that the offspring of those females that regularly interacted with humans displayed significantly faster growth rates than the risk-avoider counterparts. This advantage for fearless mothers in terms of boosted neonatal growth rates could be mirrored in birds accessing garden feeders, seagulls or pigeons utilizing urban resources, or seals approaching city harbours. Here, we add a new piece to the complex puzzle of how humans are manipulating wildlife living within human-dominated landscapes.

opencc-zeroMay 2024View details →

Ecosystem-wide responses to fire and large mammal herbivores in an African savanna

Fire and large mammal herbivores (LMH) are the principal top-down forces maintaining savanna structure. Nonetheless, experiments designed to investigate interactions between fire and LMH are rare in savannas, and relationships between environmental variation and biodiversity in the context of fire and LMH are poorly understood. This study addresses these gaps by manipulating the presence of LMH and early and late dry season fires in a tropical African savanna. In addition, this work simultaneously explores environmental variables including soil and foliar quality, vegetation cover, and nearby water sources to more holistically describe factors affecting savanna functioning and biodiversity. After one year of experimental treatments, changes in vegetation were already apparent. Shrub abundance and richness and grass richness were higher in the absence of LMH, while grass biomass increased three-fold in burned plots as compared to unburned plots. Foliar nutrients tended to increase in open plots, while phenolics decreased. Amphibian abundance decreased with early burns and was higher with LMH. In contrast, small mammal abundance and richness increased without LMH and with time since fire. Richness and foraging of LMH were highest after late burns. These results demonstrate ecosystem-wide effects of LMH, illustrating the importance of considering multiple taxa when designing fire management programs. For example, burning negatively affected amphibians and small mammals and changed vegetation at the same time it increased LMH foraging. In the long-term, this experiment will shed light on interacting effects of fire and LMH on savanna biodiversity and function.

opencc-by-4.0Nov 2019View details →

Figure. Camera traps points (l) in study area. in Camera trapping of medium and large-sized mammals in western Black Sea deciduous forests in Turkey

Figure. Camera traps points (l) in study area.

Fig. 11 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 11. Plot of length versus distal articular width of Mc−III in some hipparions.

Fig. 6 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 6. Length versus width plot of Deinotherium M3s.

Fig. 1 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 1. Location map (A) and stratigraphic context (B) of the Yulafll localities.

Fig. 3 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 3. Length versus width plot of m1 in the genus Indarctos, showing continuous variation.

Fig. 5 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 5. Length versus width plot of Deinotherium P4s.

Fig. 7 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig. 7. Length versus width plot of Choerolophodon m3s.

Fig.12 in Late Miocene large mammals from Yulafli, Thrace region, Turkey, and their biogeographic implications

Fig.12. Length vs. width plot of p3s and p4s in Hippopotamodon antiquus and Microstonyx major.

opencc-by-nc-4.0Apr 2019View details →

Figure 2 in Medium and large sized mammals of the Boqueirão da Onça, North of Bahia State, Brazil

Figure 2. Mammals registered in Boqueirão da Onça, Bahia State, northeastern Brazil. (A) Tamandua tetradactyla; (B) Euphractus sexcinctus; (C) Tolypeutes tricinctus; (D) Mazama gouazoubira; (E) Pecari tajacu; (F) Tayassu pecari; (G) Cerdocyon thous; (H) Leopardus tigrinus; (I) Leopardus pardalis; (J) Panthera onca; (K) Puma concolor; (L) Herpailurus yagouaroundi; (M) Conepatus semistriatus; (N) Kerodon rupestris; (O) Dasyprocta nigriclunis.

opencc-by-nc-4.0Apr 2019View details →

Figure 1 in Medium and large sized mammals of the Boqueirão da Onça, North of Bahia State, Brazil

Figure 1. Mosaic formed by the National Park (NP) Boqueirão da Onça and the Environmental Protection Area (EPA) Boqueirão da Onça. Insertions on the left indicate the distribution of the Caatinga biome in northeastern Brazil and the location of the study area in the north of Bahia State, Brazil.

opencc-by-nc-4.0Aug 2019View details →

Figure 4 in Medium- and large-sized mammal composition in the Chapada dos Veadeiros National Park and adjacent areas, state of Goiás, Brazil

Figure 4. Non-Metric Multidimensional Scaling (NMDS) with Bray-Curtis distance matrix between the frequencies of mammalian registered in each camera trap located in the Chapada dos Veadeiros National Park, state of Goiás, central Brazil.

opencc-by-nc-4.0Aug 2019View details →

Figure 3 in Medium- and large-sized mammal composition in the Chapada dos Veadeiros National Park and adjacent areas, state of Goiás, Brazil

Figure 3. Rarefaction curves of the number of mammalian species recorded in the Chapada dos Veadeiros National Park and its surroundings during the dry and rainy seasons, state of Goiás, central Brazil.