Habitat destruction and overexploitation are the main threats to biodiversity and where they co‐occur, their combined impact is often larger than their individual one. Yet, detailed knowledge of the ...spatial footprints of these threats is lacking, including where they overlap and how they change over time. These knowledge gaps are real barriers for effective conservation planning. Here, we develop a novel approach to reconstruct the individual and combined footprints of both threats over time. We combine satellite‐based land‐cover change maps, habitat suitability models and hunting pressure models to demonstrate our approach for the community of larger mammals (48 species > 1 kg) across the 1.1 million km2 Gran Chaco region, a global deforestation hotspot covering parts of Argentina, Bolivia and Paraguay. This provides three key insights. First, we find that the footprints of habitat destruction and hunting pressure expanded considerably between 1985 and 2015, across ~40% of the entire Chaco – twice the area affected by deforestation. Second, both threats increasingly acted together within the ranges of larger mammals in the Chaco (17% increase on average, ± 20% SD, cumulative increase of co‐occurring threats across 465 000 km2), suggesting large synergistic effects. Conversely, core areas of high‐quality habitats declined on average by 38%. Third, we identified remaining priority areas for conservation in the northern and central Chaco, many of which are outside the protected area network. We also identify hotspots of high threat impacts in central Paraguay and northern Argentina, providing a spatial template for threat‐specific conservation action. Overall, our findings suggest increasing synergistic effects between habitat destruction and hunting pressure in the Chaco, a situation likely common in many tropical deforestation frontiers. Our work highlights how threats can be traced in space and time to understand their individual and combined impact, even in situations where data are sparse.
1. Habitat loss is the primary cause of local extinctions. Yet, there is considerable uncertainty regarding how fast species respond to habitat loss, and how time-delayed responses vary in space. 2. ...We focused on the Argentine Dry Chaco (c. 32 million ha), a global deforestation hotspot, and tested for time-delayed response of bird and mammal communities to landscape transformation. We quantified the magnitude of extinction debt by modelling contemporary species richness as a function of either contemporary or past (2000 and 1985) landscape patterns. We then used these models to map communities' extinction debt. 3. We found strong evidence for an extinction debt: landscape structure from 2000 explained contemporary species richness of birds and mammals better than contemporary and 1985 landscapes. This suggests time-delayed responses between 10 and 25 years. Extinction debt was especially strong for forest specialists. 4. Projecting our models across the Chaco highlighted areas where future local extinctions due to unpaid extinction debt are likely. Areas recently converted to agriculture had highest extinction debt, regardless of the post-conversion land use. Few local extinctions were predicted in areas with remaining larger forest patches. 5. Synthesis and applications. The evidence for an unpaid extinction debt in the Argentine Dry Chaco provides a substantial window of opportunity for averting local biodiversity losses. However, this window may close rapidly if conservation activities such as habitat restoration are not implemented swiftly. Our extinction debt maps highlight areas where such conservation activities should be implemented.
Tropical deforestation is a main driver of the global biodiversity crisis. Impact assessments typically focus on species' presence, which means impacts are detected when local extinctions have ...occurred – and thus when it is too late. Here, we pioneer the combined use of two approaches that can detect deforestation impacts earlier, at the level of populations (using occupancy modelling) and at the level of individuals (using stress hormonal indicators). We tested this approach for the collared peccary (Pecari tajacu) in the Argentine Chaco, a global deforestation hotspot. We used camera-trap data to model peccary occupancy in relation to woodland cover and loss, and measured glucocorticoid metabolites in peccary feces to assess individuals' stress level in deforestation areas. We found that peccary occupancy was highest in remote areas with high woodland cover, but low otherwise. Peccaries were typically absent from areas where deforestation had been widespread recently. Where peccaries were present, physiological stress was correlated with the extent of edge between cropland and forest (a proxy for food availability), and not with deforestation. This, and the observation that peccaries disappear quickly as deforestation progresses, suggests that peccaries do not adapt well to the new conditions in deforestation frontiers. In terms of conservation management, our results underpin the importance of protecting large, contiguous woodland blocks to prevent large mammals from going extinct in deforestation frontiers. More broadly, we show how combining stress hormonal indicators and occupancy modelling can provide deep insights into processes underlying local extinctions in dynamic landscapes.
•We linked occupancy models and stress hormone analyses to assess deforestation impacts.•Peccaries disappeared quickly from deforestation landscapes.•Food limitation, not deforestation, was the main factor causing individual stress.•Peccaries in the Chaco have a low resilience towards deforestation.•Large and contiguous woodland patches are needed to protect large mammals in deforestation frontiers.
The COVID-19 pandemic highlighted the potential of using data from long-term citizen science projects to answer questions about the impacts of unexpected events on biodiversity. We evaluate the ...suitability of data from the citizen science platforms iNaturalist and eBird to describe the effects of the “anthropause” on biodiversity observation in Colombia. We compared record distribution according to human footprint, sampling behaviors, overall and conservation priority species composition during the strictest phase of the COVID-19 lockdown in 2020 to the same periods in 2015–2019. Overall participation in both platforms during the lockdown was high when compared to previous years, but records were concentrated on highly-transformed regions, had lower sampling efforts, and fewer species were recorded. For eBird, species composition was similar to that observed in previous years, and records of species of conservation concern declined in proportion to the decrease in overall species richness across samples. For iNaturalist, the species pool sampled each year remained too dissimilar for comparisons. Once differences in observer behaviors are accounted for, data from these platforms can be used in unplanned comparisons of relatively common species, in regions with high levels of human transformation, and at narrowly defined geographical contexts. To increase the potential of citizen science to monitor rarer species, more natural areas, or be used in large-scale analyses, we need to build and strengthen more diverse networks of observers that can further promote decentralization, democratization, and cost-effectiveness in biodiversity research.
•We compared iNaturalist and eBird data from 2020 to five previous years.•Biodiversity records during the lockdown came from highly-disturbed regions.•Lower sampling efforts led to fewer total and priority species recorded.•These data may show impacts of the anthropause within narrow ecological contexts.•We need to build and strengthen more diverse networks of biodiversity observers.
Land-use change is a root cause of the extinction crisis, but links between habitat change and biodiversity loss are not fully understood. While there is evidence that habitat loss is an important ...extinction driver, the relevance of habitat fragmentation remains debated. Moreover, while time delays of biodiversity responses to habitat transformation are well-documented, time-delayed effects have been ignored in the habitat loss versus fragmentation debate. Here, using a hierarchical Bayesian multi-species occupancy framework, we systematically tested for time-delayed responses of bird and mammal communities to habitat loss and to habitat fragmentation. We focused on the Argentine Chaco, where deforestation has been widespread recently. We used an extensive field dataset on birds and mammals, along with a time series of annual woodland maps from 1985 to 2016 covering recent and historical habitat transformations. Contemporary habitat amount explained bird and mammal occupancy better than past habitat amount. However, occupancy was affected more by the past rather than recent fragmentation, indicating a time-delayed response to fragmentation. Considering past landscape patterns is therefore crucial for understanding current biodiversity patterns. Not accounting for land-use history ignores the possibility of extinction debt and can thus obscure impacts of fragmentation, potentially explaining contrasting findings of habitat loss versus fragmentation studies.
Abstract
Understanding and mapping anthropogenic threats on species distributions is a crucial task in conservation science to identify priority areas and propose appropriate conservation strategies. ...Yet, there is a big challenge to quantify how these threats are associated with species distribution patterns at multiple temporal scales. For birds, existing national and global analyses have mostly focused on forest specialists and they tend to consider only one time period. Here, we evaluated spatial and temporal changes in human footprint within the distributions of Colombian birds from 1970 to 2018, and projected them into 2030. We show that widespread increases in human footprint were common within the distribution of terrestrial birds. Endemic and threatened birds have been disproportionately affected by past increases in human footprint within their distribution, and this trend will continue into the future. Several areas harboring high diversity of forest-specialists remained relatively intact up to 2018. However, our predictions show significantly higher and faster (>2% annual change) levels of transformation within these areas by 2030. Importantly, our results suggest that non-forest birds could be experiencing habitat quality declines that are just as significant as those shown for forest birds. Our results show that mitigating negative anthropogenic effects on bird habitats in Colombia requires an array of conservation strategies that range from strict habitat protection to mixed management. These analyses can serve as inputs in conservation decision tools that consider spatiotemporal variation of anthropic threats under multiple scenarios of change.
Land-use change is a global threat to biodiversity, but how land-use change affects species beyond the direct effect of habitat loss remains poorly understood. We developed an approach to isolate and ...map the direct and indirect effects of agricultural expansion on species of conservation concern, using the threatened giant anteater (
Myrmecophaga tridactyla
) in the Gran Chaco as an example. We reconstructed anteater occupancy change between 1985 and 2015 by fitting single-season occupancy models with contemporary camera-trap data and backcasting the models to 1985 and 2000 land-cover/use maps. Based on this, we compared the area of forest loss (direct effect of agricultural expansion) with the area where forests remained but occupancy still declined (indirect effect of agricultural expansion). Anteater occupancy decreased substantially since 1985, particularly after 2000 when agriculture expanded rapidly. Between 1985 and 2015, ~ 64,000 km
2
of forest disappeared, yet occupancy declined across a larger area (~ 102,000 km
2
), extending far into seemingly untransformed habitat. This suggests that widespread sink habitat has emerged due to agricultural land-use change, and that species may lose their habitat through direct and indirect effects of agricultural expansion, highlighting the urgent need for broad-scale conservation planning in the Chaco. Appropriate management responses could proactively protect more habitat where populations are stable, and restore habitat or address causes of mortality in areas where declines occur. Our work also highlights how occupancy modelling combined with remote sensing can help to detect the direct and indirect effects of agricultural expansion, providing guidance for spatially targeting conservation strategies to halt extinctions.
Noise is one of the fastest growing and most ubiquitous type of environmental pollution, with prevalence in cities. The COVID-19 confinement in 2020 in Colombia led to a reduction in human activities ...and their associated noise. We used this unique opportunity to measure the impacts of noise on urban soundscapes, and explore the effects of urbanization intensity independently of human activity. We launched a community science initiative inviting participants to collect audio recordings from their windows using smartphones. Recordings were taken during severe mobility restrictions (April), and during a period of lightened restrictions (May–June). From the data collected, we measured changes in sound pressure levels (SPL), acoustic structure (soundscape spectro-temporal characteristics), and human perception between the two periods. A 12% increase in human activities had a detectable acoustic footprint, with a significant increase of SPL (2.15 dB, 128% increase), a shift towards dominance of low-frequency broadband signals, and a perceived dominance of human-made over wildlife sounds. Measured changes in SPL and acoustic structure were directly proportional to urbanization; however, perception of these changes was not. This gap may be associated with a masking effect generated by noise or a disconnect of humans from nature in large cities. The mobility restrictions created a chance to better understand the impacts of urbanization and human activities on the soundscape, while raising public awareness regarding noise pollution effects on people and wildlife. Information analyzed here might serve in urban planning in developing countries where urban expansion is occurring in a rapid, unplanned fashion.
•We led a citizen science acoustic sampling across Colombia during COVID-19 lockdown.•We measured the impact of human activities in the soundscape of cities.•The acoustic impact of human activities was proportional to urbanization.•The perceived change in soundscape components was not related to urbanization.•Masking from anthropic noise may affect people's soundscape perception.
Mining is a driver for biodiversity loss worldwide. However, studies of its effects on wildlife are scarce, and few involve activities and environmental management carried out by mining companies. We ...evaluated the effect of mining activity at multiscale landscape approach on the diversity of dung beetles and bats in the largest open-pit mine in Colombia, located in the tropical dry forest (TDF), one of the most threatened ecosystems due to human activities. The landscape scale effect assessment was carried out with a multiscale analysis at 0.2, 0.5, 1, 1.5, and 2 km of radius around sampling points in 2005–2006, 2009–2010, 2012–2013, and 2016–2017. The vegetation cover was measure through remote sensing and fieldwork for the four periods of each scale. Once predictor variables (vegetation cover and mining) were identified at a landscape scale for each buffer. Generalized linear models were run to know the scale of the effect, and to measure the effects of the vegetation transformation by mining activity on diversity (0D, 1D) and abundance. The scale of the effect for dung beetles, and bats corresponded mostly to 0.2 km. Diversity metrics showed positive relationships with the percentage of natural cover but negative with the percentage of non-natural cover. Dung beetles had higher resilience to mining activities than bats. The implementation of environmental management tools such as maintaining natural areas and rehabilitation of disturbed areas is necessary, especially to mitigate the impacts of open-pit coal mining on different groups of fauna in critically endangered ecosystems such as TDF.
•Dung beetles are more resilient to open-pit coal mining landscape changes than bats.•Dung beetles and bats respond differently to landscape scales in open-pit coal mining.•Tropical dry forest areas are crucial landscape element for wildlife conservation in mining areas.•Rehabilitation is a positive strategy for wildlife restoration in open-pit coal mining.
The ability of animals to adjust their behaviour can influence how they respond to environmental changes and human presence. We quantified activity patterns of terrestrial mammals in oil palm ...plantations and native riparian forest in Colombia to determine if species exhibited behavioural changes depending on the type of habitat and the presence of humans. Despite the large sampling effort (12,403 camera-days), we were only able to examine the activity patterns of ten species in riparian forests and seven species in oil palm plantations, with four species (capybara, giant anteater, lesser anteater and common opossum) being represented by enough records (i.e.
n
> 20) in both oil palm and forest to allow robust comparisons. Only capybaras showed an apparent change in activity patterns between oil palm plantations and riparian forests, shifting from being crepuscular in forest to predominantly nocturnal inside oil palm plantations. Further, capybaras, giant anteaters and white-tailed deer appeared to modify their activities to avoid human presence inside oil palm plantations by increasing nocturnality (temporal overlap
Δ
^
ranged from 0.13 to 0.36), whereas jaguarundi had high overlap with human activities
Δ
^
=0.85 (0.61–0.90). Species pair-wise analysis within oil palm revealed evidence for temporal segregation between species occupying the same trophic position (e.g. foxes and jaguarundi), whereas some predators and their prey (e.g. ocelots and armadillos) had high overlaps in temporal activity patterns as might be expected. Our findings shed light on the potential behavioural adaptation of mammals to anthropogenic landscapes, a feature not captured in traditional studies that focus on measures such as species richness or abundance.
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