More Like this

1. Baseline and stress-induced corticosterone levels across birds and reptiles do not reflect urbanization levels

   https://doi.org/10.1093/conphys/coz110  

   Injaian, Allison S ; Francis, Clinton D ; Ouyang, Jenny Q ; Dominoni, Davide M ; Donald, Jeremy W ; Fuxjager, Matthew J ; Goymann, Wolfgang ; Hau, Michaela ; Husak, Jerry F ; Johnson, Michele A ; et al ( January 2020 , Conservation Physiology)

   Abstract Rates of human-induced environmental change continue increasing with human population size, potentially altering animal physiology and negatively affecting wildlife. Researchers often use glucocorticoid concentrations (hormones that can be associated with stressors) to gauge the impact of anthropogenic factors (e.g. urbanization, noise and light pollution). Yet, no general relationships between human-induced environmental change and glucocorticoids have emerged. Given the number of recent studies reporting baseline and stress-induced corticosterone (the primary glucocorticoid in birds and reptiles) concentrations worldwide, it is now possible to conduct large-scale comparative analyses to test for general associations between disturbance and baseline and stress-induced corticosterone across species. Additionally, we can control for factors that may influence context, such as life history stage, environmental conditions and urban adaptability of a species. Here, we take a phylogenetically informed approach and use data from HormoneBase to test if baseline and stress-induced corticosterone are valid indicators of exposure to human footprint index, human population density, anthropogenic noise and artificial light at night in birds and reptiles. Our results show a negative relationship between anthropogenic noise and baseline corticosterone for birds characterized as urban avoiders. While our results potentially indicate that urban avoiders are more sensitive to noise than other species, overall our study suggests that the relationship between human-induced environmental change and corticosterone varies across species and contexts; we found no general relationship between human impacts and baseline and stress-induced corticosterone in birds, nor baseline corticosterone in reptiles. Therefore, it should not be assumed that high or low levels of exposure to human-induced environmental change are associated with high or low corticosterone levels, respectively, or that closely related species, or even individuals, will respond similarly. Moving forward, measuring alternative physiological traits alongside reproductive success, health and survival may provide context to better understand the potential negative effects of human-induced environmental change. 

   more » « less
2. Wildfire alters the disturbance impacts of an emerging forest disease via changes to host occurrence and demographic structure

   https://doi.org/10.1111/1365-2745.13495  

   Simler‐Williamson, Allison B. ; Metz, Margaret R. ; Frangioso, Kerri M. ; Rizzo, David M. ; Thrall, ed., Peter ( September 2020 , Journal of Ecology)

   Anthropogenic activities have altered historical disturbance regimes, and understanding the mechanisms by which these shifting perturbations interact is essential to predicting where they may erode ecosystem resilience. Emerging infectious plant diseases, caused by human translocation of nonnative pathogens, can generate ecologically damaging forms of novel biotic disturbance. Further, abiotic disturbances, such as wildfire, may influence the severity and extent of disease‐related perturbations via their effects on the occurrence of hosts, pathogens and microclimates; however, these interactions have rarely been examined.

   The disease ‘sudden oak death’ (SOD), associated with the introduced pathogenPhytophthora ramorum, causes acute, landscape‐scale tree mortality in California's fire‐prone coastal forests. Here, we examined interactions between wildfire and the biotic disturbance impacts of this emerging infectious disease. Leveraging long‐term datasets that describe wildfire occurrence andP. ramorumdynamics across the Big Sur region, we modelled the influence of recent and historical fires on epidemiological parameters, including pathogen presence, infestation intensity, reinvasion, and host mortality.

   Past wildfire altered disease dynamics and reduced SOD‐related mortality, indicating a negative interaction between these abiotic and biotic disturbances. Frequently burned forests were less likely to be invaded byP. ramorum, had lower incidence of host infection, and exhibited decreased disease‐related biotic disturbance, which was associated with reduced occurrence and density of epidemiologically significant hosts. Following a recent wildfire, survival of mature bay laurel, a key sporulating host, was the primary driver ofP. ramoruminfestation and reinvasion, but younger, rapidly regenerating host vegetation capable of sporulation did not measurably influence disease dynamics. Notably, the effect ofP. ramoruminfection on host mortality was reduced in recently burned areas, indicating that the loss of tall, mature host canopies may temporarily dampen pathogen transmission and ‘release’ susceptible species from significant inoculum pressure.

   Synthesis. Cumulatively, our findings indicate that fire history has contributed to heterogeneous patterns of biotic disturbance and disease‐related decline across this landscape, via changes to the both the occurrence of available hosts and the demography of epidemiologically important host populations. These results highlight that human‐altered abiotic disturbances may play a foundational role in structuring infectious disease dynamics, contributing to future outbreak emergence and driving biotic disturbance regimes.

    

   more » « less
3. Trends in forest fragment research in Madagascar: Documented responses by lemurs and other taxa

   https://doi.org/10.1002/ajp.23092  

   Kling, Katherine J. ; Yaeger, Kimberley ; Wright, Patricia C. ( January 2020 , American Journal of Primatology)

   The rise in research investigating fragmentation and its impact on primates and other taxa reflects the growing presence of fragmented landscapes themselves. Although numerous studies report the negative effects of fragmentation on biodiversity, it is difficult to generalize responses to fragmentation for specific taxonomic groups, such as non‐human primates, when studies have not employed a definitive concept of fragmentation or fragments themselves. Madagascar's high degree of fragmentation, wealth of endemic taxa, and extensive history of ecological research provide the opportunity to compare fragmentation studies across similar contexts. We conducted a literature search of peer‐reviewed articles on fragmentation in Madagascar to characterize its trends. A total of 70 articles, 46 of which concentrated on lemurs, tested the impacts of fragmentation on Malagasy taxa, while additional sources conducted research in one or more fragments without testing its effects (n = 112 total, 79 on lemurs). Studies on lemurs most frequently tested fragmentation's impacts on genetics and biodiversity metrics (n = 16 and 15 studies, respectively), although health, modeling, behavioral, and cross‐disciplinary techniques were also reported. Responses to fragmentation were reported for 49 lemur species, with most studies concentrated in eastern Madagascar (87%). Although there was variation in the metrics reported in studies testing the effects of fragmentation on Malagasy species, the most common measures were fragment area, isolation, or comparison to a control site. Landscape‐scale approaches and examination of fragmentation per se were rarely employed. Characterizing trends of fragmentation research in Madagascar emphasizes the challenges of documenting fragmentation's effects while highlighting the benefits of research within fragmented landscapes, particularly when combined with consideration for how the matrix within human‐modified landscapes may impact primate populations.

    

   more » « less
4. Movement ecology of vulnerable lowland tapirs between areas of varying human disturbance

   https://doi.org/10.1186/s40462-022-00313-w  

   Medici, E. P. ; Mezzini, S. ; Fleming, C. H. ; Calabrese, J. M. ; Noonan, M. J. ( March 2022 , Movement Ecology)

   Animal movement is a key ecological process that is tightly coupled to local environmental conditions. While agriculture, urbanisation, and transportation infrastructure are critical to human socio-economic improvement, these have spurred substantial changes in animal movement across the globe with potential impacts on fitness and survival. Notably, however, human disturbance can have differential effects across species, and responses to human activities are thus largely taxa and context specific. As human disturbance is only expected to worsen over the next decade it is critical to better understand how species respond to human disturbance in order to develop effective, case-specific conservation strategies.

   Here, we use an extensive telemetry dataset collected over 22 years to fill a critical knowledge gap in the movement ecology of lowland tapirs (Tapirus terrestris) across areas of varying human disturbance within three biomes in southern Brazil: the Pantanal, Cerrado, and Atlantic Forest.

   From these data we found that the mean home range size across all monitored tapirs was 8.31 km²(95% CI 6.53–10.42), with no evidence that home range sizes differed between sexes nor age groups. Interestingly, although the Atlantic Forest, Cerrado, and Pantanal vary substantially in habitat composition, levels of human disturbance, and tapir population densities, we found that lowland tapir movement behaviour and space use were consistent across all three biomes. Human disturbance also had no detectable effect on lowland tapir movement. Lowland tapirs living in the most altered habitats we monitored exhibited movement behaviour that was comparable to that of tapirs living in a near pristine environment.

   Contrary to our expectations, although we observed individual variability in lowland tapir space use and movement, human impacts on the landscape also had no measurable effect on their movement. Lowland tapir movement behaviour thus appears to exhibit very little phenotypic plasticity in response to human disturbance. Crucially, the lack of any detectable response to anthropogenic disturbance suggests that human modified habitats risk being ecological traps for tapirs and this information should be factored into conservation actions and species management aimed towards protecting lowland tapir populations.

    

   more » « less
5. Increasing Anthropogenic Disturbance Restricts Wildebeest Movement Across East African Grazing Systems

   https://doi.org/10.3389/fevo.2022.846171  

   Stabach, Jared A. ; Hughey, Lacey F. ; Crego, Ramiro D. ; Fleming, Christen H. ; Hopcraft, J. Grant ; Leimgruber, Peter ; Morrison, Thomas A. ; Ogutu, Joseph O. ; Reid, Robin S. ; Worden, Jeffrey S. ; et al ( March 2022 , Frontiers in Ecology and Evolution)

   The ability to move is essential for animals to find mates, escape predation, and meet energy and water demands. This is especially important across grazing systems where vegetation productivity can vary drastically between seasons or years. With grasslands undergoing significant changes due to climate change and anthropogenic development, there is an urgent need to determine the relative impacts of these pressures on the movement capacity of native herbivores. To measure these impacts, we fitted 36 white-bearded wildebeest ( Connochaetes taurinus ) with GPS collars across three study areas in southern Kenya (Amboseli Basin, Athi-Kaputiei Plains, and Mara) to test the relationship between movement (e.g., directional persistence, speed, home range crossing time) and gradients of vegetation productivity (i.e., NDVI) and anthropogenic disturbance. As expected, wildebeest moved the most (21.0 km day –1 ; CI: 18.7–23.3) across areas where movement was facilitated by low human footprint and necessitated by low vegetation productivity (Amboseli Basin). However, in areas with moderate vegetation productivity (Athi-Kaputiei Plains), wildebeest moved the least (13.3 km day –1 ; CI: 11.0–15.5). This deviation from expectations was largely explained by impediments to movement associated with a large human footprint. Notably, the movements of wildebeest in this area were also less directed than the other study populations, suggesting that anthropogenic disturbance (i.e., roads, fences, and the expansion of settlements) impacts the ability of wildebeest to move and access available resources. In areas with high vegetation productivity and moderate human footprint (Mara), we observed intermediate levels of daily movement (14.2 km day –1 ; CI: 12.3–16.1). Wildebeest across each of the study systems used grassland habitats outside of protected areas extensively, highlighting the importance of unprotected landscapes for conserving mobile species. These results provide unique insights into the interactive effects of climate and anthropogenic development on the movements of a dominant herbivore in East Africa and present a cautionary tale for the development of grazing ecosystems elsewhere. 

   more » « less