Burrow Density Research Articles

Extent and biogeochemical impact of Skolithos piperock in the lower Cambrian Zabriskie Quartzite (California, USA)

The advent of bioturbation in the early Paleozoic and the subsequent intensification of sediment mixing by benthic animals dramatically altered marine ecosystems and biogeochemical cycling. However, the timing and pace of the transition to ubiquitous well-bioturbated sediments in the uppermost seafloor remain under debate. Skolithos ‘piperock’, a classic Cambrian ichnofabric composed of densely packed vertical burrows, has often been invoked as evidence for an early ramping up of infaunalization and intense sediment disruption, but its biogeochemical impact has not been quantitatively explored in this context. Here, we relate high-resolution sedimentological and bioturbation data from 182 m of the Zabriskie Quartzite of the Death Valley region of California—a locality known for hosting piperock—to a new numerical three-dimensional diagenetic model to investigate the effect of Skolithos on sediment oxygen penetration and organic carbon remineralization. Our modeling indicates that increasing Skolithos burrow density substantially expands the local oxic zone and, in contrast with other modes of bioturbation, can also result in decreased sulfur oxidation. However, our field data indicate true ‘piperock’ is relatively scarce in the Zabriskie Quartzite, even among horizons that are of identical lithology to those containing piperock and that house individual Skolithos burrows. This suggests that, in the Zabriskie and potentially other Cambrian piperock-bearing units, the broader impact of piperock on seafloor ecology, chemistry, and sediment properties may have been restricted in scope.

Spatial difference of salt dynamics within burrows in high salinity zone (high intertidal zone & supratidal zone) of mudflat

Surface evaporation and seawater concentration in the tidal flat have been demonstrated as sources of salt for phreatic brine layers. However, the mechanisms of salt replenishment in such layers remain unclear. Here, the transport processes and factors influencing surface salt in mudflat under the influence of bioturbation were examined in the high salinity zone (high intertidal zone & supratidal zone) along the southern coast of Laizhou Bay, China. In this study, the laboratory model and numerical model of salt transport in the mudflat brine distribution area under the influence of crab burrows were constructed through in-situ investigation to simulate the salt transport process in the mudflat brine distribution area under different tidal amplitudes and different beach salinity, and the influence of the diameter and density of crab burrows on the water-salt exchange process was analyzed. The results indicate that in the salt-crust-free region, the salinity change in burrow-dense area (BDA) lags behind that of independent burrow (IB). At the same time, the salinity increase of IB is at most 17 ppt higher than that of BDA, and the salinity decrease of IB is at most 9 ppt lower than that of BDA, which made BDA promoting more salt accumulation and facilitating the salt transport to deeper layers. In the salt-crust-bearing region, due to the high salt content on the beach surface and the weak tidal amplitude, salt is continuously released and accumulated in the surface during multiple tidal cycles, but the ability to transport to the deep layer is weak. In this case, burrows characterized by larger diameters become the preferential paths for salt transport. In addition, crab burrows affect the evaporation of sediments. In this study, the surface salinity of sediments under the influence of burrows is around 10–45 ppt higher than that without burrows.

Effects of burrowing crabs on coastal sediments and their functions: A systematic meta‐analysis

AbstractBurrowing ecosystem engineers, such as termites, crabs, marmots, and foxes, can profoundly affect the biological structure and ecosystem functions of their environments. However, the relative importance of the effects of burrowing engineers on sediments are challenging to predict and are expected to be influenced by engineer density, engineer functional traits (e.g., burrow morphology), and environmental conditions (e.g., geomorphology, vegetation presence). To develop robust hypotheses predicting the impacts of burrowing ecosystem engineers, we conducted a systematic meta‐analysis evaluating the effects of burrowing crabs on sediment properties, nutrient stocks, and ecosystem functions in soft‐sediment coastal habitats (e.g., salt marshes, mangrove forests, tidal flats). Additionally, we tested the impacts of crab burrow density, burrowing crab superfamily (a proxy for crab burrow morphology and diet), and biotic conditions (i.e., vegetation) on the effects of burrowing crab engineers on coastal sediments. Burrowing crabs rework and oxygenate sediments and accelerate rates of nutrient cycling (i.e., nitrification and CO2 flux). However, the magnitude and direction of burrowing crab effects depend on burrowing crab superfamily, the presence of vegetation, and their interaction. Crab burrow density did not consistently predict burrowing engineer effects on sediments. Future efforts need to focus on implementing rigorous manipulative experiments to assess crab ecosystem engineering effects, since methodological variation has hindered efforts to generalize their effects. Our findings suggest that crab engineering effects are predictable across environmental contexts, and understanding the context dependency of crab engineering effects may promote the management and restoration of the critical ecosystem services that are mediated by crab engineers.

Grazing affects ecosystem traits by regulating plateau pika activities at the landscape scale

The mechanism underlying the effects of livestock grazing on grassland ecosystem traits has been greatly discussed. However, as a common small burrowing mammal on the Tibetan Plateau grasslands, the plateau pika's (Ochotona curzoniae) influence on alpine grassland ecosystem traits has rarely been investigated, especially beyond the plot scale. In this study, we flew an unmanned aerial vehicle (UAV) over a grassland landscape under grazing and nongrazing treatments. Mounted visible spectral remote sensing, in combination with field surveys, was utilized to explore how livestock and pika grazing modify grassland ecosystem traits at the landscape scale on the Tibetan Plateau (TP). Using object-oriented classification and partial least squares regression, we retrieved the pika burrow distribution and grassland ecosystem traits. Then, the relationships among livestock grazing, pika burrowing and ecosystem traits were evaluated. The results indicated that livestock grazing reduces the alpine meadow community height by 0.13 cm and the species number by 0.25 while increasing the vegetation coverage by 9.69 % and the aboveground biomass (AGB) by 10.07 g/m2. A lower statue grassland community with greater coverage caused by livestock grazing promotes pika burrowing. Pika burrow density increases 100/ha per 1.70 % increase in vegetation coverage, a 1.87 g/m2 increase in AGB or a 0.08 m decrease in community height. Under livestock grazing, both community structure and nutrients are more strongly associated with pika burrow density. The structural equation model demonstrated that livestock grazing regulates pika burrow density by moderating structural value and subsequently affecting nutritional value. Pika burrowing activity explains 40 % of the total variation in nutritional value. Our findings revealed an intrinsic linkage between mammal activities and alpine grassland ecosystems, which can provide guidelines for grassland management through pika population control by adjusting grazing intensity on the TP.

Preference for ground cover when selecting burrow entrances in plateau pikas.

Burrow-dwelling animals such as the plateau pika (Ochotona curzoniae) often seek sturdy entrances for their burrows, which can reduce the need for frequent maintenance. The toughness of the ground surface is often reinforced by the interweaving of plant roots and often varies with the root characteristics. To better understand ground cover preferences when selecting burrow entrances by plateau pikas, we investigated the ratios of different ground covers at the rear of the entrances, as well as their coverage and underlying soil compaction in an undegraded alpine meadow on the Qinghai-Xizang Plateau. The results indicated a clear preference hierarchy of sedges > forbs > grass > bare soil. This distribution was aligned with the soil compaction hierarchy of the topsoil layer beneath each cover type. The sedge coverage was significantly negatively correlated with burrow density, suggesting that plateau pikas opt for sturdy entrances with a natural inclination toward energy conservation. However, there is consensus that the population density of plateau pikas often reaches its maximum on almost nonvegetated "black soil beaches." We hypothesized that the survival benefits brought about by vegetation degradation would be higher than the maintenance costs of burrow entrances.

Giant root-rat engineering and livestock grazing activities regulate plant functional trait diversity of an Afroalpine vegetation community in the Bale Mountains, Ethiopia

Disturbances from rodent engineering and human activities profoundly impact ecosystem structure and functioning. Whilst we know that disturbances modulate plant communities, comprehending the mechanisms through which rodent and human disturbances influence the functional trait diversity and trait composition of plant communities is important to allow projecting future changes and to enable informed decisions in response to changing intensity of the disturbances. Here, we evaluated the changes in functional trait diversity and composition of Afroalpine plant communities in the Bale Mountains of Ethiopia along gradients of engineering disturbances of a subterranean endemic rodent, the giant root-rat (Tachyoryctes macrocephalus Rüppell 1842) and human activities (settlement establishment and livestock grazing). We conducted RLQ (co-inertia analysis) and fourth-corner analyses to test for trait-disturbance (rodent engineering/human activities) covariation. Overall, our results show an increase in plant functional trait diversity with increasing root-rat engineering and increasing human activities. We found disturbance specific association with traits. Specifically, we found strong positive association of larger seed mass with increasing root-rat fresh burrow density, rhizomatous vegetative propagation negatively associated with increasing root-rat old burrow, and stolonifereous vegetative propagation positively associated with presence of root-rat mima mound. Moreover, both leaf size and leaf nitrogen content were positively associated with livestock dung abundance but negatively with distance from settlement. Overall, our results suggest that disturbances by rodents filter plant traits related to survival and reproduction strategies, whereas human activities such as livestock grazing act as filters for traits related to leaf economics spectrum along acquisitive resource-use strategy.

No man’s land support the endemic Red Sea ghost crab (Ocypode saratan) in the Gulf of Eilat

Tourism pressure on the Red Sea ecosystem have posed significant threats to numerous endemic species, including the Ghost Crab Ocypode saratan, which is exclusively found along a small stretch of beach in the Eilat/Aqaba Red Sea Gulf. Due to the limited understanding of their ecology, we investigated how tourism impacts the behavior of this species. Employing a natural setup, we compared burrow dimensions, pyramid structures, and density across three distinct beach sections subjected to varying levels of human interference. Access to a secluded beach, referred to as “No Man’s Land,” provided a crucial control for our study. This facilitated a comparative analysis of ghost crab activity among beaches experiencing differing levels of human disturbances: (1) a tourist beach characterized by continual high disturbance, (2) a naval beach subject to moderate and sporadic disturbances, and (3) the isolated “no man’s land” beach devoid of human presence. Our observations revealed notable differences in ghost crab density among the three beaches. Furthermore, we observed that on the secluded beach, larger individuals tended to establish burrows farther from the waterline and construct taller sand pyramids. Given the significance of sexual selection processes, their conservation becomes imperative for the survival and potential expansion of the ghost crab population across the Gulf of Eilat/Aqaba. We propose a straight-forward and cost-effective strategy: the designation of short, secluded beach enclaves along this gulf. We believe that this approach will mitigate adverse impacts of tourisms while simultaneously benefiting various sandy beach species.

Response mechanism of rodent burrow density to natural environmental factors in desert areas based on multisource data

Timely and accurate prediction and early warning of rodent infestation are highly important for the sustainable development of desert ecosystems. This study combines data from 1376 UAV images of actual rodent burrows with natural environmental factor data, aiming to reveal the mechanism through which these factors affect rodent burrow density in the desert areas. The relationships between rodent burrow density and the 9 plant communities and 34 plant species in this area were analyzed by the K-W test and Spearman rank correlation analysis, respectively. The Boruta algorithm and the boosted regression trees (BRT) model were used to determine the six main factors influencing rodent burrow density from a total of 32 factors and to determine the distribution pattern of the burrows. The results show that (1) the density of rodent burrows in the Junggar Basin desert area gradually decreases from south to north and from west to east. (2) There were significant differences in rodent burrow density across the different plant community types (P = 0.048**). A total of 50.0 % of the species significantly influenced rodent burrow density at at least one level. (3) Among the 17 factors with lag effects, nine had the most significant correlation with rodent burrow density in April. Only two natural environmental factors demonstrated lag effects of less than one month. (4) The soil clay content, elevation, Normalized Difference Salinity Index (NDSI), vegetation cover, precipitation, and soil bulk density were the most important influencing factors on rodent burrow density. Considering the pairwise interactions among factors, the collective impact of these factors on rodent burrow density is at least sevenfold greater than the independent effect of a single factor. This study provides a theoretical basis for obtaining a timely and accurate understanding of the spatial distribution of rodent burrows, mitigating the degradation trend of desert ecosystems, and ensuring healthy and sustainable development.

Abundance estimates of Gunnison's prairie dogs compared to the number of active burrows

AbstractReliable estimates of prairie dog (Cynomys spp.) population size and distribution are critical for assessing the status of prairie dogs and for selecting sites to reintroduce black‐footed ferrets (Mustela nigripes). The density of active prairie dog burrows has commonly been used as an index of prairie dog abundance. Indices derived from active burrow counts were developed for black‐tailed (C. ludovicianus) and white‐tailed (C. leucurus) prairie dogs, but their efficacy has not been evaluated for all prairie dog species and studies affirming their validity with robust abundance estimators are few. We indexed or estimated the abundance of Gunnison's prairie dogs (C. gunnisoni) in the Aubrey Valley, Arizona, USA, in 2006 at 2 different time periods using 4 different methods—maximum above ground counts (MAGC), minimum number known alive (MNKA), capture‐mark‐recapture (CMR), and mark‐resight—and compared these estimates to active burrow counts in 2005 and 2006. We found no positive relationship between active burrow counts and any abundance estimators. Mark‐resight estimates of abundance were greater than the MNKA and were positively correlated with both the MNKA (r2 = 0.30) and CMR estimates (r2 = 0.49). Both CMR estimates and MAGC were typically below the MNKA and therefore biased low. Our results indicated that more rigorous estimation methods may be necessary to accurately estimate prairie dog abundance and assess habitat quality for ferret conservation.

Implications of bioturbation induced by Procambarus clarkii on seepage processes in channel levees

River levees are subject to bioturbation by various animals which can actively excavate into earthen structures producing an internal erosion that, during the passage of a flood, can grow in time making the levee unstable. This phenomenon can lead to river levee breaching and, as a consequence, collapse, even for relatively minor flood events. A well-known animal burrower is represented by the North American crayfish Procambarus clarkii (P. clarkii), an invasive species in Europe, mainly introduced for commercial purposes, causing a decline in biodiversity and profound habitat changes. The physical damages caused by P. clarkii on levees and banks, such as in rice fields, irrigation ditches, and small channels, have not been fully studied and behavioral components underlying this impact are mostly occasional. To understand the impact of burrowing activity on the seepage process, a field survey was done in a drainage channel in Tuscany, Italy, to evaluate the density and geometry of the internal burrows that were excavated by the crayfish. Based on these observations and some previous laboratory experiments, three dimensional (3D) numerical simulations of the seepage processes were done inside burrowed levees. Numerical results allowed the increase in the hydraulic vulnerability of levees to the process of internal seepage to be disclosed. In particular, for a given river water level, the reduction of the time scale for the phreatic line to reach the levee field side appears to be a function of a quantity here defined as the burrow hydraulic gradient. This quantity is here defined as the ratio between the hydraulic head inside the burrow and the horizontal distance from its end to the field side of the levee. Moreover, a comparison between the 3D with the analogous more common two dimensional (2D) numerical simulations illustrated the schematization which is better suited for describing the seepage processes when animal burrows, not only by crayfish, are present.

Small-scale spatial distribution of ghost shrimp and macrobenthic fauna in an Amazon macrotidal dissipative sandy beach

ABSTRACT Spatial changes in environmental characteristics strongly influence the structure of benthic communities on sandy beaches, where the patterns of occurrence are mainly controlled by morphodynamic characters and biological interactions. Despite being very abundant and extensive, the Amazonian sandy beaches are among the coastal environments less well known to science. On these beaches, the ghost shrimp Lepidophthalmus siriboia Felder and Rodrigues, 1993 is an important component of the intertidal macrofauna. The present study describes the small-scale distribution patterns of L. siriboia and of the macrobenthic communities in a dissipative macrotidal Amazonian sandy beach. Samples were collected in the intertidal zone of two areas: Area 1, next to a tidal channel; and Area 2, away from the tidal channel. In Area 1, with finer sediments, there was a higher burrow density of L. siriboia and higher density and species richness of macrofauna. In both areas, the burrow density of L. siriboia increased towards the sea. The faunal distribution patterns can be explained by changes in flooding and the type of substratum across the shore and alongshore. These findings add to our knowledge of tropical sandy beach ecology and reinforce the idea that tropical macrotidal beaches have a complexity of morphological features, which are drivers of macrofaunal structure.

Mesocarnivores den site selection in arid ecosystems; A case study of Rüppell's fox and sand cat in central Iran

Understanding the relationships between species and their pattern of coexistence is essential in conservation planning. Rüppell's fox and sand cat are two poorly known species of desert areas that coexist in most parts of the desert belt of Africa and the Middle East. However, their habitat selection in many parts of their distribution are unknown. In this research, using the data collected from a three-year monitoring plan, we investigated the relationship between the den sites of Rüppell's fox and sand cat and habitat variables based on the generalized linear mixed model (GLMM) method. The results showed that for Rüppell's foxes, only the density of rodent burrows had a significant and positive effect. In the sand cat model, in addition to prey, vegetation density (P-value < 0.05) and vegetation height (P-value < 0.10) had significantly positive effects and elevation had a significantly negative effect (P-value < 0.10). We found that the sand cat is more specialized in habitat selection and depends more on the habitat cover. While the Rüppell's fox chose a more diverse range of soil and vegetation classes, the sand cat selected its den sites exclusively in sandy loam soils with the predominant cover of Haloxylon spp. and Caligonum spp. Acting as a generalist species, Rüppell's fox displayed a more pronounced response to human presence and selected dens with a broader view of their surroundings. These findings enhance our understanding of mesocarnivore coexistence in desert regions and provide valuable insights for the conservation planning of these species.

Walkways as an environmental enrichment tool on sandy beaches? A case study with ghost crabs (Crustacea, Ocypodidae)

Confined to a few favorable patches of habitat within a mosaic of physical drivers, many species disappear from human-disturbed beaches. However, mobile species may change their distribution and select more appropriate habitats as a response to disturbance. Ghost crabs are one of the few beach resident animals capable of moving over considerable distances, but usual habitat homogeneity of urban beaches theoretically prevents them from finding refuge. Here, I tested whether access walkways provide a habitat for ghost crabs on four beaches in southeastern Brazil. I counted and measured burrow opening diameter under walkways and in surrounding transects located at various distances from these structures between June 2020 and May 2021. Mean burrow density was three times higher in transects out of walkways than under the walkways. However, burrows were larger and positioned farther from the waterline under walkways. Walkways thus possibly provide protection for ghost crabs from trampling and vehicle traffic in urban beaches and could therefore be applied as an environmental enrichment tool in the management and conservation of sandy beach biodiversity.

Study the Impact of Plateau Pika Activity on the Ecological Dynamics of the Qinghai-Tibet Plateau

The Tibetan Plateau, the world's largest plateau, harbors diverse ecosystems that play vital roles in the global environment. This study aims to investigate the ecological impact of the plateau pika, an endemic species, on the plateau's water resources, carbon storage, biodiversity, and climate. The research advocates for a balanced approach to pika control, emphasizing ecological preservation while addressing the associated challenges. Various statistical tests were employed to quantify the relationship between plateau pika activity and ecological dynamics. Correlation analysis revealed a significant negative correlation between pika burrow density and soil moisture content. T-tests demonstrated a significant difference in soil carbon content between areas with high and low pika burrow densities. A chi-squared test found no significant association between pika population density and the presence of vulnerable species. Ecological protection and sustainable development are crucial, with plant-based pesticides like ricin offering an effective and environmentally friendly means of pika control. However, ecological restoration should be the core of rodent control efforts to maintain a balanced ecosystem. Combining grazing policies with ecological grassland control measures can help mitigate rodent damage while improving grassland productivity.

The long-term dynamics of invasive signal crayfish forcing of fluvial sediment supply via riverbank burrowing

Animals are important drivers of sediment dynamics. Invasive signal crayfish (Pacifastacus leniusculus) have been shown to supply sediment to rivers by burrowing into riverbanks. Burrowing directly transfers excavated sediment into the river and also has an additional indirect affect by promoting riverbank failure. While previous research has isolated burrow densities at a point in time, rates of burrow construction and of burrow loss due to erosion are unknown, which introduces uncertainty into estimates of how much sediment burrows contribute to rivers. Here we report results from a 5-year study that evaluated the temporal dynamics of crayfish populations, rates of burrow loss due to erosion, and the mass of sediment directly supplied to rivers by burrow excavation. At ten reaches across five lowland streams in England, we estimated the mass of sediment displaced by 1861 new and previously constructed burrows. Both crayfish and burrow densities were variable over time, suggesting that burrows contribute temporally variable amounts of fine sediment to riverine systems. 42 % of observed burrows were constructed within the previous 365 days, and individual burrows lasted on average 461 days. Applying this to comparable historical data, an average of 2.0 t km−1 a−1 of sediment was excavated to construct burrows in the study reaches, which is eight times more than estimated in previous studies. Whilst total burrow densities in each year were not consistently correlated with contemporary crayfish densities, the mass of sediment excavated over the prior year was strongly correlated with contemporary crayfish densities. Current fine sediment management practices are largely aimed at controlling fine sediment delivery, predominately from agricultural activities, but biotic burrowing into riverbanks may represent an important and overlooked source of fine sediment supply. Incorporation of biotic processes in sediment dynamics would improve the accuracy of fluvial sediment budgets and enhance the knowledge base underpinning effective fine-sediment management practices.

Burrowing crabs' influence on tidal marsh vegetation species composition and abundance in a temperate back-barrier marsh, Cape Cod, Massachusetts, USA

Emergent vegetation in coastal marshes across the Northeastern United States have been declining and changing in relative species composition due to abiotic factors such as accelerated sea level rise, storm intensity, excess nutrients, and other anthropogenic disturbances. A possible biotic factor in marsh decline is increased perturbation from burrowing crabs. Uca pugilator and Minuca pugnax (fiddler crabs) whose populations are increasing in many marshes in the eastern US, likely due to disruptions in food webs and expanding habitat from sea level rise. High densities of crab burrows contribute to creek bank erosion and possibly in other factors of marsh peat degradation. When burrowing crabs were excluded from large scale (9 m2) plots in a Cape Cod, MA, marsh for five months, vegetation species richness increased significantly, as did abundance of woody shrubs and the forb, Suaeda maritima (L.). Conversely, burrowing crab exclusion resulted in less Spartina alterniflora (Loisel) and less bare ground - indicating that the other types of vegetation were able to occupy more space in the absence of crab burrowing and sediment sorting activity. The experimental enclosure results were compared with vegetation and burrow density monitoring data taken from nearby long-term monitoring plots. Of the sixteen analyses, we found only one similar result between the 5 month exclusions and monitoring plots; high burrow densities were associated with higher density of S. alterniflora. In contrast to the exclusions, high burrow densities were positively correlated with abundance of Iva frutescens and Suaeda maritima. Six other species (or groupings of rare plants) were negatively associated with burrow densities, four of these are sensitive to inundation and are considered characteristic of the high marsh zone. Different interpretations of the effects of burrowing crabs will result depending on whether correlations are observed from monitoring plots or longer term, large-scale exclusions are conducted; both are needed to assess the rapid vegetation and faunal shifts that are occurring in temperate salt marshes. We suggest that Uca pugilator and Minuca sp. will benefit from sea level rise induced habitat expansion at the expense of the abundance and species richness of flooding-sensitive plants. The erosion and vegetation disturbance that high burrowing crab densities lead to will further exacerbate the decline of these species that are receding at the seaward edge of their distributions.

Toward broad-scale mapping and characterization of prairie dog colonies from airborne imagery using deep learning

Monitoring wildlife is fundamental to managing the health of rangelands but challenging due to the extensive and dynamic nature of these ecosystems. The black-tailed prairie dog (Cynomys ludovicianus) is considered both a keystone species of conservation concern and an agricultural pest. This animal is an example of a wildlife species for which detailed monitoring is both high priority and difficult to accomplish cost-effectively using ground-based methods. In this study, we conducted a robust evaluation of the potential to use deep learning to detect prairie dog burrows from remotely sensed imagery acquired from unoccupied aerial systems (UAS). We processed UAS imagery to create RGB, topographic position index (TPI) and normalized difference vegetation index (NDVI) products at varying spatial resolutions (2–30 cm). We then evaluated the minimum set of inputs and image resolution required to train a deep convolutional neural network (CNN) for burrow detection and scale this up to identify entire colonies. We validated results at the scale of individual burrows, sub-colony burrow density and range-wide colony area using ground and digitized observations. We found the 2 cm imagery proved computationally impractical for scaling, but performance did not decline between 2 and 5 cm imagery, and models performed well up to 10–15 cm. The top models always included TPI and the combination of RGB + TPI tended to perform best across spatial resolutions. Adding NDVI generally did not improve model performance. At 5 cm resolution, the top models achieved high precision and recall for detecting individual burrows (F-score 0.84–0.87) and burrow density was strongly correlated with validation data (r = 0.94–0.95). In pastures with active colonies, overlap between predicted and ground delineated colonies was high (60–94%). The CNN-based approach could not distinguish between currently active colonies and a colony that had recently become inactive due to a sylvatic plague (Yersinia pestis) epizootic. However, further analysis showed that CNN-derived burrow density was related to colony age and satellite-derived vegetation conditions in active colonies, and that the plague-affected colony deviated from expected vegetation trends. We conclude that a deep learning algorithm can accurately detect prairie dog burrows from UAS imagery acquired at 5–10 cm resolution, and that scaling from individual burrows to entire colonies is achievable but warrants further research. Combining CNN-derived burrow density maps with satellite-derived vegetation conditions may help identify recent colony abandonment, despite ongoing presence of burrows.

The relationship between mammalian burrow abundance and bankrupt bush (Seriphium plumosum) encroachment

Background: Much of the Grassland Biome in South Africa is prone to shrub encroachment, leading to loss of ecosystem services, habitat heterogeneity and species diversity. Burrowing mammals are an important component of grasslands as these animals create microhabitats for other taxa, including smaller mammal species, birds, reptiles and invertebrates. However, our understanding of how shrub encroachment affects burrowing mammals is poor. Objectives: Here we assessed the relationship between burrow abundance and bankrupt bush, Seriphium plumosum, encroachment as well as burrowing mammal diversity in bankrupt bush encroached and non-encroached grasslands. Method: Shrub density, medium and large mammal burrow abundance and density were measured in 24 encroached and 24 non-encroached areas randomly selected in the Telperion Nature Reserve, Mpumalanga, South Africa. In addition, burrowing mammal diversity was assessed using camera traps in a subset of six encroached and six non-encroached areas. Results: Our results show that the abundance and density of medium and large burrows were significantly lower in encroached areas than in non-encroached areas (p = 0.011 and p &lt; 0.001, respectively). The relationship between burrow abundance and bankrupt bush encroachment was negative (rho = -0.456, p = 0.001). However, burrowing mammal diversity had no significant difference between encroached and non-encroached areas. Conclusion: Our data, therefore, suggest that with increasing bankrupt bush encroachment and a decreased abundance in burrowing mammal ecosystem services, a negative effect will occur on burrowing mammal communities, leading to the reduction in species-specific habitat heterogeneity and possibly animal biodiversity.

Human activities modulate reciprocal effects of a subterranean ecological engineer rodent, Tachyoryctes macrocephalus, on Afroalpine vegetation cover.

Human activities, directly and indirectly, impact ecological engineering activities of subterranean rodents. As engineering activities of burrowing rodents are affected by, and reciprocally affect vegetation cover via feeding, burrowing and mound building, human influence such as settlements and livestock grazing, could have cascading effects on biodiversity and ecosystem processes such as bioturbation. However, there is limited understanding of the relationship between human activities and burrowing rodents. The aim of this study was therefore to understand how human activities influence the ecological engineering activity of the giant root-rat (Tachyoryctes macrocephalus), a subterranean rodent species endemic to the Afroalpine ecosystem of the Bale Mountains of Ethiopia. We collected data on human impact, burrowing activity and vegetation during February and March of 2021. Using path analysis, we tested (1) direct effects of human settlement on the patterns of livestock grazing intensity, (2) direct and indirect impacts of humans and livestock grazing intensity on the root-rat burrow density and (3) whether human settlement and livestock grazing influence the effects of giant root-rat burrow density on vegetation and vice versa. We found lower levels of livestock grazing intensity further from human settlement than in its proximity. We also found a significantly increased giant root-rat burrow density with increasing livestock grazing intensity. Seasonal settlement and livestock grazing intensity had an indirect negative and positive effect on giant root-rat burrow density, respectively, both via vegetation cover. Analysing the reciprocal effects of giant root-rat on vegetation, we found a significantly decreased vegetation cover with increasing density of giant root-rat burrows, and indirectly with increasing livestock grazing intensity via giant root-rat burrow density. Our results demonstrate that giant root-rats play a synanthropic engineering role that affects vegetation structure and ecosystem processes.

Natural history and ecology of the slender crayfish (Faxonius compressus): an ecosystem engineer in the Western Highland Rim, USA

ABSTRACT Ecosystem engineers influence the physical environment, which changes the distribution and availability of resources to other organisms. Based on their burrowing abilities, freshwater crayfish have been widely recognised as ecosystem engineers. Crayfishes construct burrows that range from simple, rudimentary depressions in aquatic systems, to complex, labyrinth-like terrestrial burrows that may be significant distances from permanent water bodies. Here, we investigate ecosystem engineering and burrowing of the slender crayfish, Faxonius compressus, which lives in lotic environments characterised by an abundance of small cobble- and gravel-sized substrates. Without larger substrates to burrow under, we found F. compressus populations construct extremely high densities of burrows across riffle, run and pool macrohabitats. Based on the average number of burrows, a 5 × 100 m pool is estimated to contain an average of 25,860 burrows. We also conducted behavioural observations of this species to glean information on their natural history. Faxonius compressus regularly inhabits and competes for ownership of burrows which serve as a shelter from predators. Importantly, these burrows are not only used by F. compressus; we documented other crayfishes and fish species utilising these burrows. In total, we documented two other crayfishes and six fish species utilising F. compressus burrows. We discuss the ecosystem engineering abilities of this species in relation to other crayfish and suggest future avenues of research to elucidate this species’ natural and life history.