Single-season Occupancy Models Research Articles

Over the river and through the woods: Multi-scale habitat associations of two at-risk bird species in riparian forests of the Central Appalachians

Several species-specific habitat management guidelines have been created over the past decade to help recover declining populations of forest birds in eastern North America. Conserving eastern forest birds through forest management requires understanding the factors driving species occurrence patterns and how the needs of various species complement or contrast with each other. Our study assessed and compared occupancy patterns of two at-risk species associated with riparian forests: the Wood Thrush (Hylocichla mustelina) and the Canada Warbler (Cardellina canadensis). We conducted point-count surveys and vegetation sampling at 304 unique locations along 33 stream sections in central and southwestern Pennsylvania from May – June 2018 and 2019. We used single-season occupancy models to examine the influence of vegetation composition (i.e., microhabitat conditions), forest structure (i.e., from Light Detection and Ranging data, “LiDAR”), and other factors (i.e., stream order and elevation) on focal species occurrence patterns. Wood Thrush occupancy (mean ᴪˆ: 0.57) was best explained by the presence of mountain laurel (Kalmia latifolia; negative effect), elevation (negative effect), canopy height (positive effect), and canopy structural heterogeneity (positive effect). Canada Warbler occupancy (mean ᴪˆ: 0.55) was best explained by the presence of mountain laurel (positive effect), stream order (positive effect), elevation (positive effect), density of understory vegetation (positive effect), and canopy structural heterogeneity (negative effect). While both bird species occurred relatively frequently in riparian forests, our results indicate that habitat factors at multiple spatial scales play a role in regulating their occurrence patterns. Moreover, the two species exhibited contrasting habitat associations. Specifically, Canada Warblers preferred sites supporting dense mountain laurel, typically at elevations >600 m, and with a largely intact canopy. These patterns were reversed for Wood Thrushes. These contrasting associations will limit opportunities to manage riparian forests in a manner that conveys co-benefits for our two focal species. As a general rule, forest managers in our study region can target habitat management for Canada Warblers in riparian areas above 600 m and in areas below 600 m for Wood Thrushes. Given our focal species’ use of other (non-riparian) forest types as breeding habitat and broad geographic distributions, it is important to recognize that our findings may not apply outside of riparian forests or beyond the Central Appalachian Mountains.

Evaluating the predictors of habitat use and successful reproduction in a model bird species using a large‐scale automated acoustic array

The emergence of continental to global scale biodiversity data has led to growing understanding of patterns in species distributions, and the determinants of these distributions, at large spatial scales. However, identifying the specific mechanisms, including demographic processes, determining species distributions remains difficult, as large‐scale data are typically restricted to observations of only species presence. New remote automated approaches for collecting data, such as automated recording units (ARUs), provide a promising avenue towards direct measurement of demographic processes, such as reproduction, that cannot feasibly be measured at scale by traditional survey methods. In this study, we analyze data collected by ARUs from 452 survey points across an approximately 1500 km long study region to compare patterns in adult and juvenile distributions in great horned owl Bubo virginianus. We specifically examine whether habitat associated with successful reproduction is the same as that associated with adult presence. We postulated that congruence between these two distributions would suggest that all areas of the species' range contribute equally to maintenance of the population, whereas significant differences would suggest more specificity in the species' requirements for successful reproduction. We filtered adult and juvenile calls of the species for manual review using automated classification and constructed single season occupancy models to compare land cover and vegetation covariates which significantly predicted presence of each life stage. We found that habitat use by adults was significantly predicted by increasing amounts of forest cover, reduced forest basal area, and lower elevations; whereas juvenile presence was significantly predicted only by decreasing amounts of forest cover, a pattern opposite that of adults. These results show that presence of adult great horned owls is not a sufficient proxy for locations at which reproduction occurs, and also demonstrate a highly scalable workflow that could be used for similar analyses in other sound‐producing species.

Precipitation explains Wood Thrush (Hylocichla mustelina) occupancy patterns in Northern Costa Rica

Introduction: The Wood Thrush is a migratory bird that has experienced dramatic declines in its populations in recent decades. This species overwinters in forest fragments with intermediate levels of habitat modification in Central America. However, more studies detailing the use of remnant forests through time are needed to elucidate the threats this species faces in the wintering grounds. Objective: To understand the effects of environmental and forest structure variables on the occupancy of Wood Thrush in Northern Costa Rica. Methods: The study area was the Área de Conservación Guanacaste (ACG), located in Northern Costa Rica, in December 2016, and during the 2018-2019 migration season. We estimated Wood Thrush occupancy and detection probability in four locations of ACG (dry forest, cloud forest, and two locations in the wet forest) using single-season occupancy models. We also estimated Wood Thrush occupancy and probability of persistence in different months in three vegetation types (open area, secondary forest, and old-growth forest) in the wet forest of ACG using a multi-season occupancy model approach. Results: Wood Thrush occupancy was best described by precipitation in the four locations of the ACG; the probability of occupancy increased with precipitation. The average occupancy of Wood Thrushes varied with vegetation type: open area with shrubs and forest edge (0.69 ± 0.09), secondary forest (0.46 ± 0.1), and old-growth forest (0.61 ± 0.1). Wood Thrush probability of persistence responded partially to changes in precipitation, with an unexpected increase in persistence when the rainfall continued decreasing in the season. Conclusion: Wood Thrush occupancy was best predicted by changes in precipitation considering a larger spatial scale. Its probability of persistence partially varied with precipitation. An increase in persistence closer to Spring migration might be explained by the start of the breeding season of resident birds, potentially reducing territorial conflicts and conserving energy before migration. The long-term protection of wet forests in Northern Costa Rica is of paramount importance for the conservation of Wood Thrushes in their wintering grounds.

Site occupancy of select mammals in the tropical forest of Eastern Himalaya

IntroductionTerrestrial mammals play a pivotal role in tropical forest ecosystems, representing a rich and functionally diverse component of these biomes. However, they confront formidable threats globally, such as hunting, habitat loss, and fragmentation, amidst the expansion of human-altered landscapes in tropical regions. Understanding the impacts of these changes on mammal communities is crucial for designing effective conservation interventions. Northeast India's tropical forests, a biodiversity hotspot, host a diverse array of mammalian fauna. The primary challenge faced by these species involves anthropogenic activities leading to the shrinkage and fragmentation of forested habitats.MethodologyIn this study, we conducted systematic camera trapping in Mehao Wildlife Sanctuary (WLS) to assess mammal status and distribution. Employing single-season occupancy models, we evaluated factors influencing mammalian species' detection probability and spatial utilization within the landscape. ResultsThe study documented 27 mammalian species, with 12 identified as "threatened" on the IUCN Red List. Species like clouded leopard, marbled cat, Gongshan muntjac, red goral, Mishmi takin, and sambar were recorded but observed infrequently. Notably, we reported the Asiatic brush-tailed porcupine's first sighting in Mehao. Our findings revealed that undisturbed forest habitats were preferred by all species. Mainland serow dominated most of the sanctuary's area, followed by northern red muntjac, yellow-throated marten, and masked palm civet.DiscussionThe response of mammalian species to ecological and anthropogenic covariates varied significantly, underscoring the necessity for species-specific management strategies alongside a landscape-scale conservation approach. These outcomes emphasize the urgency of managing and safeguarding rare and elusive mammalian species within and around Mehao WLS.

An occupancy analysis of the factors affecting the presence of carnivores at the national park‐human community interface in Rwanda

AbstractPeople, livestock and carnivores are constantly interacting especially at the interface between community and protected areas. The carnivore guild category in Volcanoes National Park is important, and if well studied, could lead to additional research opportunities for improved wildlife management. We used single season occupancy models with multi‐species data, to understand the factors affecting species occurrence, detection and distribution among native carnivores of Volcanoes National Park while accounting for imperfect detection and the effects of site variables on the observed trends. Our findings showed that six native carnivores use the park edge, where the side‐striped jackal (Canis adustus) and serval (Leptailurus serval) are the most widespread with ψ = 0.904 (SE 0.051) and ψ = 0.415 (SE 0.086), respectively, followed by African golden cat (Caracal aurata) with ψ = 0.198 (SE 0.066), while the servaline genet (Genetta servalina), slender mongoose (Herpestes sanguineus) and spotted hyaena (Crocuta Crocuta) have very low probability of occupancy with ψ = 0.087 (SE 0.045), ψ = 0.044 (SE 0.032) and ψ = 0.022 (SE 0.022) respectively. In addition, there is high occurrence of feral dogs and human presence in the park edge. Overall, the occupancy of native carnivores increases as distance from settlements increase (β = 0.559 [SE 0.195]) except for hyaena and mongoose which showed a decrease in occupancy as distance to settlements increased. In general, native carnivores preferred sites located close to pasture areas, compared to areas used for agriculture and agroforestry. High overlapping activity between native carnivores and other wildlife varied greatly between species. This study provides the baseline information for the understanding of native carnivores using the park edge and insights on their interactions with other wildlife, livestock and human activities at the interface between the park and local communities. The co‐occurrence of livestock, feral dogs and humans, and native wildlife is a challenge for both wildlife conservation inside the protected area and local communities who might be negatively affected in different ways including interspecific competition, disease exposure and increased conflicts. We anticipate that some of the current livestock keeping are hindered by the challenges of having native carnivores dwelling along the park edge and community interface.

Fine-scale forest structure, not management regime, drives occupancy of a declining songbird, the Olive-sided Flycatcher, in the core of its range

Abstract Climate change, management legacies, pest outbreaks, and fire regimes are combining to pose a growing risk of broad-scale loss of forest cover throughout western North America. Already, habitat changes have been linked with declines in numerous bird species; understanding the relative importance of management regimes and habitat structure may be critical to conserving at-risk species. The Olive-sided Flycatcher (Contopus cooperi) is a declining songbird associated with tall, open forests in California’s Sierra Nevada, the core of its breeding range, where the management regimes of the National Park Service (NPS) and U.S. Forest Service (USFS) have led to divergent forest conditions over the past century. We combined a landscape-scale passive acoustic monitoring program, the BirdNET animal sound identification algorithm, and single-season occupancy models to explore the relationships between Olive-sided Flycatchers in the Sierra Nevada and both management regimes and fine-scale forest structure. Olive-sided Flycatcher site occupancy increased as canopy cover decreased relative to mean tree diameter, which is consistent with their preference for mature, open forests. These “open forest” conditions were most prevalent on NPS-managed lands, which is consistent with the assumption that the NPS management regime is more faithful to the historical conditions that had supported a larger Olive-sided Flycatcher population than at present. Thus, the support we found for a positive association with USFS-managed lands after controlling for “open forest” suggests that other habitat features are also important. Our results suggest that conservation strategies for Olive-sided Flycatcher breeding habitat should prioritize the protection and generation of open canopies in areas with large trees, as well as the identification of other important habitat features. Prescribed fire, mechanical thinning, and a return of Indigenous forest management practices could help to restore historical forest and fire conditions beneficial to this and other species with similar habitat requirements. Fine-scale alterations to forest structure can be implemented much more rapidly and at much broader scales than the imposition of strict protected status, suggesting that there may be multiple pathways to conservation when species respond to habitat at fine spatial scales.

Sampling Duration and Season Recommendations for Passive Acoustic Monitoring of Bats after White-Nose Syndrome

Abstract Since 2006, white-nose syndrome has caused drastic declines in populations of several hibernating bat species throughout eastern North America. Thus, there is a growing need to establish long-term monitoring programs to assess changes in bat populations over time. Information on the seasonal timing of species occurrence and the sampling effort required to acoustically detect individual bat species and obtain complete inventories will enable researchers to design and implement more effective monitoring programs. From April to October 2018 to 2021, we passively sampled for bats using full-spectrum detectors at eight permanent sites at Fort Indiantown Gap National Guard Training Center, Pennsylvania. We examined seasonal activity patterns and estimated bat species richness among sites and seasons using species accumulation curves. We also estimated probability of detection (p) and site occupancy (Ψ) using single-season occupancy models in PRESENCE software and then determined the minimum number of sampling nights needed to reliably infer the absence of each species. We identified 286,131 bat passes of eight species in 4,107 detector-nights. Seasonal patterns of activity varied among species. We needed approximately 20 sampling nights to detect 90% of the total bat species richness among sites, and we needed 4 to 10 nights to detect 90% of species richness among seasons. We needed relatively few nights (≤12 nights) to detect most species during summer; however, we needed many more nights to detect acoustically rare species. Our results indicate that the acoustic sampling effort currently required to determine the presence or probable absence of Indiana myotis Myotis sodalis, northern long-eared myotis M. septentrionalis, and tricolored bats Perimyotis subflavus during summer may not be adequate for these species in some areas and that a considerable level of effort (>40 nights) is needed to detect little brown myotis M. lucifugus. Monitoring programs that incorporate efficient sampling methodologies will be critical for future conservation efforts as populations of several bat species continue to decline.

Occupancy patterns of two contrasting carnivores in an industrial forest mosaic

Normally, industrial forest landscapes are mosaics of different exotic and native vegetation patches, and, depending on their structural and functional diversity, they may be able to support potentially important biodiversity. In Central Chile, there are 3.1 million hectares of exotic forest plantations, and these environments are included as habitat, among others, of two contrasting carnivores: the generalist culpeo fox (Lycalopex culpaeus) and the kodkod (Leopardus guigna), a forest specialist cat. For this study, we sampled a large area (∼350 km2) in the coastal range of Central Chile with camera traps (n = 500) for three consecutive years to observe the summer occupancy patterns of these two carnivores. We used single season occupancy models with covariates at landscape and local scales. The main results showed that, for the culpeo fox, the proportion of harvested area had a positive influence on its occupation, whereas for the kodkod the proportion of bare soil and leaf litter had a negative and positive influence, respectively. Since both species occupy the landscape mosaic created by the forestry industry, it would be valuable to integrate the observed occupancy patterns into conservation plans at both local and landscape levels for these species.

Pairing a user-friendly machine-learning animal sound detector with passive acoustic surveys for occupancy modeling of an endangered primate.

Population declines and range contractions due to habitat loss are pervasive among nonhuman primates, with 60% of species threatened with extinction. However, the extensive vocal activity displayed by many primates makes them excellent candidates for passive acoustic surveys. Passive acoustic survey data is increasingly being used to support occupancy models, which have proven to be an efficient means of estimating both population trends and distributions. Passive acoustic surveys can be conducted relatively quickly and at broad scales, but efficient audio data processing has long proven elusive. The machine learning algorithm BirdNET was originally developed for birds but was recently expanded to include nonavian taxa. We demonstrate that BirdNET can accurately and efficiently identify an endangered primate, the Yucatán black howler monkey (Alouatta pigra), by sound in passive acoustic survey data (collected in southeastern Chiapas, Mexico), enabling us to use a single-season occupancy model to inform further survey efforts. Importantly, we also generated data on up to 286 co-occurring bird species, demonstrating the value of integrated animal sound classification tools for biodiversity surveys. BirdNET is freely available, requires no computer science expertise to use, and can readily be expanded to include more species (e.g., its species list recently tripled to >3000), suggesting that passive acoustic surveys, and thus occupancy modeling, for primate conservation could rapidly become much more accessible. Importantly, the long history of bioacoustics in primate research has yielded a wealth of information about their vocal behavior, which can facilitate appropriate survey design and data interpretation.

Occupancy and habitat use by the Andean bear are negatively affected by human presence and forest loss

Protected areas require methodologies to monitor the status and effectiveness of species management strategies. In this work, single-species, single-season occupancy models were employed to estimate the occupancy and habitat use of the Andean bear in the Tatamá National Natural Park through a nested design of 1 km2 cells inserted in 16 km2 cells. The occupancy at 16 km2 was ψ16 = 0.89 (E.E. = 0.06), with a detectability p = 0.405 (E.E. = 0.039). When examining the factors influencing the habitat use of the Andean bear at the 1 km2 scale, the four most suitable models for calculating use indicated a most negative relationship between use and the percentage of human activities in the cell (βHA = −1.46 [E.E. 0.61]). Additionally, bear use was found to have the most positive relationship with the forest proportion in the cell (βF = 16.59 [E.E. 13.55]) and Euclidean distance to population centers (βDPC = 1.05 [E.E. 0.82]). These findings allowed for adjusting the Prevention, Surveillance, Control, and Monitoring programs and identifying areas requiring forest cover restoration. The sampling design and effort implemented is able to detect a 25% reduction in occupancy with a statistical significance of α = 0.2 and a statistical power of 1 − β = 0.8.

Playing “hide and seek” with the Mediterranean monk seal: a citizen science dataset reveals its distribution from molecular traces (eDNA)

Animal conservation relies on assessing the distribution and habitat use of species, but for endangered/elusive animals this can prove difficult. The Monk Seal, Monachus monachus, is one of the world's most endangered species of pinniped, and the only one endemic to the Mediterranean Sea. During recent decades, direct observations have been few and scattered, making it difficult to determine its distribution away from the Aegean Sea (core distribution area of the post-decline relict population). This study relies on environmental DNA (eDNA) analysis to detect the presence of the Monk Seal in 135 samples collected in 120 locations of the central/western Mediterranean Sea, spanning about 1500 km longitudinally and 1000 km latitudinally. A recently described species-specific qPCR assay was used on marine-water samples, mostly collected during 2021 by a Citizen Science (CS) project. Positive detections occurred throughout the longitudinal range, including the westernmost surveyed area (Balearic archipelago). The distribution of the positive detections indicated six “hotspots”, mostly overlapping with historical Monk Seal sites, suggesting that habitat-specific characteristics play a fundamental role. We applied single-season occupancy models to correct for detection probability and to assess the importance of site-specific characteristics. The distance from small islets and protected (or access-restricted) areas was correlated negatively with the detection probability. This novel molecular approach, applied here for the first time in an extensive CS study, proved its potential as a tool for monitoring the distribution of this endangered/elusive species.

Breaking Dawn: Factors influencing mammalian habitat usage in western Assam following socio-political instability

The impacts of conflict on nature are devastatingly adverse but differ widely in different socio-economic-political regimes. Armed conflict often facilitates illegal plunder and unsustainable use of natural resources. We studied the response of mammals in Ripu (605.27 sq.km, westernmost part of Manas Tiger Reserve) Reserved Forest (RF) in Assam, India that suffers prolonged anthropogenic pressures due to armed conflict instigated by social unrest. We used standard single-season occupancy models using sign survey to assess factors affecting the space use of mammals. Our study revealed that Ripu RF has a high proportion of area occupied by prey species of large carnivores. Asian elephant, barking deer, and wild pig occupied most of the habitat, whereas gaur, sambar and spotted deer restricted themselves to selected patches. The probability of a site being occupied by the majority of ungulates declines with an increase in anthropogenic activities, including distance to human settlement (measure of prolonged disturbance) and an increase in the proportion of secondary degraded forest. Common leopard was found to be positively associated with prey occupancy and increase in semievergreen and moist-mixed deciduous forest. Our ground efforts to strengthen community patrolling and operational execution of various alternative livelihoods has helped to improve the economic condition of patrolling staff. Strategic implementation of law enforcement could support dispersal of tigers from Phibsoo Wildlife Sanctuary (Bhutan), potentially linked to the larger tiger and elephant landscape far west (Buxa Tiger Reserve in West Bengal) in the Terai region of India. Various community-based conservation initiatives and strategies with sustained support from various agencies, including national, international, and local bodies, is required to restore this critical habitat.

Factors influencing fine-scale occupancy and detectability of an insular Atlantic Forest frog

Context Species of the tropical frog Family Hylodidae tend to be restricted to streams and, hence, have a small occupancy area. Hylodes fredi (Canedo and Pombal 2007), a diurnal stream-dwelling species endemic to the Atlantic Forest in Ilha Grande, south-eastern Brazil, is one such species. Because of scarce population studies, it is also categorised as Data Deficient (DD) in the IUCN Red List. Previous studies on the habitat use by this species did not account for imperfect detection, which could have led to biased results. Aims We aimed to systematically describe the microhabitats occupied by H. fredi, by generating a fine-scale occupancy model while accounting for imperfect detection. Methods We sampled six streams where the species is known to occur. Perpendicular transects were established in each stream and further subdivided into 10 sampling plots. Single-species and single-season occupancy models were created with the UNMARKED R package, and model selection was performed on the basis of the Akaike information criterion. Key results We observed the species in 70 of the 275 sampled sites, which resulted in a naïve occupancy of 0.28 and detectability of 0.25. The best models suggest that H. fredi occupancy increases positively with rock cover and inversely with leaf-litter cover. Detectability reduced with an increase in leaf litter cover and varied with the air temperature. Conclusions We conclude that H. fredi occupancy is affected by the presence of rock and leaf-litter cover. The data indicated that the species is restricted to the stream channel and does not seem to occupy forested areas that are distanced from the stream margins. Implications Considering that H. fredi and many other congeneric species are listed as ‘Data Deficient’ in the IUCN Red List, it is important to define a threat category so as to conserve them. Many stream-associated species tend to have their occupancy overestimated, leading to an underestimation of their threat risk. This study systematically demonstrated that H. fredi has a strict and reduced occupancy, mostly limited to the stream margins, that should be considered when determining conservation efforts for this and ecologically similar species.

Gharial (Gavialis gangeticus, Gmelin, 1789) abundance in the Rapti River, Chitwan National Park, Nepal.

Gharial (Gavialis gangeticus) is a Critically Endangered crocodilian species whose abundance in Nepalese rivers is low due to the threat they face. We estimated gharial abundance in the Rapti River, one of the major rivers in Chitwan National Park (CNP) holding the largest numbers of gharials in Nepal. The Rapti River, running across the CNP, was divided into 18 segments, each measuring ~4 km, and gharials were counted directly with three replicates. Gharial count data were analyzed using an N‐mixture model (negative binomial) and the overall occupancy of gharials was estimated using a single season occupancy model. Covariate effects were also investigated on gharial abundance. Our findings revealed that the Rapti River is home to 150 gharials (119–181), with a mean abundance of 8.3 (SD = 3.45) across each segment. The presence of humans and square of Rapti River depth were the significant covariates that had a negative and positive impact on gharial abundance, respectively. Similarly, the number of sandbank present influenced the detection probability of gharials. Our study shows that gharial population estimation can be improved using the N‐mixture model. The overall gharial occupancy estimated using single season occupancy model was 0.84 (SD = 0.08), with a detection probability of 0.37 (SD = 0.02). The management authority should concentrate on segments to minimize human disturbance (e.g., fishing, washing clothes, extraction of riverbed materials). If the gharial population in this river declines, their population in central Nepal will be threatened. Hence, we suggest designating the Rapti River section that passes across the CNP as a “no extraction zone.”

First population estimates of two Critically Endangered frogs from an isolated forest plateau in Madagascar

AbstractIn the largely deforested areas of Madagascar, small forest fragments remain as last refuges for amphibian diversity. Isolated populations of the Critically Endangered Anodonthyla vallani and Anilany helenae persist in the fragmented forest of Ambohitantely but little information is available to inform their management and any conservation interventions. We generated estimates of population size and occupancy for both species in the largest fragment of Ambohitantely Special Reserve using acoustic survey data collected from 84 sites along 12 transects in December 2018. We used a single-season occupancy model to estimate detection and occupancy and a Royal–Nichols model to estimate abundance and population size. Anilany helenae and A. vallani had high occupancy rates (80 and 93%, respectively) whereas their detection rates differed (34 and 55%, respectively). Abundance and occupancy were best explained by vegetation structure whereas detection was influenced by time of survey and rainfall. For our sampled sites the estimated population sizes of males were 855 for A. vallani, with an estimated density of 52 individuals/ha, and 388 for A. helenae, with an estimated population density of 23 individuals/ha. Given their relatively low densities, small population sizes and restricted ranges, any further habitat loss could have drastic consequences for these populations. Our results provide guidance for future species-focused studies, and can inform conservation management at the local scale. Our work will help to improve species monitoring in Madagascar and elsewhere, especially for range-restricted non-charismatic amphibians.

Species richness, relative abundance and occupancy of ground-dwelling mammals denote the ineffectiveness of chimpanzee as flagship species

In conservation biology, flagship species are defined as species that can raise support for biodiversity conservation in a given place or social context. In the newly established Gishwati–Mukura National Park in Rwanda, the Eastern chimpanzee was considered such an ambassador. To test whether the flagship species concept was effective in the park, we studied species richness, relative abundance, and species distribution (occupancy) of medium- to large-sized, ground-dwelling mammals using camera trapping technology. The impact of three environmental and three anthropogenic variables on species distribution was investigated and the ecological diversity of the fauna in the national park assessed. Over a period of 9 months, two 4 × 4 camera trapping grids were deployed in Gishwati and Mukura Forest. Sampling effort in each forest equated to 32 and 29 camera trapping locations, yielding 258 and 242 independent photographic events of eight and six species, respectively. In both forests, the Emin's giant poached rat was the most frequently encountered species, while all other species showed high relative abundance only in Gishwati Forest. The relative abundance of the endangered Eastern chimpanzee in Gishwati Forest was 0.54, the estimated occupancy was 0.31. Single-species, single-season occupancy models revealed that forest cover, altitude and distance to forest edge influenced the detectability of L'Hoest's monkey and squirrel species, while no effect was found on their occupancy. Notably, no larger herbivore or carnivore species were observed in the park, while the flagship species, i.e., the Eastern chimpanzee, was relatively abundant. Moreover, in both forests, all detected carnivores were small- to medium-sized, suggesting a meso-predator release phenomenon, i.e., populations of medium-sized predators increased after the removal of larger, top carnivores, due to relaxed competition. It appears that the prioritization of the flagship species resulted in the neglect of other mammalian species, leading eventually into the demise of entire functional guilds. Based on these results, the Gishwati–Mukura NP was categorized as a ‘depleted forest’. We, therefore, strongly object chimpanzees as a suitable flagship species—at least in the Gishwati–Mukura NP—and recommend collating more knowledge on the release of meso-predators and the loss of forest ungulates to improve their future conservation in Afro-montane forest habitats.

Distribution and habitat-use of Dhole Cuon alpinus (Mammalia: Carnivora: Canidae) in Parsa National Park, Nepal

Dhole Cuon alpinus is one of the top predators in Asian forests but is one of the least studied species of carnivores. We surveyed an area of 499 km2 of Parsa National Park (PNP) during the winter (November–January) of 2016–17 using camera-traps to determine the spatial distribution and habitat-use patterns of Dhole. We overlaid 2 x 2 km2 grid cells (n= 126) across the study area and set up a pair of motion sensor cameras in each grid cells for 21 days. We modeled the habitat-use by Dholes as a function of sampling covariates and fine-scale habitat covariates using single species single season occupancy models. We estimated the parameters in two steps. First, we defined a global model for probability of habitat-use and modeled detection probability (p) either as an intercept-only model or as a function of covariates. Second, we modeled the habitat-use probability (Ψ) incorporating the top-ranked model for probability of detection (p) in the first step. A total effort of 2,520 camera-trap-nights resulted in 63 independent detections of dholes at 27 locations in PNP. The naïve occupancy estimate of Dholes in PNP was 0.21. The estimated probability of habitat-use (Ψ) and detection (p) were 0.47±0.27 and 0.24±0.05, respectively. Grassland availability (βG= 8.00±3.09), terrain ruggedness index (βTRI= 0.73±0.34), and Sambar (prey) presence (βS= 1.06±0.51) strong positive association, whereas, stream/exposed surfaces (βSES= -0.45±0.43) had negative association with the habitat use by Dholes. Similarly, detection probability was positively associated with presence of Sambar (βS= 2.44±1.02) but negatively associated with streams/exposed surfaces (βSES= -0.99±0.32) and terrain ruggedness (βTRI= -0.09±0.23). Our study provides quantitative information on the ecology of Dholes with potential applications for improving their conservation efforts in Nepal.

Identifying and characterizing juvenile lake sturgeon ( Acipenser fulvescens , Rafinesque, 1817) occupancy hot spots within the St. Clair‐Detroit River System

Over the past two decades, extensive monitoring has been conducted in the St. Clair – Detroit River System to describe spatial and temporal patterns of lake sturgeon (Acipenser fulvescens). To characterize spatial patterns in juvenile lake sturgeon (<1000 mm TL) based on survey collections, ‘hot spots’ were identified through optimized hot spot analysis (HSA). This HSA was then interpolated by inverse distance weighted analysis to determine extent of identified ‘hot spots’ and ‘cold spots’. Additionally, habitat variables (i.e., water depth, water velocity, and dominant substrate type) were investigated using a single season occupancy model to determine their influence on juvenile lake sturgeon occupancy probability. In total, 1203 juvenile lake sturgeon were captured across 4197 surveys. Three unique ‘hot spots’ were identified; western Lake Erie, Fighting Island in the Detroit River, and the North Channel in the St. Clair River. Interpolated ‘hot spots’ encompassed 73.1 km² in western Lake Erie, 4.7 km² near Fighting Island, and 6.6 km² in the North Channel. Detection probabilities within ‘hot spots’ ranged from 8.8%–43.4%. No habitat variables significantly predicted juvenile lake sturgeon occupancy. Juvenile lake sturgeon were captured in western Lake Erie where the water depth was >5.1 m and odds of occupancy increased with increased water velocity. Juvenile lake sturgeon in the Detroit and St. Clair River ‘hot spots’ were captured at sites with mean benthic water velocities ranging from 0.20–0.60 m/s and where water depth was >7.3 m. Irrespective of waterbody, 69% of all juveniles were detected over dominant sand and gravel substrates. These results provide valuable insight about juvenile habitat use that can help managers formulate effective conservation and restoration strategies supporting the continued recovery of Great Lakes lake sturgeon.

Varying degrees of spatio-temporal partitioning among large carnivores in a fenced reserve, South Africa

Context The spatio-temporal partitioning of large carnivores is influenced by interspecific competition and coexistence within small, enclosed reserves. Lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) are the three largest African carnivores and have the greatest potential for intra-guild competition, particularly where space is limited. Aim To investigate the spatio-temporal partitioning between lions, spotted hyaenas and leopards in a small (~75 000 ha), enclosed nature reserve, Madikwe Game Reserve (Madikwe), South Africa. Methods We deployed 110 camera traps (baited n = 55 and unbaited n = 55) across Madikwe from 26 August 2019 until 6 May 2020. Von Mises kernel density plots were used to investigate daily temporal partitioning among the three species. A multiple-species, single-season occupancy model was used to investigate daily space use patterns. Key results We found both temporal and spatial exclusion between lions and spotted hyaenas on Madikwe. However, no evidence was found of spatio-temporal partitioning between lions and leopards, and spotted hyaenas and leopards. Conclusions Exploitative and interference competition on Madikwe might be high enough to warrant spatio-temporal partitioning between lions and spotted hyaenas to avoid the negative effects of intra-guild competition. Contrastingly, patterns observed between leopards and both lions and spotted hyaenas preclude the possibility of top-down control by superior carnivores. Implication These findings call for an adaptive management approach, where both carnivore and prey species compositions are constantly monitored. Management strategies such as these will allow for the conservation of valuable resources (i.e. prey species) to ensure the persistence of large carnivore populations across African ecosystems.

Effect of Prescribed Fire and Mechanical Treatments on Northern Bobwhite Occupancy in Mesic Pine Flatwoods

We examined whether roller-chopping, mowing, and prescribed fire used to restore groundcover in pine flatwoods habitats affected northern bobwhite (Colinus virginianus; hereafter, bobwhite) occupancy. We surveyed bobwhites using repeated point counts (n = 3), April–June each year, to determine response to prescribed fire and mechanical treatments on Osceola National Forest (Osceola, 78 plots) and St. Sebastian River Preserve State Park (Sebastian, 11 plots) in Florida, USA, 2013–2019. We measured groundcover each year at randomly placed transects within 200-m radius point-count plots. To assess the importance of management covariates, we fit single season occupancy models to predict occupancy (ψ) and detection (p). Detection probability was 0.12 (standard error [SE] = 0.05) and 0.35 (SE = 0.05) on Osceola and Sebastian, respectively. Modeled occupancy on both sites was best predicted by presence of roller-chopping, years since fire, and year. Predicted occupancy was highest on plots with 1 year since fire (Osceola, 0.22 [SE = 0.10]; Sebastian, 0.67 [SE = 0.18]). Predicted occupancy was higher on roller-chopped plots (Osceola, 0.33 [SE = 0.15]; Sebastian, 0.85 [SE = 0.15]) than on mowed (Osceola, 0.08 [SE = 0.03]) or untreated plots (Osceola, 0.07 [SE = 0.03]; Sebastian, 0.38 [SE = 0.34]). Roller-chopping and fire reduced density of palmetto (Seranoa spp.)-shrub vegetation and increased grasses and forbs. To increase bobwhite occupancy and improve habitat suitability of degraded mesic pine flatwoods, we recommend roller-chopping and a 2-year fire frequency.