Spatial Habitat Use Research Articles

Temporal niche partitioning as a potential mechanism for coexistence in two sympatric mesopredator sharks

Global marine biodiversity declines require bold and ambitious plans to safeguard ecosystem services. Overfishing, habitat loss and projected climate impacts have yielded deleterious effects on marine predators, in particular, driving increasing threat of extinction for many shark species with implications for ecosystem health. Identifying and protecting critical habitat areas for sharks is fundamental to their protection, and may allow for species recovery. Here we use baited remote underwater video stations to investigate spatial and temporal patterns of habitat use by sharks in a Special Area of Conservation (SAC) that is centrally important to the regional blue economy in the UK, the Cardigan Bay SAC. Our results show heterogeneous spatial habitat use and temporal trends in habitat sharing between smallspotted catsharks Scyliorhinus canicula and nursehounds S. stellaris. Nearshore reef habitats are substantially more important than non-reef habitats for both species. The relative abundance of each species, however, is roughly inversely seasonally proportional, with S. canicula and S. stellaris relative abundance highest in March and September, respectively. Temporal niche partitioning may be an important mechanism in marine systems, but has not been widely investigated in sympatric shark communities. These findings are directly relevant for ongoing development of the Welsh Marine Evidence Strategy (2019-2025) and the Welsh National Marine Plan, particularly to inform spatial planning to strengthen the role of SAC management design in protecting important shark areas.

Oyster reefs as habitat for aquatic macrofauna in a Gulf of Mexico estuary: biotic complexity at spatial, ecological, and demographic scales

Oysters are important marine foundation species across the world, particularly in estuaries of the Gulf of Mexico. One important function of oysters in estuaries is the provision of 3-dimensional habitat that is used by a wide range of species. In this study, the biotic diversity of mid-bay intertidal oyster reefs found in a Gulf of Mexico estuary was examined at nested ecological and demographic scales. Fishery-independent data collections made in East Matagorda Bay, Texas, USA, were used to compare community structure and diversity at mid-bay reefs to undifferentiated shoreline habitats. Despite similar diversity metrics, there were differences in community structure that were driven by differences in spatial habitat use by several common species. Below the community scale, demographic differences in spotted seatrout Cynoscion nebulosus habitat use were observed, with smaller and younger individuals found along reefs, and larger and older individuals found along shorelines. This finding was more pronounced for male spotted seatrout in the spring. The observed spatial habitat use patterns at nested ecological scales (community, inter-species, intra-species) highlight the importance of oyster reefs for maintaining diversity in Gulf of Mexico estuaries, and more broadly support the notion that heterogeneity in localized habitats drives biotic diversity at the estuary scale. Conservation of oyster reefs as critical habitat should be considered along with conservation of oysters themselves when balancing the ecological value of oysters against the commercial value of oyster fisheries.

First telemetry insights into the movements and vertical habitat use of megamouth shark (Megachasma pelagios) in the northwest Pacific

The megamouth shark (Megachasma pelagios) is one of the ocean's largest and most enigmatic elasmobranchs, with only a few hundred individuals ever recorded. Most of what is known about the species comes from rare fishery bycatch, stranding, or sighting events, precluding an in-depth understanding of its movement ecology. Here, we report the results from three megamouth sharks outfitted with pop-up satellite archival transmitting tags to assess the species' horizontal and vertical movement patterns. Deployments of 12, 58, and 244 d in duration provided the first direct evidence of multi-month fidelity to the waters east of Taiwan and seasonal movement out of the region. Depth and temperature data revealed a pattern of normal diel vertical migration, with the majority of the day spent in the mesopelagic zone and night in the epipelagic. Vertical habitat use suggests potential behavioral thermoregulation and was consistent with tracking of migrating mesopelagic prey across diel periods. We discuss the specialized analytical methods needed to reconstruct the spatial habitat use of deep-diving megamouth shark from tag sensor measurements of the magnetic field, as well as avenues for future research on this understudied megaplanktivore.

Effects of telemetry collars on two free-roaming feral equid species.

There are two species of free-roaming feral equids in North America: horses (Equus caballus) and donkeys or "burros" (E. asinus). Both species were introduced as domestic animals to North America in the early 1500s and currently inhabit rangelands across the western United States, Canada, and all continents except Antarctica. Despite their global distribution, little is known about their fine scale spatial ecology. Contemporary research tools to assess space use include global positioning system (GPS) tracking collars, but older models were problematic due to stiff collar belting causing poor fit. We tested modern designs of GPS collars on n = 105 horses and n = 60 burros for 4 years in five populations (3 horse, 2 burro) across the western United States, to assess whether collars posed welfare risks to horses or burros. We found no difference in survival of collared versus uncollared mares and jennies, and no difference in survival of their foals. In 4036 of 4307 observations for horses (93.7%) and 2115 of 2258 observations for burros (93.6%), collars were observed symmetrical, maintaining proper fit on the neck. Fur effects from collars (sweaty neck, indented fur, broken fur) were seen in 3% of horse observations and 25% of burro observations. Superficial effects (chafes and marks on skin surface) were seen in 2% of horse observations and 11% of burro observations; no severe effects from collars were seen. Body condition was not affected by collars; mean body condition of collared horses was 4.70 ± 0.54 (mean ± s.d) and 4.71 ± 0.65 for collared burros. Behavior results indicated minimal effects; collared horses stood slightly more than uncollared, and collared burros stood and foraged more in one population, but not in the other. For 6.3% of observations of horses and 6.4% of observations of burros, we found an effect of time wearing a collar on the cumulative sum of fur effects which increased over time (burros: rs = 0.87, P = <0.0001; horses: rs = 0.31, P = 0.002). Burros also showed an increase over time in the number of superficial effects, but horses did not. Collars occasionally moved into the wrong position, shifting forward over the ears; we observed this on 19 horses and 1 burro. Of those, most collars went over the ears in summer (n = 12). All collars were equipped with a remote release mechanism as well as a timed-release mechanism for redundancy, thus removed when observed in wrong position to avoid rubbing or discomfort. Our finding of no consequential physical effects in 98% of horse observations, and 89% of burro observations suggests the consequences of collars on free-roaming equid welfare and survival is biologically insignificant, although collars should be monitored regularly and continue to be equipped with a remote release mechanism to remove a collar if needed. With frequent welfare-driven, visual monitoring, collaring of free-roaming equids can be a safe and useful tool to increase our understanding of their spatial ecology, demography, habitat use, behavior, and interactions with other wildlife.

Variability in the summer movements, habitat use and thermal biology of two fish species in a temperate river

The ability of fish to cope with warm water temperatures in summer depends on factors including their thermal traits and the ability of individuals to access cool-water refugia. Knowledge is highly limited on the in situ responses of many fishes to elevated summer temperatures, including whether they express behavioural thermoregulation. The responses of two riverine species to summer water temperatures were tested here using the movement metrics, spatial habitat use and body temperatures of individual European barbel Barbus barbus (‘barbel’) and common bream Abramis brama (‘bream’) versus river temperatures. Acoustic biotelemetry was applied in the lower River Severn basin, western Britain, in summer 2021 (barbel) and 2022 (bream), where individuals could move across > 150 km of river, including a tributary of cooler water. Across all individuals, bream occupied 37 km of river length (mainstem only), with low inter-individual variability in their spatial habitat use, movements and body temperatures. In contrast, barbel occupied 62 km of river (main river/tributary), with relatively high inter-individual variability in spatial habitat use, movements and body temperatures, with higher variation in body temperatures as river temperatures increased (maximum mean daily temperature difference between individuals on the same day: 4.2 °C). Although warmer individuals generally moved more, their activity was greatest at relatively low temperatures and higher flows, and neither species revealed any evidence of behavioural thermoregulation during elevated temperatures. Enabling phenotypically diverse fish populations to express their natural behaviours and thermal preferences in summer water temperatures thus requires maintaining their free-ranging in thermally heterogenous habitats.

Movements and habitat use of native and invasive piscivorous fishes in a temperate and channelized lowland river

AbstractLowland temperate rivers provide important habitats for piscivorous fishes, but with their year-round spatial and temporal habitat use is often poorly understood, including their use of off-channel habitats. Here, the movements and habitat use of the piscivorous native Northern pike Esox lucius and invasive pikeperch Sander lucioperca were investigated using acoustic telemetry in the highly regulated (through impoundment) lower River Severn, Western England over a 12-month period, where off-channel habitat availability was limited to a single boat marina. The movements of both species varied with season and temperature, with both species moving greater distances in spring. Increasing water temperatures up to 15 °C resulted in a higher frequency of movements of both species, but movements then decreased at temperatures higher than this. Northern pike detections in the river increased in periods of lower river discharge and warmer temperatures, with the off-channel refuge providing an important habitat all year round (78% of detections occurred there). While 63% of pikeperch detections also occurred in the marina, 89% of these detections occurred between December and April. These results thus emphasise the importance of this limited off-channel habitat as potential spawning locations for invasive pikeperch and foraging areas for native Northern pike.

A comparison of tag retention and mortality from two tagging methods for internal tag placement in Channel Catfish

AbstractObjectiveDocumenting the movement of Channel Catfish Ictalurus punctatus through telemetry, where a transmitter tag is surgically implanted in the fish, can provide valuable insight into the species' spatial ecology and habitat use. However, since fish in the order Siluriformes can expel foreign objects such as tags from their body cavity, the utility of telemetry technology may be limited for Channel Catfish. This study aimed to determine (1) how quickly Channel Catfish reject tags that were surgically implanted into the body cavity, (2) if surgical implantation of transmitter tags causes mortality, and (3) what surgical method is best to minimize tag rejection and/or mortality.MethodsThree surgical trials were conducted on Channel Catfish (n = 24) using two tag implantation methods: a nontethered method, in which the tag was freely implanted into the body cavity, and a tethered method, where the tag was attached to the pectoral girdle. Fish were observed in the lab for 30 days for trials 1 and 2 and 225 days for trial 3 following tag implantation.ResultNo complete tag rejections occurred during any of the three experimental trials. However, all five tethered fish experienced mortality during trial 3 (58–221 days postsurgery). Necropsies indicated that the tethered tagging method led to septicaemia infections and internal lacerations from the tether, which were not observed in the nontethered fish. Tags in the nontethered fish were in the process of being absorbed into the intestinal tract, which over time might have led to tag rejection.ConclusionWhile rejection is possibly the end point of the nontethered tagging method, our results suggest it is nevertheless the better tagging method for Channel Catfish given higher survival.

Impact of anthropogenic infrastructure on aquatic and avian predator–prey interactions in a modified lowland river

Abstract The relationship between aquatic and avian predators and prey is a fundamental process that influences the ecological dynamics of freshwater communities; a landscape of fear underpins spatial and temporal habitat use of prey, i.e., non‐consumptive predation effects. For example, complex marginal vegetation and other natural in‐river refuges are known to be important for prey to manage predation risk and predators must alter their behaviour in response to habitat patches prey occupy. However, it is unclear how prey respond to predators, and vice versa, in heavily modified degraded lowland rivers with a high degree of river maintenance measures; a component critical for flood risk management globally. Such modifications could lead to prey seeking refuge at hazardous anthropogenic infrastructure, but a robust quantification of predator–prey interactions in this context is required to develop this understanding. Using multi‐beam sonar (Dual‐Frequency Identification Sonar), we non‐invasively and simultaneously quantified the temporal rate of predator–prey interactions, the attack behaviour of predators, and the refuge seeking behaviour of prey at a pumping station intake during winter in a heavily modified lowland river. Prey fish experienced temporally dynamic, density‐dependant, and species‐specific predation risks from two dissimilar predators (i.e., aquatic vs. avian); pike (Esox lucius) and cormorant (Phalacrocorax carbo). Generalised linear modelling revealed that prey refuge use was positively associated with predator attack rate. Non‐consumptive effects were evidenced by quantified changes to shoal structure (density, area), shoaling (group aggregation), and schooling (coordinated directional movement), including diurnal migrations to and from the pumping station intake for refuge. Our results show that in the absence of natural refuge habitats the natural landscape of fear shifted and speculate that prey fish were paradoxically dependant on hazardous anthropogenic infrastructure, i.e., a pumping station intake, for refuge from predators in a degraded lowland river. These findings strongly enhance our understanding of the impact of anthropogenic infrastructure on predator–prey interactions by demonstrating how flood risk management, including river maintenance measures, and associated anthropogenic infrastructure can impact the behavioural game played between aquatic and avian predators and their prey.

Spatial behaviors and seasonal habitat use of the increasingly endangered thick-billed parrot (Rhynchopsitta pachyrhyncha)

The thick-billed parrot (Rhynchopsitta pachyrhyncha) inhabits highland pine forests in the Sierra Madre Occidental ranges of northwestern Mexico. Their populations have declined significantly to < 2000 individuals due to habitat loss, illegal hunting and increasing predation. Despite their ecological and cultural importance and increasingly endangered status, the species is data deficient. Our study aimed to inform and enhance conservation management strategies for thick-billed parrots with information on their spatial ecology, habitat use, migratory behaviors and social associations. We deployed biotelemetry devices to conduct the first tracking study of wild thick-billed parrots. Our study revealed that thick-billed parrots are seasonal migrators, departing their breeding habitats around October and returning from southern habitats around April. Our research also identified previously unknown overwintering sites and migratory stopover locations, as well as a new nesting site. The parrots exhibited high spatial variability in range shifting behavior, but all tracked parrots exhibited range shifts during migration, with durations of 3–181 days and distances of 173–765 km. They traveled in close social groups and migratory routes primarily followed high-elevation forests along the Sierra Madre Occidental ranges. Home range analysis indicated smaller breeding site ranges and larger overwintering ranges, possibly reflecting nesting constraints and winter food resource dispersion. Parrot spatial associations favored high-elevation forest landscapes with tall and wide-trunked trees, underscoring the importance of preserving old-growth forests for nesting and foraging. Less than 20% of parrot habitats have formal regulatory protections. Conservation management efforts must focus on increasing protections for nesting areas, overwintering habitats, and key migratory stopover sites. As climate change exacerbates regional threats, integrated management plans involving local stakeholders and communities are essential for the parrots' long-term survival and the preservation of their old-growth forest habitats.

Offshore industry and whales: Pygmy blue whale acoustic behavior and movement patterns in the Otway Basin

The offshore Otway region of Australia is designated as a Biologically Important Area for foraging for blue whales. Understanding the acoustic behavior of blue whales in these foraging grounds will enable an improved understanding of the residency time of individual animals and facilitate improved management of the population. JASCO deployed a directional AMAR G4 for part of the 2020 pygmy blue whale foraging season. The recorded vocalizations, including song and D-calls, have been analyzed in detail to determine bearings, received level, and estimated ranges. Bearings to detected vocalizations were determined using a maximum-likelihood-estimator, with a fluid only propagation model corrected for the layered elastic seafloor used to determine ranges. An analysis of the distribution of different vocalizations across the listening range of the AMAR over time has been conducted and correlated with AIS information from shipping traffic. The results have been used to provide a brief insight into the acoustic behavior and movement patterns of individual pygmy blue whales within the region, furthering our understanding of spatial habitat use in association with commercial shipping lanes and oil and gas operations.

Small Space but High Diversity: Spatial and Temporal Habitat Use by Endangered Eurasian Curlew at Wintering Sites Throughout Europe

Small Space but High Diversity: Spatial and Temporal Habitat Use by Endangered Eurasian Curlew at Wintering Sites Throughout Europe

Camera Trap Methods and Drone Thermal Surveillance Provide Reliable, Comparable Density Estimates of Large, Free-Ranging Ungulates.

Camera traps and drone surveys both leverage advancing technologies to study dynamic wildlife populations with little disturbance. Both techniques entail strengths and weaknesses, and common camera trap methods can be confounded by unrealistic assumptions and prerequisite conditions. We compared three methods to estimate the population density of white-tailed deer (Odocoileus virgnianus) in a section of Pilot Mountain State Park, NC, USA: (1) camera trapping using mark-resight ratios or (2) N-mixture modeling and (3) aerial thermal videography from a drone platform. All three methods yielded similar density estimates, suggesting that they converged on an accurate estimate. We also included environmental covariates in the N-mixture modeling to explore spatial habitat use, and we fit models for each season to understand temporal changes in population density. Deer occurred in greater densities on warmer, south-facing slopes in the autumn and winter and on cooler north-facing slopes and in areas with flatter terrain in the summer. Seasonal density estimates over two years suggested an annual cycle of higher densities in autumn and winter than in summer, indicating that the region may function as a refuge during the hunting season.

Algerian and European hedgehogs cohabiting in periurban environments: spatial behaviour and habitat use

Habitat fragmentation is one of the most important threats to biodiversity in the last decades. Numerous species are forced to adapt to human presence as urbanization keeps increasing. Some studies show the impact of habitat changes in various species; however, there is little knowledge about the effect of habitat disturbance on hedgehogs in the Iberian Peninsula. We radio tracked 31 male hedgehogs: 14 European hedgehogs and 17 Algerian hedgehogs, being 18 individuals indigenous and 13 translocated. We analysed their home ranges, spatial behaviour and habitat use in a suburban area of Valencia City, Spain, where the two species coexist. Our results show that there are phenologic variations of activity levels, which differ between species, being maximum in spring for the European hedgehog and in summer for the Algerian hedgehog. We did not detect a territorial behaviour or interspecific spatial competition. However, we could detect a clear “release effect”, with translocated individuals presenting increased home range sizes and activity levels as they explore the unknown environment. Furthermore, we found that both species showed a clear preference for the pine forest habitat, avoiding all other habitat types, especially those with high human presence. Our results also suggest that the European hedgehog has a more generalist character than the Algerian hedgehog regarding habitat use. In conclusion, this study highlights the importance of conserving a connected mosaic of green patches in urbanized environments for the conservation of hedgehog populations.

Spatial- and Temporal-Trajectory Analysis of the Crested Ibis (Nipponia nippon) by Fusing Multiple Sources of Data.

The Crested Ibis (Nipponia nippon) is an endangered animal with an extremely high ecological, humanistic, and scientific value. However, this species still faces survival challenges, due to rapidly shrinking foraging grounds, the serious interference of human behavior, and increased habitat requirements. Geographical environment is a significant factor affecting Crested Ibis behavior-pattern analysis and habitat protection. The spatial and temporal trajectory contains habitat location and period information, a vital record of the Crested Ibis' habits, and the basis of all research. Nevertheless, there are only a handful of studies on the missing trajectory data and fusing multiple sources of environmental data-research methods. We studied the spatial and temporal habitat use of the tracked Crested lbis by fusing multiple data-sources in China. This paper adopts the LSTM (long short-term memory) model to supplement the missing trajectory data and perform cluster mining; and a random forest model is used to predict the habitat of the Crested Ibis with high fitting accuracy (R2 = 84.9%). The results show that the Crested Ibis distribution-pattern is characterized by high altitude and proximity to woodland and rivers. Additionally, the habitat dependence on the village implicates human agricultural activities in positively impacting its reproduction. This paper provides a complete method for analyzing Crested Ibis' spatial and temporal trajectory by fusing multi-source data, which is crucial for protecting the survival and reproduction of the Crested Ibis.

Can a mesocarnivore fill the functional role of an apex predator?

AbstractAs keystone species, apex predators play a role in structuring most ecosystems through competition and facilitation, thereby affecting community structure, prey abundance and behavior, vegetation, and abiotic processes. Apex predators are also highly threatened and have been extirpated from much of North America, leading to mesocarnivores, such as coyotes (Canis latrans), becoming de facto apex predators in many ecosystems. However, it is unknown if these mesocarnivores can fill the same functional keystone role as true apex predators. We compared the spatial and temporal habitat use of mesocarnivores in two similar study systems, one with pumas (Puma concolor) and one without, to determine how the role of coyotes in structuring the carnivore community changes in the absence of pumas. We used multispecies occupancy and relative abundance models to examine the spatial avoidance of pumas and coyotes by the smaller mesocarnivores, and temporal overlap and avoidance‐attraction ratios to examine temporal avoidance. We found that coyotes partially fill the functional role of apex predators, but with weaker effects than pumas. Where pumas were absent, site use intensity and relative abundance increased for coyotes (180% and 1250%) and raccoons (Procyon lotor, 308% and 3273%) and decreased for bobcats (Lynx rufus, 36% and 55%), gray foxes (Urocyon cinereoargenteus, 13% and 32%), and striped skunks (Mephitis mephitis, 3% and 12%). Coyotes and raccoons shifted their temporal activity away from pumas, while gray foxes shifted their activity closer to pumas. Detection likelihood decreased for all species after detection of a puma (67%–93%) or coyote (46%–94%) in both sites, but small mesocarnivores avoided pumas more than coyotes in the study area with both. Interactions between carnivores are complex and best understood with multiple measures and in the context of the full community. While coyotes appear to suppress smaller mesocarnivores by some measures (e.g., temporal avoidance), they do not by others (e.g., spatial avoidance) and have overall weaker effects than pumas. Our results suggest that coyotes are not a substitute for apex predators, and conserving true apex predators is likely important for maintaining ecosystem health.

Divergent post-breeding spatial habitat use of Laysan and black-footed albatross

Understanding the at-sea movements of wide-ranging seabird species throughout their annual cycle is essential for their conservation and management. Habitat use and resource partitioning of Laysan (Phoebastria immutabilis) and black-footed (Phoebastria nigripes) albatross are well-described during the breeding period but are less understood during the post-breeding period, which represents ~40% of their annual cycle. Resource partitioning may be reduced during post-breeding, when birds are not constrained to return to the nest site regularly and can disperse to reduce competitive pressure. We assessed the degree of spatial segregation in the post-breeding distributions of Laysan (n = 82) and black-footed albatrosses (n = 61) using geolocator tags between 2008 and 2012 from two large breeding colonies in the Northwestern Hawaiian Islands, Midway Atoll, and Tern Island. We characterized the species-and colony-specific foraging and focal distributions (represented by the 95 and 50th density contours, respectively) and quantified segregation in at-sea habitat use between species and colonies. Laysan and black-footed albatross showed consistent and significant at-sea segregation in focal areas across colonies, indicating that resource partitioning persists during post-breeding. Within breeding colonies, segregation of foraging areas between the two species was more evident for birds breeding at Tern Island. Spatial segregation decreased as the post-breeding season progressed, when spatial distributions of both species became more dispersed. In contrast to studies conducted on breeding Laysan and black-footed albatross, we found that sea surface temperature distinguished post-breeding habitats of black-footed albatrosses between colonies, with black-footed albatrosses from Midway Atoll occurring in cooler waters (3.6°C cooler on average). Our results reveal marked at-sea segregation between Laysan and black-footed albatross breeding at two colonies during a critical but understudied phase in their annual cycle. The observed variation in species-environment relationships underscores the importance of sampling multiple colonies and temporal periods to more thoroughly understand the spatial distributions of pelagic seabirds.

Habitat Use of Wintering Mule Deer Across a Juniper-Treated and Burned Landscape

In eastern Oregon, western juniper (Juniperus occidentalis) encroachment has degraded vast amounts of wildlife habitat; thus, the removal of juniper has become a common restoration practice. Vegetative responses following juniper treatment have been well documented; however, wildlife, especially mule deer (Odocoileus hemionus) responses have not. We deployed camera traps at 40 sites within the Phillip W. Schneider Wildlife Area in northeastern Oregon to assess habitat use of wintering mule deer during two winters with different conditions, a mild winter in 2017−2018 and a harsher winter in 2018−2019. We assessed mule deer spatial habitat use using N-mixture models accounting for imperfect detection. We assessed temporal use by fitting kernel density functions to the timestamps of mule deer photographs. Spatial analysis indicated that during a mild winter, mule deer used unburned juniper treatment habitats more than untreated and unburned habitats. Once burned, however, juniper treatment habitats were used the least. During a harsher winter, mule deer spatially responded negatively to total precipitation rather than habitat conditions. Temporal analysis indicated that mule deer did not change their activity pattern between the two winters and used a mosaic of habitats to meet their daily requirements. Our results highlight the importance of juniper removal from encroached sage-steppe habitat but also emphasize the importance of habitat heterogeneity. Our results also demonstrate that wildland fires can negate the benefit of juniper treatment to wintering mule deer.

High‐resolution drone imagery reveals drivers of fine‐scale giant otter habitat selection in the land‐water interface

AbstractNeotropical freshwater habitats are particularly sensitive to degradation by human activity. Piscivorous semi‐aquatic freshwater megafauna inhabit both the terrestrial and aquatic mediums and thus may be good indicators of wetland habitat quality. However, the drivers of their space use at the terrestrial and aquatic landscape levels are not well understood. We studied the spatial behavior and habitat use of giant otters in Madre de Dios, Peru, inhabiting areas with variable levels of protection. We combined unmanned aerial vehicle (UAV) and satellite images to develop different terrestrial and water‐associated land cover variables. We tested the influence of these predictors on giant otter habitat use at multiple spatial scales, comparing used and available locations. Giant otters favored bank areas with dense forest canopy cover. In the aquatic medium, giant otters showed positive selection for open water and fallen logs and avoided floating vegetation. These findings may be explained by preference for optimal fish habitat to maximize foraging yield and bank areas that provide more cover from predators and higher quality denning locations. Variables developed from UAV images outperformed satellite‐derived variables. Despite recent signs of deforestation in lake banks in unprotected areas, spatial model predictions indicated that unprotected oxbow lakes did not differ in their habitat suitability from protected freshwater habitats. Management implications of our findings include identification of factors driving habitat suitability to guide policy and decisions regarding protection or restoration of oxbow lake ecosystems to support giant otter populations. In addition, we demonstrate that UAVs have value in complementing satellite‐derived images and providing a cost‐effective methodology to assess habitat quality for semi‐aquatic species at the land‐water interface.

European flounder foraging movements in an estuarine nursery seascape inferred from otolith microchemistry and stable isotopes

Despite the importance of estuarine nurseries in the regulation of many fish stocks, temporal and spatial movements and habitat use patterns of juvenile fish remain poorly understood. Overall, combining several movement metrics allowed us to characterize dispersal patterns of juvenile flounder, Platichthys flesus, along an estuarine seascape. Specifically, we investigated otolith microchemistry signatures (Sr:Ca and Ba:Ca ratios) and stable isotope ratios (δ13C and δ15N) in muscles of these juveniles, during three consecutive years to assess inter-annual fluctuations in their home range and isotopic niches. The morphological condition and lipid content of individuals were lower in years of high as compared to low dispersal along the estuarine gradient. We discuss these results in relation to the ecosystem productivity and intra- and inter-specific competition level, which in turn affects movements and foraging behaviors of juvenile flounders.

Importance of private working lands for the conservation of neotropical birds on an urban-wilderness gradient

Global biodiversity and land conservation initiatives rely on an accurate understanding of the spatial distribution of species populations and communities. Identifying the spatial habitat use of wildlife communities across land uses and levels of human modification provides the opportunity to produce more efficient and effectual conservation plans. Our goal was to model breeding bird community occupancy across a complete spectrum of human land use modification to determine the habitat characteristics that best maximized the conservation of bird diversity. We used repeat-visit point counts on private and public lands to record the detection/non-detection of breeding bird species across the land use gradient. We modeled multiple proportional land cover and landscape structure covariates and employed a hierarchical multi-species occupancy model to analyze the habitat use of each species and to estimate guild-level species richness dynamics across the study area. We detected a total of 70 breeding bird species and our model estimated a total of 78 species within the total metacommunity. We found that insectivorous species richness was lowest in urban and suburban areas (xˆ = 7), but highest on multiple use working lands with low to moderate levels of human modification (xˆ = 22), not in the fully preserved protected areas (xˆ = 16). In contrast, the richness of the predominately human commensal omnivorous species was highest in urban and suburban areas (xˆ = 10) and across much of the more human modified landscape and lowest in the preserved lands (xˆ = 3). Moderately disturbed working lands, which primarily consisted of a mixture of rotating silvicultural tracts, agriculture, low density housing, and riparian corridors, supported the most species (xˆ = 36) and were especially important for the occupancy of breeding neotropical insectivores. These findings highlight the potential conservation benefits for incorporating private working lands with multiple land uses and land covers into future conservation planning scenarios, both for their wildlife conservation potential and as buffers around traditional protected areas.