Habitat Use Research Articles

Habitat use by pudu deer (Pudu puda) in native forests of coastal range in Southern Chile

Habitat use by pudu deer (Pudu puda) in native forests of coastal range in Southern Chile

Mississippi River-floodplain connectivity level mediates fish assemblage dynamics

The life histories of many Louisiana fishes are tied to the timing, magnitude, and duration of the Mississippi River flood pulse. Anthropogenic modifications designed to control and restrict flood waters have decoupled Louisiana’s floodplains from the seasonal flood pulse, influencing the aquatic food web. Culvert and rock weir repair within the Richard K. Yancey Wildlife Management Area aims to improve water quality and maintain appropriate water depth for native Louisiana fishes. In this study we conducted high-resolution imaging sonar (ARIS Explorer 3000) monitoring of the floodplain fish assemblage across seasons prior to hydrologic restoration. Imaging sonars may be used to obtain quantitative ecological and behavioral information without the selectivity biases of traditional techniques through the recording of continuous video-like datasets that are not constrained by environmental factors such as turbidity. Our first objective was to test the hypothesis that seasonal inundation levels and proximity to the Mississippi River affect the abundance and size class distribution of the floodplain-associated fish assemblage. Our second objective was to characterize species composition and ecological function of each acoustically-detected size class using historical fisheries datasets collected by the Louisiana Department of Wildlife and Fisheries. To do so, we employed the multi-gear mean standardization technique for standardizing catch per unit effort of passive and active gear types used within the historical dataset in order to produce a non-exhaustive list of potentially recorded species by the imaging sonar. Our study demonstrated a size class dependent use of floodplain habitats mediated by inundation level, but not the distance from the Mississippi River. Our results illustrated a trend of increased detections of all size classes during high-water connected-spring and summer periods, as well as during disconnected-summer periods immediately following the seasonal flood pulse. Continued monitoring of the fish assemblage will provide additional data to better describe the complex dynamic patterns the floodplain fish assemblage may exhibit in response to the seasonal flood pulse and hydrologic restoration efforts.

First observations of blacktip shark (Carcharhinus limbatus) aggregation and initial satellite-tracked movements of multiple shark species in a southwestern atlantic Bay

The Brazilian coast, especially Rio de Janeiro, is vital as a migratory corridor, nursery, and refuge for 113 elasmobranch species, including 68 sharks. Advances in conservation technologies, such as satellite-linked transmitters with Unmanned Aerial Vehicles (UAVs) approach, are crucial for monitoring species in remote, hard-to-reach habitats. This study aimed to provide preliminary insights into the movement patterns of multiple shark species using satellite telemetry and UAV-assisted monitoring, as well as to document the first observations of blacktip shark (Carcharhinus limbatus) aggregations in Ilha Grande Bay. Between 2022 and 2024, 06 (six) sharks from three species: 01 (one) mako shark (Isurus oxyrinchus), 01 (one) hammerhead shark (Sphyrna zygaena), and 04 (four) blacktip shark (C. limbatus) were tagged using satellite telemetry tags to assess their spatial distribution, habitat use, and potential environmental drivers. Satellite tracking data of four female blacktip sharks revealed a strong site fidelity to Ilha Grande Bay, potentially linked to reproductive behavior, indicating that the region may serve as a critical habitat and a possibly refuge influenced by seasonal movements and thermal conditions. Additionally, drone surveys have revealed the first unprecedented aggregation of blacktip sharks offering new insights into the shark ecology in the region. The integration of satellite telemetry and drone monitoring proved to be a valuable approach for assessing shark movements and behavior in remote coastal ecosystems. These findings underscore the importance of Ilha Grande Bay as a key habitat for shark conservation, highlighting the need for further studies to assess environmental drivers and potential conservation measures.

Habitat use of obligate alpine geckos from southern New Zealand

Habitat use of obligate alpine geckos from southern New Zealand

Ecotones in the Spotlight-Habitat Selection of the Golden Jackal (Canis aureus Linnaeus, 1758) in the Agricultural Landscapes of Central Europe.

The large-scale expansion of the golden jackal (Canis aureus) across Europe in recent decades has been strongly influenced by its successful space and habitat use. In this study, we analyzed the habitat selection of seven golden jackals tracked with GPS collars between 15 March 2021 and 25 November 2022 in a predominantly agricultural landscape in the southwestern part of the Pannonian Basin, Central Europe. Animals were tracked for an average of 29 weeks, and GPS collars recorded a total of 29,840 hourly localization points, which were compared to a high-resolution land cover dataset. We found that golden jackals maintain smaller home ranges in agricultural landscapes than in more pristine environments. Based on Jacobs' index values calculated for monthly habitat preferences and the distribution of distances from land cover edges, we also found that preferences for the various habitat types differed significantly among individuals. Most of the time, golden jackals stayed near the edges of forests, agricultural lands, and shrublands, while they stayed away from artificial areas, wetlands, and water bodies. Forests and shrublands providing cover and safety were generally preferred by the golden jackals, especially during breeding and pup-rearing periods, while there was a strong avoidance of agricultural lands in general. Overall, our findings suggest that despite individual differences in the availability of habitat types within home ranges, forest-agricultural ecotones with relative proximity to food and shelter play a key role in the habitat selection of golden jackals.

Analysis of mixtures of birds and insects in weather radar data

Abstract Weather radars are increasingly used to study the spatial-temporal dynamics of airborne birds and insects. These two taxa often co-occur and separating their contributions is crucial for reliable interpretation of their movement patterns. Most studies have restricted analyses to locations, seasons, and periods in which one or the other taxa dominates. In this study, we describe an analytical method to estimate the proportion of birds and insects in cases where both taxa share the same airspace. Our approach partitions vertical profiles of biological reflectivity into bird and insect components, using assumptions of downwind heading selection by insects and information on expected airspeeds for birds and insects. We evaluated our method in regions, where existing approaches of studying bird migration with weather radars can be particularly challenging due to high airborne insect density: the tropics (Colombia) and the southern temperate zone (Southeast Australia). We found that bird and insect signals routinely reached similar magnitudes in these regions. Retrieved patterns of bird and insect occurrence across daily and annual cycles reflected expected biological patterns that are indicative of migratory and non-migratory movements in both climates and migration systems, particularly broad-front migration in birds. Contrary to fixed airspeed thresholding, we were able to partition birds along the full range of bird-insect proportions, retaining more spatial-temporal complexity that was crucial to revealing aerial habitat use of both taxa. Our analytical procedure readily extends existing vertical profiling approaches, empowering ecologists to explore complex aerial ecosystems across a diverse range of climates, as well as potential diurnal movements of birds and insects that remain heavily understudied.

Physiological traits explain the response of dung beetles to land use at local and regional scales

Physiological traits in insects are useful to understand their distribution at different spatial scales, their presence and abundance, and the use of different habitats. This study explored physiological parameters of dung beetles in two contrasting ecoregions of Argentina: Paranaense Forest and Dry Chaco. We capture dung beetles from both regions and habitats with different degrees of disturbance within each region, and performed lab experiments on metabolic rate and thermal tolerance. This study revealed that dung beetles inhabiting regions or habitats with higher temperatures (Dry Chaco and open pastures) showed greater temperature tolerance compared to those inhabiting regions or habitats with lower temperatures (Paranaense Forest and habitats preserving tree canopy). Furthermore, in the Dry Chaco, more species exploit open disturbed habitats, indicating less physiological sensitivity to temperature changes than dung beetles in the Paranaense Forest. This study is the first to compare dung beetle assemblages at both regional and local scales. The findings highlight the importance of preserving tree canopy in land use planning to mitigate microclimatic changes, especially in humid forests, to support dung beetle populations and their crucial ecosystem roles in the face of climate change.

Temporal trends in estuarine-resident fishes: Functional traits and responses to environmental and climatic variability.

Temporal trends in estuarine-resident fishes: Functional traits and responses to environmental and climatic variability.

Ecological Factors at Fine Spatial Scale Associated With Habitat Use by Tigers in Western Terai Arc Landscape, Nepal

Ecological Factors at Fine Spatial Scale Associated With Habitat Use by Tigers in Western Terai Arc Landscape, Nepal

Monitoring Fish Assemblages in Seasonal Off‐Channel Habitats Using Underwater Video and Computer Vision

ABSTRACTFloodplains provide suitable spawning and rearing habitats for many freshwater fishes and refugia from high flow events. Here, we study seasonal habitat use at the northern edge of the distribution for several spring‐spawning fishes in a major Norwegian river drainage and employ underwater video and computer vision to automatically detect, identify, and enumerate species in a seasonal, off‐channel backwater slough. Fish actively migrated upriver from their overwintering habitat during the spring runoff, and entered the backwater on the first day it became accessible from the mainstem. A convolutional neural network model was trained to automatically detect species in video obtained via an underwater camera placed at the entrance of the backwater and tested on a representative sample of conditions encountered over the course of a summer season. When we analysed the distribution of prediction scores for tracked fish, we found that the software performed variably for the different species and that the concordance between true counts and software predictions generally improved with increasing mean prediction probability cutoff levels. The intraclass correlation coefficient between the true count and the prediction scores at different cutoff levels showed that the concordance was overall best for roach, followed by pike and tadpoles (frogs and toads). Finally, we found no clear effects of abiotic or optical conditions on the accuracy of the software across a range of prediction probability cut‐off levels. We conclude that underwater video provides a feasible, non‐invasive means to studying fish in seasonal habitats during vulnerable phases of their life cycle.

A Simple, Quantitative Determination of the Appropriate Duration of Site Closure to Improve Occupancy Modelling for Nomadic Species

ABSTRACTAimOccupancy models are ubiquitous in ecological and biogeographical applications, but they rely upon an assumption of site closure that is sometimes applied across many weeks or even months. Nomadic species challenge this approach because they are likely to exhibit within‐season movements that violate the assumption of closure. Assuming closure for nomadic species across a full season likely results in depressed estimates of detection probability and inflated estimates of occupancy that can obscure important habitat associations. However, selecting an appropriate duration over which to assume site closure can also be a challenge, especially with continuous survey methods, like acoustic surveys or camera traps, where ‘surveys’ and ‘seasons’ can be ambiguous.InnovationWe present a simple framework for quantitatively assessing the most appropriate duration over which to assume site closure by directly comparing models with differing season lengths. We demonstrate our framework using simulated data, as well as a passive acoustic monitoring dataset of a nomadic bird, the Clark's nutcracker, collected during one summer across over 25,000 km2 of the Sierra Nevada, California. We applied dynamic occupancy models to data collected during a single calendar season to optimise the occupancy approach for the nutcracker.Main ConclusionsWe used our method to select an appropriate duration over which to assume site closure for the Clark's nutcracker, and our simulations indicated that this method is robust under a variety of scenarios. Our empirical and simulated results suggest that quantitatively determining the duration of the closure assumption can enable a more accurate understanding of the population dynamics and habitat use of nomadic species, especially when surveys are conducted with emerging continuous, or near‐continuous monitoring technologies. Our relatively simple framework can be used to improve occupancy modelling for other nomadic species, which will ultimately improve the efficacy of conservation measures taken to protect these species.

Ecological niche and habitat use of Antarctic krill (Euphausia superba) and the pelagic tunicate (Salpa thompsoni) under future climate change: further overlap or separation?

Ecological niche and habitat use of Antarctic krill (Euphausia superba) and the pelagic tunicate (Salpa thompsoni) under future climate change: further overlap or separation?

The value of social media wildlife sightings for elusive species monitoring: a population assessment of servals in a South African urban nature reserve

Data sourced from social media platforms is an underutilised resource for wildlife research, especially in studying enigmatic species. This study evaluates the potential of such data to provide population and behavioural insights into an elusive species, the serval (Leptailurus serval), from Rietvlei Nature Reserve, an urban protected area in South Africa. We collected 153 visitor sightings of servals within the reserve from different online platforms spanning from June 2011 to August 2024, from which we identified 30 different individual servals, including three long-term residents. Analysis of these sightings revealed a stable serval population with evidence of reproduction within the reserve and migration through a permeable border fence. Behavioural information from the sightings, such as prey captured and habitat use, align with existing knowledge of serval ecology. Even though data sourced from passive contributions by the public generally falls short in terms of data quality and detail, this study demonstrates that a well-supported social media community can be a valuable source of behavioural and basic population data of elusive species in a specific protected area. This approach allows for cost-effective wildlife research that is beneficial to both wildlife management and the formulation of conservation strategies.

Foraging and habitat use in common duikers, Sylvicapra grimmia within the Soutpansberg, South Africa

Foraging and habitat use in common duikers, Sylvicapra grimmia within the Soutpansberg, South Africa

Association patterns between farmland abandonment and the non-native Common Waxbill (Estrilda astrild) in the eastern Iberian Peninsula

Abstract Pet trading has led to a growing number of bird introductions worldwide, which has negatively affected recipient ecosystems and native species. Studying the seasonal and spatial distribution patterns of native and non-native bird species, such as the Common Waxbill (Estrilda astrild), is fundamental for understanding the ecological interactions between these two groups of species. For this purpose, we ran a year-round survey of passerine communities in two Mediterranean wetlands of the eastern Iberian Peninsula and investigated Common Waxbill’s feeding preferences. We studied the Common Waxbill association with native birds and their habitat use. The cluster analysis indicated that the Common Waxbill was the most abundant species of a distinct community, with peak presence in autumn. The random forests analysis revealed that it preferred human-modified land uses. Furthermore, farmland abandonment and the presence of two invasive plants, Pampas Grass (Cortaderia selloana) and Giant Reed (Arundo donax), positively influenced Common Waxbill presence. However, when eaten plants were divided into native, non-native and invasive, the Common Waxbill did not exhibit any preference. This corroborates that the Common Waxbill has significant ecological plasticity, which allows it to exploit a wide range of feeding resources in human-modified habitats. This study enhances knowledge of the interactions between native birds and invasive plants due to farmland abandonment, and of one of the most globally widespread non-native bird species. It highlights the need to monitor both groups of species and their long-term interactions.

Molecular Survey of Hemosporidian Parasites in Owls in Mainland Portugal.

Owls play an important role as avian hosts for hemosporidians via overlap in habitat use and activity with these arthropod vectors, thereby resulting in susceptibility to morbidity and, in some cases, mortality upon infection. This study analyzed the hemosporidians in tissues collected from individual dead owls (n=240) in various regions of mainland Portugal; the owls were primarily obtained from wildlife rehabilitation centers (WRCs). Hemosporidian species were detected using nested PCRs, targeting the cytochrome b gene of the mitochondria. For species and lineage identification, 19 positive PCR samples were selected and sequenced by the Sanger method. In total, 51% (n=122) of the 240 owl samples tested positive for at least one hemosporidian species: 31% (n=75) were positive for Haemoproteus-Plasmodium spp., whereas 44% (n=106) were positive for Leucocytozoon spp. Only 7% (n=16) were positive for Haemoproteus-Plasmodium spp. alone and 20% (n=47) for Leucocytozoon spp. alone, whereas 25% (n=59) of owls had mixed infections. Owl species, age, and geographic region of collected samples were significantly associated with hemosporidian prevalence: Eurasian Eagle-Owls (Bubo bubo), adults, and individuals from the Alentejo region presented higher prevalences than other species, ages, and geographic regions. Our findings highlight the potential impact of hemosporidians on owl conservation, particularly their effect on species currently threatened with extinction and the possible repercussions on reintroduction or translocation projects. This study emphasizes the role of WRCs in disease surveillance and suggests the importance of considering prophylactic measures in these settings. Given the high prevalence of hemosporidians, further studies involving live owls, both wild and captive, are encouraged, along with integrating clinical and hematologic data.

Spatio-Temporal Characterization of Nest-Niche in Passerine Birds Co-Occurring in Olive Agro-Ecosystems: Partitioning of Nesting Sites, Breeding Chronology, and Productivity

Many birds regard partitioning feeding and breeding resources as a strategy to escape competition and co-occurring breeding species. During the breeding season, breeding requirements are essential, yet the patterns and drivers of segregation between and within populations are poorly understood. We monitored the habitat use and chronology of the four co-occurring passerines Eurasian Blackbird, European Greenfinch, Common Chaffinch, and European Serin to examine levels of habitat partitioning and success rates during the breeding season. We recorded nesting sites, nest supports, nest placement, breeding chronology, and productivity in four olive orchards in Fez, central Morocco, from March to August 2018–2019. Our results showed substantial spatial segregation in nesting sites, nest supports, and tree vertical placements. Breeding birds showed significant temporal segregation during the nesting, laying, and hatching phases. These findings suggest distinct spatial and temporal differences in habitat selection among co-occurring passerines, which are suggested to increase avoidance of intra and interspecific competition for resources. Breeding success was very high in European Serin and Eurasian Blackbird. Failure factors were recorded: eggs of European Serin were threatened principally by desertion, abortion, and destruction, and eggs of European Greenfinch were impacted by poaching by children. Our findings provide the first data on the spatial and temporal partitioning of breeding resources among passerines species in Northwest African and probably Mediterranean agroecosystems.

Acoustic characteristics and context of buzzes and rasps produced by northern bottlenose whales (Hyperoodon ampullatus)

ABSTRACT Deep-diving northern bottlenose whales (Hyperoodon ampullatus) rely on sound for orientation, foraging and communication. While their regular echolocation clicks have been described, characterisations of other click types are limited. Here we quantify acoustic and behavioural differences between two types of rapid click trains: buzzes and rasps. Sound and movement data were collected from 15 animal-attached DTag deployments around Jan Mayen Island (Norway) from 2013–2016. Buzzes and rasps were manually identified, and random forest analyses revealed a classification accuracy of 93.7% (n = 129 respectively). Rasps occurred more often near the surface whereas buzzes were primarily emitted at depth during foraging dives, had shorter inter-click-intervals (U = 263, p < 0.001), longer durations (U = 14413, p < 0.001), and coincided with increased movement more often than rasps (U = 10384, p < 0.001). On-axis clicks from nearby whales showed further differences in duration and frequency content between individual buzz and rasp clicks. Our findings demonstrate that buzzes and rasps are acoustically and contextually distinct, with buzzes associated with foraging and rasps with communication. These differences will allow identification of buzzes and rasps and inference of behaviour and habitat use in passive acoustic data, enhancing research on this cryptic beaked whale.

Appropriate use of acoustics for surveying koalas and interpreting habitat use: a rebuttal to Smith and Pile (2024)

ABSTRACT Passive acoustic monitoring is a major new tool for applied ecology and conservation, allowing cost-effective biodiversity monitoring for vocal species. However, like all survey methods, care needs to be taken in how such data are collected, analysed and interpreted. We respond to a recent paper by Smith and Pile (2024) that made simplistic use of koala calling to make assertions about sex-based habitat use, and we point out serious flaws in how the data were used. We respond by outlining recommended practices for collecting, analysing and interpreting acoustic data, especially those targeting koalas. Smith and Pile (2024) used raw single-visit male calling rate to suggest that this creates problems for defining koala habitat use of males compared to females. Conversely, we argue that raw calling data should not be used to make these assessments because imperfect detection (false negatives) needs to be accounted for prior to estimating occupancy or density. Because male koalas are the primary sex that bellows, the method is sex-biased, although sex ratios for koalas are commonly 1:1. Further, assessment of sex-based habitat use is best undertaken at fine scales by radio-tracking and GPS-tracking, especially at night when koalas are actively browsing. Such studies reveal minor differences but substantial overlap in habitat use between the sexes. When analysing acoustic surveys, the environment needs to be assessed in the local landscapes surrounding sensors (e.g. 500 m buffer) rather than the actual sensor location. Passive acoustics can provide cost-effective assessments of occupancy at regional scales when applied across many sites. Alternatively, when used in arrays, acoustic surveys can provide density estimates at local scales. These multiple lines of complementary, supporting evidence are presented to support previous findings for koalas based on passive acoustics, contrary to the aproach proposed by Smith and Pile (2024).

Wildfire in rainforest margins is associated with variation in mammal diversity and habitat use

Wildfire in rainforest margins is associated with variation in mammal diversity and habitat use