Diel Activity Research Articles

Giant pangolin and white-bellied pangolin observations from a World Heritage site

Abstract Pangolins are one of the most threatened mammal groups, as a result of habitat loss and exploitation for their meat, scales, and other body parts. However, there is a lack of quantitative data on pangolin populations; their behaviour and ecology make them challenging to survey. We undertook systematic camera-trap surveys of the 5260 km2 World Heritage Dja Faunal Reserve, Cameroon, sampling 305 sites in eight grids over 28,277 camera-trap days. We recorded 768 images of giant pangolin in 99 independent detections at 57 sites (RAI = 0.35), and 2282 images in 355 detections (RAI = 1.26) of white-bellied pangolin at 137 sites. Ground-dwelling giant pangolins were largely confined to the core of the Reserve. Semi-arboreal white-bellied pangolins were predominantly distributed in the northeast, east and south of the Reserve. Lower occupancy in the west and northwest could partly be due to pressures from human settlements around the Hydromekin Dam and Sud-Cameroun Hévéa rubber plantation. Our study suggests that at the ground-level the two species do not spatially segregate, and both were active throughout the night. We found high diel activity overlap, although there was a significant difference in activity peak times. There was also evidence of white-bellied pangolin possibly exhibiting fine-scale behavioural avoidance of giant pangolin.

Can behaviour and physiology mitigate effects of warming on ectotherms? A test in urban ants.

Global climate change is expected to have pervasive effects on the diversity and distribution of species, particularly ectotherms whose body temperatures depend on environmental temperatures. However, these impacts remain difficult to predict, in part because ectotherms may adapt or acclimate to novel conditions or may use behavioural thermoregulation to reduce their exposure to stressful microclimates. Here we examine the potential for physiological and behavioural changes to mitigate effects of environmental warming on five species of ants in a temperate forest habitat subject to urban warming. We worked in eight urban and eight non-urban forest sites in North Carolina, USA; sites experienced a 1.1°C range of mean summer air temperatures. At each site, we documented species-specific microclimates (ant operative temperatures, Te ) and ant activity on a transect of 14 bait stations at three times of day. In the laboratory, we measured upper thermal tolerance (CTmax ) and thermal preference (Tpref ) for each focal species. We then asked whether thermal traits shifted at hotter sites, and whether ants avoided non-preferred microclimates in the field. CTmax and Tpref did not increase at warmer sites, indicating that these populations did not adapt or acclimate to urban warming. Consistent with behavioural thermoregulation, four of the five species were less likely to occupy baits where Te departed from Tpref . Apparent thermoregulation resulted from fixed diel activity patterns that helped ants avoid the most inappropriate temperatures but did not compensate for daily or spatial temperature variation: Hotter sites had hotter ants. This study uses a novel approach to detect behavioural thermoregulation and sublethal warming in foraging insects. The results suggest that adaptation and behaviour may not protect common temperate forest ants from a warming climate, and highlight the need to evaluate effects of chronic, sublethal warming on small ectotherms.

Species-specific responses of mammal activity to exurbanization in New Hampshire, USA

Abstract Urbanization and habitat fragmentation can disrupt wildlife behavior and cause declines in biodiversity and ecosystem function. Most urban wildlife research has compared highly urbanized regions with rural areas. However, human development is also rapidly occurring in exurban areas, which consist of a matrix of lower-density housing and natural patches. Thus, although such “exurbanization” is intensifying, little research has examined how mammals respond to exurban development. To address this knowledge gap, we evaluated the activity of 12 species using 104 camera traps in exurban and rural areas across southeastern New Hampshire, USA, during summer 2021 and winter 2021–2. We quantified species’ activity levels (overall portion of daily activity) and patterns (variation of diel activity period) to test hypotheses regarding how species’ space requirements and nocturnality modulated their responses to exurban development. We found mixed support for our hypotheses. Two species with large space requirements (bobcats Lynx rufus and white-tailed deer Odocoileus virginianus) reduced activity levels in exurban areas, following hypothesized predictions, while other species (e.g., coyote Canis latrans) did not. As predicted, nocturnal species were less likely to shift activity patterns, but this varied across species and seasons. We also found evidence for a coupled predator–prey response among bobcats and lagomorphs in summer, with similarly altered activity in exurban areas. These results suggest that wildlife modify activity in response to exurban development with substantial species and season-specific variation within the mammal community, highlighting the complex ways wildlife adapt to urbanization and the potential consequences thereof for mammal communities.

Spatiotemporal distributions of mammals occurring in an agro-prairie ecosystem.

Anthropogenic activities since the European colonization of the North American Great Plains have drastically altered landscape composition and configuration, subsequently affecting native biodiversity. These contemporary human-modified landscapes may affect mammal species' distributions, diel activity patterns, habitat use, and interspecific interactions, though a better understanding of these effects on mammals occurring in remaining prairie landscapes is needed. To fill this gap, we surveyed 381 randomly selected sites in 2018, 2019, and 2020 using motion-sensing camera traps across the western part of the US state of Kansas (7,160,077 ha). Sites were separated by ≥2 km ( = 8.16 km, SD = 3.61), and cameras were secured to a metal post 40 cm above ground and randomly oriented toward the north or south. We placed an olfactory attractant (mixture of skunk essence and petroleum jelly) on a wooden stake 3 m in front of each camera. Cameras were in place at each site for 28 consecutive days for each year. We manually identified all mammal species detected at each site, collating these data into a database that included taxonomic information for 14 families of mammals (Antilocapridae, Bovidae, Canidae, Cervidae, Cricetidae, Dasypodidae, Didelphidae, Erethizontidae, Felidae, Heteromyidae, Leporidae, Mephitidae, Mustelidae, Procyonidae, Sciuridae, and Muridae) comprising 28 total species. We recorded 31,178 mammal photographs (nonindependent events) over 27,954 camera trap nights during 2018 (n = 10,351), 2019 (n = 9478), and 2020 (n = 8125). Additionally, we included the time and date of each photocapture. Moreover, we gathered survey-specific data useful for modeling species-specific detection along with site-level habitat composition data taken at each site each year. These data will be useful for examining habitat use, species distributions, diel activity patterns, and spatiotemporal interactions between species and across guilds of mammals occurring in a rapidly changing agro-prairie ecosystem. There are no copyright restrictions, but we ask researchers to cite this paper when using these data for publication.

Diel activity, habitat utilization, and response to anthropogenic interference of small Indian civets (<i>Viverricula indica</i>) in Shanghai urban areas based on camera trapping

Diel activity, habitat utilization, and response to anthropogenic interference of small Indian civets (<i>Viverricula indica</i>) in Shanghai urban areas based on camera trapping

Effects of sardines as an attractant on carnivore detection and temporal activity patterns at remote camera traps

Context Adding an attractant to remote camera traps has become a popular method to increase detections of cryptic carnivores. However, there is ongoing debate about whether this practice can bias the behaviour and activity patterns of these species. Aims Our aim was to determine how using a popular attractant at camera traps could affect carnivore detection probabilities and temporal activity. Methods We used an experimental design in which we randomly set half of our camera traps on arrays at two sites in western North Carolina with an attractant: canned sardines in oil. Halfway through the survey season, we switched which camera traps had sardines and which did not. We estimated detection probability for each carnivore species observed using occupancy models, and we used kernel density estimations to evaluate changes in diel activity patterns between camera traps with and without an attractant. Key results We found that when sardines were used at camera traps, detectability of bobcats (Lynx rufus), coyotes (Canis latrans), northern raccoons (Procyon lotor), Virginia opossums (Didelphis virginiana), and eastern spotted skunks (Spilogale putorius) more than doubled, but there was little or no effect on striped skunk (Mephitis mephitis) detectability. Of the species we most frequently detected (coyotes, raccoons, and opossums), activity patterns between camera traps with and without a sardine attractant overlapped moderately to highly, and a significant effect on diel activity patterns was observed only for raccoons. Conclusions Use of attractants can greatly increase the probability of detecting nearly all carnivores at camera traps. The effects of attractants on diel activity patterns are species-specific, with two of our three most-detected species unaffected by their use, suggesting that attractants can be used to effectively study these behaviours in some carnivore species. Implications A sardine attractant can increase the detection of many carnivore species, using camera traps, without causing a significant deviation of diel activity patterns, thus allowing for unbiased investigations into most species’ spatio–temporal behaviour in the Appalachian Mountains – and likely other systems.

Estimation of diel activity patterns of wild boars using camera trap surveys in Shizukuishi, Iwate Prefecture

Estimation of diel activity patterns of wild boars using camera trap surveys in Shizukuishi, Iwate Prefecture

Shifts in diel activity of Rocky Mountain mammal communities in response to anthropogenic disturbance and sympatric invasive white-tailed deer

Shifts in diel activity of Rocky Mountain mammal communities in response to anthropogenic disturbance and sympatric invasive white-tailed deer

Marbled cats in Southeast Asia: Are diurnal and semi‐arboreal felids at greater risk from human disturbances?

AbstractSoutheast Asia supports the greatest diversity of felids globally, but this diversity is threatened by the severe forest loss and degradation occurring in the region. The response of felids to disturbances appears to differ depending on their ecology. For example, the largely terrestrial and nocturnal leopard cat (Prionailurus bengalensis) thrives near forest edges and in oil palm plantations where it hunts rodents (Muridae) at night, thereby avoiding human activity peaks. Conversely, we hypothesized that the sympatric and similar‐sized marbled cat (Pardofelis marmorata) would respond negatively to edges and relatively open oil palm plantations as they are more arboreal than leopard cats, rely on tree connectivity for hunting, and are diurnal so have less potential to temporally avoid humans. We used camera trapping from Southeast Asia to test habitat associations at multiple spatial scales using zero‐inflated Poisson generalized linear mixed models and hierarchical occupancy modeling. We found that marbled cats were positively associated with large intact forests and, in contrast to leopard cats, negatively associated with oil palm plantations. Furthermore, we found preliminary evidence suggesting marbled cats may adapt their diel activity to become more crepuscular in degraded forests, likely shifting their activity to avoid humans. These findings suggest that the marbled cat's International Union for Conservation of Nature (IUCN) Red List conservation status should potentially be upgraded from Near Threatened to Vulnerable, matching other forest‐dependent felids in the region. We posit our findings may be generalizable such that semi‐arboreal and diurnal felids could face greater threats from habitat degradation than their terrestrial and nocturnal relatives.

Spatial and temporal separation of toothed whales in the western North Atlantic

A diverse group of toothed whale species inhabits the pelagic habitats of the western North Atlantic, competing for overlapping prey resources. Historical data deficits have limited fundamental research into many of these species, such as establishing baselines of distribution and abundance, so their occurrence and habitat use patterns are not well characterized. Periodic cycles in activity have been reported at a range of temporal scales for odontocetes in other regions, such as seasonal movements, foraging activity modulated by lunar cycles, and diel activity patterns. A variety of spatial, temporal, and behavioral separation strategies have also been observed among predator guilds in both marine and terrestrial systems, and these may also contribute to observed spatiotemporal patterns in activity. Recently, passive acoustic data has been applied to monitor odontocete species continuously, with improved detection and species discrimination for some cryptic species. We used a long-term passive acoustic data set collected at sites spanning the western North Atlantic shelf-break region to quantify presence and characterize seasonal, lunar, and diel activity patterns for 10 species. Our results demonstrated strong regional preferences and clear patterns of spatiotemporal separation between species with similar foraging ecology. Latitudinal shifts in seasonal presence peaks may suggest meridional seasonal migrations for some dolphin species. We also observed strong diel activity patterns that were modulated by both seasonal and lunar cycles. This study reveals complex behavioral patterns arising in response to natural cycles playing out over multiple temporal scales and provides new insights into habitat partitioning among toothed whale species.

Characterising diel activity patterns to design conservation measures: Case study of European bat species

Although diel activity time is a major axis of species' niche space, very few conservation measures focus on preserving daily periods free of anthropogenic pressures. While the spatial ecology of bats has received much attention, less is known about their temporal ecology, the knowledge being dispersed in studies of limited taxonomical, spatial and temporal range. We used data from the French bat monitoring program based on citizen science and standardised acoustic recordings (4409 sites monitored and 9807 nights monitored from 2014 to 2020) to characterise the diel activity patterns of 20 bat species so that their consideration in mitigation measures can help conservation. We designed a method to extract times of key descriptors and describe bat activity distribution throughout the night. We found that bat species could be separated in three functional groups characterised by a crepuscular activity, an activity that occurs when it is completely dark or an intermediate activity. We showed variations of diel activity patterns depending on season. We argue that accounting for these complex diel activity patterns would help design efficient mitigation measures, for instance to reduce the exposure of bats to light pollution or wind turbines. Overall, we advocate multi-taxa approaches to design conservation policies adapted to both the temporal and spatial distributions of species.

Home range and activity patterns of the Critically Endangered endemic pygmy raccoon of Cozumel Island, México

AbstractIndividuals from island and continental mammal populations have shown a number of differences in their behavioral ecology. We predicted that, like other island carnivores exhibiting dwarfism, the pygmy raccoon (Procyon pygmaeus), a Critically Endangered carnivore endemic to Cozumel Island, México, would show differences in its home ranges and activity patterns when compared to its mainland counterpart, the racoon, P. lotor. We radio-tracked 11 individuals (six males, five females) from February to July 2017 and used location data derived from triangulation to estimate the home range size, diel activity patterns, and distances traveled of pygmy raccoons. Individuals showed an average home range size between 96.9 ± 18.8 ha (95% minimum convex polygon) and 123.3 ± 31.2 ha (95% fixed kernel). Home ranges of males (109.4–142.8 ha) were larger than those of females (81.8–99.9 ha). Average home ranges were in the lower extreme of those reported for continental raccoons. Activity patterns of pygmy raccoons generally begin at sunset and continue up to 04:00 with rare activity peaks during the day; there were no significant differences in activity patterns between sexes. Data on spatial needs of individuals, and differences between sexes or insular versus continental populations have implications for conservation planning and management.

Disentangling vertebrate spatio-temporal responses to anthropogenic disturbances: evidence from a protected area in central Myanmar

AbstractUrbanization of natural landscapes and increasing human populations have brought people and our companion animals into closer contact with wildlife, even within protected areas. To provide guidance for human–wildlife coexistence, it is therefore critical to understand the effects of anthropogenic disturbances and how well native wildlife species survive in human-dominated landscapes. We investigated the spatio-temporal responses of 10 vertebrate taxa, with an emphasis on the Endangered Eld's deer Rucervus eldii thamin, to anthropogenic disturbances in Shwesettaw Wildlife Sanctuary, Myanmar. We quantified anthropogenic disturbances as distance from human settlements, distance from a highway, and the presence of people and free-ranging dogs Canis familiaris. Anthropogenic disturbances had stronger negative impacts on the detection of native wildlife species than on occupancy. Eld's deer avoided areas close to human settlements and showed low diel activity overlap with both people and dogs, although we found a positive association with human presence at the camera-trap sites. Five species exhibited lower diel activity overlap with people in the rainy season when human activity is the highest in our study area. All studied wildlife species shifted to nocturnal activity or did not show any clear activity pattern during the cool-dry season when the presence of dogs increased. The ecological and conservation impacts of dogs are underestimated in South-east Asia, particularly in Myanmar, and this case study highlights the impacts of dogs on the temporal use of habitat by wildlife and the need for better practices in the management of dogs within protected areas.

Physiological and Behavioral Effects of Angling Stress on Kelp Bass, an Important Game Fish in Southern California

AbstractGame fish populations in North America face increasing pressure from recreational anglers, yet sublethal effects from mandatory catch‐and‐release regulations remain unknown for many targeted species. In southern California, Kelp Bass Paralabrax clathratus populations have significantly declined in recent decades, prompting changes in management and increasing release rates. To assess acute effects of current fishing regulations, we collaborated with recreational anglers to evaluate short‐term, sublethal impacts of capture stress on Kelp Bass physiology and behavior. To evaluate the timeline and magnitude of physiological stress, blood samples were collected at time points (10–120 min) after angling and confinement and compared to control fish sampled in less than 3 min. Postrelease recovery was determined by comparing biomarker levels between control fish and recaptured fish that were rapidly sampled after a time at liberty ranging from 3 h to 186 d. Biomarker levels in fish recaptured multiple times were compared to previous samples to evaluate repetitive angling effects on physiological responses. Circulating cortisol, glucose, and lactate were elevated and steadily increased in the hour after capture, although angling duration and handling duration were not correlated with biomarker response. Fish size significantly affected fish stress, with larger fish experiencing less stress and rapid recovery within 24 h. Behavioral control fish, which ingested acoustic accelerometers hidden inside bait, exhibited strong diel activity that was reduced for 30 h in angled fish. Tracked individuals exhibited high individual variation in rate of movement and area use, with no noticeable postrelease impacts. Although this study found Kelp Bass to be resilient to angling stresses, evaluation of long‐term effects from catch and release is warranted. This fishery may also benefit from slot limit regulations, improved angler engagement programs, and education on best practices that minimize fish stress during catch and release.

Consistent diel activity patterns of forest mammals among tropical regions

An animal’s daily use of time (their “diel activity”) reflects their adaptations, requirements, and interactions, yet we know little about the underlying processes governing diel activity within and among communities. Here we examine whether community-level activity patterns differ among biogeographic regions, and explore the roles of top-down versus bottom-up processes and thermoregulatory constraints. Using data from systematic camera-trap networks in 16 protected forests across the tropics, we examine the relationships of mammals’ diel activity to body mass and trophic guild. Also, we assess the activity relationships within and among guilds. Apart from Neotropical insectivores, guilds exhibited consistent cross-regional activity in relation to body mass. Results indicate that thermoregulation constrains herbivore and insectivore activity (e.g., larger Afrotropical herbivores are ~7 times more likely to be nocturnal than smaller herbivores), while bottom-up processes constrain the activity of carnivores in relation to herbivores, and top-down processes constrain the activity of small omnivores and insectivores in relation to large carnivores’ activity. Overall, diel activity of tropical mammal communities appears shaped by similar processes and constraints among regions reflecting body mass and trophic guilds.

Why are animals conspicuously colored? Evolution of sexual versus warning signals in land vertebrates.

Conspicuous colors (e.g., red, yellow, blue) have evolved numerous times across animals. But the function of this coloration can differ radically among species. Many species use this coloration as a sexual signal to conspecifics, whereas others use it as a warning signal to predators. Why do different species evolve conspicuous coloration in association with one function as opposed to the other? We address this question in terrestrial vertebrates (tetrapods) using phylogenetic approaches, and test whether day-night activities of species help determine these patterns. Using phylogenetic logistic regression, we found that conspicuous, sexually dimorphic coloration is significantly associated with diurnal lineages (e.g., many birds and lizards). By contrast, the evolution of warning signals was significantly associated with large-scale clades that were ancestrally nocturnal (e.g., snakes, amphibians), regardless of the current diel activity of species. Overall, we show that the evolution of conspicuous coloration as warning signals or sexual signals is influenced by the ecology of species, both recently and in the ancient past.

Mosquito host-seeking diel rhythm and chemosensory gene expression is affected by age and Plasmodium stages

Malaria parasites can affect vector-related behaviours, increasing transmission success. Using Anopheles gambiae and Plasmodium falciparum, we consider the effect of interaction between infection stage and vector age on diel locomotion in response to human odour and the expression of antennal chemosensory genes. We identified age-dependent behavioural diel compartmentalisation by uninfected females post-blood meal. Infection disrupts overall and diel activity patterns compared with age-matched controls. In this study, mosquitoes carrying transmissible sporozoites were more active, shifting activity periods which corresponded with human host availability, in response to human odour. Older, uninfected, blood-fed females displayed reduced activity during their peak host-seeking period in response to human odour. Age- and infection stage-specific changes in odour-mediated locomotion coincide with altered transcript abundance of select chemosensory genes suggesting a possible molecular mechanism regulating the behaviour. We hypothesize that vector-related behaviours of female mosquitoes are altered by infection stage and further modulated by the age post-blood meal of the vector. Findings may have important implications for malaria transmission and disease dynamics.

Seasonal and diel activity patterns of small mammal guilds on the Pannonian Steppe: a step towards a better understanding of the ecology of the endangered Hungarian birch mouse (Sicista trizona) (Sminthidae, Rodentia)

Temporal activity differences facilitate species’ coexistence by reducing interspecific competition. Such patterns can be studied via diel activity analysis, but obtaining data in cryptic mammals is difficult. We investigated the annual and diel activity pattern of such a small mammal, the endangered Hungarian birch mouse (Sicista trizona trizona), in its only known habitat. We employ trail cameras for the first time to reveal the diel and annual activity of a sminthid species. Data acquisition included the spring and summer seasons between 2019 and 2022 and was extended to detect the activity overlaps with other common coexisting rodents and shrews. The diel activity results rely on 581 detections of S. trizona over 5670 trap-nights of camera trap deployment characterising also activity pattern of the small mammal community in this Central European grassland ecosystem. S. trizona was not recorded during the day but was active at dawn and night, and in comparison with other coexisting species, its activity level was high. The presumed cold sensitivity was not confirmed as we detected activity at −6 °C. Diel activity peaked in early May in the mating season. Although the diel activity pattern of co-occurring small mammal species was also nocturnal, activity overlaps were relatively high suggesting that temporal niche partitioning is limited within the habitat. Our work provides the first insight into temporal overlaps within a small mammal community in a natural European grassland, moreover, also the first documented research on the activity pattern of a sminthid in its natural habitat.

Individual differences in diel and vertical activity patterns in a large pelagic predator, the oceanic whitetip shark

Individual differences in diel and vertical activity patterns in a large pelagic predator, the oceanic whitetip shark

Bumble bees exploit known sources but return with partial pollen loads when foraging under low evening light

Diel activity of diurnal pollinating insects declines well before the end of day, but a few species, such as bumble bees, can continue foraging in the period before sunset, when light levels decrease. Foraging during this time could be costly for individuals, and key decisions regarding the daily cessation of foraging behaviour have to be made during this period of rapid abiotic change. However, little is known about the behaviour of diurnal bees under these light conditions. We conducted a field experiment in a mixed agricultural landscape to investigate pollen foraging in the hour before sunset in the buff-tailed bumble bee, Bombus terrestris , comparing it to an hour during the afternoon. We monitored activity at the colony entrance and collected pollen sacs from returning foragers. Overall, there were fewer exits and returns in the evening period than in the afternoon period. Evening foragers returned to the colony with partial pollen loads when compared to daytime foragers, and those returning in lower light levels had smaller loads. Additionally, we found that the same flower taxa were being exploited in the evenings as in the daytime. We found no effect of individual size on the likelihood of evening foraging or the size of pollen loads. Our results suggest that B. terrestris are facultative evening foragers that opportunistically exploit profitable flowers they have encountered during the day. Evening foragers decide to return to the colony with partial pollen loads in this period of the foraging day, which results in a largely reduced pollen influx to the colony at the end of the day. Our findings indicate that the gradual decline in light is likely to be an important factor guiding the decisions of bumble bees and other diurnal pollinators of whether to extend or end foraging, and when to return to the colony. • Bumble bees are facultative evening foragers. • Pollen foraging in the evening comes at an acquisition cost. • Light intensity is a key limiting factor for pollen collection. • Evening foragers have the same floral preferences as daytime foragers. • Individual size does not affect pollen foraging in the late evening.