Variation In Activity Patterns Research Articles

Deep learning-based analysis of daily activity patterns of farmed dromedary camels

IntroductionThis study addresses the need for automated monitoring solutions to evaluate the daily activity patterns of camels, which is critical for improving animal welfare and farm management practices. By leveraging advanced deep learning techniques, this research aims to identify and analyze five key daily activities—sleeping, sitting, standing, eating, and drinking—using video recordings from a camel farm in Fujairah, United Arab Emirates.MethodsThe dataset was collected over two 7-day phases in November and December 2022. In Phase 1, video recordings were analyzed to monitor the activities of two camels and measure the duration of each activity. In Phase 2, the study expanded to include six camels, enabling an evaluation of individual behavioral variations. The YOLOv7 object detection algorithm was used to train and validate the model on images extracted from the recordings, achieving high accuracy in detecting and classifying the defined activities.ResultsThe results showed notable variations in activity patterns between Phases 1 and 2. Average standing time decreased from 9.8 hours (40.8%) to 6.0 hours (25.1%), and sleeping time dropped from 4.3 hours (18.0%) to 2.8 hours (11.7%). Conversely, sitting time increased from 6.2 hours (25.8%) to 9.9 hours (41.5%), and eating time rose from 3.1 hours (12.8%) to 4.6 hours (19.2%). Drinking time remained consistent at an average of 37 minutes (2.6%) across both phases. Activity peaks were observed during early mornings and after 16:00, with midday hours dominated by resting in shaded areas. Evening and nighttime activities primarily included sitting, minimal head movements, and occasional standing or walking.DiscussionThe established deep learning framework demonstrated reliable performance in detecting and analyzing camel activity patterns, offering a practical solution for continuous monitoring and improved farm management. However, further research is recommended to validate the model’s performance across different seasons and environmental conditions to enhance its robustness and adaptability.

Daily activity is repeatable but varies across the breeding season in female great tits

Abstract Wild animals typically organize activity around a 24-h day and daily timing across the year is optimized for both survival and reproductive success. Among-individual variation in chronotype, where individuals differ in when they begin or end their active day relative to a cue such as photoperiod, often exists within a population. Both intrinsic and extrinsic factors contribute to this variation and activity patterns may change across and within different life-history stages as energetic investment changes. Here we describe population level changes in free-living female great tit (Parus major) activity patterns of onset and offset of activity as well as assess variation and repeatability in daily activity both within- and across-breeding stages. We fitted individual females with accelerometers to track activity prior to nest building through chick rearing. Prior to clutch initiation females began their active day before sunrise, however, in the days prior to laying their first egg, activity was delayed until after sunrise. Females ended activity prior to sunset across the monitoring period and earliest during egg laying and incubation. In addition, females exhibited greater among- and within-individual variance in activity during parental care. Female daily activity was moderately repeatable within breeding stages and strongly covaried across several breeding stages. These findings expand our understanding of individual variation in activity patterns during reproduction and the potential fitness implications of chronotype in wild animals.

We prefer nighttime, they prefer daytime: Biological rhythm variability in cave‐dwelling whip spiders (Amblypygi: Charontidae) in the Neotropics

AbstractThe lack of understanding regarding how endogenous and behavioral factors affect the biological rhythms of amblypygid arachnids in cave environments underscores a gap in chronobiologic knowledge for this group. This study investigates the influence of specialization on subterranean habitats and the presence of biological rhythms on the locomotor activity patterns of the troglobitic and troglophilic species of the genus Charinus. Specimens collected from carbonate caves in Brazil were subjected to experimental treatments of constant light (LL), constant darkness (DD), and light–dark cycles (LD). The results revealed variations in the distribution of main periods among species, without a uniform pattern. Although some specimens showed greater variability in activity patterns in the DD and LL treatments, no significant differences were observed between troglobites and troglophiles. The lack of a clear distinction in rhythms between the two groups suggests the dynamic nature of circadian rhythms in these populations, where individual variations in activity patterns indicate this behavioral diversity. Additionally, intraspecific competition for food resources, probably intensified by the oligotrophic conditions of the cave environments, may play an important role in shaping these patterns and differences in activity phases. The presence of infradian rhythms and weak circadian rhythms in some individuals underscores the importance of considering non‐photic zeitgebers for a deeper understanding of these rhythms in cave organisms.

Diel movement patterns in nominally nocturnal coral reef fishes (Haemulidae and Lutjanidae): Intra vs. Interspecific variation

Movement of animals, habitat connectivity, and nutrient transport are key elements in the ecological functioning of coral reef ecosystems. However, most studies have focused on the diurnal component of these aspects; nocturnal patterns are less known. Our study aims to address this knowledge gap by assessing diel movement patterns in ecologically and commercially important nocturnal coral reef fishes. We evaluate 122-days of acoustic telemetry data from 4 nocturnal species in 2 coral reef fish families (Haemulidae and Lutjanidae) on the Great Barrier Reef. For all species, we found a clear division between daytime resting areas on the reef and a move towards off-reef areas at night. This was highlighted in the low number of detections at night and the high average transitions between receivers at twilight. Over our study period, average nocturnal space use area (minimum convex polygon) of Plectorhincus gibbosus was 328,089 m2, Plectorhincus lineatus 28,828 m2, and Lutjanus carponotatus 20,369 m2. However, results from a Principal Component Analysis revealed that space use, and movement, varied substantially within species; for 3 of the 4 species the main axis of variation correlated with individual-level behaviour. These large differences in individual space use patterns highlight the need for caution when using species averages when considering ecosystem functions. Overall, our preliminary observations provide a glimpse into the large spatial extent, potential habitat connectivity, and intra and interspecific variation in activity patterns among large nocturnal Indo-Pacific reef fishes. This highlights their potential importance in maintaining ecosystem links between coral reefs and adjacent habitats.

Evolutionary Systems Biology Identifies Genetic Trade-offs In Rice Defense Against Above- and Belowground Attackers.

Like other plants, wild and domesticated rice species (Oryza nivara, O. rufipogon, and O. sativa) evolve in environments with various biotic and abiotic stresses that fluctuate in intensity through space and time. Microbial pathogens and invertebrate herbivores such as plant-parasitic nematodes and caterpillars show geographical and temporal variation in activity patterns and may respond differently to certain plant defensive mechanisms. As such, plant interactions with multiple community members may result in conflicting selection pressures on genetic polymorphisms. Here, through assays with different above- and belowground herbivores, the fall armyworm (Spodoptera frugiperda) and the southern root-knot nematode (Meloidogyne incognita), respectively, and comparison with rice responses to microbial pathogens, we identify potential genetic trade-offs at the KSL8 and MG1 loci on chromosome 11. KSL8 encodes the first committed step towards biosynthesis of either stemarane- or stemodane-type diterpenoids through the japonica (KSL8-jap) or indica (KSL8-ind) allele. Knocking out KSL8-jap and CPS4, encoding an enzyme that acts upstream in diterpenoid synthesis, in japonica rice cultivars increased resistance to S. frugiperda and decreased resistance to M. incognita. Furthermore, MG1 resides in a haplotype that provided resistance to M. incognita, while alternative haplotypes are involved in mediating resistance to the rice blast fungus Magnaporthe oryzae and other pests and pathogens. Finally, KSL8 and MG1 alleles are located within trans-species haplotypes and may be evolving under long-term balancing selection. Our data are consistent with a hypothesis that polymorphisms at KSL8 and MG1 may be maintained through complex and diffuse community interactions.

Analysis of functional network asymmetry in major depressive disorder under four fNIRS tasks

Research in functional asymmetry of Major Depressive Disorder (MDD) under different tasks is crucial for clinical diagnose. Fifty individuals with MDD and twenty healthy controls (HCS) were recruited for hemodynamic data collection under four fNIRS tasks (Emotional picture, Verbal fluency, Fingering and Negative emotional picture description task). Integral values and functional connectivity strength were employed to probe neural activation and functional connectivity in frontal and temporal lobes in MDD. Following, asymmetry characteristic of the frontal cortex between MDD and HCS under four tasks were carefully analyzed and compared. Individuals with MDD demonstrated heightened connectivity between the frontal and right temporal lobes and reduced connectivity between the frontal and left temporal lobes compared to HCS in all tasks. Additionally, MDD exhibited attenuated activation in the left frontal lobes and exaggerated activation in the right frontal lobes, diverging from HCS. Furthermore, the disparities in left-right asymmetry characteristic of frontal cortex activation between MDD and HCS were more pronounced during the combined task. Further research is required to grasp the neurophysiological mechanisms governing left-right asymmetry across various tasks and the influence of task-induced brain fatigue on cerebral cortex hemodynamics in MDD. The left-right asymmetry feature provides valuable neurophysiological insights for diagnosing MDD clinically. Variations in activation patterns and functional connectivity features between MDD and HCS are closely tied to the task chosen. Thus, in clinical practice, carefully selecting appropriate fNIRS tasks and relevant features can significantly improve the diagnostic accuracy of MDD.

Investigating the association between symptoms and functional activity in brain regions in schizophrenia: A cross-sectional fmri-based neuroimaging study

Schizophrenia is a persistent neurological disorder profoundly affecting cognitive, emotional, and behavioral functions, prominently characterized by delusions, hallucinations, disordered speech, and abnormal motor activity. These symptoms often present diagnostic challenges due to their overlap with other forms of psychosis. Therefore, the implementation of automated diagnostic methodologies is imperative. This research leverages Functional Magnetic Resonance Imaging (fMRI), a neuroimaging modality capable of delineating functional activations across diverse brain regions. Furthermore, the utilization of evolving machine learning techniques for fMRI data analysis has significantly progressive. Here, our study stands as a novel attempt, focusing on the comprehensive assessment of both classical and atypical symptoms of schizophrenia. We aim to uncover associated changes in brain functional activity. Our study encompasses two distinct fMRI datasets (1.5T and 3T), each comprising 34 schizophrenia patients for the 1.5T dataset and 25 schizophrenia patients for the 3T dataset, along with an equal number of healthy controls. Machine learning algorithms are applied to assess data subsets, enabling an in-depth evaluation of the current functional condition concerning symptom impact. The identified voxels contribute to determining the brain regions most influenced by each symptom, as quantified by symptom intensity. This rigorous approach has yielded various new findings while maintaining an impressive classification accuracy rate of 97 %. By elucidating variations in activation patterns across multiple brain regions in individuals with schizophrenia, this study contributes to the understanding of functional brain changes associated with the disorder. The insights gained may inform differential clinical interventions and provide a means of assessing symptom severity accurately, offering new avenues for the management of schizophrenia.

The computational and neural substrates of individual differences in impulsivity under loss framework.

Numerous neuroimaging studies have identified significant individual variability in intertemporal choice, often attributed to three neural mechanisms: (1) increased reward circuit activity, (2) decreased cognitive control, and (3) prospection ability. These mechanisms that explain impulsivity, however, have been primarily studied in the gain domain. This study extends this investigation to the loss domain. We employed a hierarchical Bayesian drift-diffusion model (DDM) and the inter-subject representational similarity approach (IS-RSA) to investigate the potential computational neural substrates underlying impulsivity in loss domain across two experiments (n = 155). These experiments utilized a revised intertemporal task that independently manipulated the amounts of immediate and delayed-loss options. Behavioral results demonstrated positive correlations between the drift rate, measured by the DDM, and the impulsivity index K in Exp. 1 (n = 97) and were replicated in Exp. 2 (n = 58). Imaging analyses further revealed that the drift rate significantly mediated the relations between brain properties (e.g., prefrontal cortex activations and gray matter volume in the orbitofrontal cortex and precuneus) and K in Exp. 1. IS-RSA analyses indicated that variability in the drift rate also mediated the associations between inter-subject variations in activation patterns and individual differences in K. These findings suggest that individuals with similar impulsivity levels are likely to exhibit similar value processing patterns, providing a potential explanation for individual differences in impulsivity within a loss framework.

Activity of bats (Chiroptera) in extensive livestock systems in the Colombian Caribbean

Introduction: Extensive cattle ranching in tropical dry forest areas (TDF) has caused the transformation of natural ecosystems and altered the behavior of associated organisms, generating variation in activity patterns. In bats, the activity pattern is affected by the composition and vegetation structure of the ecosystem, and by the climatic season (dry and rainy). Objetive: In this study, the effect of conventional management systems (CS) and silvopastoral (SPS) of extensive livestock management on the bat activity patterns in the Colombian Caribbean was determined. Methods: The activity pattern of bats in TDF fragments associated with CS and SPS was compared within an annual cycle. The daily activity patterns of 11 species with records of more than 10 days in within management systems were determined. Results: Greater bat activity was recorded during the rainy season. We found that although bats show behavioral adaptation to the different management systems, in TDF fragments associated with SPS there is greater bat activity throughout the year, compared to the activity recorded in CS. Species with higher energetic requirements and degree of specialization (Phyllostomus hastatus, P. discolor and Glossophaga soricina) modified their activity patterns between CS and SPS management types. Conclusion: The TDF fragments associated in SSP, due to the vegetation composition and structure, probably favor the constant supply of resources suitable for the bats assemblage stability.

Cortical changes during the learning of sequences of simultaneous finger presses

Abstract The cortical alterations underpinning the acquisition of motor skills remain debated. In this longitudinal study in younger adults, we acquired performance and neuroimaging (7 T MRI) measures weekly over the course of 6 weeks to investigate neural changes associated with learning sequences of simultaneous finger presses executed with the non-dominant hand. Both the intervention group (n = 33), which practiced the finger sequences at home, and the control group (n = 30, no home practice) showed general performance improvements, but performance improved more and became more consistent for sequences that were intensively trained by the intervention group, relative to those that were not. Brain activity for trained sequences decreased compared with untrained sequences in the bilateral parietal and premotor cortices. No training-related changes in the primary sensorimotor areas were detected. The similarity of activation patterns between trained and untrained sequences decreased in secondary, but not primary, sensorimotor areas, while the similarity of the activation patterns between different trained sequences did not show reliable changes. Neither the variability of activation patterns across trials, nor the estimates of brain structure displayed practice-related changes that reached statistical significance. Overall, the main correlate of learning configural sequences was a reduction in brain activity in secondary motor areas.

Influence of Recent Standing, Moving, or Sitting on Daytime Ambulatory Blood Pressure.

Background There are no recommendations for being seated versus nonseated during ambulatory blood pressure (BP) monitoring (ABPM). The authors examined how recent standing or moving versus sitting affect average daytime BP on ABPM. Methods and Results This analysis used baseline assessments from a clinical trial in desk workers with office systolic BP (SBP) 120 to 159 mm Hg or diastolic BP (DBP) 80 to 99 mm Hg. ABPM was measured every 30 minutes with a SunTech Medical Oscar 2 monitor. Concurrent posture (standing or seated) and moving (steps) were measured via a thigh-worn accelerometer. Linear regression determined within-person BP variability explained (R2) by standing and steps before ABPM readings. Mean daytime BP and the prevalence of mean daytime BP >135/85 mm Hg from readings after sitting (seated) or after recent standing or moving (nonseated) were compared with all readings. Participants (n=266, 59% women; age, 45.2±11.6 years) provided 32.5±3.9 daytime BP readings. Time standing and steps before readings explained variability up to 17% for daytime SBP and 14% for daytime DBP. Using the 5-minute prior interval, seated SBP/DBP was lower (130.8/79.7 mm Hg, P<0.001) and nonseated SBP/DBP was higher (137.8/84.3 mm Hg, P<0.001) than mean daytime SBP/DBP from all readings (133.9/81.6 mm Hg).The prevalence of mean daytime SBP/DBP ≥135/85 mm Hg also differed: 38.7% from seated readings, 70.3% from nonseated readings, and 52.6% from all readings (P<0.05). Conclusions Daytime BP was systematically higher after standing and moving compared with being seated. Individual variation in activity patterns could influence the diagnosis of high BP using daytime BP readings on ABPM.

Predation risk in tree squirrels: implications of the presence of free‐ranging dogs

AbstractSmall mammals show variations in activity patterns due to the use of resources and the risk of predation. However, in the case of tree squirrel species, the factors that affect their activity patterns are poorly studied. We used camera trapping to investigate the activity patterns of three different squirrel species of the genus Sciurus, two species of squirrel (Sciurus aureogaster and S. oculatus) from Mexico and one from the Iberian Peninsula (S. vulgaris). In addition, we compared their activity patterns with the potential predator community and their most important predators (Mexico: gray fox Urocyon cinereoargenteus, ringtail Bassariscus astutus, Opossum Didelphis virginiana; Spain: red fox Vulpes vulpes, pine and stone marten Martes spp.), and with feral and free‐ranging dogs (Canis lupus familiaris). We evaluated the predation risk by the carnivore community on the squirrels when they descend to the ground by studying their temporal overlap and observing if the squirrels have different activity patterns adjusted to the carnivore community in each study area. The results showed that the three species of squirrels consistently descended to the ground during the day, showing a variable maximum peak of activity between 8:00 and 12:00 h. Temporal overlap of activity patterns of the three species with the carnivore community was low (Δ = 0.12–0.36), same as with the main predators (Mexico: gray fox Δ = 0.14–0.21, ringtail Δ = 0.08–0.09, opossum Δ = 0.06–0.07; Spain: red fox Δ = 0.39, martens Δ = 0.22). However, temporal overlap of activity patterns with the domestic dog was moderate‐high in the three squirrel species (Mexico Δ = 0.55–0.88, Spain Δ = 0.79). These results show that the species of the genus Sciurus have adjusted their activity patterns of ground use to reduce predation risk by wild predators but not with feral and free‐ranging dogs, something which can pose a serious conservation problem for these species.

Colony specificity and starvation-driven changes in activity patterns of the red ant Myrmica rubra.

Although the activity levels of insect societies are assumed to contribute to their ergonomic efficiency, most studies of the temporal organization of ant colony activity have focused on only a few species. Little is known about the variation in activity patterns across colonies and species, and in different environmental contexts. In this study, the activity patterns of colonies of the red ant Myrmica rubra were characterized over 15 consecutive days. The main goals were to evaluate the colony specificity of the activity patterns and the impact of food deprivation on these patterns. We found that the average activity level varied across colonies and remained consistent over 1 week, providing evidence that the activity level is a colony-specific life trait. Furthermore, all colonies applied an energy-saving strategy, decreasing their average levels of activity inside the nest, when starved. Starvation induced no consistent change in the activity level outside of the nest. An analysis of activity time series revealed activity bursts, with nestmates being active (or inactive) together, the amplitudes of which reflected the ants' degree of synchronization. Food deprivation increased the amplitude and number of these activity bursts. Finally, wavelet analyses of daily activity patterns revealed no evidence of any periodicity of activity bouts occurring inside or outside of the nest. This study showed that M. rubra ant colonies are characterized by specific activity levels that decrease in response to starvation with the adoption of an energy-saving strategy. In addition, our results help to understand the functional value associated with synchronized and/or periodic fluctuation in activity, which has been debated for years.

Time-of-day bias in diurnal raptors in arid region of Rajasthan

Activity patterns of raptors may vary through the day and influence their detectability which may further affect their abundance estimate. In this study, we exhibit the effect of time-of-day bias (survey time), in different seasons (summer vs winter) and landscape feature (cultivated land, wasteland, flooded vegetation, desert, human habitation, grassland, barren land) on the detection and abundance of diurnal raptors in the arid region of Rajasthan, India. We used 50 transects, using the roadside point count method between March 2019 and February 2020 and recorded 3927 observations of 35 species belonging to 14 sub-family. To evaluate the effect of predictive variables, i.e., time-of-day, season and landscape features on abundance estimate of each species of raptors, the Generalised Linear Model (GLM) was used. Chi-square test (χ2) was used to assess the relationship between each species abundance and the period of day. The effect of time-of-day bias on abundance estimate was significant in case of Red headed falcon (χ2 = 6.60, p < 0.001 ), Steppe eagle (χ2 = 7.89, p < 0.001 ), and Black wing kite (χ2 = 26.46, p < 0.001 ), while it was not significant for Shikra (χ2 = 0.306, p = 0.97 ), Long legged buzzard (χ2 = 0.42, p = 0.93 ) and Pallid harrier (χ2 = 0.115, p = 0.12 ). We did not observe any significant relationship between time-of-the day bias and abundance of raptors in different seasons and landscape features for any raptor species. Raptors showed variation in activity patterns with respect to the activity of their prey species and foraging strategies. The road count method for raptor surveys is widely used, but very few studies have undertaken and considered time-of-day bias in abundance estimate. This study can help bridge this gap and design a suitable method for survey raptors.

Spatiotemporal Patterns of Snake Captures and Activity in Upland Pine Forests

Patterns of species' occurrences across space and time are fundamental components to understanding their ecology, as this variation often reflects responses to local environmental gradients. We built species-specific models to understand the spatial and temporal factors predicting captures and activity of five snake species in upland pine forests: copperhead (Agkistrodon contortrix), racer (Coluber constrictor), coachwhip (Masticophis flagellum), western ratsnake (Pantherophis obsoletus), and western ribbonsnake (Thamnophis proximus). From mid-May to mid-July across 3 y (2018, 2019, 2020), we monitored boxtraps in two upland pine forests experiencing different management regimes: (1) subjected to frequent thinning and prescribed burning, and (2) subjected to infrequent thinning and prescribed burning. Significantly more copperheads and western ribbonsnakes were captured at the infrequently thinned and burned forest, whereas significantly more racers were captured at forest subjected to frequent thinning and burning. As the summer progressed, captures decreased each subsequent month for both racers and western ratsnakes, with the fewest captures in July. Western ratsnakes were the only species to exhibit a response to the weather in that activity decreased with increasing rainfall. No variables were significant predictors of coachwhip captures. The variation in captures across space may be attributed to the physiological tolerances of each species based on their habitat preferences or differences in prey availability at each forest. Interactions between the physiological tolerances, foraging behaviors, or their reproductive phenology may be underlying the temporal variation in activity patterns.

Divergent predator activity muddies the dynamic landscape of fear

AbstractThe landscape of fear (LOF) hypothesis is a unifying idea explaining the effects of predators on the space use of their prey. However, empirical evidence for this hypothesis is mixed. Recent work suggests that the LOF is dynamic, depending on the daily activity of predators, which allows prey to utilize risky places during predator down times. While this notion clarifies some discrepancies between predictions and observations, support for a dynamic LOF remains mixed. The underlying assumption of a dynamic LOF is strong predictability in predator activity cycles. Work in multi‐predator systems demonstrates the effect of differential behavior between predator species on the predictions of prey space use. However, none have considered the effect of intraspecific variation in predator behavior. Most, if not all, dynamic LOF studies base inference on the species‐level average activity pattern, implicitly assuming similarity within the predator population. We examined the dynamics and intraspecific variation in activity cycles within a population of coyotes (Canis latrans). We found seasonality in the predictability of coyote behavior, as well as divergent nocturnal and crepuscular activity patterns between individuals during summer. Activity dynamics were not related to range size, sex, body mass, or habitat complexity, but did vary by year. These results suggest that the predictability of activity patterns is seasonally dynamic, and failure to account for intraspecific variation in activity may cloud inference in LOF studies. We argue that future studies should not neglect the potential complexity of predator behavior with simplistic assumptions. By considering intraspecific variation in activity patterns, we may gain a clear picture of LOF dynamics.

Diel and monthly activity pattern of brown bears and sika deer in the Shiretoko Peninsula, Hokkaido, Japan.

Mammals exhibit several types of diel activity pattern, including nocturnal, diurnal, crepuscular, and cathemeral. These patterns vary inter- and intra-specifically and are affected by environmental factors, individual status, and interactions with other individuals or species. Determining the factors that shape diel activity patterns is challenging but essential for understanding the behavioral ecology of animal species, and for wildlife conservation and management. Using camera-trap surveys, we investigated the species distributions and activity patterns of terrestrial mammals on the Shiretoko Peninsula, Hokkaido, Japan, with particular focus on brown bears and sika deer. From June to October 2019, a total of 7,530 observations were recorded by 65 camera-traps for eight species, including two alien species. The diel activity pattern of brown bears was diurnal/crepuscular, similar to that of bears in North America, but different from European populations. Bear observations were more frequent during the autumnal hyperphagia period, and adult females and sub-adults were more diurnal than adult males. In addition, bears inside the protected area were more diurnal than those outside it. These findings suggest that appetite motivation, competitive interactions between conspecifics, and human activities potentially affect bear activity patterns. Similar to other sika deer populations and other deer species, the diel activity patterns of sika deer were crepuscular. Deer showed less variation in activity patterns among months and sex-age classes, while adult males were observed more frequently during the autumn copulation period, suggesting that reproductive motivation affects their activity patterns.

Time partitioning among neotropical frugivorous bats: effects of phylogeny, body size, and abundance

Introduction: Resource partitioning by promoting coexistence is essential to determine species richness and composition in natural communities. However, the partitioning of time has been questioned as a mechanism that promotes the coexistence of ecologically similar species. Objective: To determine the importance of the partitioning of time as a mechanism that promotes coexistence, we compared the activity patterns of tropical frugivorous bats. Methods: We captured bats with mist nets from sunset to sunrise in three study sites (tropical dry forest, wet forest, and rainforest) to calculate activity patterns of the species using Kernel density estimation. We used the superposition coefficient (Δ1) to compare activity patterns between (1) bat assemblages of study sites, (2) frugivorous species in the same site, and (3) populations of the same species among different sites. To determine whether the overlap in the activity patterns was related to the ecological similarity of species, we evaluated the association between Δ1 and similarity in abundances and body mass and phylogenetic closeness. Results: We found geographical variations in the overall activity patterns of the assemblages of the three localities. Likewise, we found variations in activity patterns between species at each study site and between populations in different study sites. Overlap in activity patterns tended to decrease as species were phylogenetically more closely related and similar in abundance and body size. Conclusions: Our results provide empirical support for the role of temporal segregation in activity patterns as a mechanism that promotes the coexistence of ecologically similar species in nature.

Actigraphy in mechanically ventilated pediatric ICU patients: comparison to PSG and evaluation of behavioral circadian rhythmicity

ABSTRACT Sleep disruption is common in pediatric intensive care unit (PICU) patients, but measuring sleep in this population is challenging. We aimed to evaluate the utility of actigraphy for estimating circadian rhythmicity in mechanically ventilated PICU patients and its accuracy for measuring sleep by comparing it to polysomnogram (PSG). We conducted a single-center prospective observational study of children 6 months – 17 years of age receiving mechanical ventilation and standard, protocolized sedation for acute respiratory failure, excluding children with acute or historical neurologic injury. We enrolled 16 children and monitored them with up to 14 days of actigraphy and 24 hours of simultaneous limited (10 channel) PSG. Daily actigraphy-based activity profiles demonstrated that patients had a high level of nighttime activity (30–41% of total activity), suggesting disrupted circadian activity cycles. Among n = 12 patients with sufficient actigraphy and PSG data overlap, actigraphy-based sleep estimation showed poor agreement with PSG-identified sleep states, with good sensitivity (94%) but poor specificity (28%), low accuracy (70%,) and low agreement (Cohen’s kappa = 0.2, 95% CI = 0.08–0.31). Using univariate linear regression, we identified that Cornell Assessment of Pediatric Delirium scores were associated with accuracy of actigraphy but that other clinical factors including sedative medication doses, activity levels, and restraint use were not. In this population, actigraphy did not reliably discern between sleep and wake states. However, in select patients, actigraphy was able to distinguish diurnal variation in activity patterns, and therefore may be useful for evaluating patients’ response to circadian-oriented interventions.

Testing hypotheses of habitat use and temporal activity in relation to body plan in a Mediterranean lizard community

A body plan (bauplan) is a suite of morphological characters shared by phylogenetically related animals at some point during their development. Despite its value, the bauplan concept is still rarely employed to characterize functional groups in community ecology. Here, we examine habitat use and spatio-temporal activity correlates of an entire seven-species community of lizards with different bauplans. The study was carried out in three locations in central Italy, encompassing a complex landscape with a patchy mosaic of a wide variety of habitats and microclimates. We tested four hypotheses regarding niche breadth, habitat use, and activity patterns. The first hypothesis, niche complementarity, in which species with similar body shapes should non-randomly partition available habitats, was not supported. By contrast, the hypotheses that larger bodied species should have a wider niche breadth, that slower species should inhabit habitat types of higher cover, and species inhabiting open sunny habitats should exhibit more seasonally variable activity patterns, were all supported by the data. Sympatric lizard communities in our study area were clearly organized by autecological constraints and eco-physiological attributes.