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Simple Summary: While humans are diurnal, commonly used laboratory rodents are nocturnal, i.e., sleeping mostly during the day and being active at night. The unique day- or night-active lifestyle has been shaped by their evolutionary history and likely involves the interplay between the circadian time-keeping system and various arousal- or sleep-promoting factors, e.g., light or melatonin. In the present review, we first discuss the similarities and differences in these regulatory processes between the two chronotypes and the potential mechanisms that could have contributed to the diurnality–nocturnality switch. Next, using a few sleep-related conditions as examples, we discuss the advantages of using diurnal rodent models in translational research, especially under conditions in which circadian rhythm disruption, altered photic response, or melatonin secretion is involved. Diurnal and nocturnal mammals have evolved unique behavioral and physiological adaptations to optimize survival for their day- or night-active lifestyle. The mechanisms underlying the opposite activity patterns are not fully understood but likely involve the interplay between the circadian time-keeping system and various arousal- or sleep-promoting factors, e.g., light or melatonin. Although the circadian systems between the two chronotypes share considerable similarities, the phase relationships between the principal and subordinate oscillators are chronotype-specific. While light promotes arousal and wakefulness in diurnal species like us, it induces sleep in nocturnal ones. Similarly, melatonin, the hormone of darkness, is commonly used as a hypnotic in humans but is secreted in the active phase of nocturnal animals. Thus, the difference between the two chronotypes is more complex than a simple reversal, as the physiological and neurological processes in diurnal mammals during the day are not equivalent to that of nocturnal ones at night. Such chronotype differences could present a significant translational gap when applying research findings obtained from nocturnal rodents to diurnal humans. The potential advantages of diurnal models are being discussed in a few sleep-related conditions including familial natural short sleep (FNSS), obstructive sleep apnea (OSA), and Smith–Magenis syndrome (SMS). Considering the difference in chronotype, a diurnal model will be more adequate for revealing the physiology and physiopathology pertaining to human health and disease, especially in conditions in which circadian rhythm disruption, altered photic response, or melatonin secretion is involved. We hope the recent advances in gene editing in diurnal rodents will promote greater utility of the diurnal models in basic and translational research. [ABSTRACT FROM AUTHOR]

For behavioural ecologists who study nocturnal animals, recording behaviour at night is essential but expensive. Added difficulties arise when filming minifauna, as the most popular methods of recording nocturnal behaviour (i.e. trail cameras) function at a minimum focal distance of 3 m or greater. Infrared (IR)-sensitive camcorders can provide excellent footage of smaller animals at a shorter distance but can cost over $1000 USD. In addition, these pricey cameras rarely stand up to the elements in the field and are also limited by short battery life. Here, we provide a field-tested method to record nocturnal behaviour, of both small and large animals, at a fraction of the cost. We have had great success modifying inexpensive, commercially available action cameras (GoPro Hero4 camcorders) to be IR sensitive, powering these units with cellular phone power banks and continuously recording behaviour overnight while using an array of a dozen cameras. In total, all components of a recording kit are available for under $150 USD at the time of this writing (February 2024) and can be easily assembled using the guidelines described in the present paper. This paper provides researchers with an economical strategy to record continuous behaviour in nocturnally active animals, with a kit that outperforms most currently available camera options across various contexts. While the proposed kit may provide the greatest benefits to researchers studying minifauna, the recording set-up can be easily and cheaply adapted to capture nocturnal megafauna behaviour. As such, we hope these methods increase the accessibility of science and expand the experimental toolkits of biologists interested in the fascinating, but much understudied, world of nocturnal animal behaviour. • Traditional infrared-sensitive camcorders are expensive and impractical for fieldwork. • We present an economical, field-tested solution: modified commercial action cameras. • We give a step-by-step guide, detailing how to configure a complete recording kit. • Benefits include long recording times, portability, HD and high-speed recording. • We hope our kit makes scientifically exploring nocturnal behaviour more accessible. [ABSTRACT FROM AUTHOR]

Earth's rotation shapes a 24‐h cycle, governing circadian rhythms in organisms. In mammals, the core clock genes, CLOCK and BMAL1, are regulated by PERIODs (PERs) and CRYPTOCHROMEs (CRYs), but their roles remain unclear in the diamondback moth, Plutella xylostella. To explore this, we studied P. xylostella, which possesses a simplified circadian system compared to mammals. In P. xylostella, we observed rhythmic expressions of the Pxper and Pxcry2 genes in their heads, with differing phases. In vitro experiments revealed that PxCRY2 repressed monarch butterfly CLK:BMAL1 transcriptional activation, while PxPER and other CRY‐like proteins did not. However, PxPER showed an inhibitory effect on PxCLK/PxCYCLE. Using CRISPR/Cas9, we individually and in combination knocked out Pxper and Pxcry2, then conducted gene function studies and circadian transcriptome sequencing. Loss of either Pxper or Pxcry2 eliminated the activity peak after lights‐off in light–dark cycles, and Pxcry2 loss reduced overall activity. Pxcry2 was crucial for maintaining endogenous rhythms in constant darkness. Under light–dark conditions, 1 098 genes exhibited rhythmic expression in wild‐type P. xylostella heads, with 749 relying on Pxper and Pxcry2 for their rhythms. Most core clock genes lost their rhythmicity in Pxper and Pxcry2 mutants, while Pxcry2 sustained rhythmic expression, albeit with reduced amplitude and altered phase. Additionally, rhythmic genes were linked to biological processes like the spliceosome and Toll signaling pathway, with these rhythms depending on Pxper or Pxcry2 function. In summary, our study unveils differences in circadian rhythm regulation by Pxper and Pxcry2 in P. xylostella. This provides a valuable model for understanding circadian clock regulation in nocturnal animals. [ABSTRACT FROM AUTHOR]

Simple Summary: The behaviours and needs of nocturnal animals can be overlooked by humans, potentially because of our poor night vision and diurnal waking hours. Despite certain challenges in studying many nocturnal animals, appropriate provisions for their welfare should be supported in both wild and managed environments. To investigate this issue and explore ways to offer technology-enhanced welfare, husbandry practices and enrichment opportunities for nocturnal species, we conducted a multidisciplinary workshop (Moon Jam). During the event, species experts provided animal welfare briefs that related to specific challenges for nocturnal animals in different contexts. Teams of participants addressed these challenges in collaborative design sessions, producing a collection of hand-crafted models to share their ideas. An important aspect of the workshop was to be inclusive of all the stakeholders involved, including zoo management teams, animal stewards and zoo visitors, as well as the individual species. In this paper, we present our reflections on managed nocturnal animal welfare, framing these within current practices and Moon Jam workshop outputs. We contribute a set of guidelines for those involved with caring for zoo-housed nocturnal species, emphasizing the provision of technology-enhanced husbandry and enrichment opportunities. This paper addresses the potential for technology to support husbandry and enrichment opportunities that enhance the welfare of zoo and sanctuary-housed nocturnal and crepuscular species. This topic was investigated through the medium of a multidisciplinary workshop (Moon Jam) that brought together species experts, zoo designers, Animal-Computer Interaction researchers and post-graduate students in collaborative discussions and design sessions. We explain the context through an examination of existing research and current practices, and report on specific challenges raised and addressed during the Moon Jam, highlighting and discussing key themes that emerged. Finally, we offer a set of guidelines to support the integration of technology into the design of animal husbandry and enrichment that support wellbeing, to advance the best practices in keeping and managing nocturnal and crepuscular animals. [ABSTRACT FROM AUTHOR]

Monitoring nocturnal animals in the field is an important task in ecological research and wildlife conservation, but the complexity of nocturnal images and low light conditions make it difficult to cope with traditional image processing methods. To address this problem, researchers have introduced infrared cameras to improve the accuracy of nocturnal animal behaviour observations. Object detection in nighttime images captured by infrared cameras faces several challenges, including low image quality, animal scale variations, occlusion, and pose changes. This study proposes the YOLOv8‐night model, which effectively overcomes these challenges by introducing a channel attention mechanism in YOLOv8. The model is more focused on capturing animal‐related features by dynamically adjusting the channel weights, which improves the saliency of key features and increases the accuracy rate in complex backgrounds. The main contribution of this study is the introduction of the channel attention mechanism into the YOLOv8 framework to create a YOLOv8‐night model suitable for object detection in nighttime images. When tested on nighttime images, the model performs well with a significantly higher mAP (0.854) than YOLOv8 (0.831), and YOLOv8‐night scores 0.856 on mAP_l, which is obviously better than YOLOv8 (0.833) in terms of processing large objects. The study provides a reliable technical tool for ecological research, wildlife conservation and environmental monitoring, and offers new methods and insights for the study of nocturnal animal behaviour. [ABSTRACT FROM AUTHOR]

This article discusses the formation of images in the human eye and the persistence of ancient theories on image formation among students. The study presents an instructional material called the dark box-cat family experiment, which allows students to test and discuss their theories on image formation using concrete experiences. The experiment involves placing wooden cat figures inside a dark box and observing their visibility under different conditions. The results of the experiment aim to challenge the ancient theories and promote scientific knowledge on image formation. The article suggests that incorporating historical and philosophical knowledge in science education can enhance learning. [Extracted from the article]

Sleep serves vital physiological functions, yet how sleep in wild animals is influenced by environmental conditions is poorly understood. Here we use high-resolution biologgers to investigate sleep in wild animals over ecologically relevant time scales and quantify variability between individuals under changing conditions. We developed a robust classification for accelerometer data and measured multiple dimensions of sleep in the wild boar (Sus scrofa) over an annual cycle. In support of the hypothesis that environmental conditions determine thermoregulatory challenges, which regulate sleep, we show that sleep quantity, efficiency and quality are reduced on warmer days, sleep is less fragmented in longer and more humid days, while greater snow cover and rainfall promote sleep quality. Importantly, this longest and most detailed analysis of sleep in wild animals to date reveals large inter- and intra-individual variation. Specifically, short-sleepers sleep up to 46% less than long-sleepers but do not compensate for their short sleep through greater plasticity or quality, suggesting they may pay higher costs of sleep deprivation. Given the major role of sleep in health, our results suggest that global warming and the associated increase in extreme climatic events are likely to negatively impact sleep, and consequently health, in wildlife, particularly in nocturnal animals. [ABSTRACT FROM AUTHOR]

Anti‐predation strategies are critical to animal survival and are fundamental to deciphering predator–prey interactions. As an important defense strategy, sensory predator detection (such as through acoustic and visual cues) enables animals to assess predation risk and execute predator‐avoidance behavior; however, there are limited studies on the anti‐predation behavior of nocturnal animals. The prey of bats provides an excellent representative system for examining the anti‐predation behavior of nocturnal animals. Here, we broadcasted different types of echolocation calls of the bird‐eating bat Ia io to two wild passerine birds, namely, Zosterops japonicus and Sinosuthora webbiana, that are preyed upon by I. io, and presented the birds with individual bats under different light intensities. The results showed that both bird species were able to perceive the low‐frequency audible portion of the bats' echolocation calls; however, they did not exhibit escape responses to the acoustic stimuli. In the dark and under moonlit conditions, both bird species were unable to respond to active bats at close range and the birds only exhibited evasive flight behavior when bats approached or touched them. These results suggest that nocturnal passerine birds may not be able to use acoustic or visual cues to detect bats and adopt evasive maneuvers to avoid predation. This work suggests that bat predation pressure may not elicit primary predator‐avoidance responses in nocturnal passerine birds. The results provide new insights into the anti‐predation behavior of nocturnal animals. [ABSTRACT FROM AUTHOR]

Nocturnal temperatures are increasing at a pace exceeding diurnal temperatures in most parts of the world. The role of warmer nocturnal temperatures in animal ecology has received scant attention and most studies focus on diurnal or daily descriptors of thermal environments' temporal trends. Yet, available evidence from plant and insect studies suggests that organisms can exhibit contrasting physiological responses to diurnal and nocturnal warming. Limiting studies to diurnal trends can thus result in incomplete and misleading interpretations of the ability of species to cope with global warming. Although they are expected to be impacted by warmer nocturnal temperatures, insufficient data are available regarding the night‐time ecology of vertebrate ectotherms. Here, we illustrate the complex effects of nocturnal warming on squamate reptiles, a keystone group of vertebrate ectotherms. Our review includes discussion of diurnal and nocturnal ectotherms, but we mainly focus on diurnal species for which nocturnal warming affects a period dedicated to physiological recovery, and thus may perturb activity patterns and energy balance. We first summarise the physical consequences of nocturnal warming on habitats used by squamate reptiles. Second, we describe how such changes can alter the energy balance of diurnal species. We illustrate this with empirical data from the asp viper (Vipera aspis) and common wall lizard (Podarcis muralis), two diurnal species found throughout western Europe. Third, we make use of a mechanistic approach based on an energy‐balance model to draw general conclusions about the effects of nocturnal temperatures. Fourth, we examine how warmer nights may affect squamates over their lifetime, with potential consequences on individual fitness and population dynamics. We review quantitative evidence for such lifetime effects using recent data derived from a range of studies on the European common lizard (Zootoca vivipara). Finally, we consider the broader eco‐evolutionary ramifications of nocturnal warming and highlight several research questions that require future attention. Our work emphasises the importance of considering the joint influence of diurnal and nocturnal warming on the responses of vertebrate ectotherms to climate warming. [ABSTRACT FROM AUTHOR]

Motion‐triggered light‐emitting diodes (LED) could reduce light pollution; however, its effect on nocturnal animals is poorly known. Here, we investigated how bats respond to the motion‐triggered lighting of a bicycle path, an infrastructure that is increasingly being built to support human mobility. We measured the acoustic activity of bats in relation to the activity of LED lights. The responses of bats varied during the night and between functional guilds: Edge‐space foraging bats avoided LED lighting, but the response was less clear during early and late night. Open‐space foraging and narrow‐space foraging bats avoided the LED lighting, especially late at night. The foraging intensity remained relatively stable across the night for bats of all guilds. We conclude that the motion‐sensitive LED lighting of bicycle paths induces a guild‐specific avoidance response in bats, which could be mitigated by shorter lighting periods. [ABSTRACT FROM AUTHOR]

Moonlight exerts profound ecological, behavioural and physiological effects on animals. However, lunar cycles are characterised by complex changes in the illuminance and timing of illumination, making it challenging to re‐create and manipulate moonlight cycles in the laboratory using artificial lights. As a result, ecological experiments on the effects of moonlight cycles are uncommon, and existing studies often oversimplify the re‐creation of moonlight. This limitation extends to experimental studies of the effects of light pollution on nocturnal animals, which often fail to adequately represent natural nocturnal light.To address the lack of open‐source solutions for re‐creating and manipulating moonlight cycles, we developed the software‐hardware system MoonShine. This has two components: (1) MoonShineR, an R package with additional R scripts, which predicts moonlight ground illuminance (in lux) at defined intervals, for a specified location and time range; (2) MoonShineP, a Python program running on a Raspberry Pi computer, which uses the illuminance values from MoonShineR to gradually dim and brighten a diffused array of individually addressable LEDs, allowing realistic natural light regimes to be re‐created in a laboratory environment. MoonShine includes multiple features to re‐create and manipulate light cycles. It supports colour‐shifting of the LED light (by adjustment of RGBW intensity ratios) to approximate the spectrum of natural moonlight, and to mimic habitat‐specific conditions or certain types of light pollution.We tested the accuracy of MoonShineR's moonlight illuminance predictions by comparison to field radiometer measurements at equatorial and temperate latitude sites. We demonstrated the accuracy of MoonShineP's moonlight re‐creation, by comparing its measured LED illuminances to the intended values and its measured LED spectrum against natural moonlight.MoonShine allows researchers to re‐create a range of natural nocturnal lighting scenarios in the laboratory. It can be used to re‐create full natural moonlight cycles with a relatively realistic spectral composition, generate manipulated moonlight schedules, or simulate light pollution. Furthermore, the moonlight illuminance predicted by MoonShineR is useful for field ecologists who require moonlight as a quantitative model predictor. Finally, to provide laboratory‐housed animals with full diurnal light cycles, MoonShine allows researchers to re‐create natural twilight and sunlight regimes. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) affects most of the population. Through the retinohypothalamic tract, ALAN modulates the activity of the central circadian oscillator and, consequently, various physiological systems, including the cardiovascular one. We summarised the current knowledge about the effects of ALAN on the cardiovascular system in diurnal and nocturnal animals. Based on published data, ALAN reduces the day-night variability of the blood pressure and heart rate in diurnal and nocturnal animals by increasing the nocturnal values of cardiovascular variables in diurnal animals and decreasing them in nocturnal animals. The effects of ALAN on the cardiovascular system are mainly transmitted through the autonomic nervous system. ALAN is also considered a stress-inducing factor, as glucocorticoid and glucose level changes indicate. Moreover, in nocturnal rats, ALAN increases the pressure response to load. In addition, ALAN induces molecular changes in the heart and blood vessels. Changes in the cardiovascular system significantly depend on the duration of ALAN exposure. To some extent, alterations in physical activity can explain the changes observed in the cardiovascular system after ALAN exposure. Although ALAN acts differently on nocturnal and diurnal animals, we can conclude that both exhibit a weakened circadian coordination among physiological systems, which increases the risk of future cardiovascular complications and reduces the ability to anticipate stress. [ABSTRACT FROM AUTHOR]

In nonclinical toxicology studies, lab animals are fasted typically overnight, to reduce variability in some clinical pathology parameters. However, fasting adds undue stress, and this is particularly concerning in rodents given their fast metabolic rates. Furthermore, as rodents are nocturnal animals, an overnight fasting may cause a protracted negative metabolic state even when the fasting has technically ended, given their minimal activity and food consumption during the day. Therefore, to evaluate the impacts of different fasting durations (±DietGel supplementation) on rats' welfare, we assessed the traditional and ancillary clinical pathology parameters in Sprague-Dawley rats, along with body weight, organ weight, and histopathology. Although most endpoints were comparable between the different fasting durations (±DietGel supplementation), the long fasting times (≥8 hr) without DietGel supplementation caused significant decreases in body weight, liver weight, liver glycogen content, serum glucose, triglyceride, and creatinine concentrations—all findings suggestive of a negative energy balance that could impact animal welfare and consequently, data quality; while the short fasting time (4 hr) and DietGel supplementation were associated with higher triglycerides variability. Hence, we propose that short fasting time should be adequate for most toxicology studies in rats, and long fasting times should only be accommodated with scientific justification. [ABSTRACT FROM AUTHOR]

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Animal movement throughout the landscape is a key concept for population viability. Human footprint can reduce animal movement through barrier effects such as habitat change and fragmentation, or through enhanced resources. Artificial light at night (ALAN) can affect the movement of nocturnal animals such as bats that are highly mobile in the landscape. Very few studies have explicitly quantified the choices that moving bats make when they encounter a light source on their flight routes. We assessed whether ALAN of different colours (green, red and white) compared to control conditions affected the use of ecological corridors, considering (i) activity and (ii) movement along the corridor, for open, edge (i.e. light‐opportunistic) and narrow‐space (i.e. light‐averse) foraging bats. We modelled the effects of 28 independent lampposts at four experimental sites on bat activity and movement (i.e. the number of trajectories towards the lamppost and the probability of lamppost crossing). Each lamppost was sampled two to three times over eight complete nights using paired passive acoustic stereo recorders to record bat activity and reconstruct bat trajectories. Narrow‐space foragers were much less active in presence of any light source, and fewer flew towards any lit lampposts. Open and edge‐space foragers were more active close to white and green lights, and to a lesser extent red light, compared to unlit control sites. Edge‐space foragers overall flew more towards white and green lampposts, but had a lower probability of fully crossing a white and red‐lighted site. The study shows that ALAN can strongly alter bat movements along landscape structures, for light‐averse but also light‐opportunistic species. Such changes in flight behaviour may involve bypasses or detours, which may force bats to fly longer distances at night which could ultimately affect fitness. Our findings suggest that avoiding artificial lighting close to flight routes will benefit bats. [ABSTRACT FROM AUTHOR]

The spatial and trophic ecology of the culpeo fox (Lycalopex culpaeus) was studied in the Salar de Punta Negra basin and the Llullaillaco National Park, in the high Andes of the Region of Antofagasta in northern Chile. The objectives of this study were to understand the feeding ecology, habitat use, and home range and activity pattern of culpeo fox. The study was conducted in an area of approximately 2800 km2 inside the Punta Negra salt flat basin, Llullaillaco NP, the surrounding mountains, and within areas of mining operations. We used methodologies including camera trapping, live trapping and satellite monitoring of L. culpaeus individuals, and diet analysis. Fifteen captures and five recaptures of culpeos were made, and three of them were equipped with satellite tracking collars. The home ranges estimated using the Minimum Convex Polygon (MPC 95%) were: 1029 km2 (female), 809 km2 (female) and 215 km2 (male). Culpeo foxes were nocturnal animals. A larger sample of 282 fecal scats was collected, with the main trophic prey in culpeo fox diet by frequency of occurrence being rodents (74.3%), arthropods (48%), camelids carrion (43.6%), birds (16.3%), vegetation (13.8%) and reptiles (2.5%). Niche breadth was low (0.367). [ABSTRACT FROM AUTHOR]

African giant pouched rat (AGPR) is widely used both to conduct research projects and for meat consumption. However, being a nocturnal animal, light exposure requires a specific attention in order to improve their rearing environment. The study aimed to appreciate the effects of light exposure on hematological and oxidative stress parameters in AGPR bred in captivity. Twenty adult males AGPR weighing 945 ± 171 g were randomly allocated into four photoperiod regimes: 0L/24D, 12L/12D, 18L/06D, and 24L/0D. Housed singly during 56 days, animals received food and water ad libitum. At the end of the trial, blood and serum were collected for studied parameters analysis. The study revealed a significant (p < 0.05) increase of the number of red blood cell (RBC), white blood cell (WBC), hemoglobin (HGB), and hematocrit (HCT) in animals kept in the darkness condition compared to those reared under extended photoperiods. Except for malondialdehyde (MDA) level which was not affected by photoperiod, catalase (CAT), and superoxide dismutase (SOD) activity increased significantly (p < 0.05) for any light exposure up to 12 h per day. In conclusion, photoperiod affects the most hematological characteristics measured and has stressful effects in AGPR. This new knowledge provides a relevant information for the rearing environment of African giant pouched rat. [ABSTRACT FROM AUTHOR]

Simple Summary: Human disturbances affect the activity patterns of mammals. This should be considered when managing national parks, especially in densely populated tropical volcanic landscapes. This study was conducted at the Gunung Merapi National Park between 2019 and 2021, and it aimed to determine the interaction between humans and mammals, both temporally and spatially. We found that medium-sized mammals responded to human activities in complex ways: barking deer (Muntiacus muntjac) and leopard cats (Prionailurus bengalensis) modified their activity times to avoid encounters with humans, while the wild boars (Sus scrofa) tended to avoid humans, choosing locations where there was no human presence. Nocturnal animals tended not to be disturbed because they occupied a different temporal niche to humans. No significant behavioral changes in mammals were observed in response to the human disturbances in this area. However, the presence of poachers and exotic predators (such as domestic dogs) should be a concern to national park managers. As a mitigation effort, human activity should be regulated, both temporally and spatially, in the GMNP. Moreover, education regarding domestic dog ownership and an inventory of dog ownership in the surrounding communities should also be carried out to prevent further disturbances to the mammals in the Merapi volcanic ecosystem. A comprehensive understanding of the consequences of human interactions with mammals is a critical factor in supporting and conserving species in landscapes dominated by humans, which are increasingly threatened. This study aimed to identify the spatial and temporal interactions between humans and mammals. A non-parametric statistical approach with kernel density was used to detect human–mammal temporal interactions. The species interaction factor (SIF) was applied to calculate the spatial overlap based on the two-species occupancy detection model. The activity patterns of medium mammals were nocturnal, diurnal, and cathemeral. The human–medium mammal pairs with SIF values that were <1 and statistically significant included the human–long-tailed macaque (Macaca fascicularis) pair, the human–leopard cat (Prionailurus bengalensis) pair, and the human–barking deer (Muntiacus muntjac) pair. Based on their SIF values and the high overlap in their activity times, the human–macaque pairings had a high risk of conflict. Barking deer and leopard cats displayed a coexistence with humans via time-sharing activities. Due to temporal niche variations with human activities, the existence of nocturnal mammals was relatively uninterrupted. This study showed that most mammals are able to adapt spatially and temporally to various human activities. Nonetheless, efforts to mitigate human–wildlife conflict must be maintained, particularly in the case of severely endangered species, such as the Sunda pangolin. [ABSTRACT FROM AUTHOR]

Chronobiological variations are in the fabric of life. The first ideas regarding the possible effects of circadian rhythm on surgical outcomes were published in the early 2000s. Some studies support and oppose this idea. The lack of experimental evidence in a controlled setting has led to this study. This study aimed to explore the chronobiological implications of surgical outcomes. The rats were divided into four groups. A random pattern dorsal skin flaps were elevated in all groups at six h intervals. Flap necrosis rates and melatonin, oxidant, and antioxidant factors were studied. Flap survival was better in the 06:00 h group. The flap necrosis was higher in the 18:00 h group. Some of the biochemical parameters displayed circadian variations. As an independent variable, the time of surgical intervention changed the flap survival rates. It should be noted that the study was held in a nocturnal animal model thus the pattern of flap survival can be in reversed fashion in a clinical scenario. This study is the first experimental evidence for "Chronosurgery" in a controlled setting. Further studies in all aspects of surgical disciplines are required. [ABSTRACT FROM AUTHOR]

Background: Gastrointestinal motility measurements in mice are currently performed under suboptimal conditions, as these nocturnal animals are measured during light conditions. In addition, other stressors, like individual housing, placement in a new cage during observation, and lack of bedding and cage enrichment cause animal discomfort and might contribute to higher variability. Here we aimed to develop a refined method of the widely‐used whole‐gut transit assay. Methods: Wildtype mice (N = 24) were subjected to the standard or refined whole‐gut transit assay, either with or without a standardized slowing in gastrointestinal motility induced by loperamide. The standard assay consisted of a gavage with carmine red, observation during the light period and individual housing in a new cage without cage enrichment. For the refined whole‐gut transit assay, mice were gavaged with UV‐fluorescent DETEX®, observed during the dark period, while pairwise housed in their home cage with cage enrichment. Time until excretion of the first colored fecal pellet was assessed, and pellets were collected to assess number, weight, and water content. Key Results: The DETEX®‐containing pellets were UV‐detectable, allowing to measure the mice in their active period in the dark. The refined method caused less variation (20.8% and 16.0%) compared to the standard method (29.0% and 21.7%). Fecal pellet number, weight, and water content was significantly different between the standard and refined method. Conclusions & Inferences: This refined whole‐gut transit assay provides a reliable approach to measure whole‐gut transit time in mice in a more physiological context, with reduced variability compared to the standard method. [ABSTRACT FROM AUTHOR]

Scorpions are incredible venomous animals found on almost every continent. According to fossil data, these animals have been able to adapt to the different environments from the Cambrian period until today with minimal anatomical changes. Scorpions are mostly nocturnal animals, and their ability to detect and tolerate light stimuli seems to be an essential tool for their subsistence, homing and mating. Centruroides suffuses is the most predominant specie of scorpions in Durango City, Mexico. Interestingly, and despite their life-threatening venom, these predatory arthropod animals have been adopted by locals as part of the landscape and daily life, by including them as part of their folklore and their economic resources, and learning how to take advantage of their abundance. In addition, the venom of scorpions possesses potential for therapeutic uses, while the scorpions themselves represent a nutritional food resource rich in protein, which has been poorly explored so far. Therefore, they are an excellent model for exploring the interplay between light sensibilities, survival and therapeutic–medicinal uses. Here, we review some of the potential benefits of scorpions and share the ways people in Durango City, Mexico, use UV light devices to detect and avoid or catch them for business and research purposes. [ABSTRACT FROM AUTHOR]

Background. Animals rely on sound for daily activities, and anthropogenic noise is a pollutant that alters the natural soundscape within which they are active. As human infrastructure expands, broadband anthropogenic noise increases, which can affect behaviors of nocturnal animals. Mice are nocturnal animals that produce ultrasonic calls as part of their behavioral repertoire. Methods. We assessed effects of anthropogenic and natural noise on the behaviors of wild deer mice (Peromyscus maniculatus) and woodland jumping mice (Napaeozapus insignis), two species of mice that produce ultrasonic calls. We measured activity, foraging behavior at a foraging tray, and calling behavior to broadcasts of natural and anthropogenic noise, compared to a baseline with no broadcasting, at 25 focal areas in the Southern Appalachian Mountain Range of North Carolina, USA. Results. Deer mice exposed to anthropogenic noise spent less time in focal areas with broadcasted anthropogenic noise. Mice took longer to begin foraging in the presence of anthropogenic noise, they spent less time at the foraging tray, and left fewer husks but consumed the same number of seeds as mice exposed to natural noise. Deer mice were less likely than woodland jumping mice to be the first to enter the focal area and approach food when in the presence of anthropogenic noise. Both species produced few ultrasonic calls in the presence of broadcasted natural and anthropogenic noise compared to their baseline level of calling. We present the first calls recorded from woodland jumping mice. Conclusion. Anthropogenic noise affects activity, foraging behavior, and calling behavior of nocturnal mice. Natural noise also affects the calling behavior of mice. Mouse species respond differently to anthropogenic noise, with deer mice appearing more sensitive to anthropogenic noise than woodland jumping mice. Responses to noise could have important effects on the ecology of mice and these two species respond differently. Species differences should be considered when mitigating the effects of noise in conservation ecology. [ABSTRACT FROM AUTHOR]

Over the past decades, tracking technologies have become more ubiquitous and helped uncover crucial spatiotemporal relationships in nature. In order to apply these technologies to small animals and reduce any potential adverse impact of devices, geopositioning methodologies compatible with lightweight devices are highly sought after. Measured by lightweight geolocators, atmospheric pressure provides an untapped opportunity for global geopositioning, as its natural temporal variation is unique to each location.In this study, we estimate the position of birds by comparing pressure data recorded by the geolocator with reference data from a global weather reanalysis database. The method produces a likelihood map of the position based on (1) a mask of the locations for which the ground‐level elevation matches the pressure measured by the geolocator and (2) a mismatch between the temporal time series measured by the geolocator and the reanalysis dataset. This new method is introduced step by step and applied to 16 tracks of nine long‐ and short‐distance migrant species.Using known positions of double‐tagged individuals (light and pressure data), we demonstrate that our method is almost three times more accurate than light‐based positioning with an average error of 44 km in our trials. In contrast to the traditional light‐based approach, pressure geolocation can provide useful information for short stationary periods (less than a day) and is not affected by the equinox problem nor by any shading effects due to weather or animal behaviour. To facilitate the application of the method, we developed an R package GeoPressureR, together with a user guide GeopressureManual and starting code GeoPressureTemplate.The use of pressure sensors to position animals has the potential to become widespread thanks to the combination of both affordable lightweight devices (<0.4 g) and this method to estimate position of the device precisely and accurately. In particular, such devices can now be applied to short‐distant migrants (>100 km), forest‐dwelling species, nocturnal animals and altitudinal migrants. [ABSTRACT FROM AUTHOR]

Recent biologging technology reveals hidden life and breeding strategies of nocturnal animals. Combining animal movement patterns with individual characteristics and landscape features can uncover meaningful behaviours that directly influence fitness. Consequently, defining the proximate mechanisms and adaptive value of the identified behaviours is of paramount importance. Breeding female barn owls (Tyto alba), a colour-polymorphic species, recurrently visit other nest boxes at night. We described and quantified this behaviour for the first time, linking it with possible drivers, and individual fitness. We GPS-equipped 178 female barn owls and 122 male partners from 2016 to 2020 in western Switzerland during the chick rearing phase. We observed that 111 (65%) of the tracked breeding females were (re)visiting nest boxes while still carrying out their first brood. We modelled their prospecting parameters as a function of brood-, individual- and partner-related variables and found that female feather eumelanism predicted the emergence of prospecting behaviour (less melanic females are usually prospecting). More importantly we found that increasing male parental investment (e.g., feeding rate) increased female prospecting efforts. Ultimately, females would (re)visit a nest more often if they had used it in the past and were more likely to lay a second clutch afterwards, consequently having higher annual fecundity than non-prospecting females. Despite these apparent immediate benefits, they did not fledge more chicks. Through biologging and long-term field monitoring, we highlight how phenotypic traits (melanism and parental investment) can be related to movement patterns and the annual potential reproductive output (fecundity) of female barn owls. [ABSTRACT FROM AUTHOR]

Agricultural expansion has had a detrimental effect on tropical forests and the animal communities that depend on them. Agroforestry systems, however, with their more complex tree and plant communities, have been shown to be important habitats for a range of globally threatened species, including nocturnal animals. Here, we present novel data on the encounter rates of seven species of nocturnal mammals in relation to agroforestry systems within four national parks and associated plantations in Bangladesh to examine if encounter rates were influenced by the human population density, presence of plantations, and human access as represented by a Human Influence Index of anthropogenic disturbance. We walked 70.3 km of transects with only semi-natural forest, 26.9 km of transects with semi-natural forest and gardens, and 21.7 km of transects with semi-natural forest and monocultures over 55 nights from 2017–2019. Of the seven species of nocturnal mammals we detected, all were present in Satachari National Park, whereas six occurred in Lawachara National Park, Rajkandi Forest Range, and Rema-Kalenga Wildlife Sanctuary. Within these national parks, three species (Bengal slow loris, large Indian civet, particolored flying squirrel) were more frequently recorded in areas with human disturbance, especially agroforestry plantations. With declining forest cover in Bangladesh, we highlight here the potential of agroforestry systems as emerging important habitats for these species. We encourage long-term studies of these lesser-studied taxa to understand fully the capacity of agroforestry systems in order to support their long-term conservation. [ABSTRACT FROM AUTHOR]

Multimammate mice are prolific breeders, can cause significant agricultural damage, and are reservoir hosts for a number of pathogens. They are nocturnal and given their success in urbanised rural environments, we were interested in how they would respond to increasingly bright anthropogenic spaces. We evaluated the locomotor activity of southern multimammate mice (Mastomys coucha), under four treatments: in an outdoor enclosure with natural light and temperature fluctuations, in a laboratory under a standard light regime, and two artificial light at night (ALAN) regimes (2 Lux) of varying proximity. The study animals remained nocturnal for the duration of the experiments. They were more active under the laboratory conditions with lower day-time light levels compared to the outdoor treatment but reduced their activity under ALAN. When the night light originated remotely, activity levels decreased by more than 50%, whereas under direct ALAN from above the cages, there was a 75% decrease in activity. The onset of activity was later during the two LAN treatments. We concluded that Mastomys coucha is strongly averse to light and show severe behavioural and circadian responses to light at night. We predict that it is unlikely that Mastomys will flourish in cities, but that they could thrive in and around dark urbanised refugia. [Display omitted] • Mastomys coucha is a pest species of medical and economic importance. • The mice are more active in the darker lab compared to the natural treatment. • The mice show a reduction in activity of up to 75% under ALAN. • Activity levels are dependent on the proximity and intensity of ALAN light source. • M. coucha is highly averse to LAN and unlikely to invade brightly lit cities. [ABSTRACT FROM AUTHOR]

Autonomous Recording Units (ARU) are a passive acoustic monitoring technology that are useful for detecting the presence and distribution of cryptic and nocturnal animals in challenging, remote environments as they can be deployed for extended periods of time. However, ARUs vary in their detection ability, thus making it critical to evaluate them in real world environments. In American Samoa, three Procellariiform seabird species nest on the remote island of Ta'ū in difficult to access summit scrub habitat, for which we have little knowledge about their presence. Given the lack of knowledge about the distribution of these three species, coupled with the need to test different ARUs, our goal was to investigate the differences in detection probability for Song Meter sensors (Song Meter SM2 and SM4) under different habitat and environmental conditions on the island of Ta'ū. Detection ranges for seabird calls varied from <10 m in high wind conditions, up to 90 m in low wind conditions. Under ideal conditions detection range varied from 40 to 100 m for Song Meter SM4 sensors and 40 to 70 m for SM2 sensors. Knowing the detection capabilities of ARUs will allow better design of sensor spacing, and a combination of acoustic recording with in situ weather data will allow for calculations of detectable areas and facilitation of determining animal densities. [ABSTRACT FROM AUTHOR]

Animal Vehicle Collision, commonly called roadkill, is an emerging threat to drivers and wild animals, increasing fatalities every year. Currently, prevalent methods using visible light cameras are efficient for animal detection in daylight time. This paper focuses on locating wildlife close to roads during nocturnal hours by utilizing thermographic obtained images, thus enhancing vehicle safety. In particular, it proposes an intelligent system for animal detection during nighttime that combines the technique of Histogram of Oriented Gradients (HOG) with a Convolutional Neural Network (CNN). The proposed intelligent system is benchmarked against a variety of CNN's like basic CNN and VGG16-based CNN and also with the machine learning algorithms such as Support Vector Machine (SVM), Random Forest (RF), Decision Tree Algorithm (DT), Linear Regression (LR), and Gaussian Naïve Bayes (GNB). The proposed detection system was tested on a set of real-world data acquired with a thermal camera on the move in the city of San Antonio, TX, USA that includes images of wild deer. Obtained results exhibit that the HOG-CNN combination achieved approximately 91% correct detection accuracy of wild deer on roadsides, while it outperformed the rest of the tested machine learning algorithms. [ABSTRACT FROM AUTHOR]

The group Anguimorpha represents one of the most unified squamate clades in terms of body plan, ecomorphology, ecophysiology and evolution. On the other hand, the anguimorphs vary between different habitats and ecological niches. Therefore, we focused on the group Anguimorpha to test a possible correlation between heart morphology and ecological niche with respect to phylogenetic position in Squamata with Sphenodon, Salvator, and Pogona as the outgroups. The chosen lepidosaurian species were investigated by microCT. Generally, all lepidosaurs had two well‐developed atria with complete interatrial septum and one ventricle divided by ventricular septa to three different areas. The ventricles of all lepidosaurians had a compact layer and abundant trabeculae. The compact layer and trabeculae were developed in accordance with particular ecological niche of the species, the trabeculae in nocturnal animals with low metabolism, such as Sphenodon, Heloderma or Lanthanotus were more massive. On the other hand athletic animals, such as varanids or Salvator, had ventricle compartmentalization divided by three incomplete septa. A difference between varanids and Salvator was found in compact layer thickness: thicker in monitor lizards and possibly linked to their mammalian‐like high blood pressure, and the level of ventricular septation. In summary: heart morphology varied among clades in connection with the ecological niche of particular species and it reflects the phylogenetic position in model clade Anguimorpha. In the absence of fossil evidence, this is the closest approach how to understand heart evolution and septation in clade with different cardiac compartmentalization levels. [ABSTRACT FROM AUTHOR]

We focus our research on how the core-shell organization controls behavior of the suprachiasmatic nucleus (SCN), how the core and shell are synchronized to the environment, what impact they have on the behavior of the SCN under different lighting conditions, and what mechanisms disrupt synchronization. To this end, we use a reduced Kuramoto model, with parameters inferred from experimental observations and calibrated for mice, and perform a detailed comparison between the model and experimental data under light-dark (LD), dark-dark (DD), and light-light (LL) conditions. The operating limits of free-running and entrained SCN activity under symmetric LD cycles are analyzed, with particular focus on the phenomena of anticipation and dissociation. Results reveal that the core-shell organization of the SCN enables anticipation of future events over circadian cycles. The model predicts the emergence of a second (dissociated) rhythm for large and small LD periods. Our results are in good qualitative and quantitative agreement with experimental observations of circadian dissociation. We further describe SCN activity under LL conditions and show that our model satisfies Aschoff's first rule, according to which the endogenous free-running circadian period observed under complete darkness will shorten in diurnal animals and lengthen in nocturnal animals under constant light. Our results strongly suggest that the Kuramoto model captures essential features of synchronization and entrainment in the SCN. Moreover, our approach is easily extendible to an arbitrary number of groups, with dynamics described by explicit equations for the group phase and synchronization index. Viewed together, the reduced Kuramoto model presents itself as a useful tool for exploring open problems in the study of circadian rhythms, one that can account for evolving views of the circadian system's organization, including peripheral clocks and inter-hemispheric interaction, and can be translated to other nocturnal and diurnal animals, including humans. [ABSTRACT FROM AUTHOR]

We present the first records of the post-release follow-up and monitoring of a rehabilitated two-toed sloth (Choloepus hoffmanni) as well as freezing behavior and an inferred antagonistic interaction for this species. Two-toed sloths are nocturnal and arboreal mammals whose survival relies on their capability to remain undetected by predators. Nevertheless, in the Guayas province of Ecuador, they are among the most common mammal species in rehabilitation centers. The liberation of animals back to the forest is the main goal of rehabilitation, while the follow-up of post-release human support of animals facilitates their re-establishment in their natural habitat. Follow-up, direct observation, and Bluetooth-based monitoring of the two-toed sloths secured the survival of this species in this part of Ecuador. The range of detectability of the device used indicates its suitability for tracking low-mobility animals. After the first five days, the number of trees used per day increased, and 19 trees within 1152 m² were visited. Daylight and movement time range showed a correlation towards detectability. The follow-up effort allowed for keeping the two-toed sloth safe for 10 days after release. Due to the difficulty monitoring nocturnal animals, economic constraints in conservation, accessibility, and safety of the animals, biodegradable Bluetooth-based backpacks are recommended to ease the location of the animal and support its survival in the wild. [ABSTRACT FROM AUTHOR]