Nocturnal Behavior Research Articles

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

Long-term behavioral tracking can capture and quantify natural animal behaviors, including those occurring infrequently. Behaviors such as exploration and social interactions can be best studied by observing unrestrained, freely behaving animals. Weakly electric fish (WEF) display readily observable exploratory and social behaviors by emitting electric organ discharge (EOD). Here, we describe three effective techniques to synchronously measure the EOD, body position, and posture of a free-swimming WEF for an extended period of time. First, we describe the construction of an experimental tank inside of an isolation chamber designed to block external sources of sensory stimuli such as light, sound, and vibration. The aquarium was partitioned to accommodate four test specimens, and automated gates remotely control the animals' access to the central arena. Second, we describe a precise and reliable real-time EOD timing measurement method from freely swimming WEF. Signal distortions caused by the animal's body movements are corrected by spatial averaging and temporal processing stages. Third, we describe an underwater near-infrared imaging setup to observe unperturbed nocturnal animal behaviors. Infrared light pulses were used to synchronize the timing between the video and the physiological signal over a long recording duration. Our automated tracking software measures the animal's body position and posture reliably in an aquatic scene. In combination, these techniques enable long term observation of spontaneous behavior of freely swimming weakly electric fish in a reliable and precise manner. We believe our method can be similarly applied to the study of other aquatic animals by relating their physiological signals with exploratory or social behaviors.

Larval behavior and dispersal mechanisms in shore crab larvae (Carcinus maenas): Local adaptations to different tidal environments?

Using a combination of empirical and model studies we tested whether European shore crab larvae (Carcinus maenas) from environments with different tidal regimes in the North Sea area have different swimming behaviors, and whether this affects connectivity and settlement success of larvae. Laboratory studies demonstrated the presence of an inherited tidal migration rhythm in newly hatched crab larvae from the mesotidal Danish Wadden Sea, and field studies showed that postlarvae swam in surface water almost exclusively during flood tides, suggesting that larvae use selective tidal stream transport to control the dispersal process. In contrast, shore crab larvae from microtidal Skagerrak displayed a nocturnal vertical migration behavior that appeared to switch to a diurnal behavior at the end of the postlarval phase, indicating an adaptation to avoid visual predators and to use wind‐driven transport to reach shallow settlement areas. A biophysical model showed that tidal‐migrating larvae in the Wadden Sea had two times higher settlement success than larvae with a diel behavior. However, no differences in settlement success were found between the two larval behaviors in microtidal Skagerrak, where lower fitness is suggested for tidal‐migrating larvae due to higher predation mortality from visual predators. We suggest that the differences in inherited larval behavior in larvae from meso‐ and microtidal regions reflect local adaptations maintained through natural selection of successful recruits. Consistent with recent population genetic studies, modeled connectivity of shore crabs indicated an oceanographic dispersal barrier to gene flow in Eastern Wadden Sea that may facilitate such adaptations.

Facultative nocturnal behaviour in snakes: experimental examination of why and how with Ratsnakes (Elaphe obsoleta) and Racers (Coluber constrictor)

Diel activity patterns are often fixed within species such that most animals can be classified as diurnal, crepuscular, or nocturnal, and have sensory abilities that reflect when they are active. However, many snake species appear capable of switching between diurnal and nocturnal activity. Here, we evaluate the hypothesis that some species are constrained in their activity by the sensory cues used for foraging. We experimentally assessed differences between two sympatric snake species in their ability to alter diel activity patterns, to address why those snakes that switch do so (do thermal constraints force them to be active in otherwise nonpreferred conditions?), and to explore how sensory abilities to locate prey facilitate or constrain this shift. Ratsnakes (Elaphe obsoleta (Say in James, 1823)) were active when temperature was optimal, regardless of light level, suggesting their activity pattern is genuinely plastic. Consistent with our predictions, Ratsnakes successfully detected prey in low and high light using visual or chemical cues, and were most successful when cues were coupled. Racers (Coluber constrictor L., 1758) were almost exclusively diurnal, regardless of temperature, and became less active when daytime temperatures were suboptimal. The ability of Ratsnakes to shift activity may confer a foraging advantage and should buffer Ratsnakes and similarly flexible species from climate change, whereas climate change may pose a more serious threat to inflexible species such as Racers.

Behavioural flexibility allows an invasive vertebrate to survive in a semi-arid environment

Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad (Rhinella marina) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April-October). We investigated whether cane toads have shifted their ancestral nocturnal rehydration behaviour to one that exploits water resources during the day. Such a shift in hydration behaviour could increase the fitness of individual toads by reducing exposure to desiccation and thermal stress suffered during the day even within terrestrial shelters. We used a novel method (acoustic tags) to monitor the daily hydration behaviour of 20 toads at two artificial reservoirs on Camfield station, Northern Territory. Remarkably, cane toads visited reservoirs to rehydrate during daylight hours, with peaks in activity between 9.00 and 17.00. This diurnal pattern of rehydration activity contrasts with nocturnal rehydration behaviour exhibited by adult toads in their native geographical range and more mesic parts of Australia. Our results demonstrate that cane toads phase shift a key behaviour to survive in a harsh semi-arid landscape. Behavioural phase shifts have rarely been reported in invasive species but could facilitate ongoing invasion success.

Cognitive Behavioral Therapy for Insomnia in Posttraumatic Stress Disorder: A Randomized Controlled Trial

Examine whether cognitive behavioral therapy for insomnia (CBT-I) improves sleep in posttraumatic stress disorder (PTSD) as well as nightmares, nonsleep PTSD symptoms, depression symptoms, and psychosocial functioning. RANDOMIZED CONTROLLED TRIAL WITH TWO ARMS: CBT-I and monitor-only waitlist control. Department of Veterans Affairs (VA) Medical Center. Forty-five adults (31 females: [mean age 37 y (22-59 y)] with PTSD meeting research diagnostic criteria for insomnia, randomly assigned to CBT-I (n = 29; 22 females) or monitor-only waitlist control (n = 16; nine females). Eight-session weekly individual CBT-I delivered by a licensed clinical psychologist or a board-certified psychiatrist. Measures included continuous monitoring of sleep with diary and actigraphy; prepolysomnography and postpolysomnography and Clinician-Administered PTSD Scale (CAPS); and pre, mid, and post self-report questionnaires, with follow-up of CBT-I participants 6 mo later. CBT-I was superior to the waitlist control condition in all sleep diary outcomes and in polysomnography-measured total sleep time. Compared to waitlist participants, CBT-I participants reported improved subjective sleep (41% full remission versus 0%), disruptive nocturnal behaviors (based on the Pittsburgh Sleep Quality Index-Addendum), and overall work and interpersonal functioning. These effects were maintained at 6-mo follow-up. Both CBT-I and waitlist control participants reported reductions in PTSD symptoms and CAPS-measured nightmares. Cognitive behavioral therapy for insomnia (CBT-I) improved sleep in individuals with posttraumatic stress disorder, with durable gains at 6 mo. Overall psychosocial functioning improved following CBT-I. The initial evidence regarding CBT-I and nightmares is promising but further research is needed. Results suggest that a comprehensive approach to treatment of posttraumatic stress disorder should include behavioral sleep medicine. TRIAL NAME: Cognitive Behavioral Treatment Of Insomnia In Posttraumatic Stress Disorder. URL: http://clinicaltrials.gov/ct2/show/NCT00881647. NCT00881647.

Optimal hunting conditions drive circalunar behavior of a diurnal carnivore

Foraging requirements and predation risk shape activity patterns and temporal behavior patterns widely across taxa. Although this has been extensively studied in small mammals, the influence of predation and prey acquisition on the activity and behavior of large carnivores has received little attention. The diurnal activity described as typical for cheetahs ( Acinonyx jubatus ) has been explained in terms of their avoidance of antagonistic interactions with other larger predators. However, a recent study revealed that cheetahs are frequently active at night, especially during periods of full moon. Being both predator and “prey” in an environment with comparatively high densities of larger and competitively dominant nocturnal predator species, we investigated whether cheetah nocturnal behavior could be explained by favorable conditions for 1) predator avoidance or 2) prey acquisition. We used a data set of continuously recorded behavior created using machine-learning techniques on behavioral data collected in the field to transform recorded 2D activity values from radio-collars into 3 distinct behavioral states (feeding, moving, and resting). We found that 32.5% of cheetah feeding behavior occurred at night and that, in the dry season, nocturnal feeding behavior was positively correlated with moonlight intensity. Our results suggest that nocturnal and circalunar behavior of cheetahs is driven by optimal hunting conditions, outweighing the risks of encountering other predators. Using novel methodology, the results provide new insights into the temporal distribution of behavior, contributing to our understanding of the importance of moonlight and season on the behavior patterns of diurnal species.

Correlation between nocturnal scratch behavior assessed by actigraphy and subjective/objective parameters in patients with atopic dermatitis

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disorder caused by multiple factors. Pruritus, and consequent scratch behavior, is one of the major exacerbating factors of AD and is associated with the itch-scratch cycle [1]. Unconscious nocturnal scratch behavior induces sleep disturbance and symptomatic worsening, resulting in a decreased quality of life [2]. Actigraphy is a non-invasive method of monitoring the human rest-activity cycle. Although several studies have used actigraphy [...]

Influence of Vegetation on the Nocturnal Foraging Behaviors and Vertebrate Prey Capture by Endangered Burrowing Owls

Marsh, A., T. I. Wellicome, and E. Bayne. 2014. Influence of vegetation on the nocturnal foraging behaviors and vertebrate prey capture by endangered Burrowing Owls. Avian Conservation and Ecology 9(1): 2.http://dx.doi.org/10.5751/ACE-00640-090102

Cone-like rectification properties of cGMP-gated channels in transmutated retinal photoreceptors of nocturnal geckoes.

Photoreceptors of nocturnal geckoes are scotopic, with rod-shaped outer segments, and sensitivities to light similar to the one of retinal rods from other species of lower vertebrates. However, these cells are not rods, but they originated from cones of ancestral diurnal geckoes with pure-cone retinas, after being forced to adapt to a nocturnal behavior. Several interesting adaptations of these rod-like cones have been studied to date; molecular biology and functional studies confirmed that several proteins of the phototransductive cascade display structural and functional properties that indicate their origin from cones rather than from rods. In this paper, we investigate, with whole cell voltage clamp in the photoreceptor detached outer segment preparation, the voltage rectification properties of cGMP-gated channels in three species, Gekko gecko, Tarentola mauritanica, and Hemidactylus frenatus. We show that the current-voltage properties in the physiological voltage range are reminiscent of the ones of cGMP-gated channels from cones rather than from rods of other cold-blooded vertebrates. The origin and the relevance of the mechanisms investigated are discussed.

Things that go bump in the night: diagnosing sleep-related movement disorders without a sleep laboratory.

It is common for general physicians to experience diagnostic doubt and trepidation whenever faced with patients who exhibit abnormal nocturnal behaviours or excessive movements at night. There is also a perception that expensive and often poorly available overnight tests are usually required for diagnostic precision. In fact, the majority of conditions, whether they be parasomnias or, more rarely, nocturnal seizures, can be reliably diagnosed from a directed history, if available. Although the evidence base for treating parasomnias and sleep-related movement disorders remains minimal, accurate recognition is important for a variety of reasons. This review covers the diagnostic features of the full range of parasomnias and movement disorders that might present to a multidisciplinary adult sleep clinic. Throughout, it will be argued that the recognition of key or salient features obtained from a good history is the most important diagnostic tool. Indeed, when diagnostic doubt remains after a thorough sleep history, it is relatively rare for detailed tests to add much in the way of useful information.

Unexpected EEG Abnormalities in Adults with Parasomnia ? A Case Series

Patients with complex nocturnal behaviors (parasomnia, sleepwalking) can sometimes be difficult to distinguish from those with epilepsy.The differential diagnosis includes identifying abnormalities on electroencephalography (EEG) that are specific for epilepsy - epileptiform discharges. Although these are rarely seen in individuals without epilepsy, and unknown to be associated with sleep disorders, we unexpectedly identified focal epileptiform abnormalities among multiple patients who presented with clinical features suggestive of parasomnia rather than epilepsy—they did not have a history of epileptic seizures or risk factors for epilepsy. The individual history of each patient and the type of abnormality are discussed in the context of any potential for increased cortical irritability.

Nocturia reported in nightly sleep diaries: Common occurrence with significant implications?

Nocturia (nocturnal awakenings associated with urination) is so common a nocturnal behavior that its association with poor sleep is often overlooked. This study examined nocturia and its potential role in poor sleep by examining reported nightly awakenings and associated bathroom trips. Sleep diaries were kept by 119 adults with poor sleep for intervals up to 14 days. Diaries collected data on nightly number of awakenings and nightly number of bathroom trips. The proportion of nocturnal awakenings accompanied by voiding for each night was calculated and averaged within each individual. Demographics and various health conditions were examined in relation to this measure. Nocturia was defined when at least two-thirds of all awakenings were associated with nocturnal voiding. Absence of nocturia was defined when less than one-third of awakenings were associated with voiding. Remaining cases were defined as having possible nocturia. Estimates of nocturia derived from prestudy screening were related to nocturia as defined by sleep diaries. Neither gender nor sleep apnea was associated with nocturia. Unadjusted analyses indicated that individuals with nocturia were more likely to have arthritis and attribute their nighttime awakenings to urge to void than individuals without nocturia. Nocturia is an exceedingly common phenomenon and may be associated with multiple morbidities. RESULTS are discussed in terms of causality and whether the perceived urge to void precedes or follows nocturnal awakening. Correlates of nocturia have important implications, because they can inform interventions that target brain (e.g., cognitive-behavioral treatments for insomnia, sedative/hypnotic medications) versus bladder (e.g., bladder control exercises, medications affecting urine production or urgency).

NIGHT-Care: A Passive RFID System for Remote Monitoring and Control of Overnight Living Environment

An Ambient Intelligence platform, NIGHTCare, for remote monitoring and control of overnight living environment is here proposed. The platform, entirely based on RFID passive technology is able to recognize nocturnal behaviors and activities, generates automatic alarms in case of anomalous or pathological events and support diagnostics. The results of a complete test in real scenario are presented, together with a numerical assessment of electromagnetic safety issues.

The active nightlife of diurnal birds: extraterritorial forays and nocturnal activity patterns

Most birds are socially monogamous, diurnally active and have small home ranges. These birds occasionally undertake extraterritorial forays, presumably to seek extrapair copulations. We used automated radiotelemetry to examine nocturnal forays and activity of a diurnal, socially monogamous passerine, the yellow-breasted chat, Icterina virens. Males and females forayed during both day and night, but night forays were more common. In addition to varying between day and night, there were sex- and breeding-stage-specific differences in foraying behaviour. Males forayed more than females and more frequently when their female was not fertile. Conversely, females primarily forayed when fertile. We suggest that females foray at night to avoid detection, because their mate's knowledge of potential extrapair copulations may result in harassment or decreased parental care. Both sexes were nocturnally active; however, the activity of males peaked when their mates were fertile, probably to prevent their mates from foraying and guarding them from foraying males. The nocturnal behaviour of chats suggest that extraterritorial forays may be more common than previously thought and that nocturnal behaviours may be crucial for understanding the strategies males and females use to acquire extrapair copulations.

Does Nocturnality Drive Binocular Vision? Octodontine Rodents as a Case Study

Binocular vision is a visual property that allows fine discrimination of in-depth distance (stereopsis), as well as enhanced light and contrast sensitivity. In mammals enhanced binocular vision is structurally associated with a large degree of frontal binocular overlap, the presence of a corresponding retinal specialization containing a fovea or an area centralis, and well-developed ipsilateral retinal projections to the lateral thalamus (GLd). We compared these visual traits in two visually active species of the genus Octodon that exhibit contrasting visual habits: the diurnal Octodon degus, and the nocturnal Octodon lunatus. The O. lunatus visual field has a prominent 100° frontal binocular overlap, much larger than the 50° of overlap found in O. degus. Cells in the retinal ganglion cell layer were 40% fewer in O. lunatus (180,000) than in O. degus (300,000). O. lunatus has a poorly developed visual streak, but a well developed area centralis, located centrally near the optic disk (peak density of 4,352 cells/mm2). O. degus has a highly developed visual streak, and an area centralis located more temporally (peak density of 6,384 cells/mm2). The volumes of the contralateral GLd and superior colliculus (SC) are 15% larger in O. degus compared to O. lunatus. However, the ipsilateral projections to GLd and SC are 500% larger in O. lunatus than in O. degus. Other retinorecipient structures related to ocular movements and circadian activity showed no statistical differences between species. Our findings strongly suggest that nocturnal visual behavior leads to an enhancement of the structures associated with binocular vision, at least in the case of these rodents. Expansion of the binocular visual field in nocturnal species may have a beneficial effect in light and contrast sensitivity, but not necessarily in stereopsis. We discuss whether these conclusions can be extended to other mammalian and non-mammalian amniotes.

Nocturnal resource defence in aphid‐tending ants of northern Patagonia

Interspecific competition plays a key role in the organisation of ant communities. In ant–plant interactions, individual host plants are usually occupied by a single ant colony, and co‐occurring ant species compete for hosts. Here indirect evidence of competition between three dominant ant species that tend aphids on two biennial thistles in northern Patagonia is described, and a novel defensive behaviour in temperate ant assemblages is reported. This study has found that: (i) dominant ant species were not spatially segregated, thus enhancing the probability of fights and invasions of host plants; (ii) ant species did not show preferences for a thistle species or for any plant characteristic, and thus all plants have similar chances of being colonised by all dominant ant species; (iii) the resident ant species remained on the same plant during the whole plant life cycle, monopolising plant resources (aphids); and (iv) all dominant species, whose nests are on the ground, assigned some ants to stay on the host plant during the night, when the low temperatures typical of this temperate environment greatly reduce foraging activities. When these ‘nocturnal guards’ were experimentally removed from the host plant, other ants from the same colony rapidly appeared showing aggressive behaviours. Taking all these findings together, it is suggested that interspecific competition influences the distribution of ants on their host plants and involves nocturnal defensive behaviours despite unfavourable thermal conditions. This illustrates how habitat features, such as the short life cycle of thistles and the low night‐time temperatures that reduce ant foraging and thus make plants more vulnerable to invasion, might affect the distribution and behaviour of ants.

Heart rate circadian profile in the differential diagnosis between Parkinson disease and multiple system atrophy

Clinical diagnostic criteria indicate presence of autonomic features as the primary hallmark of Multiple System Atrophy (MSA). However involvement of the autonomic system is also a recognized feature of Parkinson's Disease (PD), yielding a broad clinical overlap between the two diseases. Laboratory assessments may help in the differential diagnosis between PD and MSA. Ambulatory Monitoring of Blood Pressure (AMBP) is a suitable tool to study the circadian rhythm of blood pressure (BP) and heart rate (HR). Different studies reported a reduction of physiological BP nocturnal dipping in PD and MSA patients, but failed to identify a distinctive pattern discriminating the two diseases. On the other hand, HR nocturnal behavior has not been exhaustively analyzed. In the present study we compared the profiles of HR circadian rhythm in 61 PD and 19 MSA patients who underwent 24 h AMBP.We found higher nocturnal HR (nHR) (71.5 beats/min ± 7.4) in MSA compared with PD (63.8 beats/min ± 9.6) as well as significantly lower nocturnal decline of HR (ndHR) in MSA (7.3% ± 8.2) vs. PD (14% ± 7.5). At a Receiver Operating Curve analysis nHR and ndHR significantly discriminated MSA from PD. nHR showed a sensitivity of 84.2% and a specificity of 62.3% (AUC 0.76; 95% IC 0.65–0.85); ndHR showed a sensitivity of 68% of and a specificity of 77% (AUC 0.72; 95% IC 0.61–0.82).According to our findings, nHR is increased and ndHR is reduced in MSA compared to PD. Moreover, these two indices discriminate between the two diseases with acceptable accuracy.

Light Pollution Modifies the Expression of Daily Rhythms and Behavior Patterns in a Nocturnal Primate

Among anthropogenic pressures, light pollution altering light/dark cycles and changing the nocturnal component of the environment constitutes a threat for biodiversity. Light pollution is widely spread across the world and continuously growing. However, despite the efforts realized to describe and understand the effects of artificial lighting on fauna, few studies have documented its consequences on biological rhythms, behavioral and physiological functions in nocturnal mammals. To determine the impacts of light pollution on nocturnal mammals an experimental study was conducted on a nocturnal primate, the grey mouse lemur Microcebus murinus. Male mouse lemurs (N = 8) were exposed 14 nights to moonlight treatment and then exposed 14 nights to light pollution treatment. For both treatments, chronobiological parameters related to locomotor activity and core temperature were recorded using telemetric transmitters. In addition, at the end of each treatment, the 14th night, nocturnal and feeding behaviors were explored using an infrared camera. Finally, throughout the study, body mass and daily caloric food intake were recorded. For the first time in a nocturnal primate, light pollution was demonstrated to modify daily rhythms of locomotor activity and core temperature especially through phase delays and increases in core temperature. Moreover, nocturnal activity and feeding behaviors patterns were modified negatively. This study suggests that light pollution induces daily desynchronization of biological rhythms and could lead to seasonal desynchronization with potential deleterious consequences for animals in terms of adaptation and anticipation of environmental changes.

分娩前後における飼育下ニシゴリラ (Gorilla gorilla) の夜間行動の変化

分娩前後における飼育下ニシゴリラ (Gorilla gorilla) の夜間行動の変化

The genome of Mesobuthus martensii reveals a unique adaptation model of arthropods

Representing a basal branch of arachnids, scorpions are known as ‘living fossils’ that maintain an ancient anatomy and are adapted to have survived extreme climate changes. Here we report the genome sequence of Mesobuthus martensii, containing 32,016 protein-coding genes, the most among sequenced arthropods. Although M. martensii appears to evolve conservatively, it has a greater gene family turnover than the insects that have undergone diverse morphological and physiological changes, suggesting the decoupling of the molecular and morphological evolution in scorpions. Underlying the long-term adaptation of scorpions is the expansion of the gene families enriched in basic metabolic pathways, signalling pathways, neurotoxins and cytochrome P450, and the different dynamics of expansion between the shared and the scorpion lineage-specific gene families. Genomic and transcriptomic analyses further illustrate the important genetic features associated with prey, nocturnal behaviour, feeding and detoxification. The M. martensii genome reveals a unique adaptation model of arthropods, offering new insights into the genetic bases of the living fossils.