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Inactivity is a common daytime behavior expressed by wild cats in zoos. It is not clear whether this inactivity is due to the constraints of the captive environment or is a result of a more natural behavior by these animals. Therefore, this work evaluated the behavior of two Panthera onca captive specimens, including their inactivity, during the evening/night period. The jaguars were filmed individually in different days, starting at 5:30 pm and finishing between 7:00 pm and 1:30 am, including non-feeding and feeding days. Regardless of whether they were fed or not, both jaguars expressed a significant rate of inactivity. In addition, when fed, one of the jaguars increased its movements and active behaviors, although its inactivity remained high, while the other jaguar further reduced the expression of such behaviors. Therefore, this work concludes that these jaguars were just as inactive during the evening/night period as they were during daytime. Excessive inactivity might be regarded as a negative behavior; with its highest expression being an effect of the captive environment, which might compromise the welfare of the assessed jaguars and possibly of other wild cats. In addition, since the behavioral expression varied between the studied jaguars, depending on the feeding or non-feeding status, we recommend that futures studies should taking into account the individual variations, especially when there are differences in age, health, and management conditions between the specimens. [ABSTRACT FROM AUTHOR]

Although inbred domesticated strains of rats and mice serve as traditional mammalian animal models in biomedical research, the nocturnal habits of these rodents make them inappropriate for research that requires a model with human-like diurnal activity rhythms. We conducted a literature review and recorded locomotor activity data from four rodent species that are generally considered to be diurnally active, the Mongolian gerbil (Meriones unguiculatus), the degu (Octodon degus), the African (Nile) grass rat (Arvicanthis niloticus), and the antelope ground squirrel (Ammospermophilus leucurus). Our data collected under 12-hour light/dark cycles confirmed and expanded the existing literature in showing that the activity rhythms of antelope ground squirrels and African grass rats are stronger and more concentrated in the light phase of the light/dark cycle than the activity rhythms of Mongolian gerbils and degus, making the former two species preferable and more reliable as models of consistent diurnal activity in the laboratory. Among the two more strongly diurnal species, antelope ground squirrels are more exclusively diurnal and have more robust activity rhythms than African grass rats. Although animals of these two species are not currently available from commercial suppliers, African grass rats are indigenous to a wide area across the north of Africa and thus available to researchers in the eastern hemisphere, whereas antelope ground squirrels can be found throughout much of western North America’s desert country and, therefore, are more easily accessible to North American researchers. [ABSTRACT FROM AUTHOR]

Abstract The mating system represents one key element of a species' life history. Although some life history traits of the edible dormouse (Glis glis) have been investigated thoroughly, little information is available about the mating system of this arboreal, nocturnal, hibernating rodent. Molecular studies have suggested that polygynandry and high prevalence of multiple sired litters are typical among small rodent species. Previous behavioral studies have proposed a promiscuous mating system for the edible dormouse, but clear evidence is still missing. In this study, the genetic mating system of G. glis was evaluated by genotyping free-living dam-offspring groups. Based on the assumption that males establish territories at least during the mating season, male individuals in the vicinity of the selected females were included in the investigation. Parentage assignment was conducted by applying the COLONY and GERUD software, using 19 polymorphic microsatellite loci. Multiple mating within this population of edible dormice was detected by both programs, since all investigated litters were sired by at least two males. Therefore, the results provide the first evidence of polygynandrous mating and multiple paternity occurring in a wild population of edible dormice. However, paternity analysis of the chosen males revealed a low assignment rate of offspring to the candidate sires. These findings support previous hypotheses of non-territoriality in males. [ABSTRACT FROM AUTHOR]

Abstract Different species exhibit individual daily and annual activity patterns in response to a range of intrinsic and extrinsic drivers. Historically, research on the activity budgets of large wild animals focused on daylight hours due to the logistical difficulties of observing animals at night. Thanks to recent advances in animal-attached technology, however, this research can be extended to a 24-h timeframe. Taking advantage of GPS collars with activity sensors collecting a large amount of data per hour, we separately studied diurnal and nocturnal activity patterns of Alpine chamois (Rupicapra rupicapra), in order to identify the factors affecting them and the correlation between them. From March 2010 to November 2013, we collected data on 17 chamois in the Swiss National Park, a strict Alpine nature reserve where human management was forbidden and human harassment quite rare. Environmental factors were found to significantly influence both diurnal and nocturnal activity rhythms, with temperature and seasonality playing a pivotal role. Surprisingly, we detected a stable peak of activity in the first part of the night, which varied only slightly over the year. In summer, the nocturnal activity of males was inversely correlated to diurnal activity, arguably to compensate for scarce diurnal food intake. Conversely, winter nocturnal activity was positively related to the diurnal activity and served as a cumulative opportunity for energy intake. Chamois showed a weak lunarphilia, with a slight increase in activity levels during moonlit nights, especially during the mating season. In conclusion, our findings denote chamois as a cathemeral species able to adapt its behavioural patterns to match varying environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract Landscape conversion to agriculture is the primary cause for habitat loss worldwide. As partial mitigation, agricultural landscapes may be designated as ecological corridors due to their presumed habitability and permeability to wildlife. Behavioral changes following anthropogenic disturbance can affect species' spatio-temporal activity patterns and modify interactions, and thus influence habitat preferences. Understanding how human activity affects wildlife behavior and how such behavioral changes scale up to the community may enhance the effectiveness of conservation schemes. We used camera traps to measure the activity of five mammal species along a disturbance gradient in an agricultural-natural mosaic landscape designated as a national ecological corridor. Wildlife diurnal activity was minimal around towns, where humans were active during the day. Nevertheless, predator activity increased near towns and at other sites of high disturbance. Although attracted to highly disturbed areas, predators avoided humans temporally by restricting activity to night-time, whereas prey activity relative to less disturbed areas was negligible. We conclude that perceived threat from humans during daytime combined with elevated nocturnal predation risk exclude prey species from large areas of an agricultural region designated as ecological corridor. Human activity may have triggered a cascading effect mediated by predators' diel activity shifts, which reduced landscape permeability to prey. Our study underlines the need to consider wildlife diel activity patterns for conservation and environmental management planning. Highlights • Co-occurring mammal species avoid human disturbance by shifting their activity times. • Where human presence is high, species are forced into shorter activity time-windows. • Canine meso-predators thrive in farmed areas, but become almost entirely nocturnal. • Avoiding humans temporally leads prey to simultaneous activity with their predators. • Human- and predator avoidance lead to the exclusion of prey from suitable habitat. [ABSTRACT FROM AUTHOR]

One of the least known aspects of the biology of diurnal birds is their nocturnal behavior, which limits our knowledge on their circadian cycles and total home ranges. We studied the nocturnal behavior of the Pale-breasted Thrush (Turdus leucomelas) in a suburban area in Brazil to investigate the relationship between the night roost and diurnal home range (DHR). Birds returned every night to the same roosts in tall trees with dense canopy. In contrast to their nesting habits, birds did not use buildings as nocturnal roosts. In 4 of 9 cases, night roosts were completely outside the DHR. When they were inside the DHR, night roosts were not close to the core area of the DHR. Our results, together with data for a few other bird species, show that considering nocturnal roosting behavior is essential for a more accurate estimate of home ranges of diurnal birds. [ABSTRACT FROM AUTHOR]

Ecoacoustic monitoring has proved to be a viable approach to capture ecological data related to animal communities. While experts can manually annotate audio samples, the analysis of large datasets can be significantly facilitated by automatic pattern recognition methods. Unsupervised learning methods, which do not require labelled data, are particularly well suited to analyse poorly documented habitats, such as tropical environments. Here we propose a new method, named Multiresolution Analysis of Acoustic Diversity (MAAD), to automate the detection of relevant structure in audio data. MAAD was designed to decompose the acoustic community into few elementary components (soundtypes) based on their time–frequency attributes. First, we used the short-time Fourier transform to detect regions of interest (ROIs) in the time–frequency domain. Then, we characterised these ROIs by (1) estimating the median frequency and (2) by running a 2D wavelet analysis at multiple scales and angles. Finally, we grouped the ROIs using a model-based subspace clustering technique so that ROIs were automatically annotated and clustered into soundtypes. To test the performance of the automatic method, we applied MAAD to two distinct tropical environments in French Guiana, a lowland high rainforest and a rock savanna, and we compared manual and automatic annotations using the adjusted Rand index. The similarity between the manual and automated partitions was high and consistent, indicating that the clusters found are intelligible and can be used for further analysis. Moreover, the weight of the features estimated by the clustering process revealed important information about the structure of the acoustic communities. In particular, the median frequency had the strongest effect on modelling the clusters and on classification performance, suggesting a role in community organisation. The number of clusters found in MAAD can be regarded as an estimation of the soundtype richness in a given environment. MAAD is a comprehensive and promising method to automatically analyse passive acoustic recordings. Combining MAAD and manual analysis would maximally exploit the strengths of both human reasoning and computer algorithms. Thereby, the composition of the acoustic community could be estimated accurately, quickly and at large scale. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: I report on the nocturnal behavior of Fongoli chimpanzees in a savanna mosaic during different seasons and lunar phases and test the hypothesis that hot daytime temperatures influence activity at night. I predicted that apes would be more active at night during periods of greater lunar illuminosity given diurnal primates’ lack of visual specializations for low‐light conditions and in dry season months when water scarcity exacerbated heat stress. Materials and Methods: I observed chimpanzees for 403 hrs on 40 nights between 2007 and 2013 and categorized their activity as social, movement, or vocalization. I scored their activity as occurring after moonrise or before moonset and considered the influence of moon phase (fuller versus darker phases) as well as season on chimpanzee nocturnal behavior in the analyses. Results: Results indicate that apes were more active after moonrise or before moonset during fuller moon phases in the dry season but not the wet season. Most night‐time activity involved movement (travel or forage), followed by social behavior, and long‐distance vocal communication. Discussion: Animals in highly seasonal habitats often exhibit thermoregulatory adaptations but, like other primates, chimpanzees lack physiological mechanisms to combat thermal stress. This study provides evidence that they may exhibit behaviors that allow them to avoid high temperatures in a savanna environment, such as feeding and socializing at night during the hottest time of year and in the brightest moon phases. The results support theories invoking thermal stress as a selective pressure for hominins in open environments where heat would constrain temporal foraging niches, and suggest an adaptability of sleeping patterns in response to external factors. [ABSTRACT FROM AUTHOR]

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Rapid expansion of human activity has driven well-documented shifts in the spatial distribution of wildlife, but the cumulative effect of human disturbance on the temporal dynamics of animals has not been quantified. We examined anthropogenic effects on mammal diel activity patterns, conducting a meta-analysis of 76 studies of 62 species from six continents. Our global study revealed a strong effect of humans on daily patterns of wildlife activity. Animals increased their nocturnality by an average factor of 1.36 in response to human disturbance. This finding was consistent across continents, habitats, taxa, and human activities. As the global human footprint expands, temporal avoidance of humans may facilitate human-wildlife coexistence. However, such responses can result in marked shifts away from natural patterns of activity, with consequences for fitness, population persistence, community interactions, and evolution. [ABSTRACT FROM AUTHOR]

Visual navigation is a benchmark information processing task that can be used to identify the consequence of being active in dim-light environments. Visual navigational information that animals use during the day includes celestial cues such as the sun or the pattern of polarized skylight and terrestrial cues such as the entire panorama, canopy pattern, or significant salient features in the landscape. At night, some of these navigational cues are either unavailable or are significantly dimmer or less conspicuous than during the day. Even under these circumstances, animals navigate between locations of importance. Ants are a tractable system for studying navigation during day and night because the fine scale movement of individual animals can be recorded in high spatial and temporal detail. Ant species range from being strictly diurnal, crepuscular, and nocturnal. In addition, a number of species have the ability to change from a day- to a night-active lifestyle owing to environmental demands. Ants also offer an opportunity to identify the evolution of sensory structures for discrete temporal niches not only between species but also within a single species. Their unique caste system with an exclusive pedestrian mode of locomotion in workers and an exclusive life on the wing in males allows us to disentangle sensory adaptations that cater for different lifestyles. In this article, we review the visual navigational abilities of nocturnal ants and identify the optical and physiological adaptations they have evolved for being efficient visual navigators in dim-light. [ABSTRACT FROM AUTHOR]

The visual systems of many animals, particularly those active during the day, are optimized for high spatial acuity. However, at night, when photons are sparse and the visual signal competes with increased noise levels, fine spatial resolution cannot be sustained and is traded-off for the greater sensitivity required to see in dim light. High spatial acuity demands detectors and successive visual processing units whose receptive fields each cover only a small area of visual space, in order to reassemble a finely sampled and well resolved image. However, the smaller the sampled area, the fewer the photons that can be collected, and thus the worse the visual sensitivity becomes--leading to the classical trade-off between sensitivity and resolution. Nocturnal animals usually resolve this trade-off in favour of sensitivity, and thus have lower spatial acuity than their diurnal counterparts. Here we review results highlighting how hawkmoths, a highly visual group of insects with species active at different light intensities, resolve the trade-off between sensitivity and spatial resolution. We compare adaptations both in the optics and retina, as well as at higher levels of neural processing in a nocturnal and a diurnal hawkmoth species, and also give a perspective on the behavioral consequences. We broaden the scope of our review by drawing comparisons with the adaptive strategies used by other nocturnal and diurnal insects. [ABSTRACT FROM AUTHOR]

Ballooning behaviour is a key trait in spiders, generally performed by juveniles, which allows dispersal from short to long distances. Although aerial dispersal can be risky, the avoidance of unsuitable conditions seems to overcome its potential drawbacks. Allocosa senex (Mello-Leitão, 1945) and A. marindia Simó, Lise, Pompozzi & Laborda, 2017 are two sympatric, nocturnal, wolf spiders, inhabitants of sandy freshwater and oceanic coasts of southern South America. We tested ballooning propensity of these species under natural conditions in day (d) and night (n) experiments. We collected adult females of A. senex, A. marindia and Schizocosa malitiosa (Tullgren, 1905) (control group) carrying spiderlings on their backs. We performed trials to test pre-ballooning occurrence of individual spiderlings as follows: 64 for A. senex (30d, 32n), 40 for A. marindia (20d, 20n) and S. malitiosa (31d, 32n). Both Allocosa spp. showed significantly higher frequencies of pre-ballooning than S. malitiosa in both day and night trials. We did not find differences within species in pre-ballooning occurrence between day and night. Temperature, wind speed, humidity and atmospheric pressure were related to pre-ballooning frequencies during day and night in all species. We discuss the results in relation with microhabitat characteristics in such a dynamic environment. [ABSTRACT FROM AUTHOR]

Recent research suggests that many diurnal songbirds also sing at night. The functions of nocturnal singing by diurnally active birds are not well understood. We used automated recorders to record nocturnal singing from May through July 2014. We examined how date, temperature, wind, weather, and lunar phase influenced nocturnal vocal behaviour. We found that nocturnal singing by ovenbirds and white-throated sparrows was related to date with clear seasonal patterns that did not mirror the dawn chorus. Nocturnal singing rates declined seasonally, but peaked earlier for white-throated sparrows than for ovenbirds. Both species sang less often on nights with a full moon or precipitation. Ovenbirds also sang fewer songs on cold and windy nights while white-throated sparrows sang less often on cloudy nights. We show that nocturnal song is shaped by environmental factors and shows a seasonal pattern that may be useful for gaining insights into functions of nocturnal song. [ABSTRACT FROM AUTHOR]

The authors analyzed the daily activity rhythms of the domestic cat and of eight of the ten feral felid species that are indigenous to South America. All species showed daily rhythmicity of activity in captivity under a natural light-dark cycle. The robustness of the rhythmicity varied from species to species, but the grand mean of 34% was within the range of robustness previously described for mammalian species ranging in size from mice to cattle. There was not a sharp division between diurnal and nocturnal felids. Instead, what was found was a gradient of diurnality going from the predominantly nocturnal margay (72% of activity counts during the night) to the predominantly diurnal jaguarundi (87% of activity counts during the day) with the remaining species lying in between these two extremes. The ecological implications of temporal niche variations are discussed. [ABSTRACT FROM AUTHOR]

In the Neotropics, Ericaceae species occur mainly at high altitudes being adapted to pollination by bees or hummingbirds. These species are mainly self-compatible, a breeding commonly found at high altitudes. Agarista revoluta is an Ericaceae species that occurs in sandy coastal plains ( restinga ), a hot and dry lowland environment unusual for Ericaceae. This species has similar floral traits as other Ericaceae pollinated by bees. However, we do not know what reproductive strategies this plant use to deal with the extreme environment. We studied the floral biology, the breeding system and floral visitors of A. revoluta in the restinga . We found that the species is a generalist being visited by diurnal and nocturnal insects, and that the studied population presents a rare mixed breeding system, with both self-compatible and self-incompatible individuals. These results suggest that A. revoluta differs from other Ericaceae species from the Neotropics by presenting reproductive strategies (generalist pollination and mixed breeding system) that warrant their reproductive success in an unpredictable environment for pollination. [ABSTRACT FROM AUTHOR]

Background: Covering the eye of all snakes is a transparent integumental structure known as the spectacle. In order to determine variations in spectacle thickness among species, the spectacles of 217 alcohol-preserved museum specimens of 44 species belonging to 14 different families underwent optical coherence tomography (OCT) to measure spectacular thickness. Multivariable analyses were made to determine whether family, activity period (diurnal/nocturnal) and habitat (arboreal/terrestrial/fossorial/aquatic) influenced spectacle thickness. Results: The thinnest spectacles in absolute terms were found in the Usambara bush viper (Viperidae) with a thickness of 74 ± 9 μm and the absolute thickest spectacle was found in the red-tailed pipe snake (Cylindrophiidae) which had a spectacle thickness of 244 ± 57 μm. Fossorial and aquatic snakes had significantly thicker spectacles than arboreal and terrestrial snakes. When spectacle thickness was correlated to eye size (horizontal spectacle diameter), Gray's earth snake (Uropeltidae) had the lowest ratio (1:7) and the cottonmouth (Viperidae) had the highest ratio (1:65). Multivariable and phylogenetic analyses showed that spectacular thickness could be predicted by taxonomic family and habitat, but not activity period. Conclusion: This phylogenetically broad systematic study of the thickness of the snake spectacle showed that spectacular thickness varies greatly across snake species and may reflect evolutionary adaptation and development. [ABSTRACT FROM AUTHOR]

Animals that use deceptive visual signals to attract prey often employ colour mimicry or bioluminescence but less commonly self-excreted lures. The conspicuous web decorations and silks of some web-building spiders have been shown to visually lure prey in the daytime. However, it remains unknown whether spider webs can also lure prey at night with these self-produced silks. In this study, we tested this hypothesis by manipulating the coloration of the webs of Psechrus clavis and the presence of the web dwellers. We monitored the foraging performance of four treatment groups (spider present, normal web; spider present, blackened web; spider absent, normal web; spider absent, blackened web) and measured the reflectance spectra of spider body parts and web silks. We found that both spider body colour and web silk can lure insect prey at night. Lepidopteran insects comprised the majority of attracted prey. This study is the first to empirically demonstrate that animals can use self-produced substances to visually lure prey in a nocturnal environment and improve foraging success. [ABSTRACT FROM AUTHOR]

The effects of the moon on organisms have been documented in several animal groups. However, few field studies have considered the real amount of light intensity produced by the interaction of the moon and cloudiness as determinant of nocturnal activity patterns. Many nocturnal animals may present an endogenous cycle with lunar periodicity, but others are believed to respond directly to changing moonlight by synchronizing foraging and reproductive behaviours as well as predatory and anti-predatory strategies. In this study, we investigated whether and how natural environmental brightness affects the oviposition and nocturnal activity of Hyla intermedia. This is one of the few field studies, and the first attempt on amphibians, which tests the effect of measured environmental brightness on the reproductive behaviour of animals. Overall, the nocturnal activity and oviposition strategy of tree frogs appear to be not intrinsically related to the synodic lunar cycle; rather, the moon acts indirectly as the primary source of environmental light by determining an abrupt drop in tree frog activity when light increases beyond the threshold. Tree frogs showed a shift in microhabitat use by occupying concealed habitats in very low light condition and open habitats when moonlight was enough to allow interindividual visual recognition. In this way, males likely counterbalance the risk of being conspicuous to predators by the increased chances to be detected and localized by females through both acoustic and visual stimuli. As for oviposition, tree frogs showed a laying egg activity conditioned by the environmental brightness, with a clear preference towards dark nights resulting from the interactive effect of weather condition and moon phases. We speculate that the evolution of behaviours involving a trade-off between activity and safety could be behind the 'moonlight phobia' showed by the studied tree frog. [ABSTRACT FROM AUTHOR]

In aquatic environments, what one observes during the day can differ substantially by night. The species composition and associated ecological processes that occur during the day are often different than night. In polar seas and at great depths, "night" can span, months, years, and beyond. Teleosts and elasmobranchs have evolved unique sensory and behavioral modalities for living in darkness. As a consequence, fishers have adopted unique strategies for exploiting fish at night or in dark systems. We propose that neglecting the night has led to an incomplete understanding of aquatic organismal ecology, population/community dynamics, and ecosystem function with consequences for fisheries conservation management. To address this knowledge gap and stimulate the exchange of new data and ideas on behaviors, patterns, and processes relating to fish and fisheries in darkness, Fish at Night: an international symposium was held in Miami, Florida (USA), from 18 to 20 November, 2015. Here, we synthesize the findings from the symposium, providing an overview on the state-ofknowledge of fish studies in the dark, identifying critical information gaps, and charting a course for future research. We focus our commentary and synthesis on six areas: (1) nocturnal fish behavior and ecology; (2) fishing, fisheries, and enforcement; (3) deep and polar seas; (4) diel fish distribution and abundance comparisons; (5) methods for studying fish in darkness; (6) human threats to fish at night; and (7) larval fish at night. Taken together, we attempt to "shine a light" on fish at night, generating a greater interest and understanding of fishes and fisheries during darkness. [ABSTRACT FROM AUTHOR]

Over evolutionary time, light from the sun, moon, and stars has provided organisms with reliable information about the passage of time; but modern artificial lighting has drastically altered these cues. Evidence is accumulating that exposure to light at night—particularly blue wavelengths—from computer screens, urban light pollution, or as an occupational hazard of night-shift work has major implications for human health. Nocturnal animals in zoos are generally housed on reversed light cycles and are illuminated by blue or red artificial light so that daytime visitors can observe their active behaviors. However, previous research suggests that exposure to light all 24 h of the day and exposure to blue light during the dark phase can be harmful to human and animal health. Information about the consequences of lighting design for animal health and behavior is needed to formulate evidence-based guidelines for the exhibition of nocturnal animals in zoos. This study was conducted with nocturnal strepsirrhines at two facilities, one where the standard practice was to house nocturnal primates under blue light, and the other red. We experimentally changed the color of light illuminating habitats during the dark phase using an ABA study design and recorded continuous behavior data. We hypothesized that activity levels and time allocated to specific active behaviors would be lower under blue light compared to red. The overall percent of time spent performing active behaviors was lower when subjects were housed under blue light compared to red (generalized linear mixed models: pottos (N = 4), F 1,1169 = 54.0, p < 0.001; pygmy slow lorises (N = 2), F 1,689 = 26.4, p < 0.001; moholi bushbabies (N = 2), F 1,482 = 99.1, p < 0.001; and aye-aye (N = 1), F 1,312 = 8.4, p = 0.005). These changes were largely due to increased time spent moving around exhibits and examining objects under red light. We were also able to measure concentrations of the timekeeping hormone melatonin in the saliva of the aye-aye and found that levels were significantly lower in blue light compared to red (F 1,85 = 18.0, p < 0.001). These results offer a compelling reason to reconsider the practice of exhibiting nocturnal animals under blue light, as wavelength-dependent suppression of behavior and hormones may have important implications for animal health and welfare. [ABSTRACT FROM AUTHOR]

Few estimates of migration rates or descriptions of behavior or survival exist for wild populations of out-migrating Pacific salmon smolts from natal freshwater rearing areas to the ocean. Using acoustic transmitters and fixed receiver arrays across four years (2010-2013), we tracked the migration of >1850 wild sockeye salmon ( Oncorhynchus nerka) smolts from Chilko Lake, British Columbia, to the coastal Pacific Ocean (>1000 km distance). Cumulative survival to the ocean ranged 3-10% among years, although this may be slightly underestimated due to technical limitations at the final receiver array. Distinct spatial patterns in both behavior and survival were observed through all years. In small, clear, upper-river reaches, downstream migration largely occurred at night at speeds up to 50 km/d and coincided with poor survival. Among years, only 57-78% of smolts survived the first 80 km. Parallel laboratory experiments revealed excellent short-term survival and unhindered swimming performance of dummy-tagged smolts, suggesting that predators rather than tagging effects were responsible for the initial high mortality of acoustic-tagged smolts. Migration speeds increased in the Fraser River mainstem (~220 km/d in some years), diel movement patterns ceased, and smolt survival generally exceeded 90% in this segment. Marine movement rates and survival were variable across years, with among-year segment-specific survival being the most variable and lowest (19-61%) during the final (and longest, 240 km) marine migration segment. Osmoregulatory preparedness was not expected to influence marine survival, as smolts could maintain normal levels of plasma chloride when experimentally exposed to saltwater (30 ppt) immediately upon commencing their migration from Chilko Lake. Transportation of smolts downstream generally increased survival to the farthest marine array. The act of tagging may have affected smolts in the marine environment in some years as dummy-tagged fish had poorer survival than control fish when transitioned to saltwater in laboratory-based experiments. Current fisheries models for forecasting the number of adult sockeye returning to spawn have been inaccurate in recent years and generally do not incorporate juvenile or smolt survival information. Our results highlight significant potential for early migration conditions to influence adult recruitment. [ABSTRACT FROM AUTHOR]

The influence of natural enemies has led to the evolution of various predator avoidance strategies in herbivorous insects. Many caterpillars are exclusively active at night and rest during the day. It is widely assumed that nocturnal activity in caterpillars reduces their risk of falling prey to their natural enemies. To test this hypothesis, we compared predation pressure between day and night in tree-fall gaps and closed-canopy forest sites in an Amazonian primary lowland rainforest. Artificial clay caterpillars, showing camouflaged colouration (green), were exposed as potential prey to a natural predator community. Attacks were significantly more frequent during daytime and were reduced by about a quarter at night in tree-fall gaps, and by a third in closed-canopy forest sites. This supports the idea of time-dependent activity in caterpillars as an antipredatory adaptation. Further, independent of the time of day, predation pressure on caterpillars was significantly higher in tree-fall gaps compared to closed-canopy forest habitats. Nearly all predation events were caused by arthropods, whereas birds played a negligible role. Across both habitat types and time scales, ants acted as major predator group, emphasising their important role in population control of herbivorous insects in lowland rainforest ecosystems. This is the first experimental study using artificial caterpillars to examine whether time-scheduling of exposition might influence predation risk amongst undefended, solitary, free-living lepidopteran larvae. [ABSTRACT FROM AUTHOR]

The visual systems of many animals feature energetically costly specializations to enable them to function in dim light. It is often unclear, however, how large the behavioural benefit of these specializations is, because a direct comparison in a behaviourally relevant task between closely related day- and night-active species is not usually possible. Here we compared the orientation performance of diurnal and nocturnal species of dung beetles, Scarabaeus (Kheper) lamarcki and Scarabaeus satyrus, respectively, attempting to roll dung balls along straight paths both during the day and at night. Using video tracking, we quantified the straightness of paths and the repeatability of roll bearings as beetles exited a flat arena in their natural habitat or under controlled conditions indoors. Both species oriented equally well when either the moon or an artificial point light source was available, but when the view of the moon was blocked and only wide-field cues such as the lunar polarization pattern or the stars were available for orientation, nocturnal beetles were oriented substantially better. We found no evidence that ball-rolling speed changed with light level, which suggests little or no temporal summation in the visual system. Finally, we found that both diurnal and nocturnal beetles tended to choose bearings that led them towards a bright light source, but away from a dim one. Our results show that even diurnal insects, at least those with superposition eyes, could orient by the light of the moon, but that dim-light adaptations are needed for precise orientation when the moon is not visible. [ABSTRACT FROM AUTHOR]

The article presents summaries of articles published in the same issue and in other journals including articles in the same issue concerning the shift of mammalian species to becoming more nocturnal to so to avoid humans, the development of an artificial vision system that creates an abstract description of a scene using images taken from different viewpoints without metadata from outside sources, and an article in a 2018 issue of "Cell" on gut bacteria to protect against epileptic seizures.

Photic cues influence daily patterns of activity via two complementary mechanisms: (1) entraining the internal circadian clock and (2) directly increasing or decreasing activity, a phenomenon referred to as “masking”. The direction of this masking response is dependent on the temporal niche an organism occupies, as nocturnal animals often decrease activity when exposed to light, while the opposite response is more likely to be seen in diurnal animals. Little is known about the neural mechanisms underlying these differences. Here, we examined the masking effects of light on behavior and the activation of several brain regions by that light, in diurnal Arvicanthis niloticus (Nile grass rats) and nocturnal Mus musculus (mice). Each species displayed the expected behavioral response to a 1 h pulse of light presented 2 h after lights-off, with the diurnal grass rats and nocturnal mice increasing and decreasing their activity, respectively. In grass rats light induced an increase in cFOS in all retinorecipient areas examined, which included the suprachiasmatic nucleus (SCN), the ventral subparaventricular zone (vSPZ), intergeniculate leaflet (IGL), lateral habenula (LH), olivary pretectal nucleus (OPT) and the dorsal lateral geniculate (DLG). In mice, light led to an increase in cFOS in one of these regions (SCN), no change in others (vSPZ, IGL and LH) and a decrease in two (OPT and DLG). In addition, light increased cFOS expression in three arousal-related brain regions (the lateral hypothalamus, dorsal raphe, and locus coeruleus) and in one sleep-promoting region (the ventrolateral preoptic area) in grass rats. In mice, light had no effect on cFOS in these four regions. Taken together, these results highlight several brain regions whose responses to light suggest that they may play a role in masking, and that the possibility that they contribute to species-specific patterns of behavioral responses to light should be explored in future. [ABSTRACT FROM AUTHOR]

Searching for resources is often a challenging task, especially for small organisms such as insects. Complex stimuli have to be extracted from the environment and translated into a relevant behavioral output. A first step in this process is to investigate the relative roles of the different senses during search for various resources. While the role of olfaction is well documented in nocturnal moths, the olfactory abilities of the closely related diurnal butterflies are poorly explored. Here we investigated how olfactory information is used in the search for host plants and asked if these abilities varied with levels of stimulus complexity. Thus, we tested two nymphalid butterfly species with divergent host plant range in a two-choice olfactometer testing different combinations of host and non-host plants. The experiments show both the monophagous Aglais urticae and the polyphagous Polygonia c- album could navigate towards an odor source, but this ability varied with context. While mated females exhibited a preference for their host plant, unmated females of both species did not show a preference for host plant cues. Furthermore, both species showed inabilities to make fine-tuned decisions between hosts. We conclude that olfactory cues are important for butterflies to navigate towards targets. We argue that there are limitations on how much information can be extracted from host volatiles. These results are discussed in the light of neural processing limitations and degree of host plant specialization, suggesting the necessity of other sensory modalities to sharpen the decision process and facilitate the final oviposition event. [ABSTRACT FROM AUTHOR]

Recognition of the extent and magnitude of night-time light pollution impacts on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and diurnal species. Municipal and industrial lighting is on the cusp of a step change where energyefficient lighting technology is driving a shift from ''yellow'' high-pressure sodium vapor lamps (HPS) to new ''white'' light-emitting diodes (LEDs). We hypothesized that white LEDs would be more attractive and thus have greater ecological impacts than HPS due to the peak UVgreen- blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light 3 air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations. Our findings highlight the urgent need for collaborative research between ecologists and electrical engineers to ensure that future developments in LED technology minimize their potential ecological effects. [ABSTRACT FROM AUTHOR]

Paroedura hordiesi sp. n. is described from Montagne des Français, a karstic limestone massif in the far north of Madagascar recently established as nature reserve. The new species has the nostril in contact with the rostral scale and shares many characters with P. karstophila and especially with P. homalorhina which are also restricted to karstic habitats. Paroedura hordiesi differs from P. karstophila by a smoother skin on dorsum and legs, by original and regenerated tails being both entirely smooth, by colouration, and by larger snout-vent length. Morphologically the new species is most similar to P. homalorhina from the Ankarana reserve from which it can be distinguished by shorter limbs and a less slender habitus. Published molecular data place the new species as close relative of P. homalorhina and another undescribed species from Nosy Hara Island, while newly determined data of the cox1 gene for P. karstophila confirm the distinctness of the new species from this taxon. Integrating the information from published and novel molecular data, the new species differs from all nominal Paroedura (except P. vahiny for which no molecular data are available to date) by strong genetic divergences. P. hordiesi might be another microendemic species of the Montagne des Français region. We suggest its IUCN Red List classification as "Critically Endangered" on the basis that it has an extent of occurrence of at most 50 km, it is known from a single location, and there is a continuing decline in the extent and quality of its habitat. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article discusses a study published in the "Journal of Animal Ecology" co-authored by Laura Prugh and Christopher Golden which found that moonlight does not necessarily assist nocturnal predators find prey. Research also found that predators' responses to moonlight were based on the sensory systems of species more than their position on the food chain.

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. [ABSTRACT FROM AUTHOR]

The expression of heterothermy in the African lesser bushbaby, Galago moholi, seems to be strikingly different to most other heterotherms: G. moholi uses its ability to enter torpor only rarely and torpor is only used by a small fraction of the population. The aim of this study was, therefore, to summarize the parameters of torpor use in G. moholi to conclude the general patterns and discuss them in comparison to other heterotherms to elucidate possible causes and constraints that underlie these differences in deployment of heterothermy. Our study was carried out on wild animals using temperature loggers and open-flow respirometry for measurements of body temperature and metabolic rate, respectively. G. moholi uses torpor only as a last resort and not as a routine, seasonal behavior. Nevertheless, we found that the general physiological patterns of torpor, e.g., torpor bout duration or entry and arousal times from torpor, were mainly consistent with those described for other nocturnal daily heterotherms. The greatest difference found was the unusual low rewarming rates during arousal from torpor, probably due to already depleted internal energy stores and thus inability to mobilize sufficient energy for endogenous heating. We therefore conclude that while general physiological parameters of heterothermy seem to have remained conserved in heterotherms, the underlying causes which elicit this physiological response, and thus the extent of expression and timing of heterothermy, have evolved very differently in different groups, depending on body mass and the specific habitat and lifestyle of the species. [ABSTRACT FROM AUTHOR]

mphipods along the western Antarctic Peninsula appear to gain refuge from predators by associating with chemically defended macroalgae rather than palatable macroalgae. However, nothing is known about amphipod activity at night. If foraging on non-chemically defended macroalgae regularly occurs, then nocturnal foraging seems beneficial since visual predators are disadvantaged. To test this hypothesis, we collected three common macroalgal species and affiliated mesograzers, approximately 3 h before and after sunset. All associated mesofauna were counted and densities recorded. Amphipod densities were significantly decreased during the night on the chemically defended Desmarestia menziesii, while significantly increased on the palatable Iridaea cordata. Additionally, the amphipod Gondogeneia antarctica was found in significantly higher densities at night on Palmaria decipiens, a species shown to be readily eaten by G. antarctica and omnivorous fish. We believe that chemically defended macroalgae act as a refuge for mesograzers during the day, while more widespread foraging occurs at night. [ABSTRACT FROM AUTHOR]

Food anticipatory behavior (FAA) is induced,by limiting access to food for a few hours daily. Animals anticipate this scheduled meal event even without the suprachiasmatic nucleus (SCN), the biological clock. Consequently, a food-entrained oscillator has been proposed to be responsible for meal time estimation. Recent studies suggested the dorsomedial hypothalamus (DMH) as the site for this food-entrained oscillator, which has led to considerable controversy in the literature. Herein we demonstrate by means of c-Fos immunohistochemistry that the neuronal activity of the suprachiasmatic nucleus (SCN), which signals the rest phase in nocturnal animals, is reduced when animals anticipate the scheduled food and, simultaneously, neuronal activity within the DMH increases. Using retrograde tracing and confocal analysis, we show that inhibition of SCN neuronal activity is the consequence of activation of GABA-containing neurons in the DMH that project to the SCN. Next, we show that DMH lesions result in a loss or diminution of FAA. simultaneous with increased activity in the SCN. A subsequent lesion of the SCN restored FAA. We conclude that in intact animals, FAA may only occur when the DMH inhibits the activity of the SCN, thus permitting locomotor activity. As a result, FAA originates from a neuronal network comprising an interaction between the DMH and SCN. Moreover, this study shows that the DMH-SCN interaction may serve as an intrahypothalamic system to gate activity instead of rest overriding circadian predetermined temporal patterns. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Eye movements convey important information about brain function. Neuropsychiatric conditions and medications may produce abnormal eye movements (EMs) in sleep. Serotonergic drugs are known to increase nocturnal EMs. Few studies have quantified sleep EMs due to technical complexity. We investigated the effects of serotonergic drugs on slow EMs in sleeping patients using an objective automated EM quantification tool. Methods: We studied patients who had polysomnograms for clinical assessment. We identified 5 sertraline, 7 citalopram, and 4 fluoxetine users who were not using other psychoactive medications. Controls were 10 age-matched patients on no medications. An automated objective EM detection tool was developed. The first and last 5min of each sleep stage were assessed. ANOVA was used to assess the effects of time, stage, and medication. Results: No differences were noted between SSRI users and controls in demographics. Medications were associated with more slow EMs compared to controls (p<0.05). Among SSRI users, a non-statistical trend was noted for increasing slow EMs in the following pattern: sertraline

Mongolian Gerbils are often used as a biological model, but it remains unclear whether these rodents display nocturnal, diurnal, or crepuscular patterns of behavior. The experiments presented below studied patterns of sleep-activity, feeding, and reproductive behavior under 12:12 light dark cycles. All data from these experiments suggest a nocturnal pattern of behavior in these rodents. [ABSTRACT FROM AUTHOR]

This paper reports the results of the first study on secondary seed removal of seeds dispersed by Sykes' monkeys ( Cercopithecus albogularis) using camera traps in Africa. Patterns of primary seed dispersal are often superimposed by secondary conveyance, emphasising the need to study these secondary processes carefully. As the agents and mechanisms of seed dispersal are often concealed, being carried out by cryptic or nocturnal animals in dense vegetation, camera trapping was deemed a viable means to investigate secondary removal of seeds disseminated by C. albogularis in the Western Soutpansberg, South Africa. Camera traps were established at preferred feeding trees of the focal Sykes' monkey group to identify animal species that remove seeds and fruits spat and dropped to the forest floor and seed removal observations were carried out. This method proved to be effective in identifying seed removers and also allowed to get indications about the quantities of seeds removed. Ten animal species were recorded visiting the trees, of which eight were observed removing seeds and fruits. Overall seed and fruit removal rates were high, indicating that the foraging behaviour of C. albogularis attracts many terrestrial frugivores. [ABSTRACT FROM AUTHOR]

The Mysore slender loris, Loris lydekkerianus lydekkerianus is a nocturnal strepsirrhine primate endemic to India. As with other lorisine species, there have been few studies on this taxon and much still remains unknown about it. During a 21-month study on a Mysore slender loris population in Tamil Nadu, southern India, we collected data on the ecology and behaviour of 32 identified individuals. Certain aspects of diet and social behaviour of lorises in this population vary from what is already known for the Mysore slender loris in another part of southern India, offering a new perspective into behavioural variations in this taxon. Evidence for behavioural variation in the Mysore slender loris is significant for two reasons - one, there are few instances of clearly documented intraspecific variation in wild nocturnal primate species and two, this flexibility, it would appear, allows the Mysore slender loris to inhabit and survive in degraded and disturbed habitats across southern India, an adaptability that is thus critically linked to its conservation status. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the female rules of prioritization of multimodal cues. The material and methods used in the study are discussed, including two indoor two-stimuli experiments. The study challenges the assumption that communication in nocturnal anurans is mainly acoustic. The results of the study explain the frequent failure of field studies to find a correlation between male calling behaviour and observed mating success.

Dabbling ducks generally use distinct day roost and nocturnal habitats, the set of which constitute their 'functional unit'. The rate at which these birds may switch between day roosts has never been quantified. Using resightings of nasalsaddled birds and capture-recapture modelling in the Camargue, southern France, we estimated the weekly probability that a teal Anas crecca switches from one day roost to another one nearby (transition probabilities). We also estimated the probability that a teal survives and remains in our study area, consisting of four neighbouring roosts (apparent survival). Birds were highly faithful to one specific water body if they remained in our study area (i.e. weekly rate of switching between roosts was only about 2-6%), but the probability that an individual remained within one of the four roosts from one week to the next (local weekly apparent survival rate) was only 60-70%. Intensive search efforts led to a 60% detection probability. Low local apparent survival coupled with very high site fidelity within the system suggests that two distinct strategies may coexist, i.e. frequent movement between distant winter quarters vs very high fidelity to the very same local wetland. Such strategies may be used successively by the same individuals, or may alternatively represent distinct bird categories (i.e. transients vs residents). In any case, these different strategies suggest that habitat management procedures need to be considered at both local and flyway scales simultaneously. The former may ensure that sites repeatedly used by the same individuals can provide adequate conditions to birds when they remain in a given winter quarter, while the latter will ensure transient birds find appropriate sites within the network of distant wetlands they may use as successive wintering quarters during a season. [ABSTRACT FROM AUTHOR]

Summary: Light has profound behavioral effects on almost all animals, and nocturnal animals show sensitivity to extremely low light levels . Crepuscular, i.e., dawn/dusk-active animals such as Drosophila melanogaster are thought to show far less sensitivity to light . Here we report that Drosophila respond to extremely low levels of monochromatic blue light. Light levels three to four orders of magnitude lower than previously believed impact circadian entrainment and the light-induced stimulation of locomotion known as positive behavioral masking. We use GAL4;UAS-mediated rescue of tyrosine hydroxylase (DTH) mutant (ple) flies to study the roles of dopamine in these processes. We present evidence for two roles of dopamine in circadian behaviors. First, rescue with either a wild-type DTH or a DTH mutant lacking neural expression leads to weak circadian rhythmicity, indicating a role for strictly regulated DTH and dopamine in robust circadian rhythmicity. Second, the DTH rescue strain deficient in neural dopamine selectively shows a defect in circadian entrainment to low light, whereas another response to light, positive masking, has normal light sensitivity. These findings imply separable pathways from light input to the behavioral outputs of masking versus circadian entrainment, with only the latter dependent on dopamine. [Copyright &y& Elsevier]

Summary: Anthropogenic disturbance is a major cause of worldwide declines in biodiversity . Understanding the implications of this disturbance for species and populations is crucial for conservation biologists wishing to mitigate negative effects. Anthropogenic light pollution is an increasing global problem , affecting ecological interactions across a range of taxa and impacting negatively upon critical animal behaviors including foraging, reproduction, and communication (for review see ). Almost all bats are nocturnal , making them ideal subjects for testing the effects of light pollution. Previous studies have shown that bat species adapted to foraging in open environments feed on insects attracted to mercury vapor lamps. Here, we use an experimental approach to provide the first evidence of a negative effect of artificial light pollution on the commuting behavior of a threatened bat species. We installed high-pressure sodium lights that mimic the intensity and light spectra of streetlights along commuting routes of lesser horseshoe bats (Rhinolophus hipposideros). Bat activity was reduced dramatically and the onset of commuting behavior was delayed in the presence of lighting, with no evidence of habituation. These results demonstrate that light pollution may have significant negative impacts upon the selection of flight routes by bats. [Copyright &y& Elsevier]

Most bees forage for floral resources during the day, but temporal patterns of foraging activity vary extensively, and foraging in dim-light environments has evolved repeatedly. Facultative dim-light foraging behaviour is known in five of nine families of bees, while obligate behaviour is known in four families and evolved independently at least 19 times. The light intensity under which bees forage varies by a factor of 108, and therefore the evolution of dim-light foraging represents the invasion of a new, extreme niche. The repeated evolution of dim-light foraging behaviour in bees allows tests of the hypothesis that behaviour acts as an evolutionary pacemaker. With the exception of one species of Apis, facultative dim-light foragers show no external structural traits that are thought to enable visually mediated flight behaviour in low-light environments. By contrast, most obligate dim-light foragers show a suite of convergent optical traits such as enlarged ocelli and compound eyes. In one intensively studied species ( Megalopta genalis) these optical changes are associated with neurobiological changes to enhance photon capture. The available ecological evidence suggests that an escape from competition for pollen and nectar resources and avoidance of natural enemies are driving factors in the evolution of obligate dim-light foraging. [ABSTRACT FROM AUTHOR]

Hatchery-reared salmon, Salmo salar L., smolts are generally stocked during daylight hours, but the natural migration of smolts tends to occur at night. Recapture rates and timing of migration were compared between Atlantic salmon smolts stocked during the day and during the evening. Timing of release had no significant effect on the number of smolts recaptured, but had a strong effect on nocturnal behaviour. When stocked in the evening (but not during the day) hatchery-reared smolts moved almost exclusively during the night. This study suggests that timing the release to coincide with the natural time of smolt migration may provide valuable acclimatisation and facilitate nocturnal smolt passage. [ABSTRACT FROM AUTHOR]

The article presents a research on the evolution of primate visual systems. It differentiates nocturnal primates such as the nocturnal monkey Aotus from diurnal ones like the lemurs of the genus Eulemur. It analyzes the common assumption that ancestral primates were nocturnal. An evaluation of fossil primates' features is offered. It states also the advantages and disadvantages of the parsimony approach in interpreting past events.