Nocturnal Conditions Research Articles

Vertical and diel niches modulate thermal selection by rainforest frogs.

Thermoregulatory behaviour determines an organism's body temperature and therefore its physiological condition, and may differ for organisms situated across climate gradients. Species' preferred or selected temperatures may be higher in warmer locations-referred to as coadaptation-or lower in warmer temperatures-countergradient variation. Here, we tested if rainforest amphibians exhibited coadaptation or countergradient thermal selection across an underappreciated spatial climate gradient (vertical height from forest floor to canopy) and separating diel activity (diurnal versus nocturnal behaviour). We captured 2534 amphibians over 216 ground-to-canopy surveys, and conducted 282 thermal selection assays for 37 species while pairing microclimate measurements and mechanistic model predictions to understand vertical and daily thermal variation in the field. Amphibians exhibited countergradient thermal selection: species occupying cool nocturnal conditions in canopies selected warmer temperatures than species occupying hot diurnal conditions at the forest floor. Furthermore, amphibians selected warmer temperatures than the average conditions that they were exposed to when active, and this divergence was especially high for nocturnal arboreal species (8.68°C). This suggests that rainforest amphibians dramatically underfill the warm end of their thermal niches, a trend across local thermal gradients that reflects recent findings across elevational and latitudinal gradients. We show that considering multidimensional climate gradients is important to evaluate thermoregulatory behaviour, and its evolutionary underpinnings, for understanding species' niches and community assembly.

LIASM-NRID: Constructing an atmospheric scattering model for low-light conditions and dehazing nighttime road images

Dehazing of nighttime road images holds significant practical relevance for autonomous driving and intelligent transportation systems operating in nocturnal conditions. To address the limitations of traditional atmospheric scattering models in accurately describing the imaging process in low illumination environments such as nighttime, this study constructs a low illumination environment atmospheric scattering model. Based on this newly constructed model, we propose an algorithm specifically designed for dehazing road images at nighttime. The proposed model incorporates an incident light attenuation factor, an additive noise factor, and a global compensation factor related to the scene's depth. The proposed nighttime road image dehazing algorithm firstly suppresses the interference of additive noise in the original image using wavelet decomposition and soft thresholding operation. Then, a transmittance-solving method containing the primary structural information of the image is designed based on the color attenuation linear model, and the solved transmittance is refined based on the interval gradient image texture structure method. Consequently, the global light map estimation process is formulated as an optimization problem to ensure the accuracy of the atmospheric light value calculation. In the final stages, a novel RGB color equalization method is introduced to address the issue of non-uniform incident light color bias in the dehazed images. Additionally, to eliminate the halo problem in the dehazed images, the adaptive histogram equalization algorithm is modified by incorporating a normalized gamma correction function. The experimental results show that the proposed nighttime road image dehazing algorithm exhibits robust performance and generality across various nighttime scenes. Compared with the representative algorithms for nighttime image dehazing, it can get more excellent dehazing results and has more outstanding performance in all numerical evaluation indexes.

A framework for untangling the consequences of artificial light at night on species interactions.

Although much evidence exists showing organismal consequences from artificial light at night (ALAN), large knowledge gaps remain regarding ALAN affecting species interactions. Species interactions occur via shared spatio-temporal niches among species, which may be determined by natural light levels. We review how ALAN is altering these spatio-temporal niches through expanding twilight or full Moon conditions and constricting nocturnal conditions as well as creating patches of bright and dark. We review literature from a database to determine if ALAN is affecting species interactions via spatio-temporal dynamics. The literature indicates a growing interest in ALAN and species interactions: 58% of the studies we analysed have been published since 2020. Seventy-five of 79 studies found ALAN altered species interactions. Enhancements and reductions of species interactions were equally documented. Many studies revealed ALAN affecting species interactions spatially, but few revealed temporal alterations. There are biases regarding species interactions and ALAN-most studies investigated predator-prey interactions with vertebrates as predators and invertebrates as prey. Following this literature review, we suggest avenues, such as remote sensing and animal tracking, that can guide future research on the consequences of ALAN on species interactions across spatial and temporal axes. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Night light polarization: Modeling and observations of light pollution in the presence of aerosols and background skylight or airglow

We introduce a new polarized radiative transfer model able to compute the polarization measured by a virtual instrument in a given nocturnal environment recreating real world conditions (1-dimensional atmospheric and aerosol profiles, 3-dimensional light sources with complex and widespread geometries, terrain obstructions). Initially developed to address the issue of aurorae and nightglow polarization, the model has potential applications in the context of light pollution, or aerosols and air pollution measurements in night time conditions. We provide the physical assumptions behind the model together with the main points regarding its numerical implementation, together with the inherent constraints and liberties it brings. The model, based on single scattering equations in the atmosphere, is first tested on a few simple configurations to assess the effect of several key parameters in controlled environments. The model outputs are then compared to field measurements obtained in four wavelengths at mid-latitude in a dark valley of the French Alps, 20 km away from the closest city. In this context where the nightglow emissions are supposedly stationary and widespread, a convincing fit between the model predictions and observations is found in three wavelengths. This confrontation of ground-based records with our modeling constitutes a proof of concept for the investigation of our polarized environment in nocturnal conditions, in the presence of localized and/or extended sources. It calls for further investigations. In particular we discuss the future need for inter-calibrating the sources and the polarimeter in order to optimally extract the information contained in such measurements, and how multiple-scattering (not implemented in the present study) could impact our observations and their interpretation.

Predicting Peak Wind Gusts during Specific Weather Types with the Meteorologically Stratified Gust Factor Model

Abstract Wind gusts present challenges to operational meteorologists, both to forecast accurately and also to verify. Strong wind gusts can damage structures and create costly risks for diverse industrial sectors. The meteorologically stratified gust factor (MSGF) model incorporates site-specific gust factors (the ratio of peak wind gust to mean wind speed) with wind speed and direction forecast guidance. The MSGF model has previously been shown to be a viable operational tool that exhibits skill (improvement over climatology) in forecasting peak wind gusts. This study assesses the performance characteristics of the MSGF model by evaluating peak gust predictions during several types of gust-producing weather phenomena. Peak wind gusts were prepared and verified for seven specific weather conditions over an 8-yr period at 16 sites across the United States. When coupled with two forms of model output statistics (MOS) wind guidance, the MSGF model generally shows skill in predicting peak wind gusts at forecast projections ranging from 6 to 72 h. The model performed best during high pressure and nocturnal conditions and was also skillful during conditions involving snow. The model did not perform well during the “rain with thunder” weather type. The MSGF model is a viable tool for the operational prediction of peak gusts for most gust-producing weather types. Significance Statement Wind gusts are an important and potentially costly environmental hazard. Wind gusts affect many industrial sectors, including transportation, power generation, forestry, construction, and insurance, but predicting gusts remains a challenging component of weather forecasting. Recent studies have demonstrated that the meteorologically stratified gust factor (MSGF) model shows skill in predicting peak gusts. This study shows that the MSGF model is skillful at predicting peak gusts during specific types of gust-producing weather phenomena at forecast projections up to 72 h, providing further confirmation that the MSGF model is a viable tool for the operational prediction of peak gusts.

Driving Mechanisms of Double-Nosed Low-Level Jets during MATERHORN Experiment

AbstractIn the realm of boundary layer flows in complex terrain, low-level jets (LLJs) have received considerable attention, although little literature is available for double-nosed LLJs that remain not well understood. To this end, we use the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) dataset to demonstrate that double-nosed LLJs developing within the planetary boundary layer (PBL) are common during stable nocturnal conditions and present two possible mechanisms responsible for their formation. It is observed that the onset of a double-nosed LLJ is associated with a temporary shape modification of an already-established LLJ. The characteristics of these double-nosed LLJs are described using a refined version of identification criteria proposed in the literature, and their formation is classified in terms of two driving mechanisms. The wind-driven mechanism encompasses cases where the two noses are associated with different air masses flowing one on top of the other. The wave-driven mechanism involves the vertical momentum transport by an inertial–gravity wave to generate the second nose. The wave-driven mechanism is corroborated by the analysis of nocturnal double-nosed LLJs, where inertial–gravity waves are generated close to the ground by a sudden flow perturbation.

Transfer Learning for Clinical Sleep Pose Detection Using a Single 2D IR Camera.

Sleep quality is an important determinant of human health and wellbeing. Novel technologies that can quantify sleep quality at scale are required to enable the diagnosis and epidemiology of poor sleep. One important indicator of sleep quality is body posture. In this paper, we present the design and implementation of a non-contact sleep monitoring system that analyses body posture and movement. Supervised machine learning strategies applied to noncontact vision-based infrared camera data using a transfer learning approach, successfully quantified sleep poses of participants covered by a blanket. This represents the first occasion that such a machine learning approach has been used to successfully detect four predefined poses and the empty bed state during 8-10 hour overnight sleep episodes representing a realistic domestic sleep situation. The methodology was evaluated against manually scored sleep poses and poses estimated using clinical polysomnography measurement technology. In a cohort of 12 healthy participants, we find that a ResNet-152 pre-trained network achieved the best performance compared with the standard de novo CNN network and other pre-trained networks. The performance of our approach was better than other video-based methods for sleep pose estimation and produced higher performance compared to the clinical standard for pose estimation using a polysomnography position sensor. It can be concluded that infrared video capture coupled with deep learning AI can be successfully used to quantify sleep poses as well as the transitions between poses in realistic nocturnal conditions, and that this non-contact approach provides superior pose estimation compared to currently accepted clinical methods.

Nocturnal reef residents have deep-sea-like eyes

Swirling with colour, coral reefs teem with vivid life during daylight. But at night, a different crew emerges from the nooks and crannies. ‘The visual systems of teleost fish usually match their habitats and lifestyles’, says Fanny de Busserolles from The University of Queensland (UQ), Australia, explaining that there has been a lot of interest in the vision of the gaudy creatures that populate reefs by day. However, less was known about the vision of their nocturnal cohabitants. ‘I am particularly interested in visual adaptations and capabilities in dim light’, says de Busserolles, who is intrigued by the vision of deep-sea fish. So, when she arrived in subtropical Brisbane to work with Justin Marshall at UQ, the chance to investigate some of the nocturnal creatures residing on the Great Barrier Reef was too good to pass up.‘Holocentrids [squirrelfish and soldierfish] were the ideal family for our study due to their connection to the deep-sea environment’, says de Busserolles, explaining that the fish are linked to her love of the depths; ‘the entire family is thought to have originated in deeper water before most of its representatives migrated up to the reef’, she says. Fishing in the sea around Lizard Island, Australia, with UQ colleagues Fabio Cortesi, Sara Stieb, Martin Luehrmann and Marshall, de Busserolles collected four species of soldierfish and five different squirrelfish. ‘They were pretty hard to catch during the day because they are very shy and tend to hide in holes, caves and crevices’, de Busserolles recalls.Looking at the overall structure of the eyes back in Brisbane, de Busserolles could see that they were large, to collect as much light as possible in the dim conditions. And, when Cortesi extracted the RNA from each retina to find out which light-sensitive genes the fish were expressing, he found that all of the fish expressed one rod opsin – which they produced in high levels in their light-sensitive rod cells. In addition, the fish expressed some colour-sensitive cone opsin genes, but at much lower levels than the rod opsin, with the soldierfish expressing two cone opsins while the squirrelfish expressed three cone opsins. Luehrmann also simulated which shades the colour-sensitive cone opsins detect and it turned out that they pick up shades of green and blue. In addition, Sara Stieb revealed two types of cone in the fishes’ retinas: cones expressing the blue opsin, with a second type expressing one or two green opsin genes. ‘These findings indicate that holocentrids may be able to see colours during the day’, says de Busserolles.However, when she and Lily Fogg (also from UQ), painstakingly investigated the distribution of photoreceptor cells in the fishes’ retinas, it was apparent that their eyes are also extremely well prepared for dim nocturnal conditions. Instead of carrying a single layer of photoreceptors at the back of the eye, the fish's retinas comprised stacks of rod cells layered one on top of another, with up to 17 rod cell layers in the eyes of crimson soldierfish (Myripristis murdjan). Explaining that these ‘multibank’ retinas are mostly found in deep-sea species, de Busserolles says, ‘We do not know what the function of this adaptation is, but possible hypotheses are that they may enhance the sensitivity of the eye and/or they may provide some kind of colour vision in dim light conditions’.So, soldierfish and squirrelfish are well prepared for their nocturnal life on the Great Barrier Reef and de Busserolles and her colleagues are keen to find out just how good the fish's colour vision is, especially in the dimmest conditions.

The Food of Athene noctua in nocturnal conditions as located in University of Agriculture, Faislabad

This study was primarily focused on determining the availability of feeding niche of the little owl in University Campus. For this purpose, observations were made consecutively on the location of important sites in University Student’s Farm. This Farm is characterized by different types of tree species. Some of the important ones comprise Salmalia malabarica, Dalbergia sissoo, Cedrella toona, Terminalia arjuna and few others. The little owl mainly feeds on small insects and occasionally on very small mammals and perhaps on the small chicks. Small insects made the major portion of the diet of Athene noctua.

Characterizing urban pollution variability in Central Poland using radon-222

Abstract Four years of observations of radon, meteorology and atmospheric pollution was used to demonstrate the efficacy of combined diurnal and synoptic timescale radon-based stability classification schemes in relating atmospheric mixing state to urban air quality in Zgierz, Central Poland. Nocturnal radon measurements were used to identify and remove periods of non-stationary synoptic behaviour (13–18% of each season) and classify the remaining data into five mixing states, including persistent temperature inversion (PTI) conditions, and non-PTI conditions with nocturnal conditions ranging from well mixed to stable. Mixing state classifications were performed completely independently of site meteorological measurements. World Health Organization guideline values for daily PM2.5/PM10 were exceeded only under strong PTI conditions (3–15% of non-summer months) or often under non-PTI stable nocturnal conditions (14–20% of all months), when minimum nocturnal mean wind speeds were also recorded. In non-summer months, diurnal amplitudes of NO (CO) increased by the factors of 2–12 (3–7) from well-mixed nocturnal conditions to PTI conditions, with peak concentrations occurring in the morning/evening commuting periods. Analysis of observations within radon-derived atmospheric mixing ‘class types’ was carried out to substantially clarify relationships between meteorological and air quality parameters (e.g. wind speed vs. PM2.5 concentration, and atmospheric mixing depth vs. PM10 concentration).

Estimations of the Mexicali Valley (Mexico) Mixing Height

We report estimations of the Mexicali Valley (Mexico) mixing height for three seasons. Surface and upper air meteorological measurements were carried out nearby Cerro Prieto geothermal power plant during July 2010 (summer), January 2012 (winter), and October 2016 (autumn). Four different methods were applied to estimate the convective boundary layer (CBL) height from radiosonde (RS) profiles: the parcel method, the gradients method, the least-squares variational approach based on the slab model of the CBL structure, and a covariance method. For nocturnal conditions, we used diagnostic models based on friction velocity and Monin–Obukhov length. Under unstable conditions, we obtained (on average) mixing heights of 497 m at 06:00 LST, 1242 m at 12:00 LST, 1404 m at 15:00 LST, and 482 at 18:00 LST during summer; 754 m at 12:00 LST during winter; and 1195 m at 12:00 LST and 13:00 m between the 14:00 and 15:00 LST during the autumn. The results allowed adjusting a semiempirical model to evaluate mixing height from turbulent sensible heat flux and friction velocity data. Our results provide practical tools that could facilitate the application of regulatory dispersion models to assess air quality in the region.

A Meteorological Study of the Port Hills Fire, Christchurch, New Zealand

AbstractIn February 2017, a wildfire occurred in the Port Hills on the southern boundary of Christchurch city in New Zealand. It was one of the country’s most severe fires of the last decade in terms of the scale of evacuation, infrastructure damage, and property loss. On the third day of the fire, fire behavior was unexpectedly active, and two rapid downhill fire-spread events took place, creating a dangerous situation for firefighters. The aim of this paper is to explore the atmospheric processes that influenced the fire behavior at a range of meteorological scales, from the synoptic to meso- and microscales. Meteorological and fire data analyzed include observed data together with model simulations of weather conditions at different scales: 1) the Weather Research and Forecasting (WRF) numerical weather prediction model, which provided the regional context of the fire; and 2) the California Meteorological (CALMET) diagnostic model, which was used to undertake a higher-resolution investigation of atmospheric processes near the fire. Results indicate that the fire was not strongly seasonally influenced. Instead, it appears the fire conditions were the effect of a specific combination of synoptic weather conditions and local meteorological conditions. The first rapid downhill fire-spread event was the result of airflow interaction with the intricate terrain of the Port Hills under stable nocturnal conditions. The second downhill fire-spread event bears similarities to vorticity-driven lateral spread, because the downhill component of the spread happened on a broad fire flank perpendicular to the surface wind direction and characteristic pyrocumulus convection occurred.

Turbulent Heat and Momentum Exchange in Nocturnal Drainage Flow Through a Sloped Vineyard

High-frequency measurements are available at five heights within and above a row-gap trellised vineyard located on a 7$$^{\circ }$$ slope in the Southern Okanagan Valley, British Columbia, Canada. During a 3-week campaign in July 2016, approximately 17% of the nocturnal conditions exhibit drainage flow along the local slope. Drainage conditions are characterized by temperature inversions beginning around $$z/h_c = 0.39$$, where z is the height above ground level (a.g.l.) and $$h_c$$ is the canopy height (2.3 m a.g.l.), and near-surface lapses. Changes in the sign of the streamwise momentum flux suggest the presence of a jet maximum around $$z/h_c = 1.65$$, while a weak inflection point is observed near the canopy top, suggesting dynamical influences from both the drainage layer and canopy layer on the turbulent flow field. The largest observed fluxes in both the streamwise momentum flux and the turbulent sensible heat flux are near the top of the canopy, consistent with the location of the inflection point. Calculated two-point length scales from along-slope distributed temperature measurements reveal that turbulent structures are smallest near the canopy top. Conditional sampling of the three-dimensional velocity components and temperature indicate that a large fraction of canopy-layer transport is driven by canopy top turbulence, with sweeps dominating over ejections, particularly at $$z/h_c = 0.65$$.

Improved method for characterising temporal variability in urban air quality part I: Traffic emissions in central Poland

Four years of observations in Central Poland are used to assess the ability of a recently-improved radon-based stability classification technique to investigate temporal variability in urban air quality (specifically NOx and CO). After isolating periods of greatest synoptic non-stationarity, observations were assigned (in whole 24-h blocks) to one of four atmospheric mixing categories. Wind speed more than doubled from the most stable to the most well mixed nocturnal conditions in non-winter months, reducing nocturnal radon accumulation by a factor of five. A strong seasonality in NOx and CO concentrations was observed, contributed to by changing atmospheric mixing depths (day and night) and additional cold-season combustion sources. Peak daily NO concentrations typically increased by a factor of 2–4 from the most well-mixed to most stable conditions, with smaller changes for NO2 and CO (factor of 1.5–2). For non-winter months urban air quality was typically best in the afternoons, when mixing was deepest, but also improved in the 3–4 h after midnight due to advection of cleaner air from outside the city. Specific air quality influences were attributed to parts of Łódź and localised sources in the region, but the topographic setting of the monitoring site also played an important role. Emissions from nearby point sources were often brought to the site in katabatic flows when gradient winds were light. Observed daytime local CO contributions in summer were almost entirely attributable to vehicle emissions, whereas an additional afternoon source of around 48 mg m−2 h−1 in winter was attributed to combustion for heating (likely more at night). Winter local afternoon CO contributions attributable to local domestic combustion were estimated to be up to a factor of three less than the CO being advected to the study region from upwind European source regions.

Modeling Migratory Flight in the Spruce Budworm: Circadian Rhythm

The crepuscular (evening) circadian rhythm of adult spruce budworm (Choristoneura fumiferana (Clem.)) flight activity under the influence of changing evening temperatures is described using a mathematical model. This description is intended for inclusion in a comprehensive model of spruce budworm flight activity leading to the simulation of mass migration events. The model for the temporal likelihood of moth emigration flight is calibrated using numerous observations of flight activity in the moth’s natural environment. Results indicate an accurate description of moth evening flight activity using a temporal function covering the period around sunset and modified by evening temperature conditions. The moth’s crepuscular flight activity is typically coincident with the evening transition of the atmospheric boundary layer from turbulent daytime to stable nocturnal conditions. The possible interactions between moth flight activity and the evening boundary layer transition, with favorable wind and temperature conditions leading to massive and potentially successful migration events, as well as the potential impact of climate change on this process, are discussed.

Modeling Migratory Flight in the Spruce Budworm: Temperature Constraints

We describe an individual-based model of spruce budworm moth migration founded on the premise that flight liftoff, altitude, and duration are constrained by the relationships between wing size, body weight, wingbeat frequency, and air temperature. We parameterized this model with observations from moths captured in traps or observed migrating under field conditions. We further documented the effects of prior defoliation on the size and weight (including fecundity) of migrating moths. Our simulations under idealized nocturnal conditions with a stable atmospheric boundary layer suggest that the ability of gravid female moths to migrate is conditional on the progression of egg-laying. The model also predicts that the altitude at which moths migrate varies with the temperature profile in the boundary layer and with time during the evening and night. Model results have implications for the degree to which long-distance dispersal by spruce budworm might influence population dynamics in locations distant from outbreak sources, including how atmospheric phenomena such as wind convergence might influence these processes. To simulate actual migration flights en masse, the proposed model will need to be linked to regional maps of insect populations, a phenology model, and weather model outputs of both large- and small-scale atmospheric conditions.

Impact of thermosiphon on nocturnal yield of conventional solar still

A mathematical model to predict the thermosiphon flow rate of a single slope solar still coupled with evacuated tube collector and its validation with experiments is presented in this paper. The objective of this experimental investigation is to determine the significance of thermosiphon flow rate and its impact on the fresh water yield during nocturnal conditions. The coupled system operates under thermosiphon through a heat exchanger placed within the basin water. The work was extended to study the influence of ambient temperature on thermosiphon head generated in the system. It was interesting to observe that higher temperature of water in Evacuated Tubular Collector (ETC) tank did not contribute to better flow rate at the inlet of the siphon circuit for varying exit temperatures. Numerical analysis was performed to determine the thermosiphon flow rate and it has good agreement with the experimental results.

Day–night and seasonal variations of a subterranean invertebrate community in the twilight zone

Being characterized by the absence of light and a reduced environmental cyclicity, the subterranean domain is generally regarded as temporally stable. Yet, in the proximity of cave entrances (twilight zones), patterns of sunlight and darkness can be detected within the 24-hour day–night cycle. In parallel, changes in the abiotic and biotic conditions are expected; however, these patterns have been rarely explored in animal communities dwelling in the twilight zone. We performed a biological investigation in a small abandoned mine in the Western Alps, monitoring it once per season, both during the day and at night. At each survey, we collected data on the spatial distribution of the resident species, their activity patterns, and the main microclimatic parameters. We observed significant daily variations in the environmental conditions during winter and spring, namely higher temperature, relative humidity and availability of trophic resources at night. In conjunction with these disparate nocturnal conditions, the abundance of troglophile species was also higher, as well as the activity patterns of one of the most frequent species inhabiting the entrance area – the orb-weaver spiderMetamenardi. We further documented temporal changes in the composition of the parietal community, due to species using the mine as a diurnal, nocturnal or overwintering shelter. Overall, our results suggest that the communities of the twilight zone are not temporally stable and we highlight the importance of taking into account not only their seasonal, but also their daily variations.

The Post Nocturnal Condition: Electric Light in the Urban Environment

The Post Nocturnal Condition: Electric Light in the Urban Environment

Flying sand-dwelling spiders: aerial dispersal in Allocosa marindia and Allocosa senex (Araneae: Lycosidae)

Aerial dispersal in spiders or ballooning is typically considered to occur during the day by juvenile instars or small-sized adults. Allocosa marindia Simó, Lise, Pompozzi & Laborda, 2017 and Allocosa senex (Mello-Leitão, 1945) are two nocturnal wolf spiders that inhabit coastal sandy beaches of South America. As mothers of both species emerge from the burrows during the night to disperse the spiderlings, we expected that aerial dispersal of spiderlings could occur during that period. Our aim was to test ballooning occurrence in both species during day and night under laboratory conditions, using as a positive control, the wolf spider Schizocosa malitiosa (Tullgren, 1905). We examined ballooning behavior of once-molted spiderlings of A. marindia, A. senex and S. malitiosa, under diurnal and nocturnal conditions, recording observations in a container with grasses and sand as substrate. We exposed the spiderlings to air flow and recorded occurrences of climbing the grass, dropping on dragline and tip-toeing (pre-ballooning behaviors). The three species performed pre-ballooning behaviors during the day but also in the night, and the occurrences of these behaviors varied both within and among species. More events of pre-ballooning behavior were observed during the day than during the night. However, we found differences in the number of events of tip-toeing and dropping on dragline according to the time of the day. We discuss the possibility that microhabitat conditions could affect ballooning propensity particularly in the three coastal wolf spiders.