Diel Activity Patterns Research Articles

A noisy neighbour: acoustic competition drives changes in song traits and spatiotemporal behaviour of orthopterans

Competition for acoustic space is key for sound-communicating animals, yet little is known about whether and how it may drive evolutionary pathways, for example signal structure, as well as species distributions or individual spatial behaviour. Here we assessed the occurrence of interspecific acoustic competition in sound-communicating taxa by testing three nonmutually exclusive hypotheses explaining variability of song structure and singing activity, in two sibling species of tree crickets of the genus Oecanthus. By comparing song acoustic parameters, diel activity patterns and relative densities of singing crickets in both sympatry and allopatry, we found that the local co-occurrence of the two species drives changes in all the considered factors of song production. Namely, we report changes in temporal and structural song traits, as well as in singing activity patterns and apparent population density, with strongly asymmetrical effects, only evident for one of the two species considered. Our results highlight the role of acoustic space as a key resource that shapes biotic interactions, and eventually behaviours, in sound-communicating taxa, and represent a replicable approach in the study of acoustic assemblages.

Non-exploitative human disturbance provides shelter for prey from predator.

Human activities can influence behaviors of predators and prey, as well as predator-prey interactions. Using camera trap data, we investigated whether or to what extent human activities influenced behaviors of predators (tigers and leopards) and prey (sambar deer, spotted deer, wild boar, and barking deer), and predator-prey interactions in the Barandabhar Corridor Forest (BCF), Chitwan District, Nepal. A multispecies occupancy model revealed that the presence of humans altered the conditional occupancy of both prey and predator species. Specifically, the conditional occupancy probability of prey was substantially higher (ψ = 0.91, CI = 0.89-0.92) when humans were present than when humans were absent (ψ = 0.68, CI = 0.54-0.79). The diel activity pattern of most prey species overlapped strongly with humans, whereas predators were generally more active when humans were absent. Finally, the spatiotemporal overlap analysis revealed that human-prey interactions (i.e., the probability that both humans and prey species being present on the same grid at the same hourly period) was ~3 times higher (10.5%, CI = 10.4%-10.6%) compared to spatiotemporal overlap between humans and predators (3.1%, CI = 3.0%-3.2%). Our findings are consistent with the human shield hypothesis and suggest that ungulate prey species may reduce predation risk by using areas with high human activities.

Diel activity patterns of rocky shore macroinvertebrates in the northern Baltic Sea

Marine invertebrates on rocky shores form dynamic communities in time and space. Invertebrates constitute important links in the food chain and in biogeochemical cycles and are thus essential for functioning ecosystems. Species can be diurnal or nocturnal, and adaptions can be explained by predation pressure and resource availability. Contrary to terrestrial species, marine invertebrates are less specialised in single hosts and can, when needed, switch habitats, a trait that favours survival, growth, and reproduction.Variation in movement patterns of macroinvertebrates was studied on the northwestern Åland Islands (Åland Sea) to assess changes in activity on a diel timescale along the summer season. Two methods were used to collect representative samples of both swimming and non-swimming species. The pool of macroinvertebrate taxa in the study area was controlled for by sampling ambient macroalgae-associated fauna. Results show that all swimming and epifaunal mobile macroinvertebrate taxa move actively either in the free water body or along the sea floor within a 24-h period. A preference towards nocturnal activity could be observed as the total abundance of macroinvertebrates was higher during the night. Mean taxonomic richness was somewhat higher at night for the swimming macroinvertebrates. The community structure of mobile macroinvertebrates changed within a 24-h period as, e.g. Palaemon spp. and P. ulvae were more prevalent, and larger individuals were generally more active at night. The methods used were suitable for describing the activity patterns of macroinvertebrates on shallow rocky shores, and the results are essential for understanding the temporal dynamics of complex littoral rocky shore communities.

Neotropical understory birds and mammals show divergent behaviour responses to human pressure

Human pressures such as hunting and habitat destruction can generate a deep fear in animals and this fear can influence their diel activity patterns and use of space. However, whether these behavioural responses to human pressure are consistent among key functional groups has been poorly studied. For example, while mammal species tend to become more nocturnal in areas with high human pressure, it is unclear if co-occurring birds display similar or opposite patterns. Here we used information from camera trapping (367 camera stations and 16,939 camera/days) along a gradient of human pressure in the Colombian Llanos to assess diel activity changes in understory birds and mammals. We found that diel activity significantly changed with higher human pressure for 45% of the birds (five species) and 36% of the mammals (five species) assessed, with four of five birds becoming more diurnal and all five mammals becoming more nocturnal. The average increase in nocturnality for the mammals was 11.3% while the average increase in diurnality for the birds was 7%. There was high variation in body size and dietary guild within impacted species, and only some were directly persecuted or hunted, suggesting that there are different pathways through which human pressure can affect vertebrates’ activity patterns. The contrasting behavioural responses to humans among vertebrate functional groups has significant repercussions for the fields of community ecology, including intraguild predation and competition, and should be a significant ecosystem-level conservation consideration.

Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish

Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuticals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife.

Variation in human diel activity patterns mediates periodic increases in recreational activity on mammal behavioural response: investigating the presence of a temporal ‘weekend effect’

Variation in human diel activity patterns mediates periodic increases in recreational activity on mammal behavioural response: investigating the presence of a temporal ‘weekend effect’

Depth Partitioning and Diel Movement of Two Large Carcharhinid Sharks in Extremely Shallow Waters

Two species of carcharhinid sharks aggregate every winter at the warm water effluent of a coastal power plant on the Israeli Mediterranean coast. The two species (Carcharhinus obscurus and Carcharhinus plumbeus) cooccur in a highly confined area for several months every year and are highly associated with the area in and around the hot water effluent. Niche partitioning has recently been suggested as a mechanism that enables the coexistence of similar shark species by resource partitioning, spatial partitioning, and temporal partitioning. In this study, we used acoustic telemetry to study the individual diel movement and activity patterns within this enclosed area and examined the differences between the two species sharing it. Although this location only reaches a maximum depth of 7.5 m, we found both species perform a diel vertical movement, rising closer to the surface at night and moving deeper during daytime. Furthermore, the two shark species swam at different depths both day and night, with C. obscurus swimming in the upper column, about 2 m shallower than C. plumbeus. The very small scale of movement, which nearly equals the sharks’ body length, suggests movement patterns might be conserved at the species level. Moreover, spatiotemporal differences between the two species may reflect a mean of interspecific partitioning that occurs even in a highly confined and shallow habitat.

Diel activity patterns of vector mosquito species in the urban environment: Implications for vector control strategies.

Mathematical models have been widely used to study the population dynamics of mosquitoes as well as to test and validate the effectiveness of arbovirus outbreak responses and mosquito control strategies. The objective of this study is to assess the diel activity of mosquitoes in Miami-Dade, Florida, and Brownsville, Texas, the most affected areas during the Zika outbreak in 2016-2017, and to evaluate the effectiveness of simulated adulticide treatments on local mosquito populations. To assess variations in the diel activity patterns, mosquitoes were collected hourly for 96 hours once a month from May through November 2019 in Miami-Dade County, Florida, and Brownsville, Texas. We then performed a PERMANOVA followed by a SIMPER analysis to assess whether the abundance and species richness significantly varies at different hours of the day. Finally, we used a mathematical model to simulate the population dynamics of 5 mosquito vector species and evaluate the effectiveness of the simulated adulticide applications. A total of 14,502 mosquitoes comprising 17 species were collected in Brownsville and 10,948 mosquitoes comprising 19 species were collected in Miami-Dade County. Aedes aegypti was the most common mosquito species collected every hour in both cities and peaking in abundance in the morning and the evening. Our modeling results indicate that the effectiveness of adulticide applications varied greatly depending on the hour of the treatment. In both study locations, 9 PM was the best time for adulticide applications targeting all mosquito vector species; mornings/afternoons (9 AM- 5 PM) yielded low effectiveness, especially for Culex species, while at night (12 AM- 6 AM) the effectiveness was particularly low for Aedes species. Our results indicate that the timing of adulticide spraying interventions should be carefully considered by local authorities based on the ecology of the target mosquito species in the focus area.

Can behaviour and physiology mitigate effects of warming on ectotherms? A test in urban ants.

Global climate change is expected to have pervasive effects on the diversity and distribution of species, particularly ectotherms whose body temperatures depend on environmental temperatures. However, these impacts remain difficult to predict, in part because ectotherms may adapt or acclimate to novel conditions or may use behavioural thermoregulation to reduce their exposure to stressful microclimates. Here we examine the potential for physiological and behavioural changes to mitigate effects of environmental warming on five species of ants in a temperate forest habitat subject to urban warming. We worked in eight urban and eight non-urban forest sites in North Carolina, USA; sites experienced a 1.1°C range of mean summer air temperatures. At each site, we documented species-specific microclimates (ant operative temperatures, Te ) and ant activity on a transect of 14 bait stations at three times of day. In the laboratory, we measured upper thermal tolerance (CTmax ) and thermal preference (Tpref ) for each focal species. We then asked whether thermal traits shifted at hotter sites, and whether ants avoided non-preferred microclimates in the field. CTmax and Tpref did not increase at warmer sites, indicating that these populations did not adapt or acclimate to urban warming. Consistent with behavioural thermoregulation, four of the five species were less likely to occupy baits where Te departed from Tpref . Apparent thermoregulation resulted from fixed diel activity patterns that helped ants avoid the most inappropriate temperatures but did not compensate for daily or spatial temperature variation: Hotter sites had hotter ants. This study uses a novel approach to detect behavioural thermoregulation and sublethal warming in foraging insects. The results suggest that adaptation and behaviour may not protect common temperate forest ants from a warming climate, and highlight the need to evaluate effects of chronic, sublethal warming on small ectotherms.

Spatiotemporal distributions of mammals occurring in an agro-prairie ecosystem.

Anthropogenic activities since the European colonization of the North American Great Plains have drastically altered landscape composition and configuration, subsequently affecting native biodiversity. These contemporary human-modified landscapes may affect mammal species' distributions, diel activity patterns, habitat use, and interspecific interactions, though a better understanding of these effects on mammals occurring in remaining prairie landscapes is needed. To fill this gap, we surveyed 381 randomly selected sites in 2018, 2019, and 2020 using motion-sensing camera traps across the western part of the US state of Kansas (7,160,077 ha). Sites were separated by ≥2 km ( = 8.16 km, SD = 3.61), and cameras were secured to a metal post 40 cm above ground and randomly oriented toward the north or south. We placed an olfactory attractant (mixture of skunk essence and petroleum jelly) on a wooden stake 3 m in front of each camera. Cameras were in place at each site for 28 consecutive days for each year. We manually identified all mammal species detected at each site, collating these data into a database that included taxonomic information for 14 families of mammals (Antilocapridae, Bovidae, Canidae, Cervidae, Cricetidae, Dasypodidae, Didelphidae, Erethizontidae, Felidae, Heteromyidae, Leporidae, Mephitidae, Mustelidae, Procyonidae, Sciuridae, and Muridae) comprising 28 total species. We recorded 31,178 mammal photographs (nonindependent events) over 27,954 camera trap nights during 2018 (n = 10,351), 2019 (n = 9478), and 2020 (n = 8125). Additionally, we included the time and date of each photocapture. Moreover, we gathered survey-specific data useful for modeling species-specific detection along with site-level habitat composition data taken at each site each year. These data will be useful for examining habitat use, species distributions, diel activity patterns, and spatiotemporal interactions between species and across guilds of mammals occurring in a rapidly changing agro-prairie ecosystem. There are no copyright restrictions, but we ask researchers to cite this paper when using these data for publication.

Effects of sardines as an attractant on carnivore detection and temporal activity patterns at remote camera traps

Context Adding an attractant to remote camera traps has become a popular method to increase detections of cryptic carnivores. However, there is ongoing debate about whether this practice can bias the behaviour and activity patterns of these species. Aims Our aim was to determine how using a popular attractant at camera traps could affect carnivore detection probabilities and temporal activity. Methods We used an experimental design in which we randomly set half of our camera traps on arrays at two sites in western North Carolina with an attractant: canned sardines in oil. Halfway through the survey season, we switched which camera traps had sardines and which did not. We estimated detection probability for each carnivore species observed using occupancy models, and we used kernel density estimations to evaluate changes in diel activity patterns between camera traps with and without an attractant. Key results We found that when sardines were used at camera traps, detectability of bobcats (Lynx rufus), coyotes (Canis latrans), northern raccoons (Procyon lotor), Virginia opossums (Didelphis virginiana), and eastern spotted skunks (Spilogale putorius) more than doubled, but there was little or no effect on striped skunk (Mephitis mephitis) detectability. Of the species we most frequently detected (coyotes, raccoons, and opossums), activity patterns between camera traps with and without a sardine attractant overlapped moderately to highly, and a significant effect on diel activity patterns was observed only for raccoons. Conclusions Use of attractants can greatly increase the probability of detecting nearly all carnivores at camera traps. The effects of attractants on diel activity patterns are species-specific, with two of our three most-detected species unaffected by their use, suggesting that attractants can be used to effectively study these behaviours in some carnivore species. Implications A sardine attractant can increase the detection of many carnivore species, using camera traps, without causing a significant deviation of diel activity patterns, thus allowing for unbiased investigations into most species’ spatio–temporal behaviour in the Appalachian Mountains – and likely other systems.

Spatial and temporal separation of toothed whales in the western North Atlantic

A diverse group of toothed whale species inhabits the pelagic habitats of the western North Atlantic, competing for overlapping prey resources. Historical data deficits have limited fundamental research into many of these species, such as establishing baselines of distribution and abundance, so their occurrence and habitat use patterns are not well characterized. Periodic cycles in activity have been reported at a range of temporal scales for odontocetes in other regions, such as seasonal movements, foraging activity modulated by lunar cycles, and diel activity patterns. A variety of spatial, temporal, and behavioral separation strategies have also been observed among predator guilds in both marine and terrestrial systems, and these may also contribute to observed spatiotemporal patterns in activity. Recently, passive acoustic data has been applied to monitor odontocete species continuously, with improved detection and species discrimination for some cryptic species. We used a long-term passive acoustic data set collected at sites spanning the western North Atlantic shelf-break region to quantify presence and characterize seasonal, lunar, and diel activity patterns for 10 species. Our results demonstrated strong regional preferences and clear patterns of spatiotemporal separation between species with similar foraging ecology. Latitudinal shifts in seasonal presence peaks may suggest meridional seasonal migrations for some dolphin species. We also observed strong diel activity patterns that were modulated by both seasonal and lunar cycles. This study reveals complex behavioral patterns arising in response to natural cycles playing out over multiple temporal scales and provides new insights into habitat partitioning among toothed whale species.

Estimation of diel activity patterns of wild boars using camera trap surveys in Shizukuishi, Iwate Prefecture

Estimation of diel activity patterns of wild boars using camera trap surveys in Shizukuishi, Iwate Prefecture

Characterising diel activity patterns to design conservation measures: Case study of European bat species

Although diel activity time is a major axis of species' niche space, very few conservation measures focus on preserving daily periods free of anthropogenic pressures. While the spatial ecology of bats has received much attention, less is known about their temporal ecology, the knowledge being dispersed in studies of limited taxonomical, spatial and temporal range. We used data from the French bat monitoring program based on citizen science and standardised acoustic recordings (4409 sites monitored and 9807 nights monitored from 2014 to 2020) to characterise the diel activity patterns of 20 bat species so that their consideration in mitigation measures can help conservation. We designed a method to extract times of key descriptors and describe bat activity distribution throughout the night. We found that bat species could be separated in three functional groups characterised by a crepuscular activity, an activity that occurs when it is completely dark or an intermediate activity. We showed variations of diel activity patterns depending on season. We argue that accounting for these complex diel activity patterns would help design efficient mitigation measures, for instance to reduce the exposure of bats to light pollution or wind turbines. Overall, we advocate multi-taxa approaches to design conservation policies adapted to both the temporal and spatial distributions of species.

Home range and activity patterns of the Critically Endangered endemic pygmy raccoon of Cozumel Island, México

AbstractIndividuals from island and continental mammal populations have shown a number of differences in their behavioral ecology. We predicted that, like other island carnivores exhibiting dwarfism, the pygmy raccoon (Procyon pygmaeus), a Critically Endangered carnivore endemic to Cozumel Island, México, would show differences in its home ranges and activity patterns when compared to its mainland counterpart, the racoon, P. lotor. We radio-tracked 11 individuals (six males, five females) from February to July 2017 and used location data derived from triangulation to estimate the home range size, diel activity patterns, and distances traveled of pygmy raccoons. Individuals showed an average home range size between 96.9 ± 18.8 ha (95% minimum convex polygon) and 123.3 ± 31.2 ha (95% fixed kernel). Home ranges of males (109.4–142.8 ha) were larger than those of females (81.8–99.9 ha). Average home ranges were in the lower extreme of those reported for continental raccoons. Activity patterns of pygmy raccoons generally begin at sunset and continue up to 04:00 with rare activity peaks during the day; there were no significant differences in activity patterns between sexes. Data on spatial needs of individuals, and differences between sexes or insular versus continental populations have implications for conservation planning and management.

Consistent diel activity patterns of forest mammals among tropical regions

An animal’s daily use of time (their “diel activity”) reflects their adaptations, requirements, and interactions, yet we know little about the underlying processes governing diel activity within and among communities. Here we examine whether community-level activity patterns differ among biogeographic regions, and explore the roles of top-down versus bottom-up processes and thermoregulatory constraints. Using data from systematic camera-trap networks in 16 protected forests across the tropics, we examine the relationships of mammals’ diel activity to body mass and trophic guild. Also, we assess the activity relationships within and among guilds. Apart from Neotropical insectivores, guilds exhibited consistent cross-regional activity in relation to body mass. Results indicate that thermoregulation constrains herbivore and insectivore activity (e.g., larger Afrotropical herbivores are ~7 times more likely to be nocturnal than smaller herbivores), while bottom-up processes constrain the activity of carnivores in relation to herbivores, and top-down processes constrain the activity of small omnivores and insectivores in relation to large carnivores’ activity. Overall, diel activity of tropical mammal communities appears shaped by similar processes and constraints among regions reflecting body mass and trophic guilds.

Mosquito host-seeking diel rhythm and chemosensory gene expression is affected by age and Plasmodium stages

Malaria parasites can affect vector-related behaviours, increasing transmission success. Using Anopheles gambiae and Plasmodium falciparum, we consider the effect of interaction between infection stage and vector age on diel locomotion in response to human odour and the expression of antennal chemosensory genes. We identified age-dependent behavioural diel compartmentalisation by uninfected females post-blood meal. Infection disrupts overall and diel activity patterns compared with age-matched controls. In this study, mosquitoes carrying transmissible sporozoites were more active, shifting activity periods which corresponded with human host availability, in response to human odour. Older, uninfected, blood-fed females displayed reduced activity during their peak host-seeking period in response to human odour. Age- and infection stage-specific changes in odour-mediated locomotion coincide with altered transcript abundance of select chemosensory genes suggesting a possible molecular mechanism regulating the behaviour. We hypothesize that vector-related behaviours of female mosquitoes are altered by infection stage and further modulated by the age post-blood meal of the vector. Findings may have important implications for malaria transmission and disease dynamics.

Seasonal and diel activity patterns of small mammal guilds on the Pannonian Steppe: a step towards a better understanding of the ecology of the endangered Hungarian birch mouse (Sicista trizona) (Sminthidae, Rodentia)

Temporal activity differences facilitate species’ coexistence by reducing interspecific competition. Such patterns can be studied via diel activity analysis, but obtaining data in cryptic mammals is difficult. We investigated the annual and diel activity pattern of such a small mammal, the endangered Hungarian birch mouse (Sicista trizona trizona), in its only known habitat. We employ trail cameras for the first time to reveal the diel and annual activity of a sminthid species. Data acquisition included the spring and summer seasons between 2019 and 2022 and was extended to detect the activity overlaps with other common coexisting rodents and shrews. The diel activity results rely on 581 detections of S. trizona over 5670 trap-nights of camera trap deployment characterising also activity pattern of the small mammal community in this Central European grassland ecosystem. S. trizona was not recorded during the day but was active at dawn and night, and in comparison with other coexisting species, its activity level was high. The presumed cold sensitivity was not confirmed as we detected activity at −6 °C. Diel activity peaked in early May in the mating season. Although the diel activity pattern of co-occurring small mammal species was also nocturnal, activity overlaps were relatively high suggesting that temporal niche partitioning is limited within the habitat. Our work provides the first insight into temporal overlaps within a small mammal community in a natural European grassland, moreover, also the first documented research on the activity pattern of a sminthid in its natural habitat.

Individual differences in diel and vertical activity patterns in a large pelagic predator, the oceanic whitetip shark

Individual differences in diel and vertical activity patterns in a large pelagic predator, the oceanic whitetip shark

Impact of human disturbance in Japan on the distribution and diel activity pattern of terrestrial mammals

Human disturbance has been identified as a contributing factor to the worldwide changes in wildlife ecology. Particularly, the human disturbance forced wildlife from diurnal to nocturnal activity patterns. However, the impact of human disturbances on the spatiotemporal patterns small- and medium-sized terrestrial mammals is unknown. In this study, we then aimed to evaluate the impact of anthropogenic factors on spatial pattern and to clarify the differences in temporal patterns between human disturbed and undisturbed habitats. Our camera trap survey was conducted in northern Gifu Prefecture in central Japan from November 2019 to April 2021. We investigated the impact of human activity on relative abundance indices and the influence of the quantitative difference in human activities on diel activity patterns of 12 terrestrial mammals. In this study, the human population and bamboo forest category negatively affected the RAIs of sika deer and wild boars. Moreover, Asian black bears and wild boars showed crepuscular/nocturnal and cathemeral activity in the human undisturbed habitat, respectively, and nocturnal activity in the human disturbed habitat. Consequently, three large mammals avoided human activity temporally (Asian black bears), spatially (sika deer), and spatiotemporally (wild boars). On the other hand, there was no significant impact of human activity on the spatiotemporal patterns of other mammals. However, it is necessary for residents in the human disturbed habitat to be recognize the risk of human-wildlife conflicts.