Diel Activity Patterns Research Articles

Seasonal and diel activities of the Yangtze finless porpoise in natural and highly disturbed habitats: Implications for conservation planning of freshwater cetaceans

Abstract Knowledge of fine‐scale seasonal and diel activity patterns of animals provides insights into habitat utilization dynamics and informs conservation action planning against potential human impacts. Such information is particularly important for riverine cetaceans, such as the Yangtze finless porpoise, which is threatened by habitat loss and disturbances by a variety of human activities. Passive acoustic monitoring (PAM) techniques were used to survey the seasonal and diel activities of the Yangtze finless porpoise in two natural habitat patches of the Anqing Yangtze Finless Porpoise Natural Reserve, and in one highly disturbed area adjacent to the reserve. In the two natural habitat patches, significantly higher detection rates of porpoises were observed during autumn and winter. The detection rates during autumn and winter were significantly higher at night than during daytime, whereas during spring and summer the diel difference in porpoise detection rates was not statistically significant. In the highly disturbed habitat, the porpoise detection rates were significantly lower than those in the two natural habitats. Although seasonal differences in porpoise detection rates were not statistically significant, diel detection rates were significantly different in autumn and winter. Information on seasonal patterns of porpoise activities suggested strengthening monitoring and law enforcement during autumn and winter, during the period in which diel activity patterns implied a potential conservation gap during nighttime. Extremely low levels of porpoise activities in port areas implied an ecological impact of coastal engineering on megafauna viability through the alteration of habitat functionality. To provide information on animal occurrences and activities and to minimize the bias of ‘false‐absence’ from visual surveys, the census survey design should consider both visual and PAM techniques. In seasons when occurrences of river cetaceans and habitat use are increasing, heightened conservation monitoring and law enforcement efforts are required, particularly during nighttime.

Diversity and diel activity patterns of terrestrial mammals in the Nkuba Conservation Area, Democratic Republic of the Congo

AbstractThe Congo basin forests have vast conservation potential but because of their inaccessibility and periodic insecurity there is little formal protection or ecological research occurring there. Community-based conservation efforts in the unprotected forest corridor separating Kahuzi-Biega and Maiko National Parks in eastern Democratic Republic of the Congo aim to protect a unique forest ecosystem and facilitate the development of ecological research. To support this process, we obtained baseline data on the occurrence of terrestrial mammals in the Nkuba Conservation Area by conducting camera-trap (2014–2018) and transect (2013–2018) surveys. From camera-trap images we also extracted diel activity patterns and estimated overlap in these patterns between selected pairs of species. We identified 29 mammal species weighing > 1 kg using camera traps and 22 species in transect surveys, with a total of 33 mammal species, of which seven are categorized as threatened on the IUCN Red List. Among this mammalian community, we recorded nocturnal and diurnal species with short core activity periods, and several cathemeral species with long activity periods, with various degrees of temporal separation of diel activity between species. The presence of threatened species, including the Critically Endangered Grauer's gorilla Gorilla beringei graueri, suggests that the Nkuba Conservation Area harbours a forest community that requires continuous monitoring, further research and investment in protection from the ongoing deforestation and resource exploitation occurring in the surrounding region.

Temporal resource partitioning mediates vertebrate coexistence at carcasses: The role of competitive and facilitative interactions

Unravelling how biodiversity is maintained despite species competition for shared resources has been a central question in community ecology, and is gaining relevance amidst the current biodiversity crisis. Yet, we have still a poor understanding of the mechanisms that regulate species coexistence and shape the structure of assemblages in highly competitive environments such as carrion pulsed resources. Here, we study how large vertebrates coexist in scavenger assemblages by adapting their diel activity at large ungulate carcasses in NW Spain. We used camera traps to record vertebrate scavengers consuming 34 carcasses of livestock and hunted wild ungulates, which allowed us to assess also differences regarding carcass origin. To evaluate temporal resource partition among species, we estimated the overlap of diel activity patterns and the mean times of each scavenger at carcasses. We recorded 16 species of scavengers, 7 mammals and 9 birds, and found similar richness at both types of carcasses. Birds and mammals showed contrasting diel activity patterns, with birds using carcasses during daytime (mean= 11:38 h) and mammals mostly at night (23:09 h). The unimodal activity patterns of scavengers showed asynchronous peaks among species. Subordinate species modified their activity patterns at carcasses used by apex species to reduce temporal overlap. Also, diel activity patterns of vultures closely followed those of corvids, suggesting facilitation processes in which corvids would enhance carcass detection by vultures. Two mammal species (12.5%) increased nocturnality at carcasses of hunted ungulates, which could be a response to human disturbance. Our results suggest that both temporal segregation and coupling mediate the coexistence of large vertebrates at carcasses. These mechanisms might lead to richer scavenger assemblages and thereby more efficient ones in driving critical ecosystem functions related to carrion consumption, such as energy and nutrient recycling and biodiversity maintenance.

Size of Snake Eyes Correlates With Habitat Types and Diel Activity Patterns

Eye size influences visual acuity, sensitivity, and temporal resolution and is a result of vertebrate adaptation to the environment. The habitats of snake species are diverse, ranging from fossorial, terrestrial, arboreal, to aquatic. They also demonstrate a variety of behavioral and physiological characteristics, such as activity time, feeding patterns, and prey detection. In this study, we comparatively investigated how the relative eye size (i.e., eye diameter vs. head width) associated with the ecological (i.e., habitat), behavioral (i.e., diel activity pattern, foraging strategy), and physiological traits (i.e., the presence of pits), respectively, across six snake families from Taiwan. Among the traits we examined, we found that terrestrial and/or diurnal snakes tended to exhibit the larger relative eye size, indicating the evolutionary responses of eye size to changes in habitat types and activity patterns, respectively, while no evidence of how foraging strategies and the presence of pits affected snake eye size was found. Our findings not only shed light on the adaptive significance of the visual system in diversifying the behaviors and the environments exploited in snakes, but also underline the interactive effects of multidimensional evolutionary attributes (e.g., behavior, ecology, physiology and phylogeny) on the evolution of optimal visual performance.

Diel and monthly activity pattern of brown bears and sika deer in the Shiretoko Peninsula, Hokkaido, Japan.

Mammals exhibit several types of diel activity pattern, including nocturnal, diurnal, crepuscular, and cathemeral. These patterns vary inter- and intra-specifically and are affected by environmental factors, individual status, and interactions with other individuals or species. Determining the factors that shape diel activity patterns is challenging but essential for understanding the behavioral ecology of animal species, and for wildlife conservation and management. Using camera-trap surveys, we investigated the species distributions and activity patterns of terrestrial mammals on the Shiretoko Peninsula, Hokkaido, Japan, with particular focus on brown bears and sika deer. From June to October 2019, a total of 7,530 observations were recorded by 65 camera-traps for eight species, including two alien species. The diel activity pattern of brown bears was diurnal/crepuscular, similar to that of bears in North America, but different from European populations. Bear observations were more frequent during the autumnal hyperphagia period, and adult females and sub-adults were more diurnal than adult males. In addition, bears inside the protected area were more diurnal than those outside it. These findings suggest that appetite motivation, competitive interactions between conspecifics, and human activities potentially affect bear activity patterns. Similar to other sika deer populations and other deer species, the diel activity patterns of sika deer were crepuscular. Deer showed less variation in activity patterns among months and sex-age classes, while adult males were observed more frequently during the autumn copulation period, suggesting that reproductive motivation affects their activity patterns.

Safe from sunburn: The divergent diel pattern of a Hydrophis sea snake.

Diel activity patterns are an important aspect of wildlife ecology and evolution and provide valuable information for conservation and monitoring, yet for many species, activity patterns remain unstudied and may be presumed to mirror related taxa. Here, we describe the distinct diel patterns of an endemic population of venomous sea snakes Hydrophis platurus xanthos inhabiting a narrow range (circa 320 km2) in Golfo Dulce, Costa Rica. To investigate, we conducted a systematic visual survey over five 24‐h cycles and evaluated 339 h of previously obtained sighting data from different studies spanning a decade. While sporadic diurnal surfacing does occur, mostly for respiration, our observations revealed marked crepuscular peaks with regular surfacing through the night. We also report on observed surface behaviors that were also found to vary in frequency at different phases of the photoperiodic cycle. In particular, we show feeding as more common at night. Hydrophis platurus xanthos has developed a circadian rhythm that differs noticeably from its taxonomic parent (H. p. platurus is reported as diurnal across its Indo‐Pacific range), and no congeners have been categorized as crepuscular. Our work thus contributes to the ecological knowledge of this evolutionarily distinct marine elapid and offers insights into the potential role of environmental conditions in shaping animal activity.

Community structures of mid-sized to large-bodied mammals in tropical lowland and lower montane forests in Gunung Pueh National Park, Western Sarawak, Borneo

Habitat types are closely associated with altitude gradients in tropical rainforests and play an essential role in species assemblages where terrain heterogeneity is often used to understand effects of climate change on species distribution. The response of larger mammals to habitat variation along altitudes is largely unexplored in Borneo. This study has utilised camera traps to better understand the community structure of larger mammals in Gunung Pueh National Park. Gunung Pueh National Park (1550 m a.s.l.) contains two major habitat types, which include lowland forests (< 1100 m a.s.l.) and the lower montane (> 1100 m a.s.l.) forests. The spatio-temporal niches of mid-sized to large-bodied mammal species across these altitude gradients and habitats were assessed. Cameras located at 23 locations, along varying altitude gradients, resulted in 3109 trap nights. Using these cameras, the collected recordings have revealed a total of 22 mid-sized to large-bodied mammals, including 19 species recorded in lowland forest areas, and 18 species in the lower montane forest areas; 15 species were found in both habitats. Four species were exclusively detected in the lowland forest, namely Rusa unicolor, Viverra tangalunga, Presbytis chrysomelas, and Hystrix brachyura. Three species were detected only in the lower montane forest, namely Herpestes semitorquatus, Mustela nudipes, and Hemigalus hosei. In the lowland forest, Macaca nemestrina was recorded with the highest naïve occupancy (naïve ψ = 1.00), while Hemigalus derbyanus had the highest naïve occupancy (naïve ψ = 0.93) in the lower montane forest. The temporal diel activity patterns of selected species in the two habitats have shown relatively close similarities, with overlapping patterns ranging between 67–90%. The further conservation of a large area, which encompasses mountainous ranges, is recommended to facilitate the conservation efficacy of such Protected Areas and for supporting diverse, mid-sized to large-bodied mammals in Borneo.

Activity patterns and temporal niche partitioning in sympatric red‐legged and red‐necked pademelons

AbstractTemporal partitioning between ecologically similar species facilitates co‐occurrence and can influence the structure of mammalian assemblages. We studied diel activity patterns of two sympatric forest‐dwelling wallabies, the red‐legged pademelon (Thylogale stigmatica) and red‐necked pademelon (Thylogale thetis) in eastern Australia to better understand spatiotemporal partitioning between these closely related macropods. Temporally, both species displayed strongly crepuscular activity patterns typical of many macropod species; however, compared with T. thetis, T. stigmatica was less active during evening twilight and more active in the period prior to dawn. Spatially, T. stigmatica used dense forest cover exclusively throughout the 24‐hour cycle, while T. thetis divided its habitat spatiotemporally, spending the diurnal period under forest cover and the nocturnal period on pasture beyond the forest edge. In practical terms, this meant that T. stigmatica and T. thetis were fully spatially segregated at night, during the period they would be likely to do most of their foraging. We propose that the spatiotemporal partitioning observed is niche partitioning, and provides a mechanism for the co‐occurrence of these closely related species.

Seasonal Diel Activity Patterns of Three Sympatric Ungulates in Forested Area in Central Japan

The diel activity pattern is a key factor in the coexistence mechanism of sympatric wild animals, enabling temporal niche partitioning. Although previous studies on sympatric ungulates (sika deer, Japanese serow, and wild boar) have reported dietary and spatial niche partitioning, temporal niche partitioning in these sympatric ungulates is not well understood. In this study, we aimed to elucidate the seasonal diel activity patterns of three sympatric ungulates in Gifu Prefecture, Japan, where they have been sympatrically distributed since 1978. We placed 21 camera traps from August 2017 to November 2019, and investigated diel activity patterns and photographic frequencies over three time periods (daytime, night-time, and twilight). Although we found no seasonal changes in diel activity patterns of three ungulates, but patterns showed differences among species. While sika deer showed crepuscular activity, wild boars and Japanese serows showed nocturnal activity. In addition, Japanese serows showed temporal niche partitioning against sika deer. Consequently, we suggest that the relationship between sika deer and Japanese serow is competitive in terms of diel activity patterns.

Zoning has little impact on the seasonal diel activity and distribution patterns of wild boar (Sus scrofa) in an UNESCO Biosphere Reserve.

Understanding the spatio‐temporal distribution of ungulates is important for effective wildlife management, particularly for economically and ecologically important species such as wild boar (Sus scrofa). Wild boars are generally considered to exhibit substantial behavioral flexibility, but it is unclear how their behavior varies across different conservation management regimes and levels of human pressure. To analyze if and how wild boars adjust their space use or their temporal niche, we surveyed wild boars across the core and buffer zones (collectively referred to as the conservation zone) and the transition zone of a biosphere reserve. These zones represent low and high levels of human pressure, respectively. Specifically, we employed a network of 53 camera traps distributed in the Schaalsee UNESCO Biosphere Reserve over a 14‐month period (19,062 trap nights) and estimated circadian activity patterns, diel activity levels, and occupancy of wild boars in both zones. To account for differences in environmental conditions and day length, we estimated these parameters separately for seven 2‐month periods. Our results showed that the wild boars were primarily nocturnal, with diurnal activity occurring dominantly during the summer months. The diel activity patterns in the two zones were very similar overall, although the wild boars were slightly less active in the transition zone than in the conservation zone. Diel activity levels also varied seasonally, ranging from 7.5 to 11.0 h day−1, and scaled positively with the length of the night (R 2 = 0.66–0.67). Seasonal occupancy estimates were exceptionally high (point estimates ranged from 0.65 to 0.99) and similar across zones, suggesting that the wild boars used most of the biosphere reserve. Overall, this result suggests that different conservation management regimes (in this case, the zoning of a biosphere reserve) have little impact on wild boar behavior. This finding is relevant for wildlife management in protected areas where possibly high wild boar densities could interfere with conservation goals within these areas and those of agricultural land use in their vicinity.

Contrasting patterns of risk from human and non-human predators shape temporal activity of prey.

Spatiotemporal variation in predation risk arises from interactions between landscape heterogeneity, predator densities and predator hunting mode, generating landscapes of fear for prey species that can have important effects on prey behaviour and ecosystem dynamics. As widespread apex predators, humans present a significant source of risk for hunted animal populations. Spatiotemporal patterns of risk from hunters can overlap or contrast with patterns of risk from other predators. Human infrastructure can also reshape spatial patterns of risk by facilitating or impeding hunter or predator movement, or deterring predators that are themselves wary of humans. We examined how anthropogenic and natural landscape features interact with hunting modes of rifle hunters and mountain lions Puma concolor to generate spatiotemporal patterns of risk for their primary prey. We explored the implications of human-modified landscapes of fear for Columbian black-tailed deer Odocoileus hemionus columbianus in Mendocino County, California. We used historical harvest records, hunter GPS trackers and camera trap records of mountain lions to model patterns of risk for deer. We then used camera traps to examine deer spatial and temporal activity patterns in response to this variation in risk. Hunters and mountain lions exhibited distinct, contrasting patterns of spatiotemporal activity. Risk from rifle hunters, who rely on long lines of sight, was highest in open grasslands and near roads and was confined to the daytime. Risk from mountain lions, an ambush predator, was highest in dense shrubland habitat, farther from developed areas, and during the night and crepuscular periods. Areas of human settlement provided a refuge from both hunters and mountain lions. We found no evidence that deer avoided risk in space at the scale of our observations, but deer adjusted their temporal activity patterns to reduce the risk of encounters with humans and mountain lions in areas of higher risk. Our study demonstrates that interactions between human infrastructure, habitat cover and predator hunting mode can result in distinct spatial patterns of predation risk from hunters and other predators that may lead to trade-offs for prey species. However, distinct diel activity patterns of predators may create vacant hunting domains that reduce costly trade-offs for prey. Our study highlights the importance of temporal partitioning as a mechanism of predation risk avoidance.

Spatial and temporal partitioning of mustelids in Southeast Alaska

AbstractAs species’ distributions shift in response to changing environmental conditions, novel species interactions are emerging, challenging researchers and managers alike. When new species enter existing ecological communities, their effects on fellow guild members are difficult to predict. Competition between species within the same guild can regulate populations and influence community structure, but niche partitioning is a way for sympatric species to coexist through differential use of space, time, and resources. The fisher (Pekania pennanti) is a carnivore species that has recently colonized Southeast Alaska (SEAK), the northern margin of its range. Although currently considered at low density, the fisher has been expanding its distribution in SEAK in recent years and may impact the native SEAK forest carnivore guild through competitive interactions. We examined the potential for competition between fisher, American marten (Martes americana), and ermine (Mustela erminea) in SEAK during the winter of 2018 by investigating patterns of spatial and temporal overlap between the species at both local and landscape scales. Using data collected from remote‐sensed habitat features, climate characteristics, species detections from 25 systematic camera stations (50 unique cameras), and single‐species occupancy models, we found that fisher occupancy was positively correlated with vegetation height, and detection decreased with increased snow density. Using two‐species occupancy models, we found evidence of temporal, rather than spatial, avoidance patterns among the SEAK mustelid species investigated, although our inference was limited by sample size. Fisher, the largest mustelid evaluated, did not exhibit changes in occupancy or detection in the presence of marten or ermine. Likewise, detection and occupancy parameters of the mid‐sized marten and small‐sized ermine were not affected by the presence of the other mustelids. Instead, analysis of diel activity patterns showed that marten and ermine reduced temporal overlap with fisher, exhibiting less activity during times of peak fisher activity. Overall, these results show that mustelids in SEAK displayed a pattern of hierarchical temporal partitioning during winter, with smaller‐bodied mustelids avoiding larger, more dominant mustelids. However, if the fisher population continues to expand its range and abundance in SEAK, species interactions may shift and increase the potential for competition between the fisher, marten, and ermine mustelid guild.

Environmental influences on late-summer individual Japanese eel diel activity and space utilization patterns in a shallow western Japan brackish lake

Environmental influences on late-summer individual Japanese eel diel activity and space utilization patterns in a shallow western Japan brackish lake

What Are Sheep Doing? Tri-Axial Accelerometer Sensor Data Identify the Diel Activity Pattern of Ewe Lambs on Pasture.

Monitoring activity patterns of animals offers the opportunity to assess individual health and welfare in support of precision livestock farming. The purpose of this study was to use a triaxial accelerometer sensor to determine the diel activity of sheep on pasture. Six Perendale ewe lambs, each fitted with a neck collar mounting a triaxial accelerometer, were filmed during targeted periods of sheep activities: grazing, lying, walking, and standing. The corresponding acceleration data were fitted using a Random Forest algorithm to classify activity (=classifier). This classifier was then applied to accelerometer data from an additional 10 ewe lambs to determine their activity budgets. Each of these was fitted with a neck collar mounting an accelerometer as well as two additional accelerometers placed on a head halter and a body harness over the shoulders of the animal. These were monitored continuously for three days. A classification accuracy of 89.6% was achieved for the grazing, walking and resting activities (i.e., a new class combining lying and standing activity). Triaxial accelerometer data showed that sheep spent 64% (95% CI 55% to 74%) of daylight time grazing, with grazing at night reduced to 14% (95% CI 8% to 20%). Similar activity budgets were achieved from the halter mounted sensors, but not those on a body harness. These results are consistent with previous studies directly observing daily activity of pasture-based sheep and can be applied in a variety of contexts to investigate animal health and welfare metrics e.g., to better understand the impact that young sheep can suffer when carrying even modest burdens of parasitic nematodes.

Large-scale evolution of body temperatures in land vertebrates.

Body temperature is a crucial variable in animals that affects nearly every aspect of their lives. Here we analyze for the first time largescale patterns in the evolution of body temperatures across terrestrial vertebrates (tetrapods: including amphibians, mammals, birds and other reptiles). Despite the traditional view that endotherms (birds and mammals) have higher body temperatures than ectotherms, we find they are not significantly different. However, rates of body‐temperature evolution are significantly different, with lower rates in endotherms than ectotherms, and the highest rates in amphibians. We find that body temperatures show strong phylogenetic signal and conservatism over 350 million years of evolutionary history in tetrapods, and some lineages appear to have retained similar body temperatures over time for hundreds of millions of years. Although body temperatures are often unrelated to climate in tetrapods, we find that body temperatures are significantly related to day‐night activity patterns. Specifically, body temperatures are generally higher in diurnal species than nocturnal species, both across ectotherms and, surprisingly, across endotherms also. Overall, our results suggest that body temperatures are significantly linked to phylogeny and diel‐activity patterns within and among tetrapod groups, rather than just climate and the endotherm‐ectotherm divide.

The diel activity pattern of small carnivores of Western Ghats, India: a case study at Nelliampathies in Kerala, India

The diel activity pattern of small carnivores was studied using the camera trap technique at Nelliampathy Reserve Forest, Kerala, India. Six species of small carnivores were recorded during the study. These include Brown Palm Civet Paradoxurus jerdoni, Small Indian Civet Viverricula indica, Stripe-necked Mongoose Herpestes vitticollis, Brown Mongoose Herpestes fuscus, Nilgiri Marten Martes gwatkinsii, and Leopard Cat Prionailurus bengalensis. The maximum diel activity overlap was detected between the Brown Palm Civet and Small Indian Civet, while the activity overlap was minimal between the Stripe-necked Mongoose and Small Indian Civet.

Phenotypic variations, habitat suitability, and diel activity of the endemic brown palm civets

ABSTRACT The natural distribution and the species ecology of the lesser-known nocturnal endemic brown palm civet in the Western Ghats are definite. We used camera trap data from the Western Ghats to predict the suitable niche, coat colour pattern, and diel activity. The environmental variables like rainfall, elevation, isothermaility, tree density, and tree height profoundly influence the brown palm civet’s habitat suitability. We determined that the most suitable habitat area in the entire Western Ghats is 21,853 km2, in four well-defined isolated blocks. The brown palm civet distribution is more towards the south, ranging from Kakkad to Anamalai. The distribution on the north side is in the Nilgiris, Bhadra, and the Sahyadri. The diel activity pattern indicates that the species is nocturnal, with activity peak in the early night and ending in the early morning, and is nearly identical in different landscapes. The species has a variety of coat patterns, which we believe is due to phenotypic plasticity. The species is not a true high altitude montane shola-dependent species, unlike the other endemic species of the Western Ghats. The destruction of rainforests resulting from excessive anthropogenic pressure results in habitat fragmentation, posing a significant threat to the brown palm civet habitats.

Camera-trap data do not indicate scaling of diel activity and cathemerality with body mass in an East African mammal assemblage.

Diel activity patterns of animal species reflect constraints imposed by morphological, physiological, and behavioral trade‐offs, but these trade‐offs are rarely quantified for multispecies assemblages. Based on a systematic year‐long camera‐trap study in the species‐rich mammal assemblage of Lake Manyara National Park (Tanzania), we estimated activity levels (hours active per day) and circadian rhythms of 17 herbivore and 11 faunivore species to determine the effects of body mass and trophic level on activity levels and cathemerality (the degree to which species are active throughout the day and night). Using generalized least squares and phylogenetic generalized least squares analyses, we found no support for the hypothesis that trophic level is positively associated with activity levels. We found no support for activity levels to scale positively with body mass in herbivores or to differ between ruminants and nonruminants; in faunivores, we also did not detect relationships between body mass and activity levels. Cathemerality was positively associated with activity levels but did not scale significantly with body mass. Overall, our findings caution against trophic level or body mass‐associated generalized conclusions with regard to diel activity patterns.

Diel timing of nest predation changes across breeding season in a subtropical shorebird.

Predation is the most common cause of nest failure in birds. While nest predation is relatively well studied in general, our knowledge is unevenly distributed across the globe and taxa, with, for example, limited information on shorebirds breeding in subtropics. Importantly, we know fairly little about the timing of predation within a day. Here, we followed 444 nests of the red‐wattled lapwing (Vanellus indicus), a ground‐nesting shorebird, for a sum of 7,828 days to estimate a nest predation rate, and continuously monitored 230 of these nests for a sum of 2,779 days to reveal how the timing of predation changes over the day and season in a subtropical desert. We found that 312 nests (70%) hatched, 76 nests (17%) were predated, 23 (5%) failed for other reasons, and 33 (7%) had an unknown fate. Daily predation rate was 0.95% (95%CrI: 0.76% – 1.19%), which for a 30‐day long incubation period translates into ~25% (20% – 30%) chance of nest being predated. Such a predation rate is low compared to most other avian species. Predation events (N = 25) were evenly distributed across day and night, with a tendency for increased predation around sunrise, and evenly distributed also across the season, although night predation was more common later in the season, perhaps because predators reduce their activity during daylight to avoid extreme heat. Indeed, nests were never predated when midday ground temperatures exceeded 45℃. Whether the diel activity pattern of resident predators undeniably changes across the breeding season and whether the described predation patterns hold for other populations, species, and geographical regions await future investigations.

A closer look at pupil diversity and evolution in frogs and toads.

The eyes of frogs and toads (Anura) are among their most fascinating features. Although several pupil shapes have been described, the diversity, evolution, and functional role of the pupil in anurans have received little attention. Studying photographs of more than 3200 species, we surveyed pupil diversity, described their morphological variation, tested correlation with adult habits and diel activity, and discuss major evolutionary patterns considering iris anatomy and visual ecology. Our results indicate that the pupil in anurans is a highly plastic structure, with seven main pupil shapes that evolved at least 116 times during the history of the group. We found no significant correlation between pupil shape, adult habits, and diel activity, with the exception of the circular pupil and aquatic habits. The vertical pupil arose at least in the most-recent common ancestor of Anura + Caudata, and this morphology is present in most early-diverging anuran clades. Subsequently, a horizontal pupil, a very uncommon shape in vertebrates, evolved in most neobatrachian frogs. This shape evolved into most other known pupil shapes, but it persisted in a large number of species with diverse life histories, habits, and diel activity patterns, demonstrating a remarkable functional and ecological versatility.