Nocturnal Activity Patterns Research Articles

On the mating behaviour of captive Indian pangolin (Manis crassicaudata)

The Indian pangolin, Manis crassicaudata is under serious threat due to hunting for local consumption and for international trade in skins, scales and meat, and to a lesser extent, loss and deterioration of its habitat. This species is listed as ‘Endangered’ and included under Appendix II of CITES. Because of their nocturnal, burrowing and secretive nature, information on their biology in the wild is very limited. They are difficult to maintain and rarely breed in captivity. Although several zoos have maintained this species, births in captivity have been reported by very few zoos: Calcutta zoo, Oklahoma zoo, Nandankanan Zoological Park. Although earlier studies have described nocturnal behaviour and activity pattern of Indian pangolins in captivity, observations on their mating behaviour are limited mainly because mating is seldom observed. This study reports on mating behaviour observed in captivity.

Dieta de <em>Leopardus colocolo</em> (Carnivora: Felidae) en la Reserva Nacional de Junín, Junín, Perú

Este estudio caracteriza la dieta de Leopardus colocolo en los alrededores del lago Junín, en el centro del Perú, a partir de los restos de las presas presentes en 43 heces. El origen de las heces del predador se determinó a partir del ADN mitocondrial de las células epiteliales intestinales adheridas a la superficie de las heces, utilizando como marcador la región de control. Los restos de las presas fueron identificados utilizando literatura especializada y la comparación con especímenes de colección, identificando un total of 14 ítems alimenticios pertenecientes a mamíferos de las familias Cricetidae (6), Chinchillidae (1) y Caviidae (1) y aves de las familias Anatidae (3) y Rallidae (2), y un grupo de aves no identificadas (1). Los roedores fueron el principal componente de la dieta de L. colocolo, en frecuencia y biomasa, seguido por las aves. Entre los ítems alimenticios consumidos, el roedor cricétido pequeño Calomys sp. fue el más frecuente; sin embargo, el mayor aporte de biomasa relativa fue proporcionado por el roedor mediano Cavia tschudii. La amplitud de nicho obtenida fue baja (Bsta= 0.17), indicando una dieta especializada. Nuestros resultados confirman que, como ocurre con la mayoría de felinos pequeños neotropicales, L. colocolo es un predador especializado en la captura de vertebrados, principalmente mamíferos pequeños. No se registró variación estacional en la dieta y el análisis de las clases de edad de los roedores cricétidos mostró que los adultos fueron los más consumidos. Se infiere que L. colocolo tiene un patrón de actividad diurno y nocturno.

Influence of social factors on the nocturnal activity pattern of the noble crayfish,Astacus astacus(Crustacea, Decapoda) in recirculating aquaculture systems

The social environment plays a major role in the control of growth in many crustaceans, but little is known on the mechanisms involved. Two- and three-year-old noble crayfish, Astacus astacus are strictly nocturnally active. In the present article, we studied social effects on the pattern of nocturnal activity, represented by the time which the animals spent outside shelters. For this purpose, the activity of groups of uniformly large (‘dominant’) and uniformly small (‘subordinate’) individuals were recorded at different densities both separately and in mixed set-ups. In crowded laboratory cultures, the presence of larger (dominant) conspecifics was found to reduce the time which smaller (subordinate) individuals spent outside shelters in search of food and feeding by about one-third. It is suggested that this asymmetric inhibitory effect is an element of the functional chain which ultimately results in an extremely wide variation in individual growth rates of communally reared A. astacus. The relevance of the findings to crayfish aquaculture is discussed.

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

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

Behavioural sampling techniques and activity pattern of Indian Pangolin Manis crassicaudata (Mammalia: Manidae) in captivity

The study presents data on six Indian Pangolins Manis crassicaudata observed in captivity at the Pangolin Conservation Breeding Centre, Nandankanan, Odisha, India over 1377 hours of video recordings for each pangolin between 1500hr and 0800hr on 81 consecutive observational days. Video recordings were made through digital systems assisted by infrared enabled CCTV cameras. The data highlights patterns relate to 12 different behaviour and enclosure utilization. Different interval periods for sampling of instantaneous behaviour from video recordings have been evaluated to develop optimal study methods for the future. The activity budgets of pangolins displayed natural patterns of nocturnal activity with a peak between 20:00-21:00 hr. When out of their burrow, they spent about 59% of the time walking in the enclosure, and 14% of the time feeding. The repeatability of the behaviours has a significant negative correlation with the mean time spent in that behaviour. Focal behavioural samples significantly correlated with instantaneous samples up to 15 minutes interval. The correlation values gradually decreased with the increase in sampling interval. The results indicate that results obtained from focal sampling and instantaneous sampling with relatively shorter intervals (=5 minutes) are about equally reliable. The study suggests use of focal sampling, instead of instantaneous sampling to record behaviour relating to social interactions.

Dim light at night disrupts the short-day response in Siberian hamsters

Photoperiodic regulation of physiology, morphology, and behavior is crucial for many animals to survive seasonally variable conditions unfavorable for reproduction and survival. The photoperiodic response in mammals is mediated by nocturnal secretion of melatonin under the control of a circadian clock. However, artificial light at night caused by recent urbanization may disrupt the circadian clock, as well as the photoperiodic response by blunting melatonin secretion. Here we examined the effect of dim light at night (dLAN) (5lux of light during the dark phase) on locomotor activity rhythms and short-day regulation of reproduction, body mass, pelage properties, and immune responses of male Siberian hamsters. Short-day animals reduced gonadal and body mass, decreased spermatid nuclei and sperm numbers, molted to a whiter pelage, and increased pelage density compared to long-day animals. However, animals that experienced short days with dLAN did not show these short-day responses. Moreover, short-day specific immune responses were altered in dLAN conditions. The nocturnal activity pattern was blunted in dLAN hamsters, consistent with the observation that dLAN changed expression of the circadian clock gene, Period1. In addition, we demonstrated that expression levels of genes implicated in the photoperiodic response, Mel-1a melatonin receptor, Eyes absent 3, thyroid stimulating hormone receptor, gonadotropin-releasing hormone, and gonadotropin-inhibitory hormone, were higher in dLAN animals than those in short-day animals. These results suggest that dLAN disturbs the circadian clock function and affects the molecular mechanisms of the photoperiodic response.

Factors and mechanisms that explain coexistence in a Mediterranean carnivore assemblage: An integrated study based on camera trapping and diet

To promote management and conservation, it is useful to identify the factors that determine species distribution and to understand the mechanisms that regulate the organization of species assemblages or influence the dynamics of communities. Using information provided by 842 camera-trap photos and 8175 scats, we studied the factors that favour the coexistence of European badgers (Meles meles), red foxes (Vulpes vulpes) and stone martens (Martes foina) in a Mediterranean, agroforestry environment in the Iberian Peninsula. With extensive, simultaneous occupation of the space, and simultaneous activity during a broad time period (basically nocturnal and crepuscular activity patterns), the carnivores displayed different strategies depending on the availability of resources. In summer when plant resources were abundant and easy to access, there was a high overlap in patterns of diet and activity, and the temporal avoidance of the superior competitor allowed joint use of the same plots. In autumn, when there were fewer resources (although still sufficient) that were harder to access, the maintenance of food overlap was compensated for by avoidance and a reduction in overlapping activity. In winter and spring, the differentiation in response behaviour was evident in the partial substitution of plant resources.Differentiation in niche dimensions has been linked to complementarity, the differential needs and capacities of each species, and their biology. Differentiation in response behaviour was compatible with the hierarchical structure of the carnivores: European badger; red fox; stone marten. Knowledge of these factors and mechanisms increases our understanding and can help in the prediction of responses to disturbances. Consequently, it helps to improve management and conservation actions.

Occurrence of invasive mammals in southern Nahuel Huapi National Park

Introduced mammals in Patagonia are believed to negatively influence native ecosystems. We surveyed invasive mammals using camera traps in Nahuel Huapi National Park, Argentina, from February to May 2012. We deployed 19 cameras for about 30 days each, for a total of 645 camera days. We obtained 352 independent detections of three invasive mammal species: 67% European hare (Lepus europaeus), 32% wild boar (Sus scrofa), and 1% red deer (Cervus elaphus); no native herbivorous or omnivorous mammals were detected. All species showed nocturnal activity patterns. Hare detections reflected generalist habitat use and wild boars showed preference for more humid areas. The increased detection near roads suggests hares and wild boars are being facilitated through human disturbance, which should be considered in management decisions.

Integrating aspects of ecology and predictive modelling: implications for the conservation of the leopard cat (Prionailurus bengalensis) in the Eastern Himalaya

An understanding of species ecology is vital for effective conservation, particularly if the species forms an important constituent of the lesser mammal guild and regulates small mammal and bird populations. As the ecological role of the leopard cat (Prionailurus bengalensis) in the intricate eastern Himalayan habitats is not known, we assessed the site occupancy, detection probability and activity pattern of leopard cats in Khangchendzonga Biosphere Reserve, India, based on sign surveys and camera trapping. The estimated site occupancy was 0.352 ± 0.061 and detection probability was 0.143 ± 0.0484. Occupancy modelling indicated low elevation, high rodent abundance and tree cover as best predictors for the occupancy of leopard cat. Diet based on analysed scats revealed murids as the most dominant prey (89.2 %). Information based on photographic captures indicated that the leopard cat exhibited a nocturnal activity pattern (peak activity between 0200–0300 hours), which coincided with its principal prey (revealed through diet analysis), but mainly contradicted with other sympatric competitors, hence indicating a temporal partitioning of resources among them. Ecological niche factor analysis indicated that the leopard cat exhibits high global marginality (1.32) and low global tolerance (0.275). The habitat suitability map for leopard cats showed majority of the habitat as unsuitable (1,959.44 km2) and predicted only 164.54 km2 areas of lower temperate forests as moderate to highly suitable. As highly suitable habitats of the leopard cat are in close proximity to villages, conflict issues are a major threat and therefore need to be addressed in conservation program for this felid.

Expression and Evolution of Short Wavelength Sensitive Opsins in Colugos: A Nocturnal Lineage That Informs Debate on Primate Origins.

A nocturnal activity pattern is central to almost all hypotheses on the adaptive origins of primates. This enduring view has been challenged in recent years on the basis of variation in the opsin genes of nocturnal primates. A correspondence between the opsin genes and activity patterns of species in Euarchonta—the superordinal group that includes the orders Primates, Dermoptera (colugos), and Scandentia (treeshrews)—could prove instructive, yet the basic biology of the dermopteran visual system is practically unknown. Here we show that the eye of the Sunda colugo (Galeopterus variegatus) lacks a tapetum lucidum and has an avascular retina, and we report on the expression and spectral sensitivity of cone photopigments. We found that Sunda colugos have intact short wavelength sensitive (S-) and long wavelength sensitive (L-) opsin genes, and that both opsins are expressed in cone photoreceptors of the retina. The inferred peak spectral sensitivities are 451 and 562 nm, respectively. In line with adaptation to nocturnal vision, cone densities are low. Surprisingly, a majority of S-cones coexpress some L-opsin. We also show that the ratio of rates of nonsynonymous to synonymous substitutions of exon 1 of the S-opsin gene is indicative of purifying selection. Taken together, our results suggest that natural selection has favored a functional S-opsin in a nocturnal lineage for at least 45 million years. Accordingly, a nocturnal activity pattern remains the most likely ancestral character state of euprimates.Electronic supplementary materialThe online version of this article (doi:10.1007/s11692-013-9230-y) contains supplementary material, which is available to authorized users.

Temporal activity and dietary selection in two coexisting desert snakes, the Saharan sand viper (Cerastes vipera) and the crowned leafnose (Lytorhynchus diadema)

The Saharan sand viper (Cerastes vipera) and the crowned leafnose (Lytorhynchus diadema) are two snake species well adapted to desert sand dunes and, in Israel, coexist in the western Negev Desert. C. vipera is a sit-and-wait ambusher while L. diadema is an active hunter. We studied the seasonal and diel activity patterns and dietary selection of these two species while free-living in the field. Both species were active from early spring until late fall but displayed (i) different seasonal activity patterns –C. vipera was bimodal with peaks in spring and autumn whereas L. diadema was basically unimodal with a peak in summer; (ii) different nocturnal above-ground activity patterns –C. vipera was active mainly during the first three hours of darkness while L. diadema was constantly active during the first seven hours of darkness; and (iii) different patterns of nocturnal behavior –C. vipera moved up to 50m while L. diadema moved several hundred meters each night. Dietary selection differed between these snake species although lizards, mainly Nidua fringe-fingered lizards (Acanthodactylus scutellatus), were the main dietary item for both. We concluded that temporal partitioning in above-ground activity, different foraging strategies and differences in dietary selection may contribute towards the coexistence of the two snake species.

Lowland tapir (Tapirus terrestris) distribution, activity patterns and relative abundance in the Greater Madidi‐Tambopata Landscape

Lowland tapir distribution is described in northwestern Bolivia and southeastern Peru within the Greater Madidi-Tambopata Landscape, a priority Tapir Conservation Unit, using 1255 distribution points derived from camera trapping efforts, field research and interviews with park guards from 5 national protected areas and hunters from 19 local communities. A total of 392 independent camera trapping events from 14 camera trap surveys at 11 sites demonstrated the nocturnal and crepuscular activity patterns (86%) of the lowland tapir and provide 3 indices of relative abundance for spatial and temporal comparison. Capture rates for lowland tapirs were not significantly different between camera trapping stations placed on river beaches versus those placed in the forest. Lowland tapir capture rates were significantly higher in the national protected areas of the region versus indigenous territories and unprotected portions of the landscape. Capture rates through time suggested that lowland tapir populations are recovering within the Tuichi Valley, an area currently dedicated towards ecotourism activities, following the creation (1995) and subsequent implementation (1997) of the Madidi National Park in Bolivia. Based on our distributional data and published conservative estimates of population density, we calculated that this transboundary landscape holds an overall lowland tapir population of between 14 540 and 36 351 individuals, of which at least 24.3% are under protection from national and municipal parks. As such, the Greater Madidi-Tambopata Landscape should be considered a lowland tapir population stronghold and priority conservation efforts are discussed in order to maintain this population.

Fear of the dark or dinner by moonlight? Reduced temporal partitioning among Africa's large carnivores

Africa is home to the last intact guild of large carnivores and thus provides the only opportunity to investigate mechanisms of coexistence among large predator species. Strong asymmetric dominance hierarchies typically characterize guilds of large carnivores; but despite this asymmetry, subdominant species may persist alongside their stronger counterparts through temporal partitioning of habitat and resources. In the African guild, the subdominant African wild dogs and cheetahs are routinely described as diurnal and crepuscular. These activity patterns have been interpreted to result from the need to avoid encounters with the stronger, nocturnal spotted hyenas and lions. However, the idea that diel activity patterns of carnivore species are strongly shaped by competition and predation has recently been challenged by new observations. In a three-year study in the Okavango Delta, we investigated daily activity patterns and temporal partitioning for wild dogs, cheetahs, spotted hyenas and lions by fitting radio collars that continuously recorded activity bursts, to a total of 25 individuals. Analysis of activity patterns throughout the 24-h cycle revealed an unexpectedly high degree of temporal overlap among the four species. This was mainly due to the extensive and previously undescribed nocturnal activity of wild dogs and cheetahs. Their nocturnal activity fluctuated with the lunar cycle, represented up to 40% of the diel activity budget and was primarily constrained by moonlight availability. In contrast, the nocturnal activity patterns of lions and hyenas were unaffected by moonlight and remained constant over the lunar cycle. Our results suggest that other ecological factors such as optimal hunting conditions have shaped the diel activity patterns of subdominant, large predators. We suggest that they are "starvation driven" and must exploit every opportunity to obtain a meal. The benefits of activity on moonlit nights therefore offset the risks of encountering night-active predators and competitors.

Activity re-assignment and microclimate selection of free-living Arabian oryx: responses that could minimise the effects of climate change on homeostasis?

Predicting whether behaviour could buffer the effects of climate change on long-lived mammals requires a better understanding of the long-term behavioural responses of mammals to environmental stress. Using biologging, we measured locomotor activity and microclimate selection, over eight months, in five Arabian oryx (Oryx leucoryx) living free in a Saudi Arabian desert. The oryx displayed seasonal flexibility in activity patterns, shifting from a continuous 24-h activity pattern with crepuscular peaks in cooler months to a predominantly nocturnal activity pattern during the hottest months, without reducing the total 24-h activity level. The proportion of total 24-h activity that occurred during daylight hours was just 29±8% during the hottest months, versus 53±8% (mean±SD, n=5 oryx) in the other months. The attenuation in diurnal activity levels during the hot months was accompanied by the selection of cooler microclimates, presumably via shade seeking, during the heat of the day. Analysis of miniature black globe (miniglobe) temperature from a remote sensor on the collar of two female animals revealed that oryx selected microclimates cooler than the microclimates in direct sun at higher environmental heat loads across all periods, but with enhanced efficiency during the dry periods. We have quantified activity re-assignment and microclimate selection as responses to hot arid conditions in a free-living artiodactyl. Such flexible behavioural processes may act to buffer the adverse effects of the progressively hotter and drier conditions predicted to occur with climate change.

Home range use and habitat selection by barbastelle bats (Barbastella barbastellus): implications for conservation

We studied foraging behavior and habitat selection of barbastelle bats (Barbastella barbastellus) at two breeding colonies in southern England. In total, 28 adult female bats were radiotracked to determine home range use, habitat preferences, and patterns of nocturnal activity. Individual home ranges varied considerably, with bats traveling between 1 and 20 km to reach foraging areas (¯ X ¼ 6.8 km 6 4.8 SD). Nonreproductive females foraged at greater distances than reproductive females, providing evidence of state-dependent foraging behavior. Commutes were typically rapid and direct and bats moved freely across large open areas. Individual bats foraged independently from one another and were highly faithful to their respective core foraging areas, which formed just a small fraction of home ranges. Riparian zones and broad-leaved woodland were habitats most strongly selected for foraging. Unimproved grassland and field margins were also important components of the foraging environment. Bats night-roosted only occasionally and for short periods. Conservation efforts for B. barbastellus should target the protection and enhancement of preferred foraging habitats within 7 km of roost sites. Linear landscape elements such as tree lines and hedgerows should be managed to improve their value to foraging bats and to enhance connectivity with roost sites.

Habitat overlap between predatory benthic fish and their invertebrate prey in streams: the relative influence of spatial and temporal factors on predation risk

Summary1. The spatial heterogeneity of ecosystems as well as temporal activity patterns of organisms can have far‐reaching effects on predator–prey relationships. We hypothesised that spatiotemporal constraints in mesohabitat use by benthic fish predators would reduce habitat overlap with benthic invertebrates and lead to mesohabitat‐specific predation risks.2. We analysed the spatiotemporal activity patterns of two small‐bodied benthivorous fishes, gudgeon (Gobio gobio) and stone loach (Barbatula barbatula), and of benthic invertebrates in a small temperate stream during three 24‐h field experiments. By applying a novel method of field video observation, we monitored the spatiotemporal foraging behaviour of the fish in their natural environment. A parallel analysis of invertebrate mesohabitat use by means of small area Hess sampling allowed a direct estimation of habitat overlap at a pool–riffle scale.3. Gudgeon showed a dominant spatial activity pattern preferring pools at all times of day, whereas stone loach used both mesohabitats but with a distinct temporal (nocturnal) activity pattern. The patterns of residence were not identical with those of active foraging. Invertebrate community composition differed significantly between mesohabitats but not between times of day. More than half of the total dissimilarity between pools and riffles was accounted for by six invertebrate taxa. Five of these were subject to higher fish predation in pools than in riffles. The total prey consumption of the two fish species together in pools was about three times as high as in riffles. Trophic niche breadth of stone loach and thus its predation range was broader than that of gudgeon.4. These results indicate that the potential predation risk for stream invertebrates depends on the combination of spatial and temporal patterns of both predator and prey. Given the distinct differences in predation risk found between pools and riffles, we conclude that spatial heterogeneity at the mesohabitat scale can influence mechanisms and consequences of selective predation. We also suggest that the analysis of spatiotemporal predator–prey relationships should not be based on the premise that the main residence habitat and active foraging habitat of a predator are identical.

Time to pay attention: attentional performance time-stamped prefrontal cholinergic activation, diurnality, and performance.

Although the impairments in cognitive performance that result from shifting or disrupting daily rhythms have been demonstrated, the neuronal mechanisms that optimize fixed-time daily performance are poorly understood. We previously demonstrated that daily practice of a sustained attention task (SAT) evokes a diurnal activity pattern in rats. Here, we report that SAT practice at a fixed time produced practice time-stamped increases in prefrontal cholinergic neurotransmission that persisted after SAT practice was terminated and in a different environment. SAT time-stamped cholinergic activation occurred regardless of whether the SAT was practiced during the light or dark phase or in constant-light conditions. In contrast, prior daily practice of an operant schedule of reinforcement, albeit generating more rewards and lever presses per session than the SAT, neither activated the cholinergic system nor affected the animals' nocturnal activity pattern. Likewise, food-restricted animals exhibited strong food anticipatory activity (FAA) and attenuated activity during the dark phase but FAA was not associated with increases in prefrontal cholinergic activity. Removal of cholinergic neurons impaired SAT performance and facilitated the reemergence of nocturnality. Shifting SAT practice away from a fixed time resulted in significantly lower performance. In conclusion, these experiments demonstrated that fixed-time, daily practice of a task assessing attention generates a precisely practice time-stamped activation of the cortical cholinergic input system. Time-stamped cholinergic activation benefits fixed-time performance and, if practiced during the light phase, contributes to a diurnal activity pattern.

Modification of spontaneous activity patterns in the malaria vector Anopheles gambiae sensu stricto when presented with host‐associated stimuli

Anopheles gambiae sensu stricto Giles (Diptera: Culicidae) is the main malaria vector in sub‐Saharan Africa. Mated females show a circadian rhythm of spontaneous activity under constant environmental conditions that extends across the scotophase (subjective night). The effect of host‐associated cues [i.e. human foot odour supplemented with carbon dioxide (CO2)] on this nocturnal activity pattern is studied in laboratory‐reared A. gambiae s.s. M molecular form. Sixteen mated females (5–10 days old) are held in individual chambers (diameter 3.5 cm, length 4.5 cm) in a wind‐tunnel with a continuous flow (8.0 cm s−1) of clean air. At the onset of hours 3, 6 and 10 of the scotophase, their behaviour is recorded on video for 15 min in clean moving air and then for the next 15 min, with a specific treatment present in the clean airstream: (i) constant CO2 (4.8%) plus human odour; (ii) pulsed CO2 (5 s of every 30 s) plus human odour or (iii) control (clean air). Activities of individual mosquitoes are scored by direct observation of the video records for the incidents of ‘resting’, ‘walking’, ‘jumping’ and ‘flying’ in each of the 15‐min observation periods. There is a significant interaction between hour and treatment on mean changes in female activity level (P = 0.00004). Constant treatment increases the level of activity of A. gambiae females significantly, although only in hour 3 of the scotophase (P < 0.01), whereas pulsed and control treatments show no significant effect throughout the scotophase. Patterns of spontaneous activity in individual A. gambiae females thus appear to be modulated by host‐associated cues, resulting in a more active phase early in the night than might be expected from records of spontaneous activity under constant environmental conditions. Possible ecological and experimental implications of such an increase in activity are discussed in relation to host‐seeking behaviour.

Differential patterns of home-range, net displacement and resting sites use of Conepatus chinga in southern Brazil

Studies on the spatial ecology of Molina's hog-nosed skunk were conducted in southern Brazil. Between April 2008 and April 2009, 18 individuals were tagged with radio collars and monitored by radio-telemetry (VHF). The average home-range estimated for 12 skunks was 1.63km2±1.17km2. Males had home-ranges 2.5 times larger than females, and also showed significantly larger patterns of displacement. These differences in space probably were related not only to sexual size dimorphism, but also to differential behavior between sexes. We identified six basic types of resting sites, among which holes in the ground were the most common and comprised more than 50% of the total. Reuse of resting sites was high (32%), especially for females, which had a significantly higher rate than males. Although they showed a large proportion of home-range overlap even in the core areas, skunks exhibited a solitary life style, rarely sharing resting sites and maintaining relatively long distances from each other, equivalent to twice the distance of daily movements. The almost strictly nocturnal activity pattern observed in this study is a common characteristic of the family. Among practically all of the ecological features analyzed, males and females showed significant differences, denoting the importance of a sex-specific approach in ecological studies regarding this species.

Refugia and top-down control of the pencil urchin Eucidaris galapagensis in the Galápagos Marine Reserve

Although sea urchins can strongly influence the structure of benthic communities and are abundant in the Galápagos Islands, factors mediating predation on urchins have not been studied experimentally. Here, we examine how habitat structure and behavioral patterns of prey influence predation on the pencil urchin Eucidaris galapagensis, an abundant grazer in rocky subtidal habitats. Results indicate that the distribution, abundance and body sizes of E. galapagensis vary predictably by habitat in the central Galápagos. Urchins were five times more abundant and significantly smaller in rubble than in exposed ledge habitats. We thus hypothesized that rubble habitats provide a refuge from predation, and conducted tethering manipulations using small and large urchins as prey. Predation by the hogfish, Bodianus diplotaenia, triggerfishes, and the sea star Pentaceraster cumingi, was significantly higher in exposed than in rubble habitats for small urchins, indicating that rubble habitats represent a refuge. In addition, urchin activity over a 24-hour period indicated that E. galapagensis were significantly more abundant on exposed substrate at night than during the day as they emerged from refugia at dusk. Since the fish that prey on E. galapagensis are predominantly diurnal, we suggest that the nocturnal activity patterns of the urchins represent a predator avoidance strategy. These results underscore the importance of considering spatial refugia and prey behavior in investigations of top-down control of sea urchins in the Galápagos Marine Reserve.