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Nocturnal Activity (nocturnal + activity)
Selected AbstractsSocial organization of the Milne-Edward's pottoAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2005Elizabeth R. Pimley Abstract Nocturnal prosimian primates are often seen alone during their nocturnal activities, and are therefore categorized as "solitary". Recent research has shown that these animals actually possess social networks that differ among species. Here we present new information on one of the lesser studied prosimian primates, the potto, derived from fieldwork in Cameroon that employed radiotelemetry and behavioral observations. An analysis of association patterns and home-range overlaps between animals revealed that pottos associated more frequently with conspecifics than expected for a supposedly solitary primate. Certain males and females that were seen together regularly throughout the study, but were not observed to have contact with other pottos of the opposite sex, were labeled as "pairs". These pairs were found to have higher levels of association with each other than with other conspecifics. The only affiliative and sexual behaviors observed between members of the opposite sex occurred within the pairs of pottos. Although given the secretive nature of these primates, the possibility of extrapair copulations cannot be ruled out, their relatively small testis size indicates that sperm competition is not so important for this species. Am. J. Primatol. 66:317,330, 2005. © 2005 Wiley-Liss, Inc. [source] Hermit crabs, humans and Mozambique mangrovesAFRICAN JOURNAL OF ECOLOGY, Issue 3 2001David K. A. Barnes Abstract There is a complex interrelationship between upper shore hermit crabs (such as Coenobita sp. and Clibanarius sp.), coastal human populations and mangrove forests in Mozambique. The abundance, activity, shell selection and behaviour of three species of hermit crab are related to the level of mangrove cover. With increased density of mangrove trees, the study species of hermit crab changed in abundance, tended to become diurnal, spent more time feeding and were clustered in larger groups when doing so, and selected longer spired shells. All five of the same variables are also linked to the proximity and activity of humans through both direct and indirect actions. Direct effects included a tendency to nocturnal activity with proximity to human activity; indirect effects included increased and more clumped food supplies, and shell middens from intertidal harvesting and deforestation. Mangroves are important to local human populations as well as to hermit crabs, for a wide variety of (similar) reasons. Mangroves provide storm shelter, fisheries and fishery nursery grounds for adjacent human settlements, but they also harbour mosquito populations and their removal provides valuable building materials and fuel. Hermit crabs may be useful (indirectly) to coastal human populations by being a source of food to certain commercial species, and by quickly consuming rotting/discarded food and faeces (thereby reducing disease and pests). They can also cause minor problems to coastal human populations because they use shells of (fisheries) target mollusc species and can be more abundant than the living molluscs, thereby slowing down effective hand collection through confusion over identification. The mixture of positive and negative attributes that the three groups impart to each other in the Quirimba Archipelago, northern Mozambique, is discussed. Résumé Il existe des interrelations complexes entre les Bernard-l'Ermite du haut littoral (tels que Coenobita sp. Et Clibanarius sp.), les populations humaines côtières et les forêts de mangroves au Mozambique. L'abondance, l'activité, le choix de la coquille et le comportement de trois espèces de Bernard-l'Ermite sont liés au degré de couverture de la mangrove. Lorsque la densité des arbres de la mangrove augmente, l'abondance des espèces étudiées de Bernard-l'Ermite change, ils ont tendance à devenir diurnes, passent plus de temps à se nourrir et se rassemblent à ces moments-là en plus grands groupes, et ils choisissent aussi de plus longues coquilles. Les cinq mêmes variables sont aussi liées à la proximité et à l'activité des hommes, directement et indirectement. Parmi les effets directs, on compte une tendance à une activité nocturne lorsque les activités humaines sont proches ; les effets indirects incluent des apports de nourriture et de débris de coquilles accrus et plus regroupés résultant des marées et de la déforestation. Les mangroves sont aussi importantes pour les populations locales que pour les Bernard-l'Ermite, pour toute une série de raisons (semblables). Les mangroves constituent un abri en cas de tempête, un terrain de pêche et de frai dont bénéficient les populations humaines voisines, mais elles renferment aussi beaucoup de moustiques, et leur bois fournit un bon matériau de construction et du combustible. Les Bernard-l'Ermite peuvent être (indirectement) utiles aux populations côtières car certaines espèces commerciales sont comestibles et que tous consomment rapidement les restes de nourriture en décomposition et les excréments (réduisant ainsi les risques de maladie et d'animaux nuisibles). Ils peuvent aussi causer des problèmes mineurs aux populations côtières parce qu'ils utilisent la coquille d'espèces de mollusques qui font l'objet de la pêche et qu'ils peuvent être plus abondants que les mollusques eux-mêmes, ce qui ralentit la pêche manuelle à cause du besoin d'identification. On discute le mélange de qualités négatives et positives que les trois groupes représentent les uns pour les autres dans l'Archipel de Quirimba, au nord du Mozambique. [source] Predator avoidance behaviour in wild and hatchery-reared brown trout: the role of experience and domesticationJOURNAL OF FISH BIOLOGY, Issue 6 2003D. Álvarez Juvenile brown trout Salmo trutta from natural populations reacted to the presence of piscivorous brown trout by increasing the use of refuges. In contrast, second-generation hatchery fish and the offspring of wild fish raised under hatchery conditions were insensitive to predation risk. The diel pattern of activity also differed between wild and hatchery brown trout. Second-generation hatchery fish were predominantly active during daytime regardless of risk levels. Wild fish, however, showed a shift towards nocturnal activity in the presence of predators. These findings emphasize the potential role of domestication in weakening behavioural defences. They support the idea that the behavioural divergence between wild and domesticated individuals can arise from a process of direct or indirect selection on reduced responsiveness to predation risk, or as a lack of previous experience with predators. [source] Population status and behaviours of the Samoan flying fox (Pteropus samoensis) on Tutuila Island, American SamoaJOURNAL OF ZOOLOGY, Issue 3 2001Anne P. Brooke Abstract The small population and limited range of the Samoan flying fox Pteropus samoensis has generated concern regarding the survival of this large, diurnally active bat. During 1995,96, surveys were conducted monthly in six study valleys on Tutuila Island, American Samoa, to assess population size. The amount of diurnal and nocturnal activity was investigated to gauge the accuracy of diurnal surveys, and territorial behaviours were observed to determine how they influenced local dispersion. Individuals showed long-term fidelity to a series of roosts and small core areas that were used both nocturnally and diurnally. Territorial defence was observed only of temporary feeding territories in fruiting or flowering trees. Bats defended food resources by aerial patrols and extended aerial chases in which intruders were frequently bitten. Foraging movements changed seasonally, with up to 80% of individuals observed bypassing study valleys. The mean density of bats observed within the study valleys was 6.1 bats/km2 (range = 0.9,18.5 bats/km2). Pteropus samoensis were active both nocturnally and diurnally with greatest activity in late afternoon and evening, 16:00,22:00. Because bats were most active at night, it is probable that daytime surveys of flying bats undercount the number of individuals present. Greatest densities were found in valleys that were contiguous with large tracts of forest inaccessible to people. Most observations of roosting bats were of solitary males on dead branches that jutted above the forest canopy, while females and dependant young roosted below the canopy, hidden within vegetation. Adult male,female pairs were rarely seen together other than during the mating period in August,January. The population has increased following a ban on hunting, but reliance on mature forest makes long-term species survival dependant on protection of the limited mature forest remaining and continued hunting restrictions. [source] Possible contemporary evolution in an endangered species, the Santa Cruz Island foxANIMAL CONSERVATION, Issue 2 2009H. M. Swarts Abstract An ability to mount rapid evolutionary responses to environmental change may be necessary for species persistence in a human-dominated world. We present evidence of the possibility of such contemporary evolution in the anti-predator behaviour of the critically endangered Santa Cruz Island fox Urocyon littoralis. In 1994, golden eagles colonized Santa Cruz Island, CA and devastated the predator-naïve, endemic island fox population by 95% within 10 years. In 1992, just before the arrival of golden eagles, foxes showed substantial diurnal activity, but diurnal activity was 37.0% lower in 2003,2007, after golden eagle colonization; concurrently, overall activity declined and nocturnal activity increased. Moreover, on nearby Santa Catalina Island, where golden eagles were absent but where the fox population recently crashed due to a disease epidemic, remaining foxes were significantly more diurnally active than were those on Santa Cruz Island. The weight of evidence suggests that the change in activity pattern was a response to predation, not to low population density, and that this was probably a heritable rather than a learned behavioural trait. This behavioural change may allow for prolonged island fox persistence, but also potentially represents a loss of behavioural diversity in fox populations. [source] Partitioning of temporal activity among desert lizards in relation to prey availability and temperatureAUSTRAL ECOLOGY, Issue 1 2010CHRISTOPHER E. GORDON Abstract Partitioning of activity time within ecological communities potentially reduces interspecific competition and increases the number of species that can coexist. We investigated temporal activity in a highly diverse lizard assemblage in the Simpson Desert, central Australia, to determine the degree of partitioning that occurs. Three periods were defined, daytime (sunrise to sunset), early night (sunset to midnight) and late night (midnight to sunrise), and live captures of lizards were tallied for each period during two sampling months (September and November 2007). We also quantified the activity times of potential invertebrate prey and measured ambient temperatures during the different time periods to investigate any associations between these factors and lizard activity. Some 77% of captures of 13 lizard species were made by day, with Ctenotus pantherinus, Egernia inornata (Scincidae) and Nephrurus levis (Gekkonidae) the only species showing extended nocturnal activity. Activity of both species of skink was recorded at temperatures 4°C lower than those for agamid and varanid lizards early in the night, and at temperatures as low as 18,20°C. Surface-active invertebrates differed in composition between time periods and were less abundant during the late night period in the drier of the two sample months (September), but were distributed equally over time in the other month. Termites were active in subterranean galleries at night in September and mostly by day in November, but available at all times on surface/subsurface baits. We conclude that activity is distributed unevenly within this lizard assemblage, with partitioning facilitated by the ready availability of invertebrate prey and by lizards having relatively broad temperature tolerances that, in some cases, permit opportunistic exploitation of resources beyond usual times of activity. [source] | ||||||||||