Nocturnal activity by the primarily diurnal Central American agouti (Dasyprocta punctata) in relation to environmental conditions, resource abundance and predation risk

An animal's fitness is in part based on its ability to manage the inherent risks (foraging costs, predation, exposure to disease) with the benefits (resource gain, access to mates, social interactions) of activity (Abrams 1991, Altizer et al. 2003, Lima & Bednekoff 1999, Rubenstein & Hohmann 1989, Wikelski et al. 2001). Thus, understanding an animal's pattern of activity is key to understanding behavioural and ecological processes. However, while numerous laboratory methodologies are available to continuously quantify activity over long periods of time, logistical difficulties have greatly hindered activity studies of animals in the field (DeCoursey 1990)

When the sun never sets: diverse activity rhythms under continuous daylight in free-living arctic-breeding birds

Circadian clocks are centrally involved in the regulation of daily behavioural and physiological processes. These clocks are synchronized to the 24-hour day by external cues (Zeitgeber), the most important of which is the light-dark cycle. In polar environments, however, the strength of the Zeitgeber is greatly reduced around the summer and winter solstices (continuous daylight or continuous darkness). How animals time their behaviour under such conditions has rarely been studied in the wild. Using a radio-telemetry-based system, we investigated daily activity rhythms under continuous daylight in Barrow, Alaska, throughout the breeding season in four bird species that differ in mating system and parental behaviour. We find substantial diversity in daily activity rhythms depending on species, sex and breeding stage. Individuals exhibited either robust, entrained 24-hour activity cycles, were continuously active (arrhythmic), or showed “free-running” activity cycles. In semipalmated sandpipers, a shorebird with biparental incubation, we show that the free-running rhythm is synchronized between pair mates. The diversity of diel time-keeping under continuous daylight emphasizes the plasticity of the circadian system and the importance of the social and life-history context. Our results support the idea that circadian behaviour can be adaptively modified to enable species-specific time-keeping under polar conditions

Estudio de una escultura con inscripción ibérica procedente del santuario del Cerro de los Santos

La línea de trabajo sobre imagen en la cultura ibérica ha aportado a la arqueología ibérica excelentes resultados, tanto desde el punto de vista de la dinamización teórica de la disciplina, como en su aplicación concreta al estudio y la interpretación de determinados programas iconográficos en sus contextos arqueológicos (OLMOS 1992, 1996; ARANEGUI 1997, entre otros). Uno de los sujetos de investigación de especial relevancia de esta línea ha sido la religiosidad y sus diversas manifestaciones. En este sentido, los exvotos ibéricos labrados en caliza y bronce (RUIZ BREMÓN 1989a; PRADOS1992), sin olvidar aquellos elaborados en terracota, representan un material de estudio privilegiado

Metabolic costs of bat echolocation in a non-foraging context support a role in communication

The exploitation of information is a key adaptive behavior of social animals, and many animals produce costly signals to communicate with conspecifics. In contrast, bats produce ultrasound for auto-communication, i.e., they emit ultrasound calls and behave in response to the received echo. However, ultrasound echolocation calls produced by non-flying bats looking for food are energetically costly. Thus, if they are produced in a non-foraging or navigational context this indicates an energetic investment, which must be motivated by something. We quantified the costs of the production of such calls, in stationary, non-foraging lesser bulldog bats (Noctilio albiventris) and found metabolic rates to increase by 0.021 ± 0.001 J/pulse (mean ± standard error). From this, we estimated the metabolic rates of N. albiventris when responding with ultrasound echolocation calls to playbacks of echolocation calls from familiar and unfamiliar conspecific as well as heterospecific bats. Lesser bulldog bats adjusted their energetic investment to the social information contained in the presented playback. Our results are consistent with the hypothesis that in addition to orientation and foraging, ultrasound calls in bats may also have function for active communication

Physiology, behavior, and conservation

Many animal populations are in decline as a result of human activity. Conservation practitioners are attempting to prevent further declines and loss of biodiversity as well as to facilitate recovery of endangered species, and they often rely on interdisciplinary approaches to generate conservation solutions. Two recent interfaces in conservation science involve animal behavior (i.e., conservation behavior) and physiology (i.e., conservation physiology). To date, these interfaces have been considered separate entities, but from both pragmatic and biological perspectives, there is merit in better integrating behavior and physiology to address applied conservation problems and to inform resource management. Although there are some institutional, conceptual, methodological, and communication-oriented challenges to integrating behavior and physiology to inform conservation actions, most of these barriers can be overcome. Through outlining several successful examples that integrate these disciplines, we conclude that physiology and behavior can together generate meaningful data to support animal conservation and management actions. Tangentially, applied conservation and management problems can, in turn, also help advance and reinvigorate the fundamental disciplines of animal physiology and behavior by providing advanced natural experiments that challenge traditional frameworks

Integrating animal movement with habitat suitability for estimating dynamic landscape connectivity

Context: High-resolution animal movement data are becoming increasingly available, yet having a multitude of trajectories alone does not allow us to easily predict animal movement. To answer ecological and evolutionary questions at a population level, quantitative estimates of a species' potential to act as a link between patches, populations, or ecosystems are of importance. Objectives: We introduce an approach that combines movement-informed simulated trajectories with an environment-informed estimate of their ecological likelihood. With this approach, we estimated connectivity at the landscape level throughout the annual cycle of bar-headed geese (Anser indicus) in its native range. Methods: We used a tracking dataset of bar-headed geese to parameterise a multi-state movement model and to estimate temporally explicit habitat suitability within the species' range. We simulated migratory movements between range fragments, and estimated their ecological likelihood. The results are compared to expectations derived from published literature. Results: Simulated migrations matched empirical trajectories in key characteristics such as stopover duration. The estimated likelihood of simulated migrations was similar to that of empirical trajectories. We found that the predicted connectivity was higher within the breeding than in wintering areas, corresponding to previous findings for this species. Conclusions: We show how empirical tracking data and environmental information can be fused to make meaningful predictions about future animal movements. These are temporally explicit and transferable even outside the spatial range of the available data. Our integrative framework will prove useful for modelling ecological processes facilitated by animal movement, such as seed dispersal or disease ecology

Conservation of Galápagos Marine Iguanas (Amblyrhynchus cristatus)

Galápagos Marine Iguanas are highly abundant along many of the archipelago’s shorelines. Total estimated population size varies between 37,000 and 280,000 individuals. Marine Iguanas have evolved in the absence of major predators, and their populations are regulated by cyclically recurring famine (El Niño) and feast (La Niña) events. Population declines are strongly density-dependent: the higher the population density, the higher the mortalities during El Niños (from 10–90%). Recovery after El Niños is rapid, as females compensate by reproducing younger and laying more eggs. Marine Iguana morphology differs between islands. Seven subspecies have been proposed, although only three major clades can be distinguished genetically. Twelve populations (approximately 74% of all Marine Iguanas) still live in pristine environments, whereas five populations (26% of all Marine Iguanas) suffer from anthropogenic influences. Major conservation problems arise from introduced predators (cats, dogs, rats, and pigs) and from combinations of natural events (El Niño) and anthropogenic disasters such as oil spills. The most recent oil spill in 2001 killed 62% of all Marine Iguanas on Santa Fe Island. Management requirements for the future include: (i) investigating population trends in Western Isabela and San Cristobal islands, (ii) investigating whether harbor areas are population sinks because of environmental contaminants, (iii) establishing a recovery program for oil-contaminated iguanas, especially their reinoculation with hindgut microsymbionts, and (iv) developing husbandry techniques and establishing a captive propagation program as a population backup plan (Marine Iguanas have not been bred in captivity)

Conservation of Galápagos Marine Iguanas (Amblyrhynchus cristatus)

Galápagos Marine Iguanas are highly abundant along many of the archipelago’s shorelines. Total estimated population size varies between 37,000 and 280,000 individuals. Marine Iguanas have evolved in the absence of major predators, and their populations are regulated by cyclically recurring famine (El Niño) and feast (La Niña) events. Population declines are strongly density-dependent: the higher the population density, the higher the mortalities during El Niños (from 10–90%). Recovery after El Niños is rapid, as females compensate by reproducing younger and laying more eggs. Marine Iguana morphology differs between islands. Seven subspecies have been proposed, although only three major clades can be distinguished genetically. Twelve populations (approximately 74% of all Marine Iguanas) still live in pristine environments, whereas five populations (26% of all Marine Iguanas) suffer from anthropogenic influences. Major conservation problems arise from introduced predators (cats, dogs, rats, and pigs) and from combinations of natural events (El Niño) and anthropogenic disasters such as oil spills. The most recent oil spill in 2001 killed 62% of all Marine Iguanas on Santa Fe Island. Management requirements for the future include: (i) investigating population trends in Western Isabela and San Cristobal islands, (ii) investigating whether harbor areas are population sinks because of environmental contaminants, (iii) establishing a recovery program for oil-contaminated iguanas, especially their reinoculation with hindgut microsymbionts, and (iv) developing husbandry techniques and establishing a captive propagation program as a population backup plan (Marine Iguanas have not been bred in captivity)