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Habitat loss and attendant fragmentation threaten the existence of many species. Conserving these species requires a straightforward and objective method that quantifies how these factors affect their survival. Therefore, we compared a variety of metrics that assess habitat fragmentation in bird ranges, using the geographical ranges of 127 forest endemic passerine birds inhabiting the Atlantic Forest of Brazil. A common, non-biological metric - cumulative area of size-ranked fragments within a species range - was misleading, as the least threatened species had the most habitat fragmentation. Instead, we recommend a modified version of metapopulation capacity. The metric links detailed spatial information on fragment sizes and spatial configuration to the birds' abilities to occupy and disperse across large areas (100,000+ km(2)). In the Atlantic Forest, metapopulation capacities were largely bimodal, in that most species' ranges had either low capacity (high risk of extinction) or high capacity (very small risk of extinction). This pattern persisted within taxonomically and ecologically homogenous groups, indicating that it is driven by fragmentation patterns and not differences in species ecology. Worryingly, we found IUCN considers some 28 of 58 species in the low metapopulation capacity cluster to not be threatened. We propose that assessing the effect of fragmentation will separate species more clearly into distinct risk categories than does a simple assessment of remaining habitat.

Optical sensors have shown significant promise in offering additional data to track insect populations. This article presents a comparative study between abundance measurements obtained from a novel near-infrared optical sensor and physical traps. The optical instrument, named an Entomological Bistatic Optical Sensor System, or eBoss, is a non-destructive sensor operating in the near-infrared spectral range and designed to continuously monitor the population of flying insects. The research compares the mosquito aerial density (#/m3) obtained through the eBoss with trap counts from eight physical traps during an eight-month field study. The eBoss recorded over 302,000 insect sightings and assessed the aerial density of all airborne insects as well as male and female mosquitoes specifically with a resolution of one minute. This capability allows for monitoring population trends throughout the season as well as daily activity peaks. The results affirmed the correlation between the two methods. While optical instruments do not match traps in terms of taxonomic accuracy, the eBoss offered greater temporal resolution (one minute versus roughly three days) and statistical significance owing to its much larger sample size. These outcomes further indicate that entomological optical sensors can provide valuable complementary data to more common methods to monitor flying insect populations, such as mosquitoes or pollinators.

Aim: MacArthur and Wilson's theory of island biogeography proposes that the rate at which species colonize an island depends on the island's isolation (distance effect), whereas the local extinction rate depends on its area (area effect). Alternative hypotheses recognize that area can affect the colonization rate (target effect) and that isolation can affect the extinction rate (rescue effect) and, moreover, that these relationships may dominate. We quantify these relationships and associated turnover rates and incidence using long-term counts of breeding bird communities on islands in an inundated lake. Location: Thousand Island Lake, China. Methods: We assessed the occupancy and behaviour of breeding birds on 37 islands from 2007 to 2012. We estimated the effects of area, isolation and other biogeographical parameters on the frequencies of colonization and extinction events using multivariate logistic regression. We then extended these results to derived properties such as species turnover rates and incidence. Results: Extinction rates decreased and colonization rates increased on larger islands. Isolation had no significant effect on colonization or extinction rates. Islands had high species turnover overall, and turnover rates followed the same pattern as extinction rates with different areas and isolations. Pool turnover, which controls for the number of species in the pool, was higher on large islands. Species richness also increased with area. Our study of bird communities supported area and target effects, but not distance and rescue effects. Main conclusions: Island area was a better predictor of colonization and extinction than isolation, probably because of the relatively small scale (c.580 km²) and homogeneous vegetation structure of our research system, and the strong dispersal ability of birds. We conclude that the differences between our observations and theoretical predictions, or results from other studies that measured colonization and extinction directly, are consistent with the particular biogeography of these islands.

Human induced global change has greatly altered the structure and composition of food webs through the invasion of non‐native species and the extinction of native species. Much attention has been paid to the effects of species deletions on food web structure and stability. However, recent empirical evidence suggests that for most taxa local species richness has increased as successful invasions outpace extinctions at this scale. This pattern suggests that food webs, which represent feeding interactions at the local scale, may be increasing in species richness. Knowledge of how food web structure relates to invasive species establishment and the effect of successful invaders on subsequent food web structure remains an unknown but potentially important aspect of global change. Here we explore the effect of food web topology on invasion success in model food webs to develop hypotheses about how the distribution of biodiversity across trophic levels affects the success of invasion at each trophic level. Our results suggest a connectance (C) based framework for predicting invasion success in food webs due to the way that C constrains the number of species at each trophic level and thus the number of potential predators and prey for an invader at a given trophic level. We use the relationship between C and the proportion of species at each trophic level in 14 well studied food webs to make the following predictions; 1) the success of basal invaders will increase as C increases due to the decrease in herbivores in high C webs, 2) herbivore invasion success will decrease as C increases due to the decrease in the proportion of basal species and increase in intermediate species and omnivores in high C webs. 3) Top predator invasion success will increase as C increases due to the increase in intermediate prey species. However, it is not clear how the relative influence of trophic structure compares to empirically known predictors of invasion success such as invader traits, propagule pressure, and resource availability.

Habitat loss is the principal threat to species. How much habitat remains—and how quickly it is shrinking—are implicitly included in the way the International Union for Conservation of Nature determines a species' risk of extinction. Many endangered species have habitats that are also fragmented to different extents. Thus, ideally, fragmentation should be quantified in a standard way in risk assessments. Although mapping fragmentation from satellite imagery is easy, efficient techniques for relating maps of remaining habitat to extinction risk are few. Purely spatial metrics from landscape ecology are hard to interpret and do not address extinction directly. Spatially explicit metapopulation models link fragmentation to extinction risk, but standard models work only at small scales. Counterintuitively, these models predict that a species in a large, contiguous habitat will fare worse than one in 2 tiny patches. This occurs because although the species in the large, contiguous habitat has a low probability of extinction, recolonization cannot occur if there are no other patches to provide colonists for a rescue effect. For 4 ecologically comparable bird species of the North Central American highland forests, we devised metapopulation models with area-weighted self-colonization terms; this reflected repopulation of a patch from a remnant of individuals that survived an adverse event. Use of this term gives extra weight to a patch in its own rescue effect. Species assigned least risk status were comparable in long-term extinction risk with those ranked as threatened. This finding suggests that fragmentation has had a substantial negative effect on them that is not accounted for in their Red List category. La pérdida de hábitat es la principal amenaza para las especies. La cantidad de hábitat remanente—y la rapidez con que se pierde—están incluidas implícitamente en la forma en que la Unión Internacional para la Conservación de la Naturaleza determina el riesgo de extinción de una especie. Muchas especies en peligro tienen hábitats que también están fragmentados en diferentes grados. Por lo tanto, idealmente, la fragmentación debe ser cuantificada de manera estándar en las evaluaciones de riesgo. Aunque el mapeo de la fragmentación a partir de imágenes de satélite es fácil, son escasas las técnicas eficientes para relacionar mapas del hábitat remanente con el riesgo de extinción. Las métricas puramente espaciales de la ecología del paisaje son difíciles de interpretar y no abordan la extinción directamente. Los modelos metapoblacionales espacialmente explícitos relacionan la fragmentación con el riesgo de extinción, pero los modelos estándar solo funcionan en escalas pequeñas. Contraintuitivamente, estos modelos predicen que una especie en un hábitat extenso y contiguo tendrá menos éxito que en dos fragmentos pequeños. Esto ocurre porque aunque la especie en el hábitat extenso y contiguo tiene una baja probabilidad de extinción, la recolonización no puede ocurrir si no hay otros fragmentos que proporciones colonizadores para un efecto de rescate. Para 4 especies de aves ecológicamente comparables de los bosques de Centro América diseñamos modelos metapoblacionales con términos de autocolonización con ponderación de área; esto reflejó la repoblación de un fragmento con un remanente de individuos que sobrevivieron a un evento adverso. El uso de este término da peso adicional a un fragmento en su propio efecto de rescate. Las especies asignadas con menor riesgo fueron comparables en el riesgo de extinción a largo plazo con aquellas clasificadas como amenazadas. Este hallazgo sugiere que la fragmentación tiene un efecto negativo sustancial sobre esas especies que no esta considerado en su categoría de la lista roja.

Selective harvest, such as poaching, impacts group-living animals directly through mortality of individuals with desirable traits, and indirectly by altering the structure of their social networks. Understanding the relationship between disturbance-induced, structural network changes and group performance in wild animals remains an outstanding problem. To address this problem, we evaluated the immediate effect of disturbance on group sociality in African savanna elephants—an example, group-living species threatened by poaching. Drawing on static association data from ten free-ranging groups, we constructed one empirically based, population-wide network and 100 virtual networks; performed a series of experiments ‘poaching’ the oldest, socially central or random individuals; and quantified the immediate change in the theoretical indices of network connectivity and efficiency of social diffusion. Although the social networks never broke down, targeted elimination of the socially central conspecifics, regardless of age, decreased network connectivity and efficiency. These findings hint at the need to further study resilience by modeling network reorganization and interaction-mediated socioecological learning, empirical data permitting. The main contribution of our work is in quantifying connectivity together with global efficiency in multiple social networks that feature the sociodemographic diversity likely found in wild elephant populations. The basic design of our simulation makes it adaptable for hypothesis testing about the consequences of anthropogenic disturbance or lethal management on social interactions in a variety of group-living species with limited, real-world data.

In the face of worldwide habitat fragmentation, managers need to devise a time frame for action. We ask how fast do understory bird species disappear from experimentally isolated plots in the Biological Dynamics of Forest Fragments Project, central Amazon, Brazil. Our data consist of mist-net records obtained over a period of 13 years in 11 sites of 1, 10, and 100 hectares. The numbers of captures per species per unit time, analyzed under different simplifying assumptions, reveal a set of species-loss curves. From those declining numbers, we derive a scaling rule for the time it takes to lose half the species in a fragment as a function of its area. A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures.

Recent extinction rates are 100 to 1000 times their pre-human levels in well-known, but taxonomically diverse groups from widely different environments. If all species currently deemed \"threatened\" become extinct in the next century, then future extinction rates will be 10 times recent rates. Some threatened species will survive the century, but many species not now threatened will succumb. Regions rich in species found only within them (endemics) dominate the global patterns of extinction. Although new technology provides details of habitat losses, estimates of future extinctions are hampered by our limited knowledge of which areas are rich in endemics.

Managers in southern Africa are concerned that continually increasing elephant populations will degrade ecosystems. Culling, translocation and birth control are flawed solutions. An alternative is providing elephants more space but this hinges on identifying landscape preferences. We examined two diverse ecosystems and uncovered similarities in elephant habitat use, expressing these as ‘rules’. We considered arid Etosha National Park, (Namibia) and the tropical woodlands of Tembe Elephant Park (South Africa) and Maputo Elephant Reserve (Mozambique). Landscape data consisted of vegetation types, distances from water and settlements. To surmount issues of scale and availability we incorporated elephant movements as a function that declined as distance from an elephant's location increased. This presumes that elephants optimize trade-offs between benefiting from high-quality resources and costs to find them. Under a likelihood-based approach we determined the important variables and shapes of their relationships to evaluate and compare models separated by gender, season and location. After considering elephants' preferences for areas nearby, habitat use usually increased with proximity to water in all locations. Elephants sought places with high proportions of vegetation, especially when neighbouring areas had low vegetative cover. Lastly, elephants avoided human settlements (when present), and cows more so than bulls. In caricature, elephants preferred to move little, drink easily, eat well, and avoid people. If one makes more areas available, elephants will probably favour areas near water with high vegetative cover (of many different types) and away from people. Managers can oblige elephants’ preferences by supplying them. If so, they should anticipate higher impacts to neighbouring vegetation.

Setting conservation goals and management objectives relies on understanding animal habitat preferences. Models that predict preferences combine location data from tracked animals with environmental information, usually at a spatial resolution determined by the available data. This resolution may be biologically irrelevant for the species in question. Individuals likely integrate environmental characteristics over varying distances when evaluating their surroundings; we call this the scale of selection. Even a single characteristic might be viewed differently at different scales; for example, a preference for sheltering under trees does not necessarily imply a fondness for continuous forest. Multi-scale preference is likely to be particularly evident for animals that occupy coarsely heterogeneous landscapes like savannahs. We designed a method to identify scales at which species respond to resources and used these scales to build preference models. We represented different scales of selection by locally averaging, or smoothing, the environmental data using kernels of increasing radii. First, we examined each environmental variable separately across a spectrum of selection scales and found peaks of fit. These 'candidate' scales then determined the environmental data layers entering a multivariable conditional logistic model. We used model selection via AIC to determine the important predictors out of this set. We demonstrate this method using savannah elephants (Loxodonta africana) inhabiting two parks in southern Africa. The multi-scale models were more parsimonious than models using environmental data at only the source resolution. Maps describing habitat preferences also improved when multiple scales were included, as elephants were more often in places predicted to have high neighborhood quality. We conclude that elephants select habitat based on environmental qualities at multiple scales. For them, and likely many other species, biologists should include multiple scales in models of habitat selection. Species environmental preferences and their geospatial projections will be more accurately represented, improving management decisions and conservation planning.