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Wareham, United Kingdom

Harris J.B.C.,University of Adelaide | Harris J.B.C.,Princeton University | Dwi Putra D.,Celebes Bird Club | Gregory S.D.,University of Adelaide | And 6 more authors.
Diversity and Distributions | Year: 2014

Aim: Deforestation and climate change are two of the most serious threats to tropical birds. Here, we combine fine-scale climatic and dynamic land cover models to forecast species vulnerability in rain forest habitats. Location: Sulawesi, Indonesia. Methods: We sampled bird communities on four mountains across three seasons in Lore Lindu National Park, Sulawesi, Indonesia (a globally important hotspot of avian endemism), to characterize relationships between elevation and abundance. Deforestation from 2000 to 2010 was quantified, and predictors of deforestation were identified. Future forest area was projected under two land use change scenarios - one assuming current deforestation rates and another assuming a 50% reduction in deforestation. A digital elevation model and an adiabatic lapse rate were used to create a fine-scale map of temperature in the national park. Then, the effects of climate change were projected by fitting statistical models of species abundance as a function of current temperature and forecasting future abundance based on warming from low- and high-emissions climate change. Results: The national park lost 11.8% of its forest from 2000 to 2010. Model-based projections indicate that high-elevation species (white-eared myza Myza sarasinorum and Sulawesi leaf-warbler Phylloscopus sarasinorum) might be buffered from deforestation because their ranges are isolated from human settlement, but these species may face steep population declines from climate change (by as much as 61%). The middle-elevation sulphur-bellied whistler Pachycephala sulfuriventer is predicted to undergo minor declines from climate change (8-11% reduction), while deforestation is predicted to cause larger declines of 13-19%. Main conclusions: The biological richness and rapid deforestation now occurring inside the national park emphasize the need for increased enforcement, while our modelling suggests that climate change is most threatening to high-elevation endemics. These findings are likely applicable to other highland tropical sites where deforestation is encroaching from below and climate change is stressing high-elevation species from above. © 2014 John Wiley & Sons Ltd. Source

Cucherousset J.,Bournemouth University | Cucherousset J.,CNRS Biological Evolution and Diversity Laboratory | Acou A.,French Natural History Museum | Blanchet S.,CNRS Biological Evolution and Diversity Laboratory | And 4 more authors.
Oecologia | Year: 2011

Individual specialisation can lead to the exploitation of different trophic and habitat resources and the production of morphological variability within a population. Although the ecological causes of this phenomenon are relatively well known, its consequences on individual fitness are less recognised. We have investigated the extent of individual specialisation in resource use and trophic morphology and its fitness consequences through a combination of tagging-recapture, stable isotope analyses and telemetry. The European eel (Anguilla anguilla) was the model species as it displays significant variability in head shape. Independent to their body length, individuals with broader heads displayed a significantly higher trophic position (δ 15N) than individuals with narrower heads. This corresponded with a significantly higher proportion of prey fish in their diet compared with invertebrates and was associated with the use of a habitat niche located further from the river bank. The European eel therefore provides a rare empirical example of individual specialisation in resource use and trophic morphology in a natural population occurring at a very small spatial scale. Individuals with intermediate head morphology displayed lower body condition (a proxy of fitness) than individuals with extreme head morphology (i. e. narrower and broader headed individuals), demonstrating the existence of disruptive selection associated with individual specialisation. © 2011 Springer-Verlag. Source

Gregory S.D.,University of Adelaide | Gregory S.D.,Salmon and Trout Research Center | Ancrenaz M.,Hutan | Brook B.W.,University of Adelaide | And 5 more authors.
Diversity and Distributions | Year: 2014

Aim: Habitat fragmentation threatens species' persistence by increasing subpopulation isolation and vulnerability to stochastic events, and its impacts are expected to worsen under climate change. By reconnecting isolated fragments, habitat corridors should dampen the synergistic impacts of habitat and climate change on population viability. Choosing which fragments to reconnect is typically informed by past and current environmental conditions. However, habitat and climate are dynamic and change over time. Habitat suitability projections could inform fragment selection using current and future conditions, ensuring that corridors connect persistent fragments. We compare the efficacy of using current-day and future forecasts of breeding habitat to inform corridor placement under land cover and climate-change mitigation and no mitigation scenarios by evaluating their influence on subpopulation abundance, and connectivity and long-term metapopulation abundance. Our case study is the threatened orangutan metapopulation in Sabah. Location: Sabah, Malaysian Borneo. Methods: Using coupled niche-population models that capture a metapopulation distribution and its major processes, we forecast the effect of current-day and future-informed habitat corridor implementations under two scenarios where (1) land cover and climate change continue unabated (no mitigation) and (2) local and international cooperation mitigates their synergistic impact (mitigation). Results: We show that Future-informed corridor placement maximizes long-term metapopulation abundance when human-driven land cover and climate change alter the spatio-temporal composition of suitable habitat. By contrast, there is no apparent benefit in using future forecasts of breeding habitat to inform corridor placement if conditions remain comparatively stable. For the Sabah orangutan under unabated land cover and climate change, habitat corridors should connect current-day populated eastern habitat fragments with vacant fragments in the state's west. Main conclusions: The efficacy of habitat corridors can be improved by using habitat-suitability model projections to inform corridor placement in rapidly changing environments, even for long-lived, low-fecundity, philopatric species such as orangutan. © 2014 John Wiley & Sons Ltd. Source

Ibbotson A.T.,Salmon and Trout Research Center | Ibbotson A.T.,Queen Mary, University of London | Riley W.D.,The Center for Environment | Beaumont W.R.C.,Salmon and Trout Research Center | And 4 more authors.
Ecology of Freshwater Fish | Year: 2013

Over 3 years, 32,444 age-0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m-2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required. © 2012 John Wiley & Sons A/S. Source

Ibbotson A.T.,Salmon and Trout Research Center | Beaumont W.R.C.,Salmon and Trout Research Center | Pinder A.C.,APEM Ltd
Environmental Biology of Fishes | Year: 2011

Migration theory states that migration behavioural strategies should be optimised to maximise fitness. Many studies have shown that in downstream migrating Atlantic salmon Salmo salar L. smolts, mortality from predation is high and negatively size dependent. The most common predators are birds and piscivorous fish that are mainly daylight feeders. Given the high mortality during this stage we should expect to observe smolts to follow predator avoidance strategies that may be affected by body size. We tested the hypothesis that small smolts have a higher tendency to exhibit predator avoidance strategies (i. e. nocturnal versus diurnal migration) than larger smolts. The number and size of out-migrating/downstream-migrating wild Atlantic salmon smolts was recorded as they passed through a glass-sided channel during April-May, 1996-1999. In all years, the mean size of nocturnal migrating smolts was significantly lower than the mean size of diurnal migrating smolts. Analysis of the size of smolts, during early and late stages of the migration period showed size-dependent nocturnal migration behaviour up to the end of April. After this, no such size dependent migration pattern was observed. However, small smolts (<100 mm) were absent during this period. We suggest that nocturnal migration is an adaptive behaviour that small Atlantic salmon smolts have to avoid predation by large daylight feeding visual piscivorous predators (e. g. pike Esox Lucius L. and fish eating birds). © 2011 Springer Science+Business Media B.V. Source

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