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Shearwaters (order Procellariiformes) are an excellent study system to investigate the genetic consequences of the co-called "seabird paradox", as they are able to disperse long distances but many species exhibit natal and breeding philopatry. However, few microsatellite markers are currently available for these taxa, hampering genetic inferences.In this study, 25 novel microsatellite loci were isolated and characterized for each of two distantly related shearwater species: the wedge-tailed shearwater (Ardenna pacifica) and the tropical shearwater (Puffinus bailloni). Polymorphism tests were performed for a total of 91 A. pacifica individuals sampled at Reunion and Round Island, and 48 P. bailloni individuals from Reunion and Europa Island, in the western Indian Ocean. The analyses revealed 23 polymorphic loci for A. pacifica, with the number of alleles per locus (Na) ranging from 2 to 8 (mean = 3.957 ± 0.364). Nineteen polymorphic loci were found for P. bailloni, with Na varying from two to five (mean = 3.053 ± 0.247). The observed heterozygosity (HThe new microsatellite loci provide a valuable tool for further population genetic studies, and will allow for design of effective conservation and management plans for A. pacifica, P. bailloni and other closely-related species.

1. Estimating the contribution of demographic parameters to changes in population growth is essential for understanding why populations fluctuate. Integrated population models (IPMs) offer a possibility to estimate the contributions of additional demographic parameters, for which no data have been explicitly collected— typically immigration. Such parameters are often subsequently highlighted as important drivers of population growth. Yet, accuracy in estimating their temporal variation, and consequently their contribution to changes in population growth rate, has not been investigated. 2. To quantify the magnitude and cause of potential biases when estimating the contribution of immigration using IPMs, we simulated data (using northern wheatear Oenanthe oenanthe population estimates) from controlled scenarios to examine potential biases and how they depend on IPM parameterization, formulation of priors, the level of temporal variation in immigration and sample size. We also used empirical data on populations with known rates of immigration: Soay sheep Ovis aries and Mauritius kestrel Falco punctatus with zero immigration and grey wolf Canis lupus in Scandinavia with near-zero immigration. 3. IPMs strongly overestimated the contribution of immigration to changes in population growth in scenarios when immigration was simulated with zero temporal variation (proportion of variance attributed to immigration = 63% for the more constrained formulation and real sample size) and in the wild populations, where the true number of immigrants was zero or near-zero (kestrel 19.1%–98.2%, sheep 4.2%– 36.1% and wolf 84.0%–99.2%). Although the estimation of the contribution of immigration in the simulation study became more accurate with increasing temporal variation and sample size, it was often not possible to distinguish between an accurate estimation from data with high temporal variation versus an overestimation from data with low temporal variation. Unrealistically, large sample sizes may be required to estimate the contribution of immigration well. 4. To minimize the risk of overestimating the contribution of immigration (or any additional parameter) in IPMs, we recommend to: (a) look for evidence of variation in immigration before investigating its contribution to population growth, (b) simulate and model data for comparison to the real data and (c) use explicit data on immigration when possible.

SummarySeabirds are one of the most threatened avian taxa and are hence a high conservation priority. Managing seabirds is challenging, requiring conservation actions at sea (e.g. Marine Protected Areas - MPAs) and on land (e.g. protection of breeding sites). Important Bird and Biodiversity Areas (IBAs) have been successfully used to identify sites of global importance for the conservation of bird populations, including breeding seabirds. The challenge of identifying suitable IBAs for tropical seabirds is exacerbated by high levels of dispersal, aseasonal and asynchronous breeding. The western Indian Ocean supports ~19 million breeding seabirds of 30 species, making it one of the most significant tropical seabird assemblages in the world. Within this is the British Indian Ocean Territory (BIOT), encompassing 55 islands of the Chagos Archipelago, which supports 18 species of breeding seabird and one of the world’s largest no-take MPAs. Between January and March in 1975 and 1996, eight and 45 islands respectively were surveyed for seabirds and the data used to designate 10 islands as IBAs. A further two were proposed following an expedition to 26 islands in February/March 2006. Due to the historic and restricted temporal and spatial nature of these surveys, the current IBA recommendations may not accurately represent the archipelago’s present seabird status and distribution. To update estimates of the BIOT breeding seabird assemblage and reassess the current IBA recommendations, we used seabird census data collected in every month except September from every island, gathered during 2008–2018. The maximum number of breeding seabirds for a nominal year was 281,596 pairs of 18 species, with three species making up 96%: Sooty Tern Onychoprion fuscatus - 70%, Lesser Noddy Anous tenuirostris - 18% and Red-footed Booby Sula sula - 8%. Phenology was a complex species-specific mix of synchronous and asynchronous breeding, as well as seasonal and aseasonal breeding. Nine of the 10 designated IBAs and the two proposed IBAs qualified for IBA status based on breeding seabirds. However, not every IBA qualified each year because Sooty Terns periodically abandoned breeding islands and Tropical Shearwater Puffinus bailloni breeding numbers dropped below IBA qualifying criteria in some years. Further, one survey per year does not always capture the periodic breeding of some tropical seabirds. We propose therefore, that IBAs in BIOT are better designated at the island cluster level rather than by specific island and require two surveys six months apart per year. This work highlights the merits of long-term, systematic, versus incidental surveys for breeding tropical seabirds and the subsequent associated designation of IBAs.

Changes in phenology and distribution are being widely reported for many migratory species in response to shifting environmental conditions. Understanding these changes and the situations in which they occur can be aided by understanding consistent individual differences in phenology and distribution and the situations in which consistency varies in strength or detectability. Studies tracking the same individuals over consecutive years are increasingly reporting migratory timings to be a repeatable trait, suggesting that flexible individual responses to environmental conditions may contribute little to population-level changes in phenology and distribution. However, how this varies across species and sexes, across the annual cycle and in relation to study (tracking method, study design) and/or ecosystem characteristics is not yet clear. Here, we take advantage of the growing number of publications in movement ecology to perform a phylogenetic multilevel meta-analysis of repeatability estimates for avian migratory timings to investigate these questions. Of 2,433 reviewed studies, 54 contained suitable information for meta-analysis, resulting in 177 effect sizes from 47 species. Individual repeatability of avian migratory timings averaged 0.414 (95% confidence interval: 0.3–0.5) across landbirds, waterbirds and seabirds, suggesting consistent individual differences in migratory timings is a common feature of migratory systems. Timing of departure from the non-breeding grounds was more repeatable than timings of arrival at or departure from breeding grounds, suggesting that conditions encountered on migratory journeys and outcome of breeding attempts can influence individual variation. Population-level shifts in phenology could arise through individual timings changing with environmental conditions and/or through shifts in the numbers of individuals with different timings. Our findings suggest that, in addition to identifying the conditions associated with individual variation in phenology, exploring the causes of between-individual variation will be key in predicting future rates and directions of changes in migratory timings. We therefore encourage researchers to report the within- and between- individual variance components underpinning the reported repeatability estimates to aid interpretation of migration behaviour. In addition, the lack of studies in the tropics means that levels of repeatability in less strongly seasonal environments are not yet clear.

Conservation translocations are commonly used in recovery programmes for threatened species from a wide range of taxa but outcomes can vary considerably both within and between programmes, and the causes of success or failure are often unclear. Central to understanding translocation success is the implementation of an accompanying monitoring programme, enabling the drivers of population establishment and persistence to be explored within a population ecology framework. Here we review and assess the outcome of a translocation programme for the Endangered Mauritius Kestrel, which involved the initial translocation of captive-reared Kestrels into four isolated populations and long-term nest-site management and monitoring. We show that after 20 years these four populations have different recovery trajectories including local extinction, recent decline and comparative stability. We explore the demographic drivers behind these trajectories and how they have been influenced, and could potentially be manipulated, by conservation management actions. Metrics of breeding performance differed between populations and in part this was driven by nest-site selection, with Kestrels nesting more frequently, laying larger clutch sizes and rearing larger broods in nestboxes. We found no compelling evidence for inter-population variation in survival rates. Simulating population trajectories under a range of conservation management scenarios, including further conservation translocations or a scaling up of nest-site management, suggested that the latter would be a more effective, practical long-term solution for the population currently in decline. Our findings provide valuable insights into the merits of monitoring, population demographic reviews and the challenges associated with identifying and mitigation for the drivers of rarity in threatened species.

The Hispaniolan solenodon, Solenodon paradoxus, and Hispaniolan hutia, Plagiodontia aedium, are the Dominican Republic’s only surviving endemic non-volant land mammals, and are high priorities for conservation. The country has an extensive protected area (PA) network designed to maintain habitats and benefit biodiversity, but which faces significant anthropogenic threats likely to detrimentally impact both species. We examined how differences in habitats, forest structure, topography, and human activity influence presence of solenodons and hutias across the Dominican Republic. Systematic surveys of seven PAs were undertaken to record indirect signs, with presence-absence data analyzed using a multi-model inference approach incorporating ecological variables from both field and GIS data. Solenodons were detected relatively frequently, whereas detections of hutias were uncommon. Lower elevations, increased surrounding tree cover, canopy closure, and reduced levels of low vegetation are all associated with increased probability of detecting solenodons, whereas agriculture and mangrove represent poor-quality habitat. Increased canopy closure, tree basal area (indicating older-growth forest), and increased rock substrate (providing more den sites) are associated with increased probability of detecting hutias. Our findings indicated that human activities within PAs are likely to negatively affect both species, and conservation activities should focus on preventing encroachment and conversion of forest to agriculture to maintain high-quality forest habitats. El solenodonte de la Hispaniola, Solenodon paradoxus, y la hutia de la Hispaniola, Plagiodontia aedium, son los únicos mamíferos endémicos terrestres no voladores que sobreviven en la República Dominicana, su conservación es de alta prioridad. El país tiene una extensa red de áreas protegidas (AP) diseñada para mantener hábitats y beneficiar la biodiversidad, pero se enfrenta a amenazas antropogénicas. Sin embargo, no existen datos cuantitativos para evaluar las presiones antropogénicas que amenazan a los solenodontes y las hutias. Examinamos cómo las diferencias en los hábitats, la estructura del bosque, la topografía y la actividad humana influyen la presencia de solenodontes y hutias en toda la República Dominicana. Se realizaron encuestas sistemáticas de siete AP para registrar los signos indirectos de ambas especies, los datos de presencia/ausencia fueron analizados mediante inferencia multimodelo que incorpora variables ecológicas de los datos de campo y Sistema de Información Geográfica. Los Solenodontes se detectaron relativamente frecuentemente, mientras que las detecciones de hutias fueron menos comunes. Las elevaciones más bajas, el aumento de la cubierta arbórea circundante, el cierre del dosel y los niveles reducidos de vegetación baja se asocian con una mayor probabilidad de detectar solenodones. Mientras que la agricultura y los manglares representan un hábitat de mala calidad para el solenodonte. Aumento del cierre del dosel, área basal del árbol (que indica un bosque más antiguo) y un sustrato con mayor proporcion de roca (que proporciona más sitios para madrigueras) se asocian con una mayor probabilidad de detectar hutias. Nuestros hallazgos indican que las actividades humanas dentro de las AP pueden afectar negativamente a ambas especies. Las actividades de conservación deberían enfocarse en mantener hábitats forestales de alta calidad por medio de prevenir la invasión y la conversión de los bosques a agricultura.

Constraints on evolutionary adaptation and range shifts mean that phenotypic plasticity, which includes physiological, developmental or behavioural responses to environmental conditions, could be an important mode of adaptation to a changing climate for many species with small insular populations. While there is evidence to suggest adaptive plasticity to climate in some island populations, little is known about this capacity in species that have experienced a severe population bottleneck. In a changing climate, plasticity in the timing of life-history events, such as in breeding phenology, is adaptive if timing is optimised in seasonal environments, although these processes are poorly understood for tropical species. Here, we quantify the effects of climate on the breeding phenology and success of the Mauritius kestrel (Falco punctatus), a tropical raptor whose extinction has been averted by conservation management. We show that the timing of egg-laying is advancing in response to warming, at rates similar to temperate bird populations. Individual females show plasticity to temperature, although there is limited variation among individual responses. We show that advances in breeding phenology are likely to be adaptive, as they track changes in a seasonal climate window of favourable conditions, defined by late winter-early spring temperatures and the onset of the summer rainy season. Our results provide a rare example of a small and bottlenecked insular population that has adjusted to recent climate change through phenotypic plasticity. Furthermore, seasonal climate windows and their dynamics may be widespread mechanisms through which tropical species are impacted by and respond to climate change.

Given the recent trend towards establishing very large marine protected areas (MPAs) and the high potential of these to contribute to global conservation targets, we review outcomes of the last decade of marine conservation research in the British Indian Ocean Territory (BIOT), one of the largest MPAs in the world. The BIOT MPA consists of the atolls of the Chagos Archipelago, interspersed with and surrounded by deep oceanic waters. Islands around the atoll rims serve as nesting grounds for sea birds. Extensive and diverse shallow and mesophotic reef habitats provide essential habitat and feeding grounds for all marine life, and the absence of local human impacts may improve recovery after coral bleaching events. Census data have shown recent increases in the abundance of sea turtles, high numbers of nesting seabirds and high fish abundance, at least some of which is linked to the lack of recent harvesting. For example, across the archipelago the annual number of green turtle clutches (Chelonia mydas) is ~ 20,500 and increasing and the number of seabirds is ~ 1 million. Animal tracking studies have shown that some taxa breed and/or forage consistently within the MPA (e.g. some reef fishes, elasmobranchs and seabirds), suggesting the MPA has the potential to provide long-term protection. In contrast, post-nesting green turtles travel up to 4000 km to distant foraging sites, so the protected beaches in the Chagos Archipelago provide a nesting sanctuary for individuals that forage across an ocean basin and several geopolitical borders. Surveys using divers and underwater video systems show high habitat diversity and abundant marine life on all trophic levels. For example, coral cover can be as high as 40–50%. Ecological studies are shedding light on how remote ecosystems function, connect to each other and respond to climate-driven stressors compared to other locations that are more locally impacted. However, important threats to this MPA have been identified, particularly global heating events, and Illegal, Unreported and Unregulated (IUU) fishing activity, which considerably impact both reef and pelagic fishes.

Global-scale gene flow is an important concern in conservation biology as it has the potential to either increase or decrease genetic diversity in species and populations. Although many studies focus on the gene flow between different populations of a single species, the potential for gene flow and introgression between species is understudied, particularly in seabirds. The only well-studied example of a mixed-species, hybridizing population of petrels exists on Round Island, in the Indian Ocean. Previous research assumed that Round Island represents a point of secondary contact between Atlantic (Pterodroma arminjoniana) and Pacific species (Pterodroma neglecta and Pterodroma heraldica). This study uses microsatellite genotyping and tracking data to address the possibility of between-species hybridization occurring outside the Indian Ocean. Dispersal and gene flow spanning three oceans were demonstrated between the species in this complex. Analysis of migration rates estimated using bayesass revealed unidirectional movement of petrels from the Atlantic and Pacific into the Indian Ocean. Conversely, structure analysis revealed gene flow between species of the Atlantic and Pacific oceans, with potential three-way hybrids occurring outside the Indian Ocean. Additionally, geolocation tracking of Round Island petrels revealed two individuals travelling to the Atlantic and Pacific. These results suggest that interspecific hybrids in Pterodroma petrels are more common than was previously assumed. This study is the first of its kind to investigate gene flow between populations of closely related Procellariiform species on a global scale, demonstrating the need for consideration of widespread migration and hybridization in the conservation of threatened seabirds.

Knowledge of demographic parameters affecting population dynamics is critical to the formulation of effective conservation strategies. Sooty Falcon Falco concolor is a little-studied, Near-threatened species; estimates of global population size and trend for this species are uncertain. They lay eggs during mid-summer and sometimes nest in colonies. This unusual breeding ecology suggests that demographic parameters driving their population growth rate may differ from those of most other falcons. We studied Sooty Falcon reproduction at breeding aggregations on Fahal Island and the Daymaniyat islands in the Sea of Oman during 2007–2014, modelled population growth and identified important life history parameters using elasticity analysis. The mean (± se) clutch and brood size was 2.83 ± 0.06 and 2.11 ± 0.07, respectively. Overall, 11.7% of nests failed between the egg and nestling stages, and the failure rate differed significantly between Fahal and the Daymaniyats, and across years. The mean proportion of eggs that hatched annually was 0.66 ± 0.02, and broods were significantly smaller on the Daymaniyats than on Fahal. Falcons on Fahal Island had a higher rate of hatching, a higher rate of nests that produced at least one chick, and produced more chicks per nest than on the Daymaniyats. We suggest that Fahal's proximity to the mainland gives breeding Sooty Falcons access to a more plentiful and stable source of food, especially during the period between arrival from the wintering grounds and the onset of the autumn migration of prey birds, resulting in the better reproductive rates for falcons on Fahal Island, relative to those on the Daymaniyat Islands. The annual asymptotic population growth rate (λ) was 0.87 (95% confidence interval (CI) 0.75–0.99), suggesting a declining population, although Sooty Falcons enjoyed a slightly higher population growth rate on Fahal than on the Daymaniyats. Because our study population is on the edge of the breeding range and is isolated from other breeding areas, measures to improve reproductive success of Sooty Falcons breeding on the islands in the Sea of Oman could be important for conservation of Sooty Falcons in Oman.

Conservation decision-making for threatened species in human-modified landscapes requires detailed knowledge about spatial ecology, but robust data derived from tracking individual animals are often unavailable, with management decisions potentially based on unreliable anecdotal data. Existing data are limited for Hispaniola's two threatened non-volant land mammals, the Hispaniolan hutia (Plagiodontia aedium) and Hispaniolan solenodon (Solenodon paradoxus), with assumptions that hutias are better able to tolerate landscape disturbance. We collected spatial behaviour and habitat use data for Hispaniolan mammals during a multi-year field programme across undisturbed and modified habitats in southwestern Dominican Republic, using GPS units for hutias (11 individuals) and radio-telemetry for solenodons (22 individuals). Although significant differences exist in hutia home range estimates between different GPS error derivation strategies and estimated terrestrial/arboreal behaviour scenarios (95% KDE means = 23,582–28,612 m2), hutias almost exclusively use forest under all estimates (mean observations in forest across all strategies/scenarios = 90.3%, total range = 69.1–100%). Solenodons have larger estimated home ranges (95% KDE mean = 156,700 m2), with differences between wet and dry season estimates, and show much more variation in habitat use than hutias within the same landscape; animals regularly use both forested and modified habitats, being observed most frequently in forest (mean = 74.0%, range = 13.0–99.1%) but also occurring regularly in pasture (mean = 15.9%, range = 0–80.0%) and cropland (mean = 7.7%, range = 0–62.0%), and den in all three habitats. This new baseline on Hispaniolan mammal spatial ecology challenges anecdotal data, and suggests solenodons may be better able to tolerate disturbance and persist in modified landscapes. Keywords: Dominican Republic, Evidence-based conservation, Hutia, Kernel density estimate, Solenodon, Telemetry

Invasive species are a major threat for island biodiversity, causing species decline and extinction globally. Of all invasive mammals rats are one of the most detrimental and have been the target of numerous control and eradication programmes. In Mauritius rats have contributed to the extinction of 50% of the island's fauna and are thought to be the main threat to the endemic Mauritius olive white-eye (Zosterops chloronothos), a critically endangered passerine. Assessing the impact of rats and suitable control strategies is often problematic in such cases because of the lack of replicate populations for experiments. Here, we illustrate how to overcome this issue by combining a small-scale rat management experiment on olive white-eyes with demographic models that provide estimates of the potential effects of management on vital rates and population growth. We established poison and trapping grids within breeding territories, and show that rat management significantly decreased rat abundance and increased nesting success. An individual-based stochastic simulation model suggested that rat control could produce a 5–6 fold increase in the annual productivity of female olive white-eyes, which in turn would be sufficient to stabilise population growth. In the absence of rat management, our analysis suggests the olive white-eye population will decline by about 14% per annum. By combining low cost field experiments with widely available demographic models we highlight the value of targeted, effective rat management techniques for both short and long-term population management in threatened passerines.

Tropical cyclones are renowned for their destructive nature and are an important feature of marine and coastal tropical ecosystems. Over the last 40 years, their intensity, frequency and tracks have changed, partly in response to ocean warming, and future predictions indicate that these trends are likely to continue with potential consequences for human populations and coastal ecosystems. However, our understanding of how tropical cyclones currently affect marine biodiversity, and pelagic species in particular, is limited. For seabirds, the impacts of cyclones are known to be detrimental at breeding colonies, but impacts on the annual survival of pelagic adults and juveniles remain largely unexplored and no study has simultaneously explored the direct impacts of cyclones on different life-history stages across the annual life cycle. We used a 20-year data set on tropical cyclones in the Indian Ocean, tracking data from 122 Round Island petrels and long-term capture–mark–recapture data to explore the impacts of tropical cyclones on the survival of adult and juvenile (first year) petrels during both the breeding and migration periods. The tracking data showed that juvenile and adult Round Island petrels utilize the three cyclone regions of the Indian Ocean and were potentially exposed to cyclones for a substantial part of their annual cycle. However, only juvenile petrel survival was affected by cyclone activity; negatively by a strong cyclone in the vicinity of the breeding colony and positively by increasing cyclone activity in the Northern Indian Ocean where they spend the majority of their first year at sea. These contrasting effects raise the intriguing prospect that the projected changes in cyclones under current climate change scenarios may have positive as well as the more commonly perceived negative impacts on marine biodiversity.

The provision of supplementary food is widely used in the management of endangered species. Typically, food is provided ad libitum and often without a planned exit strategy, which can be costly. The role supplementary food plays within population demography can be challenging to identify and therefore any reduction must be carefully considered to avoid negative impacts. Here we investigate the role supplementary food plays within a reintroduced population of a Critically Endangered passerine species by quantifying its use alongside intrinsic and extrinsic factors. Specifically, we illustrate how the provision of supplementary food could be refined in response to breeding stage and the time of food provisioning and, via habitat restoration, create a long-term exit strategy based on influential plant species. The consumption of supplementary food increases during energetically expensive phases of the breeding cycle, during the morning provision of food and when natural plant resource availability is low. We also show a pattern whereby supplementary food could act as a buffer during periods of low natural resource availability during breeding. Based on these findings short-term management could take a reactive approach; refining supplementary food supply in response to breeding stages of pairs and potentially removing the provision of food in the afternoon. In the long-term key plant species, found to correlate with a decrease in supplementary food consumption, could be incorporated into habitat restoration efforts which could create a continuous natural food supply and contribute to creating a self-sustaining population and a potential exit strategy.

Summary 1. Spatial variation in habitat quality and its demographic consequences have important implications for the regulation of animal populations. Theoretically, habitat quality is typically viewed as a single gradient from ‘poor’ to ‘good’, but in wild populations it is possible that there are multiple environmental gradients that determine spatial variation in demography. 2. Understanding environmental gradients is important to gain mechanistic insights into important population processes, but also to understand how populations might respond to environmental change. Here, we explore habitat and elevation gradients and their implications for population persistence using detailed long-term data on 600 individuals of the Mauritius kestrel. These data allow us to statistically separate spatial variation in demography from variation arising out of individual or environmental quality and explore its relationships with habitat and topography. 3. Birds that breed earlier in the season have higher reproductive success, and we found that the timing of breeding varies significantly between territories. This variation is primarily driven by elevation, with birds breeding progressively later as elevation increases. 4. Pre-fledging survival from the egg to fledgling stage (independently of timing), and recruitment, also varied significantly between territories. This variation is driven by the habitat surrounding breeding sites with increasing agricultural encroachment causing survival and recruitment to decline. 5. Taken together, our results suggest that there are likely to be multiple environmental gradients affecting spatial variation in productivity in wild populations, and hence multiple and different routes through which environmental change might have consequences for population dynamics by modifying spatial processes.

International audience; Spatial patterns of site occupancy are commonly driven by habitat heterogeneity and are thought to shape population dynamics through a site-dependent regulatory mechanism. When examining this, however, most studies have only focused on a single vital rate (reproduction), and little is known about how space effectively contributes to the regulation of population dynamics. We investigated the underlying mechanisms driving density-dependent processes in vital rates in a Mauritius kestrel population where almost every individual was monitored. Different mechanisms acted on different vital rates, with breeding success regulated by site dependence (differential use of space) and juvenile survival by interference (density-dependent competition for resources). Although territorial species are frequently assumed to be regulated through site dependence, we show that interference was the key regulatory mechanism in this population. Our integrated approach demonstrates that the presence of spatial processes regarding one trait does not mean that they necessarily play an important role in regulating population growth, and demonstrates the complexity of the regulatory process.

Little is known about the ecology of the Grey-headed Fish-Eagle (GHFE; Ichthyophaga ichthyae- tus) despite it being a globally near-threatened species in apparent decline. We here present the first quantitative information on nesting ecology of this species, in a regionally significant population at Prek Toal, part of the seasonally flooded swamp forest surrounding the Tonle Sap Lake, Cambodia. We found that GHFE selected trees as nest sites that had an open crown structure and were relatively tall. Grey-headed Fish-Eagles preferred nesting closer to permanent water than expected, but the timing of breeding did not differ according to distance to permanent water: we suggest that their preference for nests near water may reflect an advantage based on prey availability. Water snakes, known prey of GHFE, were significantly more abundant at a site in permanent water than at a temporarily flooded site, in December. We also found that human habitation was negatively correlated to GHFE nest-site occupancy rates. This may reflect indirect effects of human exploitation of GHFE food supplies, which may be exacerbated in the future by changes to the Tonle Sap ecosystem resulting from upstream dam construction.

Summary 1. In recent decades there have been population declines of many UK bird species, which have become the focus of intense research and debate. Recently, as the populations of potential predators have increased there is concern that increased rates of predation may be contributing to the declines. In this review, we assess the methodologies behind the current published science on the impacts of predators on avian prey in the UK. 2. We identified suitable studies, classified these according to study design (experimental ⁄ observational) and assessed the quantity and quality of the data upon which any variation in predation rates was inferred. We then explored whether the underlying study methodology had implications for study outcome. 3. We reviewed 32 published studies and found that typically observational studies comprehensively monitored significantly fewer predator species than experimental studies. Data for a difference in predator abundance from targeted (i.e. bespoke) census techniques were available for less than half of the 32 predator species studied. 4. The probability of a study detecting an impact on prey abundance was strongly, positively related to the quality and quantity of data upon which the gradient in predation rates was inferred. 5. The findings suggest that if a study is based on good quality abundance data for a range of predator species then it is more likely to detect an effect than if it relies on opportunistic data for a smaller number of predators. 6. We recommend that the findings from studies which use opportunistic data, for a limited number of predator species, should be treated with caution and that future studies employ bespoke census techniques to monitor predator abundance for an appropriate suite of predators.

Global climate change and its impacts are being increasingly studied and precipitation trends are one of the measures of quantifying climate change especially in the tropics. This study uses daily rainfall data to determine if there are changes in the long-term trends in rainfall variability in the East Coast Mountains of Mauritius during the last few decades, and to investigate the factors influencing the trends in the inter-annual to inter-decadal rainfall variability. Statistical modelling has been used to investigate the trends in total seasonal rainfall, the number of rain days and the mean amount of rain per rainy days and the local, regional and large-scale factors that affect them on inter-annual to inter-decadal time scales. The strongest inter-decadal trend was found in the number of rain days for both rainfall seasons, and the other variables were found to have weak or insignificant trends. Both local factors, such as the surrounding sea surface temperatures and large-scale phenomena such as Indian Monsoon and the El Nino Southern Oscillation were found to influence rainfall patterns.

Knowledge of tropical raptor habitat use is limited and yet a thorough understanding is vital when trying to conserve endangered species. We used a well studied, reintroduced population of the vulnerable Mauritius Kestrel Falco punctatus to investigate habitat preferences in a modified landscape. We constructed a high resolution digital habitat map and radiotracked 13 juvenile Kestrels to quantify habitat preferences. We distinguished seven habitat types in our study area and tracked Kestrels from 71 to 130 days old during which they dispersed from their natal territory and settled within a home-range after reaching independence. Mean home-range size was 0.95 km 2 characterized by a bimodal pattern of intensity around the natal site and post-independence home-range. Compositional analysis showed that home-ranges were located non-randomly with respect to habitat but there was no evidence to suggest differential use of habitats within home-ranges. Native and semi-invaded forest and grassland were consistently preferred, whereas agriculture was used significantly less than other habitats. No difference was found between the available length of edge dividing native forest and grassland within a home-range when compared to that available within a 2.3 5-km buffer around their nest-site, based on the maximum distance a juvenile was found to disperse. Repeating the analysis in three dimensions gave very similar results. Our results suggest that Mauritius Kestrels are not obligate forest dwellers as was once thought but can also exploit open habitats such as grassland. Kestrels may be using isolated mature trees within grassland as vantage points for hunting in the same way as they use the natural stratified forest structure. We suggest that the avoidance of agriculture is partly due to a lack of such vantage points. The conservation importance of forest degradation and agricultural encroachment is highlighted and comparisons with the habitat preferences of other tropical falcons are discussed.

Many populations have recovered from severe bottlenecks either naturally or through intensive conservation management. In the past, however, few conservation programs have monitored the genetic health of recovering populations. We conducted a conservation genetic assessment of a small, reintroduced population of Mauritius Kestrel (Falco punctatus) to determine whether genetic deterioration has occurred since its reintroduction. We used pedigree analysis that partially accounted for individuals of unknown origin to document that (1) inbreeding occurred frequently (2.6% increase per generation; N(eI)= 18.9), (2) 25% of breeding pairs were composed of either closely or moderately related individuals, (3) genetic diversity has been lost from the population (1.6% loss per generation; N(eV)= 32.1) less rapidly than the corresponding increase in inbreeding, and (4) ignoring the contribution of unknown individuals to a pedigree will bias the metrics derived from that pedigree, ultimately obscuring the prevailing genetic dynamics. The rates of inbreeding and loss of genetic variation in the subpopulation of Mauritius Kestrel we examined were extreme and among the highest yet documented in a wild vertebrate population. Thus, genetic deterioration may affect this population's long-term viability. Remedial conservation strategies are needed to reduce the impact of inbreeding and loss of genetic variation in this species. We suggest that schemes to monitor genetic variation after reintroduction should be an integral component of endangered species recovery programs.

The regional population of the Grey-headed Fish-Eagle (Ichthyophaga ichthyaetus) in Southeast Asia is thought to be in recent decline and its conservation status under threat. We undertook a systematic survey in a flooded swamp forest at the Tonle Sap Lake in Cambodia and recorded 32 pairs of eagles in an area of approximately 80 km2. Three species of water snakes were identified as eagle prey items, previously unrecorded for this species. We suggest that this eagle population has significant regional importance and discuss potential anthropogenic threats to population stability, such as water snake harvesting and construction of upstream hydropower dams.

1. Life-history theory assumes that trade-offs exist between an individual's life-history components, such that an increased allocation of a resource to one fitness trait might be expected to result in a cost for a conflicting fitness trait. Recent evidence from experimental manipulations of wild individuals supports this assumption. 2. The management of many bird populations involves harvesting for both commercial and conservation purposes. One frequently harvested life-history stage is the egg, but the consequences of repeated egg harvesting for the individual and the long-term dynamics of the population remain poorly understood. 3. We used a well-documented restored population of the Mauritius kestrel Falco punctatus as a model system to explore the consequences of egg harvesting (and associated management practices) for an individual within the context of life-history theory. 4. Our analysis indicated that management practices enhanced both the size and number of clutches laid by managed females, and improved mid-life male and female adult survival relative to unmanaged adult kestrels. 5. Although management resulted in an increased effort in egg production, it reduced parental effort during incubation and the rearing of offspring, which could account for these observed changes. 6. Synthesis and applications. This study demonstrates how a commonly applied harvesting strategy, when examined within the context of life-history theory, can identify improvements in particular fitness traits that might alleviate some of the perceived negative impact of harvesting on the long-term dynamics of a managed population.

Re-introduction is a technique widely used in the conservation of threatened bird species. With advances in aviculture the use of captive-produced individuals as the release stock is becoming more commonplace, and ideally, survival of captive-produced, released individuals should be no different from their wild-bred counterparts. During the late 1980s the Critically Endangered Mauritius kestrel (Falco punctatus) was successfully re-introduced into the Bambous mountain range, Mauritius, some 30 years after its local extinction. Between 1987 and 2001 the developing population was closely monitored enabling us to construct re-sighting histories for 88 released and 284 wild-bred kestrels. We used age-structured models in the survival analysis software program MARK to determine if an individual's origin influenced its subsequent survival. Our analysis indicated no compelling evidence for reduced survival among juvenile captive-reared and released individuals, relative to their wild-bred counterparts, across the majority of cohorts and only limited evidence of a cohort-specific effect. This study illustrates that despite the lack of a formal experimental approach it is still feasible to conduct an assessment of re-introduction outcomes and techniques.

1. We studied a reintroduced population of the formerly critically endangered Mauritius kestrel Falco punctatus Temmink from its inception in 1987 until 2002, by which time the population had attained carrying capacity for the study area. Post-1994 the population received minimal management other than the provision of nestboxes. 2. We analysed data collected on survival (1987-2002) using program MARK to explore the influence of density-dependent and independent processes on survival over the course of the population's development. 3.We found evidence for non-linear, threshold density dependence in juvenile survival rates. Juvenile survival was also strongly influenced by climate, with the temporal distribution of rainfall during the cyclone season being the most influential climatic variable. Adult survival remained constant throughout. 4. Our most parsimonious capture-mark-recapture statistical model, which was constrained by density and climate, explained 75.4% of the temporal variation exhibited in juvenile survival rates over the course of the population's development. 5. This study is an example of how data collected as part of a threatened species recovery programme can be used to explore the role and functional form of natural population regulatory processes. With the improvements in conservation management techniques and the resulting success stories, formerly threatened species offer unique opportunities to further our understanding of the fundamental principles of population ecology.

Habitat conversion for agriculture is a major driver of biodiversity loss, but our understanding of the demographic processes involved remains poor. We typically investigate the impacts of agriculture in isolation even though populations are likely to experience multiple, concurrent changes in the environment (e.g. land and climate change). Drivers of environmental change may interact to affect demography, but the mechanisms have yet to be explored fully in wild populations. Here, we investigate the mechanisms linking agricultural land use with breeding success using long-term data for the formerly Critically Endangered Mauritius kestrel Falco punctatus, a tropical forest specialist that also occupies agricultural habitats. We specifically focused on the relationship between breeding success, agriculture and the timing of breeding because the latter is sensitive to changes in climatic conditions (spring rainfall) and enables us to explore the interactive effects of different (land and climate) drivers of environmental change. Breeding success, measured as egg survival to fledging, declines seasonally in this population, but we found that the rate of this decline became increasingly rapid as the area of agriculture around a nest site increased. If the relationship between breeding success and agriculture was used in isolation to estimate the demographic impact of agriculture, it would significantly under-estimate breeding success in dry (early) springs and over-estimate breeding success in wet (late) springs. Analysis of prey delivered to nests suggests that the relationship between breeding success and agriculture might be due, in part, to spatial variation in the availability of native, arboreal geckos. Synthesis and applications. Agriculture modifies the seasonal decline in breeding success in this population. As springs are becoming wetter in our study area and since the kestrels breed later in wetter springs, the impact of agriculture on breeding success will become worse over time. Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs. Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

International audience; A major question in ecology is how age-specific variation in demographic parameters influences population dynamics. Based on long-term studies of growing populations of birds and mammals, we analyze population dynamics by using fluctuations in the total reproductive value of the population. This enables us to account for random fluctuations in age distribution. The influence of demographic and environmental stochasticity on the population dynamics of a species decreased with generation time. Variation in age-specific contributions to total reproductive value and to stochastic components of population dynamics was correlated with the position of the species along the slow-fast continuum of life-history variation. Younger age classes relative to the generation time accounted for larger contributions to the total reproductive value and to demographic stochasticity in "slow" than in "fast" species, in which many age classes contributed more equally. In contrast, fluctuations in population growth rate attributable to stochastic environmental variation involved a larger proportion of all age classes independent of life history. Thus, changes in population growth rates can be surprisingly well explained by basic species-specific life-history characteristics.

International audience; Dispersal is a key process in population and evolutionary ecology. Individual decisions are affected by fitness consequences of dispersal, but these are difficult to measure in wild populations. A long-term dataset on a geographically closed bird population, the Mauritius kestrel, offers a rare opportunity to explore fitness consequences. Females dispersed further when the availability of local breeding sites was limited, whereas male dispersal correlated with phenotypic traits. Female but not male fitness was lower when they dispersed longer distances compared to settling close to home. These results suggest a cost of dispersal in females. We found evidence of both short- and long-term fitness consequences of natal dispersal in females, including reduced fecundity in early life and more rapid aging in later life. Taken together, our results indicate that dispersal in early life might shape life history strategies in wild populations.

There is growing evidence of changes in the timing of important ecological events, such as flowering in plants and reproduction in animals, in response to climate change, with implications for population decline and biodiversity loss. Recent work has shown that the timing of breeding in wild birds is changing in response to climate change partly because individuals are remarkably flexible in their timing of breeding. Despite this work, our understanding of these processes in wild populations remains very limited and biased towards species from temperate regions. Here, we report the response to changing climate in a tropical wild bird population using a long-term dataset on a formerly critically endangered island endemic, the Mauritius kestrel. We show that the frequency of spring rainfall affects the timing of breeding, with birds breeding later in wetter springs. Delays in breeding have consequences in terms of reduced reproductive success as birds get exposed to risks associated with adverse climatic conditions later on in the breeding season, which reduce nesting success. These results, combined with the fact that frequency of spring rainfall has increased by about 60 per cent in our study area since 1962, imply that climate change is exposing birds to the stochastic risks of late reproduction by causing them to start breeding relatively late in the season.

Variations in demographic rates due to differential resource allocation between individuals are important considerations in the development of accurate population dynamic models. Systematic harvesting can alter age structure and/or reduce population density, conferring indirect positive benefits on the source population as a result of a consequent redistribution of resources between the remaining individuals. Independently of effects mediated through changes in density and competition, demographic rates can also be influenced by within-individual competition for resources. Harvesting dependent life stages can reduce an individual's current reproductive costs, allowing increased investment in its future fecundity and survival. Although such changes in demographic rates are well known, there has been little exploration of the potential impact on population dynamics. We use empirical data collected from a successfully reintroduced population of the Mauritius kestrel Falco punctatus to explore the population consequences of manipulating reproductive effort through harvesting. Consequent increases in an individual's future fecundity and survival allow source populations to withstand longer and more intensive harvesting regimes without being exposed to an increase in extinction risk, increasing maximum sustainable yields. These effects may also buffer populations against the impacts of stochastic events, but directional shifts in environmental conditions that increase reproductive costs may have detrimental population-level effects.

International audience; Comparative analyses of survival senescence by using life tables have identified generalizations including the observation that mammals senesce faster than similar-sized birds. These generalizations have been challenged because of limitations of life-table approaches and the growing appreciation that senescence is more than an increasing probability of death. Without using life tables, we examine senescence rates in annual individual fitness using 20 individual-based data sets of terrestrial vertebrates with contrasting life histories and body size.Wefind that senescence is widespread in the wild and equally likely to occur in survival and reproduction. Additionally, mammals senesce faster than birds because they have a faster life history for a given body size. By allowing us to disentangle the effects of two major fitness components our methods allow an assessment of the robustness of the prevalent life-table approach. Focusing on one aspect of life history – survival or recruitment – can provide reliable information on overall senescence.

Many populations have recovered from severe bottlenecks either naturally or through intensive conservation management. In the past, however, few conservation programs have monitored the genetic health of recovering populations. We conducted a conservation genetic assessment of a small, reintroduced population of Mauritius Kestrel (Falco punctatus) to determine whether genetic deterioration has occurred since its reintroduction. We used pedigree analysis that partially accounted for individuals of unknown origin to document that (1) inbreeding occurred frequently (2.6% increase per generation; N(eI)= 18.9), (2) 25% of breeding pairs were composed of either closely or moderately related individuals, (3) genetic diversity has been lost from the population (1.6% loss per generation; N(eV)= 32.1) less rapidly than the corresponding increase in inbreeding, and (4) ignoring the contribution of unknown individuals to a pedigree will bias the metrics derived from that pedigree, ultimately obscuring the prevailing genetic dynamics. The rates of inbreeding and loss of genetic variation in the subpopulation of Mauritius Kestrel we examined were extreme and among the highest yet documented in a wild vertebrate population. Thus, genetic deterioration may affect this population's long-term viability. Remedial conservation strategies are needed to reduce the impact of inbreeding and loss of genetic variation in this species. We suggest that schemes to monitor genetic variation after reintroduction should be an integral component of endangered species recovery programs.

Spatial processes could play an important role in density-dependent population regulation because the disproportionate use of poor quality habitats as population size increases is widespread in animal populations—the so-called buffer effect. While the buffer effect patterns and their demographic consequences have been described in a number of wild populations, much less is known about how dispersal affects distribution patterns and ultimately density dependence. Here, we investigated the role of dispersal in spatial density dependence using an extraordinarily detailed dataset from a reintroduced Mauritius kestrel ( Falco punctatus ) population with a territorial (despotic) breeding system. We show that recruitment rates varied significantly between territories, and that territory occupancy was related to its recruitment rate, both of which are consistent with the buffer effect theory. However, we also show that restricted dispersal affects the patterns of territory occupancy with the territories close to release sites being occupied sooner and for longer as the population has grown than the territories further away. As a result of these dispersal patterns, the strength of spatial density dependence is significantly reduced. We conclude that restricted dispersal can modify spatial density dependence in the wild, which has implications for the way population dynamics are likely to be impacted by environmental change.

An understanding of the dispersion and migrations of different populations of Purple Sandpipers is being achieved through comparisons of their biometrics, and sightings and recoveries of marked birds. Icelandic breeding Purple Sandpipers were captured in order to describe the biometrics of this population. Measurements were compared with British wintering birds in an attempt to establish whether Icelandic Purple Sandpipers form one of the components of the British wintering population. Although bill lengths were similar to the “long‐billed” British birds, wing and foot lengths were not; being longer in the Icelandic population. It is therefore concluded that Icelandic Purple Sandpipers do not migrate to Britain. Sightings in winter in north Iceland of birds colour‐marked in Iceland whilst breeding or as chicks show that some, at least, are resident.