Frontiers in Ecology and Evolution

Once widespread around the Mediterranean, the Northern Bald Ibis (Geronticus eremita) became one of the rarest birds in the world. We trace the history of this species through different epochs to the present. A particular focus is on its life and disappearance in ancient Egypt, where it attained the greatest mythological significance as a hieroglyphic sign for blessed ancestor spirits, and on modern endeavours to rewild and restore the species. The close association of the Northern Bald Ibis with human culture in ancient Egypt, as in other regions, is caused by primarily two reasons, the characteristic appearance and behaviour, as well as the need for open foraging areas. In consequence, a mutualistic relationship between humans and birds was formed in some cultures. The benefit for the Northern Bald Ibis was mainly the availability of feeding habitats, which were cleared by humans for farming or grazing and might have contributed to the spread of the species. The benefit to people was primarily cultural and mythological, whereby the bird was worshiped in ancient Egypt and in Muslim cultures, while Christian cultures in Europe rather regarded it as bad omen or nuisance, like any black bird species. Another benefit was profane in nature, the species was also hunted for food, mainly in Europe. But alike many other species, proximity to humans also carried a high risk for the Northern Bald Ibis. We discuss various kinds of human impacts that were driving causes for the extinction of the species in almost all regions. However, the historical disappearance of populations also correlates markedly with changes in climate, especially in ancient Egypt and the Middle Ages. This fact has important implications for current conservation efforts, especially since international action plans for the Northern Bald Ibis have taken little account of climate change effects so far. The Northern Bald Ibis is an outstanding example of how an interdisciplinary cultural-historical and natural-scientific approach significantly promotes the interpretation of historical evidence as well as the implementation of current rewilding and restoration efforts.

Variation in color morph behavior is an important factor in the maintenance of color polymorphism. Alternative anti-predator behaviors are often associated with morphological traits such as coloration, possibly because predator-mediated viability selection favors certain combinations of anti-predator behavior and color. The Aegean wall lizard, Podarcis erhardii, is color polymorphic and populations can have up to three monochromatic morphs: orange, yellow, and white. We investigated whether escape behaviors differ among coexisting color morphs, and if morph behaviors are repeatable across different populations with the same predator species. Specifically, we assessed color morph flight initiation distance (FID), distance to the nearest refuge (DNR), and distance to chosen refuge (DR) in two populations of Aegean wall lizards from Naxos island. We also analyzed the type of refugia color morphs selected and their re-emergence behavior following a standardized intrusion event. We found that orange morphs have different escape behaviors from white and yellow morphs, and these differences are consistent in both of the populations we sampled. Orange morphs have shorter FIDs, DNRs, and DRs, select different refuge types, and re-emerge less often after an intruder event compared to white and yellow morphs. Observed differences in color morph escape behaviors support the idea that morphs have evolved alternative behavioral strategies that may play a role in population-level morph maintenance and loss.

Cetaceans have varied their anatomical structure, physiology and metabolism to adapt to the challenges of aquatic life. Key to this change is the deposition of blubber. This adipose tissue plays a significant regulatory and signaling role in mammalian metabolism. As foraging disruption by human activities is emerging as a key conservation threat for cetaceans, we need to understand how selection for aquatic life might have altered key nutrient sensing pathways associated with adipose signaling. We compared selection pressure on those energy metabolism biological pathways by contrasting the rate of substitution observed in genes associated with them in cetacean and artiodactyl genomes. We then estimated the likely consequence of these selection pressures for pathway functions. Here we show that genes involved in the insulin, mTOR, SIRT and NF-{kappa}B pathways were under significant positive selection in cetaceans compared to their terrestrial sister taxon. Our results suggest these genes may have been positively selected to adapt to a glucose-poor diet and it is unlikely that fat depots signaling function in the same manner as in terrestrial mammals. Secondary adaptation to life in water significantly affected functions in nutrient sensing pathways in cetaceans. Insulin is not likely to play the same role in energy balance as it does in terrestrial mammals and adiposity is not likely to have the deleterious health consequences it has in terrestrial mammals. The physiological ecology of cetacean fat deposition, and therefore its value as a condition index, needs to be interpreted in this evolutionary context.

The diet of large carnivores is of great interest to conservation managers, as it can reveal the extent of human-carnivore conflict and the impact of carnivores on species of high conservation priority. Metabarcoding of environmental DNA can identify species and is often more reliable in doing so than observational or morphological methods. Metabarcoding is particularly powerful at detecting elusive and rare species and has therefore become a widely applied tool in biodiversity research. Here, we used DNA metabarcoding of fecal samples to determine the diet of spotted hyenas in the Ngorongoro Crater, a protected area in Northern Tanzania surrounded by areas co-inhabited by pastoralists. We assessed which species hyenas preferably consumed over a 24-year period and how frequently they consumed pastoralist livestock and black rhinoceros, a species of high economic value and conservation priority. We further estimated the effects of three key socio-demographic variables - age, social rank, and sex - on the propensity of hyenas to consume livestock. We detected DNA from 20 species in 371 hyena feces. Hyenas preferably consumed blue wildebeest and Grants gazelle. Among the detected species were five domestic species and one wild species that lived in the pastoralist-inhabited areas but not the Crater. This shows that resident Crater hyenas undertake foraging trips to areas surrounding the Crater. DNA of domestic species however was rarely detected (4.1% of 434 detections), and predominantly in feces of old hyenas. This suggests that Crater hyenas rarely consume livestock and that livestock is mostly consumed by hyenas less capable of hunting fleet-footed and powerful wild prey. No DNA of black rhinoceros was detected in any of the samples, suggesting that Crater hyenas do not frequently consume rhinoceros. Our findings suggest that the impact of Crater hyenas on livestock and wildlife of high conservation priority is limited. Our study highlights the potential of DNA metabarcoding to assess the extent of human-carnivore conflict and to guide evidence-based conservation efforts to promote coexistence of carnivores, humans and species of high conservation priority.

Evolutionary radiations on oceanic archipelagos (ROAs) have long served as models for understanding evolutionary and ecological processes underlying species diversification. Yet, diversity patterns emerging from ROAs have received relatively little attention from biogeographers, even though characterizing the effect of key geo-environmental factors on island clades species distribution could be important for unraveling diversification dynamics. In this study, we conducted a comparative analysis using island-specific species richness values for approximately one hundred ROAs across major oceanic archipelagos (mostly Hawaii, Canary Islands, Galapagos and Fiji) and taxa (vascular plants, invertebrates and vertebrates). Our aim was to determine whether (1) ROA species richness patterns scale as a function of key geo-environmental factors including island area, geological age, environmental heterogeneity (elevation and topographic complexity) and inter-island isolation, and (2) whether the magnitude of the effects of these factors varies across archipelagos and taxa. Our results identified elevation as a key driver of ROA species richness patterns on islands, supporting existing theoretical and empirical work that highlighted the central role of environmental heterogeneity in driving diversification on oceanic islands. As importantly, we found that the influence of geo-environmental factors varies across archipelagos and taxa, suggesting that unique archipelagic dynamics and biological traits together shape diversification differently. Our findings emphasize the value of applying biogeographical modeling at the resolution of individual radiations to improve our understanding of evolutionary processes on oceanic archipelagos.

Chemosensory-driven hostplant specialization is a major force mediating insect ecological adaptation and speciation. Drosophila sechellia, a species endemic to the Seychelles islands, feeds and oviposits on Morinda citrifolia almost exclusively. This fruit is harmless to D. sechellia but toxic to other Drosophilidae, including the closely related generalists D. simulans and D. melanogaster, due to its high content of fatty acids. While several olfactory adaptations mediating D. sechellias preference for its host have been uncovered, the role of taste has been much less examined. We found that D. sechellia has reduced taste and feeding aversion to bitter compounds and host fatty acids that are aversive to D. melanogaster and D. simulans. The loss of aversion to canavanine, coumarin, and fatty acids arose in the D. sechellia lineage, as its sister species D. simulans showed responses akin to those of D. melanogaster. D. sechellia has increased taste and feeding responses towards M. citrifolia. These results are in line with D. sechellias loss of genes encoding bitter gustatory receptors (GRs) in D. melanogaster. We found that two GR genes which are lost in D. sechellia, GR39a.a and GR28b.a, influence the reduction of aversive responses to some bitter compounds. Also, D. sechellia has increased appetite for a prominent host fatty acid compound that is toxic to its relatives. Our results support the hypothesis that changes in the taste system, specifically a reduction of sensitivity to bitter compounds that deter generalist ancestors, contribute to the specialization of D. sechellia for its host. Summary statementTaste specializations in the specialist Drosophila sechellia include a lineage-specific reduced sensitivity to bitter compounds associated with losses of gustatory receptors, and increased appetite for Noni and host fatty acids.

Island endemic birds are under greater threat than their mainland counterparts. Sedentary living and historically reduced predation may affect island bird sociality and inform their conservation and management. However, detailed studies on their sociality are uncommon. The federally- endangered koloa maoli (Anas wyvilliana, Hawaiian duck, or koloa) is primarily threatened by hybridization with feral mallards and avian botulism outbreaks. We used capture-mark-recapture and genetic data on koloa on the island of Kaua i, a stronghold of remaining koloa, to construct social networks and examine their associations (inferred from co-occurrence in traps) and spatial genetic structure. Information on associations might shed light on preferences for or against mallards and hybrids, and inform planned translocation efforts. Microgeographic spatial genetic structuring where relatedness among individuals scales with geographic distance is a potential liability for maintaining koloa genetic diversity, and would particularly be detrimental during highly localized outbreaks of botulism that could result in the removal of entire lineages. While we found persistent social associations among adult koloa, they were not apparently influenced by plumage traits or body mass, suggesting a lack of social preference for mallard-like individuals. Importantly, we found no spatial patterns of relatedness within the largest refuge. Therefore, botulism outbreaks remain a demographic threat but are unlikely to remove correlated genetic diversity. There were no sex differences in spatial genetic structure and both sexes moved within a refuge. The lack of spatial genetic structure and the presence of many unrelated conspecifics may enable koloa to limit inbreeding and retain genetic diversity without sex-biased dispersal. In the context of future translocations, our results suggest that translocating koloa captured in the same trap together will reduce disruption of preferred associations while also retaining genetic diversity among translocated individuals. LAY SUMMARYO_LIThe koloa maoli (Hawaiian duck, or koloa) is a federally-endangered, island endemic bird. Like other Hawaiian waterbirds, koloa are threatened by introduced predators and habitat loss, but also specifically by hybridization with feral mallards and localized avian botulism outbreaks. Currently, the island of Kaua i has the largest population of non-admixed koloa. We used capture-mark-recapture and genetic data of koloa at two wetland sites on Kaua i to examine their sociality and spatial genetic structure. C_LIO_LIKoloa formed preferential social associations, but they were not based on plumage traits, body mass or genetic relatedness. C_LIO_LIThere was no spatial genetic structure for males and females within a wetland site. Our results suggested that 1) koloa have no preference for mallard-like plumage that might increase hybrid pairing, 2) localized (within-refuge) botulism outbreaks are unlikely to remove close relatives and unique genetic lineages, and 3) translocation of groups could maintain social associations without limiting genetic diversity. C_LI

Trophic interactions are hypothesized to change in response to rapid anthropogenic environmental changes. Documenting these trends may aid biological conservation. One tool to measure trophic level is stable isotope analysis. Nitrogen isotope values ({delta}15N) of bulk tissue may be used as indirect indicators of an organisms trophic level and the isotopic composition of its prey. In contrast, compound-specific isotope analysis can estimate trophic level directly. For the fishes of Chesapeake Bay, museum collections provide a unique opportunity to characterize trophic trends collected as early as the 1850s, from an ecosystem that has been overfished and subjected to increasingly high nutrient loading and land use change during the past three centuries. To assess isotope data for evidence of change in predator species trophic level, we analyzed tissue from 183 museum specimens of three predators (Striped Bass, Morone saxatilis; Summer Flounder, Paralichthys dentatus; and Bluefish, Pomatomus saltatrix) and two lower-trophic-level species (Bay Anchovy, Anchoa mitchilli; and Menhaden, Brevoortia tyrannus). Predatory Striped Bass did not show an increase through time in {delta}15N values, despite such a trend in Bay Anchovy, suggesting possible change in trophic level. Analysis of Striped Bass tissue using compound specific analysis indicates their mean trophic level has been stable for decades. These findings imply that Striped Bass are part of a diverse food web within Chesapeake Bay beyond that reflected by our two included prey species and are stable through time in their average size-specific trophic level, a valuable insight into their ecological role.

Predation is one of the driving forces that shaped the marine ecosystems through time. Apart from the anti-predatory strategies adopted by the prey, the predatory outcome is often indirectly influenced by the other members of the ecological community. Association between organisms are often found to influence the outcome and the evolution of such association may have been guided by such interactions. Mollusc-burnacle association, although common, is not explored to assess if the epibiont offers the molluscs any protection against predation (associational resistance) or increases the risk by attracting predators (shared doom). Using a series of controlled experiments with a drilling predator (Paratectonatica tigrina), its prey (Pirenella cingulata) and an epibiont (Amphibalanus amphitrite), we evaluated the effect of epibionts on the drilling behavior of the predator by documenting the successful attack (Drilling frequency, DF), and handling time. Our results show that the prey with epibionts are significantly less likely to be drilled when the predator has sufficient choice of prey, consistent with the tenets of the associational resistance. The preference of choosing the non-encrusted prey, however, diminishes with fewer available prey. The handling time is significantly higher in the attacks on the encrusted prey than non-encrusted prey, even though the barnacles are not drilled. Although the proximity of the drilling site to encrustation tends to increase the handling time, the size of encrustation does not have any effect. Because the profitability of prey largely depends on the ratio of handling time and the energetic yield from consuming the prey, the increase in handling time due to encrustation makes it less profitable for the predator. The role of encrustation as a deterrent to predation might also explain the complex shell architecture in some prey gastropods that increases the likelihood of encrustation besides providing direct resistance against predation.

Hunting strategies are key to carnivore survival (Krebs and Davies 2009;Kamil et al. 2012;Michalko and Pekar 2016). Fishing Cats (Prionailurus viverrinus) persistence in the semi-aquatic niche (Kitchener et al. 2010) despite felids being terrestrial carnivores in general (>95%) (Hunter 2019) suggests the evolution of a successful hunting strategy. Its further suggest selection for hunting in wetlands. What energy conserving strategies did the Fishing Cat borrow from its family and how were these adapted to optimize energy gained from hunting fish, its primary prey? We attempt to answer this by analyzing 197 video footages collected opportunistically from a participatory science initiative conducted over 2.5 years. We found that the felid switches between stationary and active modes of searching for prey depending on the depth of water and the corresponding loss of body heat/energy. For example, diving in deeper waters requires the submergence of the upper portions of the body and loss of more body heat/energy. Our analysis shows that the cat spent much of its time (~52%) sitting and waiting for prey (fish) to come nearer and then took limited attempts to dive into deeper water (2.78%). We suggest that this is a strategy to optimize the net energy gain. In shallow waters where the cat could forage without submerging the upper body it adopted a predominantly active mode of hunting (~96%) to flush out prey. Thus, prominent hunting strategies in the small cat lineage like sit-and-wait and active foraging is adapted to hunt in the water. We recorded a 60% hunting success in deeper waters but did not detect a successful hunt in shallow waters due to the low sample size of data from shallow water hunting. The major caveat in our study is the post-hoc analysis of opportunistically collected data as opposed to data derived from a structured design with predefined objectives. With more sampling from various seasons and landscapes, finer details can be explored which would have conservation implications. For example, we would expect variations in attempts to hunt during cold seasons because heat loss might be less of a challenge in the latter. Quantifying attempts to hunt and successful hunts across seasons could help focus management interventions to minimize negative interactions between fish cultivators and Fishing Cat. The strictly nocturnal activity of fishing cat as demonstrated in our study could be a strategy taken by the cat to avoid humans. Our approach of using participatory-science is relevant for conducting research on mammal behavior in human dominated landscapes.

The diet of an individual is a result of the availability of dietary items and the individuals foraging skills and preferences. Behavioral differences may thus influence diet variation, but the evolvability of diet choice through behavioral evolution has not been studied. We used experimental evolution combined with a field enclosure experiment to test whether behavioral selection leads to dietary divergence. We analysed the individual dietary niche via stable isotope ratios of nitrogen ({delta}15N) and carbon ({delta}13C) in the hair of an omnivorous mammal, bank vole, from 4 lines selected for predatory behavior and 4 unselected control lines. Predatory voles had higher hair {delta}15N values than control voles, supporting our hypothesis that predatory voles would consume a higher trophic level diet (more animal vs. plant foods). This difference was significant in the early but not the late summer season. The {delta}13C values also indicated a seasonal change in the consumed plant matter and a difference in food sources among selection lines in the early summer. These results imply that environmental factors interact with evolved behavioral tendencies to determine dietary niche heterogeneity. Behavioral selection thus has potential to contribute to the evolution of diet choice and ultimately the species ecological niche breadth.

Organisms are not just passive recipients of environmental pressures but are able to shape the environment they experience. However, the mechanisms and the evolutionary implications of such niche construction remains poorly understood. Larvae of the gazelle dung beetle (Digitonthophagus gazella) extensively modify their environment and benefit from microbial symbionts to digest their cellulose-rich diet. These modifications are so extensive that previous research suggests that dung beetle larvae establish an "external rumen", where behavioral adaptations promote beneficial symbionts that enhance nutrient availability in the developmental environment. However, the mechanisms underlying these environmental modifications and their impact on species differences remains unclear. To investigate the external rumen hypothesis, we study the impact of larval environmental modifications on adult life-history traits in the dung beetle Digitonthophagus gazella. We did this by transplanting eggs into modified and unmodified environments, whilst excluding maternally derived microbes. Additionally, we include a heterospecific (Onthophagus binodis) manipulated environment to investigate evolution of species-specific effects. Counter to expectations, we find larval modifications by conspecifics did not confer a benefit to D. gazella in any aspect measured. However, surprisingly, focals from heterospecific treatments emerged significantly quicker. Additionally, we highlight the primary condition of the developmental environment as an essential factor in determining fitness benefits compared to any additive environmental effects. Our research adds to the growing literature on organism by environment interactions and demonstrates the relationship between dung beetle larvae and their developmental environment are complex and are not consistent with the presence of a simple external rumen.

Density-dependent selection is an important factor shaping the evolution of life histories. In holometabolous insects, crowding in the larval and adult stages can have very different effects on key fitness components. While the nuanced effects of density-dependent selection through larval crowding in Drosophila melanogaster have been extensively studied for various life history traits, very few studies have investigated the effects of adult crowding in Drosophila. Moreover, these few studies were mostly conducted on large flies, derived from low larval density cultures, and typically treated the overall density of flies per culture container as an index of the strength of adult crowding. We hypothesized that the size of the adults should shape the impact of adult crowding, with small individuals experiencing less stress than large individuals when crowded. Consequently, the adverse fitness effects usually associated with adult crowding may not be observed for small individuals. We tested this hypothesis by subjecting flies of different sizes - regular-sized flies, and small flies derived via larval crowding or selection for rapid development to adulthood - to an episode of adult crowding and examining their mortality and fecundity. Thus, we explored the interactive effects between larval and adult crowding on key fitness components. Small body size enabled flies to handle adult crowding better, with significantly lower mortality under crowded conditions when compared to flies of large body size. Moreover, small flies showed a consistent pattern of increased fecundity upon adult crowding. This positive impact on fecundity was not observed when larger flies were crowded. It is clear from our study that the effects of adult crowding can be very nuanced and body size-specific, even to the extent of having a net beneficial effect on fitness components, contrary to previous belief.

Animals frequently defend themselves against predators using diet-derived toxins. Monarch butterflies are a preeminent example of toxin sequestration, gaining protection via cardenolides in their milkweed hosts. Few studies have considered genetic variation in sequestration ability, in monarchs or other species. Here, we use two approaches to study natural selection on cardenolide sequestration in monarchs. First, we conducted a reciprocal rearing experiment with six monarch populations and six associated host species from around the world to determine whether sequestration is higher in monarchs reared on sympatric host species. Second, we compared sequestered cardenolides in wild-caught monarchs from Guam--an island where bird predators have been functionally extirpated for >40 years--to a nearby island with intact birds. We found substantial genetic variation in sequestration ability, though no consistent sequestration advantage in sympatric combinations. One monarch population from Puerto Rico showed greatly reduced sequestration from Asclepias syriaca, likely reflecting a lack of evolutionary association with this host. Monarchs from Guam showed reduced sequestration from A. curassavica, both in a cross-island comparison and when reared under controlled conditions. Our results suggest that processes involved in toxin sequestration are subject to natural selection and may evolve in response to contemporary changes in species interactions.

Toll proteins play roles in immunity/development which have largely remained conserved. However, there are differences in Toll biology as mammalian TLRs recognise pathogen associated molecular patterns (PAMPs) but not their invertebrate homologues. The reason for the same is not known. One critical molecular difference is absence of Cysteine Rich Domain (CRD) in vertebrate Tolls and their presence in invertebrates. Interestingly, in Drosophila, all Toll proteins have CRD except Toll9. This provided us the appropriate model to investigate significance of loss of CRD in Toll evolution. CRDs nudge protein dimerization by forming disulphide bonds hence we asked if they did same in Drosophila Toll-proteins. We tested if, Toll-1(which forms homodimer) can heterodimerize with Toll-9. We found that wildtype Toll-1 didnt interact with Toll9 however; when CRD of Toll1 was deleted/mutated it formed heterodimer with Toll9. This indicates that presence of CRD limits Toll proteins to form homodimer and thus its loss was a critical event which pushed Toll proteins towards heterodimerization. We further show that Drosophila Toll9 can directly bind dsRNA, a PAMP. Interestingly, dsRNA affinity for toll-9 monomer was twice as that for the dimer, which can be attributed to CRD loss. Thus, we show that loss of CRD was a major step in Toll evolution as it resulted in functional diversity and was a first step towards heterodimer formation. Therefore, we propose that CRD loss was under positive selection and also that heterodimerization of Toll-proteins is an evolved property. One line summaryLoss of Cysteine Rich Domain in Drosophila Toll9 and recognition of dsRNA.

This study examines the dietary behaviors of both reared and wild nests of Vespula shidai in Central Japan, a region known for its rich biodiversity and unique entomophagy culture, particularly the consumption of wasp larvae and pupae, known locally as "hachinoko." This study reveal that these wasps exhibit remarkable dietary versatility, consuming a wide range of vertebrates--more varied than their counterparts in Hawaii and New Zealand. The study notes that wild nests, unlike their reared nests, consume a significantly greater variety of vertebrate species, even without supplementation. This suggests that vertebrate carcasses provide crucial nutrients that contribute substantially to wasp development. Additionally, this research highlights individual foraging preferences among nests, which are influenced by both the availability and nutritional value of prey, as well as human feeding practices. This variation in prey composition, particularly evident between reared and wild nests, underscores the complex interaction between wasps natural dietary habits and human intervention.

Oceanic islands are recognized evolutionary hotspots for terrestrial organisms, but little is known about their impact on marine organisms evolution and biogeography. The volcanic archipelagos of Macaronesia occupy a vast and complex region which is particularly suitable to investigate marine island biogeography. In this study, we used mitochondrial DNA sequences to investigate the genetic diferentiation between the populations from Webbnesia (i.e. Madeira, Selvagens and Canaries) and adjacent coasts, of 23 intertidal peracarid species. All species had unexpectedly high intraspecific genetic distances, reaching more than 20% in some cases. Between 79 and 95 Molecular Operational Taxonomic Units (MOTUs) were found in these species. Webbnesia populations displayed an impressive genetic diversity and high endemicity, with 83% of the MOTUs being private to these islands, particularly La Palma and Madeira. Network analyses suggested higher similarity between Webbnesia and Azores than with adjacent continental coasts. These results reveal an unanticipated and sweeping biogeographic discontinuity of peracaridean fauna between Webbnesia and the Iberian Peninsula, raising suspicion about the possible occurrence of identical patterns in other groups of marine invertebrates in the region. We emphasize the unique genetic heritage hosted by these islands, underlining the need to consider the fine scale endemicity in marine conservation efforts.

Foraging behavior plays a fundamental role in animal fitness and population dynamics, particularly in marine ecosystems where seabirds like petrels (small Procellariiformes) showcase a diverse array of foraging strategies finely adapted to the pelagic environment. The extent and remote nature of their foraging grounds makes direct observation of foraging behaviour impractical, thereby requiring the use of remote tracking technologies. We deployed miniaturized multi-sensor biologgers and collected fine scale movement data to investigate the at-sea behaviours of the Bermuda petrel Pterodroma cahow, a poorly studied and highly threatened gadfly petrel, specialised on mesopelagic prey. GPS-tracking data revealed extensive foraging trips, in consistent directions, over remote oceanic regions. Time-depth-recorders provided new insights into petrel feeding techniques suggesting that the meso-bathypelagic prey targeted by petrels must be available in the very upper layer of the water surface, given their very limited diving activity (99.99% of dives had 0.1 m of depth). Accelerometer data revealed 3 flying- and 3 water-related behaviours. Flying behaviours reflected the expected dynamic soaring flight strategy of procellariforms; individuals spent more than three-quarters of their time in flight with flying-non-flapping being the most common behaviour under all conditions. The behaviour classified as "flying-intensive" was infrequently observed but could indicate aerial dipping, a characteristic foraging technique of Pterodroma species. The remaining time was spent in three water behaviours: active, inactive and intensive, with the latter being less common but thought to reflect scavenging and prey seizing. Flying-related behaviours increased with negative sun elevation values, highlighting greater flight activity during night compared to the day, while water behaviours were more common during the day. While some of our findings may require further validation to confirm their relevance to foraging behaviour, our work offers new and valuable insights to consider when assessing the extent and nature of offshore anthropogenic-related risks faced by petrels.

Island archipelagos are global biodiversity hotspots since they often foster high concentrations of diverse lineages and endemic species. Here, we examine the population genetics of the endemic Bolles Laurel Pigeon Columba bollii, a frugivorous bird inhabiting subtropical laurel forests. We genotyped ten microsatellite loci using DNA obtained from moulted tail feathers collected at eight sampling sites on the four western islands of the Canarian archipelago. Analyses including F-statistics, Bayesian clustering approaches, isolation by distance tests and population graph topologies, were used to infer the genetic diversity and the population differentiation within and among insular populations. Additionally, we evaluated the effect of null alleles on data analysis. Low genetic diversity was found in all populations of Bolles Laurel Pigeon, with no significant differences in diversity among them. However, significant genetic differentiation was detected among all populations, with pigeons from La Palma and El Hierro exhibiting the closest affinity. Bayesian clustering supported population separation between islands, and also detected fine-scale structure within the Tenerife and La Gomera populations. Present-day pigeon movements appear to occur between islands, however, this has not been sufficient to remove the signature of genetic divergence among the populations of Bolles Laurel Pigeon, which was moderately linked to geographical distance. According to metapopulation structure, this study suggests that the evolutionary history of C. bollii is closely related to the geological past of these oceanic islands and the distribution range of its habitat, the laurel forest. Finally, conservation implications for the species are discussed.

Anthropogenic influences on habitats often affect predation on species by introducing novel predators, supporting additional predators, or reducing animals ability to detect or avoid predators. Other changes may reduce the ability of animals to feed, or alter their energy use. An increase in predation risk is assumed to reduce prey populations by increasing mortality, reducing foraging and growth. Often animals dont appear to have been adversely affected, or may even increase growth rate. However, theoretical predictions that may have been overlooked suggest that optimal foraging rate, mortality rate and growth rate may change in counter-intuitive ways, depending on exactly how predation risk or costs have been increased. Increasing predator density may increase mortality rate when foraging, reduce the safety of refuges, or alter the relationship between vigilance and attack likelihood. Increasing temperature may increase metabolic costs in ectotherms and reduce thermogenesis costs in endotherms, which affects the costs of active foraging and inactivity differently. Here, I review the theory on how predation risk and metabolic costs should affect foraging behaviour, mortality and growth in order to explain the great variation in behavioural responses. I show that in some situations animals may not respond behaviourally even though a change severely affects survival, and the mortality may be a poor metric of the impact of a change on population viability. In other situations a fitness proxy may change dramatically whilst fitness is unaffected due to compensatory changes in behaviour or life history. Other measures may change in a positive way whilst fitness declines. I describe how to identify the situations in the field and thereby make reliable measure of fitness in particular study systems. Overall, this work shows how behavioural theory can help understand the impacts of environmental change and highlights promising directions to better understand and mitigate their effects on ecosystems.