Large Predators Research Articles

Vertebrate coprolites from Middle Triassic Chang 7 Member in Ordos Basin, China: Palaeobiological and palaeoecological implications

The early Ladinian lacustrine ecosystem of the Chang 7 Member in the Ordos Basin was proposed as the earliest known Mesozoic-type, trophically multileveled lacustrine ecosystem after the end-Permian mass extinction (EPME). However, limited evidence of higher-order trophic levels represented by predatory fish has made this conclusion elusive. In this study, we investigated the external morphology, food inclusions, and geochemical composition of 54 vertebrate coprolites from organic-rich lacustrine sediments of Chang 7 Member, Yanchang Formation, in the Bawangzhuang section, Tongchuan City, Shaanxi Province, China. These coprolites were identified as seven morphotypes in three groups: three heteropolar spiral forms, two amphipolar spiral forms, and two non-spiral forms. Preserved inclusions (fish scales, bone fragments, teeth) indicated that the producers of these coprolites were piscivorous animals. Compared with coprolites previously researched, all coprolites described herein were inferred to be produced by fish: three heteropolar types of spiral coprolites derived from three types of hybodonts, two amphipolar spiral coprolites from coelacanth or Saurichthys with simple spiral valves, and non-spiral coprolites from at least two predatory actinopterygians. Thus, the biodiversity of the lacustrine paleoecosystem, particularly that of predators with upper trophic levels, was substantially enriched. The existence of large carnivorous predators of different taxa as apex predators in a trophically multileveled (at least six levels) lacustrine ecosystem indicates that the early Ladinian lacustrine ecosystem of the Ordos Basin marks the rebuilding of the top-predator trophic structure in the lacustrine ecosystem after the EPME.

Habitat and Marine Reserve Status Drive Reef Fish Biomass and Functional Diversity in the Largest South Atlantic Coral Reef System (Abrolhos, Brazil)

The effects of fishing have been documented across coral reefs worldwide. No-take marine reserves do not only act as a conservation tool but also allow an opportunity to study impacts of fishing, by acting as control sites. In addition, well-planned and well-managed no-take marine reserves (NTRs) provide conservation benefits that are essential to marine biodiversity and ecosystem-based management. The Abrolhos Marine National Park, off the tropical Brazilian coast, protects part of the largest coral reef system in the South Atlantic. To investigate the effects of fishing on reef fish richness, abundance, biomass, and functional diversity of the fish assemblage, we compared sites across two protection levels considering the variation in habitats (Fringing Reefs—Protected; Pinnacles Reefs—Protected; and Coastal Reefs—Open Access), using Baited Remote Underwater Stereo-Video systems (stereo-BRUVs). We adjusted generalized additive mixed models of fish assemblage characteristics with protection levels and environmental variables, such as topographic complexity (mean relief and relief variation), visibility, and benthic cover percentage. Inside NTRs, we found higher total biomass and biomass of fishery target species and carnivores, specifically for the Carcharhinidae (sharks) and Epinephelidae (groupers) families, indicating direct fisheries effects on these groups. In contrast, the ecological parameters of non-target fish were positively correlated with habitat characteristics, including mean relief and variance of relief. Moreover, fish functional diversity was higher within NTRs, demonstrating an even distribution of functional entities. The presence of large mobile predators and the overall higher biomass of carnivores inside the NTR indicate the effect of fishing exclusion. Our results point to the value of NTRs to study the effects of fishing and achieve biodiversity conservation and suggest the importance of using remote sampling methods to assess large mobile predators.

Top‐down effects on aquatic communities in subtropical lentic microhabitats

AbstractNatural lentic microhabitats are important for aquatic invertebrate communities in subtropical aquatic systems, which are usually dominated by mosquitoes, predators and zooplankton. Subtropical lentic microhabitats might be strongly affected by top‐down effects of predators. We evaluated the predator effects on aquatic macroinvertebrate and zooplankton communities by using black plastic buckets (10 L) to simulate lentic microhabitats, which were divided into four treatments: predator absence and presence, and initial (on experiment start) and final (on experiment end) community controls. Large top predators (Odonata) had a stronger effect on community structure by their sit‐and‐wait predatory behaviour. The richness of total macroinvertebrates, Culex genus (most abundant organism), and zooplankton was highest in predators' absence. On the other hand, the sit‐and‐wait behaviour increased the density of organisms by selective predation on macroinvertebrates that feed in the bottom of the system. Also, the sit‐and‐wait behaviour increased the density of gathering and filtering collectors (top swimmers) by differences in space preference. We observed a positive species‐specific relationship between Culex and predators. We concluded that predators' presence contributes to the balance of lentic microhabitat in subtropical lentic microhabitats by top‐down control.

What is a lion worth to local people – Quantifying of the costs of living alongside a top predator

The presence of large predators entails a range of costs and some benefits for the communities that live alongside them. The cost in terms of the value of livestock lost to predation is well known, but this represents only a part of the costs that people experience, as it does not account for non-market costs such as fear, avoidance behaviours and threat to human life. We quantify the total cost of lion presence for agro-pastoral communities in Zimbabwe using economic valuation techniques. The total perceived value of one additional lion was estimated to be negative US$180 per person per year, which is several hundred times larger than the market value of the average loss of livestock per household. If making simplifying economic assumptions, this discrepancy reveals the magnitude of the non-market costs associated with the presence of large predators. The disvalue of lion presence was linked to fear, ecocentric values, wealth and trust in compensation institutions. We also demonstrate the importance of considering heterogeneity in preferences within communities; segments of the population did not have net negative value attached to lions, and some disliked monetary compensation. We also estimate the willingness-to-accept for two human-wildlife conflict mitigation programs in terms of acceptable increases in lion numbers, as opposed to monetary units which is the conventional approach in economic valuation studies. We argue that estimating value in terms of biodiversity outcomes should be used more widely. We also demonstrate the distorting effect of distrust towards compensation in choice experiments and argue that economic valuation methods employing choice experiments should control for this distrust when estimating willingness-to-pay. These discoveries have relevance for a wide range of situations where potentially dangerous wildlife species co-exist with people.

Shoaling in the Trinidadian guppy: costs, benefits, and plasticity in response to an ambush predator

AbstractShoaling, the formation of social groupings in fish, can provide benefits including reduced predation risk. However, it can also inflict costs including increased competition for resources, transmission of parasites, and salience to predators. Trinidadian guppies exhibit inter-population variation in shoaling behavior where individuals coexisting with large piscivorous predators (high predation localities) spend most of their time in shoals and those coexisting with an ambush predator, Rivulus hartii (recently, Anablepsoides hartii), that preys primarily on smaller guppies (low predation localities) do not. It has been suggested that this predator selects for reduced shoaling because doing so reduces salience to the predator. Here, as far as we know, we perform the first test of this idea. First, we investigated the effectiveness of shoaling in encounters with this predator. In survival trials, where one rivulus interacted with a group of guppies, we found that the predator was more likely to attack individuals in shoals than singletons. However, we also found that attacks directed at shoals were less likely to succeed. This suggests that the optimal strategy for guppies co-existing with this predator is to reduce shoaling to reduce the probability of being attacked, and to form shoals when an attack is initiated. We then asked if guppies modified their shoaling behavior in response to visual and olfactory cues from this predator during development. We found changes in guppy behavior in response to the treatment: guppies increased shoaling behavior when there was heightened risk of predation.

Habitat structure, not the anthropogenic context or large predators, shapes occupancy of a generalist mesopredator across protected areas in South Africa

Habitat structure, not the anthropogenic context or large predators, shapes occupancy of a generalist mesopredator across protected areas in South Africa

Diet Composition and Prey Preference of Tiger, Leopard, and Dhole in Kalakkad-Mundanthurai Tiger Reserve, Southern Western Ghats, India

Comprehensive information on prey availability and diet composition is important to formulate effective conservation strategies. Data on these of large apex predators, the tiger Panthera tigris, leopard Panthera pardus, and dhole Cuon alpinus, are deficient in Kalakkad-Mundanthurai Tiger Reserve, India, which harbors low prey density. Therefore, we investigated how these predators coexisted by partitioning limited food resources. We found that prey selection and activity patterns differed among predators. The leopard (D [Jacobs' preference index] = +0.916) and dhole (D = +0.937) preferred the Indian chevrotain Moschiola indica, whereas the tiger preferred the gaur Bos gaurus (D = +0.937). Biomass of tiger's diet mainly consisted of the gaur (75%). In the dhole, the Indian chevrotain and sambar Rusa unicolor together contributed 91% of biomass, whereas 79% of leopard's biomass was contributed by the Nilgiri langur Semnopithecus johnii and the Indian chevrotain. The leopard and dhole had the highest dietary overlap (Ojk [Pianka Index] = 0.46). The highest activity overlap was found among the leopard, Indian chevrotain, and sambar. The leopard and dhole would compete for the Indian chevrotain, although the competition may be avoided by different activity patterns. Managements of the Indian chevrotain and gaur are critical for conserving large predators in the region.

Prairie dogs, cattle subsidies and alternative prey: seasonal and spatial variation in coyote diet in a temperate grassland

As the dominant predator on North America's grasslands, coyotes Canis latrans have a large influence on biodiversity, both on working ranches and in protected parks. Ground squirrel (sciurid) species and livestock carrion are often abundant on grasslands worldwide and have the potential to influence a predator's consumption of alternative prey. We collected 1321 scats in four seasons over two years in and adjacent to Grasslands National Park, Saskatchewan, to test the hypothesis that seasonal and spatial variation in consumption of sciurid prey and cattle Bos taurus carrion influenced coyote consumption of alternative prey. Sciurid (black‐tailed prairie dog Cynomys ludovicianus and Richardson's ground squirrel Urocitellus richardsonii) remains were common from spring to fall and had a strong inverse relationship with deer (mule deer Odocoileus hemionus and white‐tailed deer O. virginianus), which were most common in winter scats. Cattle remains were most common during spring, fall and winter, and occurred in 10.6% of scats annually. Biomass estimates suggest that cattle was the highest ranked food on cattle grazing land year‐round, and the 2nd ranked food, after deer, during winter on the portion of the park from which cattle were excluded. Closer proximity of scats to a prairie dog colony increased the likelihood of prairie dog remains throughout the year and reduced the likelihood of cattle remains in scats from spring to fall, but not during winter. Individual differences in foraging and ranging behavior may explain the spatial distribution of prairie dog versus cattle in scats. Further work is needed to determine whether sciurid prey, deer, or livestock carrion support large predator populations on grassland habitats to a level that may negatively affect coexisting prey species, including species at risk.

Predation promotes diversification in the mean and variance of antipredator traits

Abstract Predator species are separated along habitat gradients, with predation known to play an essential role in species' trait diversification. Because predator species differ dramatically in their hunting style and mode, a change in predator species will alter the mean and variance of prey's antipredator traits. Population trait variation has an impact on community ecology. It influences species' niche width and interactions in the food web. However, empirical studies on variance change by predation are scarce. In this study, we collected large numbers of the last instar Leucorrhinia pectoralis exuviae from lakes with predatory fish (fish lakes) and lakes with large invertebrate predators (dragonfly lakes) and compared their two antipredator traits (spines and body size). We found that individuals in dragonfly lakes grew shorter spines than individuals in fish lakes. Body size showed no significant difference between dragonfly‐lake individuals and fish‐lake individuals. Moreover, populations from dragonfly lakes showed a smaller variance of spine length than populations from fish lakes; while populations from dragonfly lakes had a larger variance in body size than populations from fish lakes. These results indicate that trait variance, as well as mean, is strongly modified by different predation regimes. Studying the mean and variance of traits can help to define the mode of selection forces (directional selection and stabilising selection) in nature. Moreover, dragonfly larvae might be ideal organisms for the study of phenotypic selection on quantitative traits in the wild.

Retrospective genomics highlights changes in genetic composition of tiger sharks (Galeocerdo cuvier) and potential loss of a south-eastern Australia population

Over the last century, many shark populations have declined, primarily due to overexploitation in commercial, artisanal and recreational fisheries. In addition, in some locations the use of shark control programs also has had an impact on shark numbers. Still, there is a general perception that populations of large ocean predators cover wide areas and therefore their diversity is less susceptible to local anthropogenic disturbance. Here we report on temporal genomic analyses of tiger shark (Galeocerdo cuvier) DNA samples that were collected from eastern Australia over the past century. Using Single Nucleotide Polymorphism (SNP) loci, we documented a significant change in genetic composition of tiger sharks born between ~1939 and 2015. The change was most likely due to a shift over time in the relative contribution of two well-differentiated, but hitherto cryptic populations. Our data strongly indicate a dramatic shift in the relative contribution of these two populations to the overall tiger shark abundance on the east coast of Australia, possibly associated with differences in direct or indirect exploitation rates.

Effect of Predator Exclusion on Softshell Clam (Mya arenaria L.) Recruitment

Despite estimates of very high (>99.9%) pre-settlement mortality, the extremely large numbers of eggs released into the plankton means that there are abundant post-larval softshell clams (Mya arenaria) available to settle and populate intertidal flats. Many seemingly suitable flats remain devoid of clams, presumably due to post-settlement predation. Predator exclusion/clam recruitment boxes (wooden frames covered top and bottom with a fine plastic screening) were set on a mudflat in Salem Harbor, Salem, MA from April to November 2019. Clam larvae were able to settle through the screen into the boxes but large (>1.9 mm) predators such as European green crabs (Carcinus maenas) and milky ribbon worms (Cerebratulus lacteus) were excluded. At the end of the study, four of five boxes contained between 121 and 290 juvenile softshell clams ranging in size from 7 mm to 32 mm shell length. A bimodal frequency distribution of sizes likely illustrates an early summer (June) set represented by a larger size grouping followed by a second late-summer set represented by a smaller size grouping. Small green crabs (9–46 mm carapace width) found in all five boxes must have grown from extremely small stage 1 crabs that were able to settle or crawl through the screening as recently settled individuals. Resulting empty clam shells could be paired to yield the equivalent of additional clams, making the total number per box between 147 and 417 individuals. No clams were found in samples outside of the boxes, indicating that the absence of a clam population on the mudflat is due to post-settlement predation and not pre-settlement mortality.

Long-term decline in northern pike (Esox lucius L.) populations in the Baltic Sea revealed by recreational angling data

In the Baltic Sea, the large predatory fish northern pike (Esox lucius L.) is important for both recreational fisheries and ecosystem functioning. As existing fishery-independent surveys do not adequately monitor pike populations, a general lack of knowledge on population status and trends poses challenges for management. Here we use recreational angling data as an alternative method to describe pike population development along the Swedish Baltic Sea coast from 1938 onwards and assess the change over time in potential mortality factors by estimating harvest by fisheries and consumption by large predators. Data from a Swedish national register on trophy-sized pike (>12 kg) showed that numbers and maximum sizes peaked in 1990–1995, after which declines in both metrics are evident. In logbooks from a sport fishing club in the Stockholm archipelago, a simultaneous decrease in maximum sizes of pike was observed, together with a decrease in the total number of pike caught per fishing day. Jointly, these data indicate a decline in the abundance of large pike since around 1990. While commercial pike fisheries in the Baltic Sea have decreased continuously since the 1950s, recreational fishing increased after 1985, when Swedish coastal waters were made open access to anglers. The declines in large pike starting in the 1990s could, thus, have been driven by an increase in mortality from recreational fisheries, which at the time primarily practiced catch and kill. Since the 2000s, bag and slot length limits, spawning closures, and a general increase in catch-and-release fishing has reduced the landings of pike in recreational fisheries. Despite these fisheries regulations and higher release rates the decline in catches of large pike has continued, indicating an effect of other mortality factors. The strong growth of grey seal (Halichoerus grypus) and great cormorant (Phalacrocorax carbo sinensis) populations suggest that predation pressure on pike has increased over time. In the Stockholm archipelago these two predators were estimated to remove 5–18 times (range based on different diet composition estimates) more pike biomass than total fisheries landings in 2014–2017. To improve the situation for northern pike in the Baltic Sea managers need to consider both fisheries restrictions and measures to decrease predation pressure and increase recruitment. Catch data from recreational fisheries may be used to evaluate such management efforts by providing information on the population development of this keystone species.

Successive extreme climatic events lead to immediate, large-scale, and diverse responses from fish in the Arctic.

The warming trend of the Arctic is punctuated by several record‐breaking warm years with very low sea ice concentrations. The nature and reversibility of marine ecosystem responses to these multiple extreme climatic events (ECEs) are poorly understood. Here, we investigate the ecological signatures of three successive bottom temperature maxima concomitant with surface ECEs between 2004 and 2017 in the Barents Sea across spatial and organizational scales. We observed community‐level redistributions of fish concurrent with ECEs at the scale of the whole Barents Sea. Three groups, characterized by different sets of traits describing their capacity to cope with short‐term perturbations, reacted with different timing and intensity to each ECE. Arctic species co‐occurred more frequently with large predators and incoming boreal taxa during ECEs, potentially affecting food web structures and functional diversity, accelerating the impacts of long‐term climate change. On the species level, responses were highly diversified, with different ECEs impacting different species, and species responses (expansion, geographical shift) varying from one ECE to another, despite the environmental perturbations being similar. Past ECEs impacts, with potential legacy effects, lagged responses, thresholds, and interactions with the underlying warming pressure, could constantly set up new initial conditions that drive the unique ecological signature of each ECE. These results highlight the complexity of ecological reactions to multiple ECEs and give prominence to several sources of process uncertainty in the predictions of climate change impact and risk for ecosystem management. Long‐term monitoring and studies to characterize the vertical extent of each ECE are necessary to statistically link demersal species and environmental spatial–temporal patterns. In the future, regular monitoring will be crucial to detect early signals of change and understand the determinism of ECEs, but we need to adapt our models and management to better integrate risk and stochasticity from the complex impacts of global change.

Protist Predation Influences the Temperature Response of Bacterial Communities.

Temperature strongly influences microbial community structure and function, in turn contributing to global carbon cycling that can fuel further warming. Recent studies suggest that biotic interactions among microbes may play an important role in determining the temperature responses of these communities. However, how predation regulates these microbiomes under future climates is still poorly understood. Here, we assess whether predation by a key global bacterial consumer—protists—influences the temperature response of the community structure and function of a freshwater microbiome. To do so, we exposed microbial communities to two cosmopolitan protist species—Tetrahymena thermophila and Colpidium sp.—at two different temperatures, in a month-long microcosm experiment. While microbial biomass and respiration increased with temperature due to community shifts, these responses changed over time and in the presence of protists. Protists influenced microbial biomass and respiration rate through direct and indirect effects on bacterial community structure, and predator presence actually reduced microbial respiration at elevated temperature. Indicator species analyses showed that these predator effects were mostly determined by phylum-specific bacterial responses to protist density and cell size. Our study supports previous findings that temperature is an important driver of microbial communities but also demonstrates that the presence of a large predator can mediate these responses to warming.

Fossil Felidae (Carnivora: Mammalia) from the Yuanmou hominid site, southern China (Late Miocene) and its significance in the living environment of the fossil ape

Abstract The Yuanmou hominid site is a rare Late Miocene fossil locality in southern China, where thousands of fossil specimens of the ape Lufengpithecus hudiensis have been found. These have been well studied, but the taxonomy of other mammalian groups is not fully understood. This is especially the case for large predator Felidae, which play a key role in the palaeo-environment in which these fossil apes lived. Here we study the systematics of fossil Felidae from Yuanmou, which is composed of four species of machairodonts: Amphimachairodus cf. horribilis, Longchuansmilus xingyongi gen. & sp. nov., aff. Yoshi sp., Machairodontinae gen. & sp. indet. and one species of feline, Felinae gen. & sp. indet. Longchuansmilus xingyongi is a member of Machairodontini, related to Lokotunjailurus and possibly two derived species of Paramachaerodus, i.e. P. orientalis and P. maximiliani. The high diversity of machairodonts suggests a unique palaeo-environment of the Yuanmou Basin during the Late Miocene, different from northern Eurasia or modern south-eastern Asia. An analysis of body size and intraguild competition suggests that aff. Yoshi sp. and Machairodontinae gen. & sp. indet. are probably regular predators of the fossil great ape, which may have pushed the high evolutionary rate of the fossil ape.

Spatial and temporal differentiation are not distinct but are covariant for facilitating coexistence of small and medium-sized carnivores in Southwestern China

Sympatric small- and medium-sized carnivores will thrive in forest ecosystems in the absence of large top predators. Spatial and temporal niche differentiation are commonly regarded as important mechanisms of coexistence for such carnivores, but how these interactions function and covariation still remains unexplored. We investigated the patterns of coexistence of six sympatric small- and medium-sized carnivores ( Mustela kathiah, Melogale moschata, Meles leucurus, Arctonyx collaris, Paguma larvata and Prionailurus bengalensis ) in Mayanghe Nature Reserve, Guizhou province, China, by employing camera traps. We used the occupancy models and kernel density estimation to quantify spatial and temporal differentiation respectively, and analyzed the covariation between the resulting indices. We concluded that first spatial and temporal differentiation contributed to coexistence together, but no one of two was significantly dominant. Second, taxonomic relationships did not facilitate differentiation in closely related carnivorous species, but most small- and medium-sized carnivores avoided Prionailurus bengalensis in spatial occupancy. Finally, when the spatial differentiation occurred to a greater extent, the temporal aspects were lessened and vice versa. Our results revealed the patterns and relationship of the spatial and temporal differentiation concerning several sympatric small- and medium-sized carnivores, which can deepen our understanding of niche differentiation and coexistence of sympatric species.

Hybrid Model of the Collapse of the Commercial Crab Paralithodes camtschaticus (Decapoda, Lithodidae) Population of the Kodiak Archipelago.

Degradation of commercial populations remains a frequent phenomenon even with the use of methods of stocktaking and control of production volume. In fish farming, the concept of “overfishing” is used with and the signs of this condition are well known. However, the processes leading to the degradation of reserves develope in various ways. According to the theory of nonlinear dynamical systems, several types of crisis development can be classified. Of particular interest are the phenomena of collapse, that is, variants of a rapid decline in numbers, which are unexpected for the organizations controlling the fishery. Immediately before the collapse, the state of the stock can be assessed as relatively stable and it may experience fluctuations. Contrary to expectations, there was no rapid recovery after a rapid reduction in cod, whitefish Coregonus clupeaformis of the Great Lakes, halibut and other valuable species. This paper considers a hybrid model for the collapse of red king crab Paralithodes camtschaticus stocks of the Kodiak archipelago of Alaska with unusual distinctive oscillating dynamics. The computational scenario in a hybrid system with survival and growth equations considers the logic of decision-making in operation management. The scenario differs in that after the fall of catches, the crab population goes into the sporadic fluctuations that do not have a regular character and are not characteristic of the population. The collapse itself occurs after a long interval of fishing while the population is in an unstable mode. The analysis shows that a long species life cycle is not a decisive factor for eliminating the risk of a collapse scenario. The presence of reserve generations does not change the situation qualitatively, the efficiency of their reproduction in crab and cod off the coast of Labrador turned out to be unexpectedly low. The status of stocks of large predators that require seasonal moratoriums on fishing must be regularly checked.

Niche partitioning in a guild of invasive mammalian predators.

Predators compete aggressively for resources, establishing trophic hierarchies that influence ecosystem structure. Competitive interactions are particularly important in invaded ecosystems where introduced predators can suppress native prey species. We investigated whether niche partitioning exists within a guild of invasive mammalian predators and determined the consequences for native species. Over 4405 camera‐trap days, we assessed interactions among three invasive predators: two apex predators (feral cats Felis catus and ferrets Mustela furo) and a mesopredator (stoats Mustela erminea), in relation to their primary prey (lagomorphs, rodents and birds) and habitat use. Further, we tested for mesopredator release by selectively removing cats and ferrets in a pulse perturbation experiment. We found compelling evidence of niche partitioning; spatiotemporal activity of apex predators maximized access to abundant invasive prey, with ferrets targeting lagomorphs and cats targeting rodents. Mesopredators adjusted their behavior to reduce the risk of interference competition, thereby restricting access to abundant prey but increasing predation pressure on diurnal native birds. Stoats were only recorded at the treatment site after both larger predators were removed, becoming the most frequently detected predator at 6 months post‐perturbation. We suggest there is spatial and resource partitioning within the invasive predator guild, but that this is incomplete, and avoidance is achieved by temporal partitioning within overlapping areas. Niche partitioning among invasive predators facilitates coexistence, but simultaneously intensifies predation pressure on vulnerable native species.

Predation risk can modify the foraging behaviour of frugivorous carnivores: Implications of rewilding apex predators for plant-animal mutualisms.

Apex predators play key roles in food webs and their recovery can trigger trophic cascades in some ecosystems. Intra‐guild competition can reduce the abundances of smaller predators and perceived predation risk can alter their foraging behaviour thereby limiting seed dispersal by frugivorous carnivores. However, little is known about how plant–frugivore mutualisms could be disturbed in the presence of larger predators.We evaluated the top‐down effect of the regional superpredator, the Iberian lynx Lynx pardinus, on the number of visits and fruits consumed by medium‐sized frugivorous carnivores, as well as the foraging behaviour of identified individuals, by examining the consumption likelihood and the foraging time.We carried out a field experiment in which we placed Iberian pear Pyrus bourgaeana fruits beneath fruiting trees and monitored pear removal by frugivorous carnivores, both inside and outside lynx ranges. Using camera traps, we recorded the presence of the red fox Vulpes vulpes, the Eurasian badger Meles meles and the stone marten Martes foina, as well as the number of fruits they consumed and their time spent foraging.Red fox was the most frequent fruit consumer carnivore. We found there were fewer visits and less fruit consumed by foxes inside lynx ranges, but lynx presence did not seem to affect badgers. We did not observe any stone marten visits inside lynx territories. The foraging behaviour of red foxes was also altered inside lynx ranges whereby foxes were less efficient, consuming less fruit per unit of time and having shorter visits. Local availability of fruit resources, forest coverage and individual personality also were important variables to understand visitation and foraging in a landscape of fear.Our results show a potential trophic cascade from apex predators to primary producers. The presence of lynx can reduce frugivorous carnivore numbers and induce shifts in their feeding behaviour that may modify the seed dispersal patterns with likely consequences for the demography of many fleshy‐fruited plant species. We conclude that knowledge of the ecological interactions making up trophic webs is an asset to design effective conservation strategies, particularly in rewilding programs.

High morphological disparity in a bizarre Paleocene fauna of predatory freshwater reptiles

BackgroundThe consequences of the K-Pg mass extinction are reflected across present biodiversity, but many faunas that appeared immediately after the extinction event were very different from current ones. Choristodera is a clade of reptiles of uncertain phylogenetic placement that have an extremely poor fossil record throughout their 150-million-year history. Yet, choristoderes survived the K-Pg event and persisted until the Miocene.ResultsI describe the skulls and skeletons of two new choristoderes from a single Paleocene ecosystem in western North America that reveal the hidden Cenozoic diversity of this reptile clade. Despite their similar size, the new species deviate dramatically in morphology. Kosmodraco magnicornis gen. et sp. nov. possesses an extremely short snout and extensive cranial ornamentation. The sacrum of K. magnicornis bears enlarged muscle attachment sites and other modifications reminiscent of some giant crocodylians. In contrast, Champsosaurus norelli sp. nov. is a longirostrine species with an uninflated and ventrally divergent postorbital skull. Together with a North American choristodere previously classified in the European genus Simoedosaurus, K. magnicornis substantiates a new clade of giant, short-snouted taxa endemic to the Americas. C. norelli is found to be an early-diverging member of the genus Champsosaurus from the Cretaceous-Paleogene of the northern hemisphere. This suggests the presence of several ghost lineages of champsosaurid that crossed the K-Pg boundary.ConclusionsThe new taxa greatly increase Cenozoic choristodere richness and strengthen the evidence for the existence of distinctive freshwater faunas in Paleogene Eurasia and North America, where this clade diversified to exploit newly available macropredatory niches in the aftermath of the asteroid impact. The new choristoderes also reveal the distinct ecological context in which extant freshwater predators of the Americas like alligatoroids and gars have their origins: Paleocene fluviolacustrine ecosystems in North America displayed high large predator diversity and morphological disparity relative to modern ones.