Mesopredators abundance is often limited by top-order predators and also by key food resources. However, the contribution of these bidirectional forces to structure carnivore community is still ...unclear. Here, we studied how the presence and absence of an apex predator which is currently recovering its former distribution range, the Iberian lynx (Lynx pardinus), determined the absolute abundance and fine-scale spatiotemporal avoidance mechanisms of two sympatric mesocarnivores (stone marten Martes foina and common genet Genetta genetta) with different dietary plasticity. We hypothesized that the lynx causes a mesopredator suppression and subordinate predators develop segregation strategies in respect to their trophic niche breadth. We placed 120 camera-traps in Southern Spain for 8 months in two consecutive years to estimate mesocarnivore abundances by using SCR Bayesian models, prey availability and assess spatio-temporal patterns. We found that the lynx reduced mesocarnivore abundance up to 10 times. Stone marten, a mesopredator with a broad food resources spectrum, showed a total spatial exclusion with the apex predator. Meanwhile, fine-scale avoidance mechanisms allowed the genet to persist in low density inside lynx territories, probably taking advantage of high availability of its preferred prey. Thus, the strength of these top-down and bottom-up effects was rather species-specific. Given the recent recovery of large carnivore populations worldwide, variation in suppression levels on different mesopredator species could modify ecosystem functions provided by the carnivore community in contrasting ways.
Monitoring populations and designing effective conservation actions for endangered species present significant challenges. An accurate understanding of current distribution, ecological traits and ...habitat requirements is imperative in formulating conservation strategies. Recent surveys on the southernmost Cuvier's Gazelle (Gazella cuvieri) population, an ungulate endemic to North Africa, showcase its importance in terms of numbers and genetic diversity. This population inhabits a remote region in the extreme north-western portion of the Sahara Desert and has not been well studied. Here, we examine the potential distribution of Cuvier's Gazelle and the environmental factors limiting the species in a Saharan environment, by combining broad-scale field survey data and species distribution models. Our objective was to identify high priority conservation areas in the southernmost known portion of the species' distribution by modelling habitat selection at the landscape scale using a predictive distribution map. Our results show that the distribution of Cuvier's Gazelle is strongly related to mountainous areas with heterogeneous terrain and remoteness from large human settlements over other ecological factors that had less impact on the species' presence and distribution. We also provide a quantitative estimate of the potential distribution range of Cuvier's Gazelle in southern Morocco, identifying two well-demarcated key areas. The two core areas currently contain enough rugged terrain isolated from human encroachment to support the endangered species in this harsh desert environment. We encourage the implementation of conservation planning for Cuvier's Gazelle as an "umbrella species", which will confer effective protection to higher-quality habitat zones and co-occurring species, leading to sustainable and ecologically responsible development in the region.
Knowledge of the feeding ecology of ungulates in arid biomes offers an interesting model for understanding the drought resistance of large desert-adapted herbivores, a crucial issue in the face of ...increasing desertification due to climate change. To assess the feeding ecology of the endangered Cuvier's gazelle (
) in the Sahara desert, we used a multi-method approach combining faecal samples, direct observations, and the recording of indirect signs of feeding. We hypothesised that browser behaviour is the best foraging strategy for species living in hyper-arid environments, mainly due to long periods without grazing opportunities. Complementarily, we explored the effects of the main environmental descriptors (rainfalls and NDVI) on feeding patterns and diet quality. We found that Cuvier's diets are based mainly on acacias (
,
) and occasionally on the annual forb
. In total, eighteen species (five trees, nine shrubs, three herbs, and one grass) belonging to fifteen families were recorded. Our result confirmed the browsers' characteristic of this species, reaffirming its ability to settle in a hostile environment. Acacias stand out as key species consumed at the southernmost limit of their range; hence, future conservation plans and strategies should take this into account for the survival of Cuvier's gazelle in desert environments.
The honey badger (Mellivora capensis) is a medium-sized carnivore distributed throughout Africa to the Arabian Peninsula, Iran, Turkmenistan, and India. However, available information on its ecology ...is very scarce. We studied its feeding ecology in the remote north-western Sahara Desert, based on the contents of 125 fecal samples collected during large scale surveys. Samples were confirmed to belong to honey badgers by camera trapping and genetic analyses. Barely 18 prey species were detected. The diet primarily consisted of spiny-tailed lizards Uromastyx nigriventris and U. dispar (72% of volume in scats). Secondary prey items were arthropods (14%), small mammals (8%), other reptiles (4%), and eggs (0.8%). Some small geographic and temporal differences were related to the consumption of beetle larvae and rodents as alternative prey. Camera trapping and distance sampling surveys showed that diel activities did not overlap between honey badgers and spiny-tailed lizards, suggesting that badgers primarily dig lizards out of their burrows when inactive. Consumption of spiny lizards by other sympatric meso-carnivores was < 6.1% of occurrence (223 analyzed scats); the honey badger behaved as a trophic specialist in the Sahara, probably thanks to exclusive anatomical adaptations for digging. We discuss the role of this circumstance minimizing the exploitative competition, which could allow the survival of this large mustelid in this low productive and highly competitive environment.
Habitat loss and landscape degradation affect carnivorous mammal populations and the ecosystem services they provide, but these services are poorly assessed in semi-arid ecosystems. In the Ziziphus ...semiarid scrublands, a priority habitat for conservation in Europe, we investigated how red fox diet relates to habitat loss and landscape alteration. We further evaluated potential top-down effects of foxes on vegetation through seed dispersal and the control of rabbit herbivory (fruit depulpation interfering seed dispersal). By sampling fox scats, we evaluated the variation in fox diet and its relationship to landscape features and rabbit abundance and activity in 17 habitat remnants distributed throughout the Ziziphus habitat range. Fox diet varied, with diet diversity peaking at intermediate land-use diversity, likely as a consequence of fox's ability to use natural foods and human-derived resources. We confirmed that red fox acts as seed disperser for many species and that it might contribute to control rabbit population and its impact on Ziziphus lotus regeneration by interference on seed dispersal, though this needs experimental corroboration. However, these services were affected by landscape degradation. Our results show that red fox is fundamental for Ziziphus semiarid ecosystem providing key ecosystem services which are presently jeopardized by strong landscape degradation.
•Ecosystem services provided by red fox are examined in protected semiarid habitat.•Red fox plays a crucial role for community-level seed dispersal in Ziziphus habitat.•Red fox mitigates the impact on seed dispersal of rabbit fruit depulpation.•These two fox services have potential to cascade on regeneration of keystone species Ziziphus lotus.•Habitat loss and landscape degradation compromise red fox ecosystem services.
Current global change scenarios demand knowledge on how anthropogenic impacts affect ecosystem functioning through changes in food web structure. Frugivorous mesocarnivores are a key link in trophic ...cascades because, while their abundance and behaviour are usually controlled by apex predators, they can provide high‐quality seed‐dispersal services to plant communities. Thus, the recent rewilding of large carnivores worldwide can trigger cascading effects for plants.
We investigated the top‐down effects of an apex predator (Iberian lynx Lynx pardinus) on seed‐dispersal services mediated by two mesocarnivore species (red fox Vulpes vulpes and stone marten Martes foina) at the plant community level by comparing areas with and without lynx in a Mediterranean mountain range in Southern Spain.
We collected scats of mesocarnivores (n = 1575) to assess frugivory and seed dispersal of 15 plant species over two consecutive fruiting seasons and two habitat types (open and forest). Specifically, we assessed the effect of lynx presence on (i) seed occurrence and fleshy‐fruit biomass per scat, (ii) number of scats containing seeds and (iii) diversity of dispersed seeds.
The quantity and diversity of dispersed seeds drastically decreased under predation risk for both mesocarnivore's species. Seed dispersal by stone martens was negatively affected by the presence of lynx, with a marked reduction in the number of scats with seeds (93%) and the diversity of dispersed seeds (46%). Foxes dispersed 68% fewer seeds in open habitats when coexisting with lynx, probably leading to differential contributions to seed‐dispersal effectiveness among habitats.
Our study reveals a novel trophic cascade from apex predators to plant communities. The behavioural responses of frugivorous mesocarnivores to predation risk and the reduction in the intensity of their faecal deposition pattern are probably related to their lower abundance when co‐occurring with apex predators. While rewilding apex predators is a successful conservation tool, attention should be paid to cascading effects across food webs, particularly where frugivore megafauna is missing and mesocarnivores provide unique services to plants.
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Resumen
El escenario actual de cambio global demanda más conocimiento sobre cómo los impactos antrópicos afectan al funcionamiento de los ecosistemas a través de cambios en la estructura de la red trófica. Los mesocarnívoros frugívoros son un eslabón clave en las cascadas tróficas ya que, si bien su abundancia y comportamiento suelen estar controlados por los superdepredadores, pueden proporcionar servicios de dispersión de semillas de alta calidad a las comunidades de plantas. Así, la reciente recuperación de grandes carnívoros en todo el mundo puede desencadenar efectos en cascada para las plantas.
Investigamos los efectos en cascada de un superdepredador (lince ibérico Lynx pardinus) sobre los servicios de dispersión de semillas mediados por dos especies mesocarnívoras (zorro rojo Vulpes vulpes y garduña Martes foina) a nivel de toda la comunidad de plantas y comparando áreas con y sin lince en las montañas mediterráneas del sur de España.
Recolectamos excrementos de mesocarnívoros (n = 1575) para evaluar la frugivoría y la dispersión de semillas de 15 especies de plantas durante dos temporadas de fructificación consecutivas y en dos tipos de hábitat (abierto y forestal). Específicamente, evaluamos el efecto de la presencia de linces sobre (i) la presencia de semillas y la biomasa de frutos por excremento, (ii) el número de excrementos que contenían semillas y (iii) la diversidad de semillas dispersadas.
La cantidad y diversidad de semillas dispersadas disminuyeron drásticamente bajo el escenario de riesgo de depredación para ambas especies de mesocarnívoros. La dispersión de semillas por las garduñas se vio afectada negativamente por la presencia del lince, con una marcada reducción en el número de excrementos con semillas (93%) y la diversidad de semillas dispersadas (46%). Los zorros dispersaron un 68% menos semillas en hábitats abiertos cuando coexistieron con el lince, lo que probablemente condujo a una contribución diferente en la efectividad de la dispersión de semillas entre hábitats.
Nuestro estudio revela una nueva cascada trófica desde los superdepredadores hasta las comunidades de plantas. Las respuestas comportamentales de los mesocarnívoros frugívoros al riesgo de depredación y la reducción de sus patrones de marcaje fecal probablemente estén relacionados con su menor abundancia cuando coexisten con los superdepredadores. Aunque la recuperación de los superdepredadores es una herramienta de conservación exitosa, se debe prestar atención a sus efectos en cascada en las redes tróficas, particularmente en escenarios donde la megafauna frugívora ha desaparecido y los mesocarnívoros brindan servicios únicos a las comunidades de plantas.
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Habitat loss and landscape degradation affect animal-mediated seed dispersal, often collapsing the regeneration of endangered plant species and habitats in anthropogenic landscapes. We first compared ...the role of red fox and other vertebrates as seed disperser for the keystone scrub Ziziphus lotus. Because it turned out that foxes are the major Z. lotus dispersers, we investigated how fox activity and dispersal service relate to habitat loss and landscape alteration in the threatened Ziziphus semiarid scrublands, a priority habitat for conservation in Europe. Considering its opportunistic behavior, we hypothesized that landscape features should affect moderately fox abundance, while influence in a large extent its dispersal service. Accordingly, we predicted that a substantial decline in Ziziphus fruit consumption rather than in disperser activity would be responsible for seed dispersal collapse under severe habitat loss. We evaluated fox activity and dispersal service in 17 populations of Z. lotus spread through the range of its habitat in Spain and found within landscapes with different land-use intensity. We certified the collapse of the dispersal service by fox under severe habitat loss and confirmed that fox activity was less affected by habitat loss or landscape alteration than consumption of Ziziphus fruits. Consequently, the decline of consumption of Ziziphus fruits under severe habitat loss triggers the collapse of its seed dispersal. Results suggest that without increase of the remnant areas other managements may not suffice to achieve seed dispersal and habitat restoring. Dispersal service and natural regeneration in many Ziziphus habitat remnants will possibly cease in the future if habitat loss continues.
Surveys based on indirect signs and camera trapping are two non-invasive methods extensively used for monitoring elusive mammals. Both approaches can be useful to obtain key information on wildlife ...in remote areas, since they may allow for the logistically viable design of optimal field frameworks. The sand cat (
Felis margarita
) is a feline that inhabits the Sahara Desert, the Arabian Peninsula, and western Asian deserts. Its basic ecology is poorly known and the status and impacts of threats are difficult to assess. Some local population declines have been detected, and more research is needed. Based on field surveys carried out in the Atlantic Sahara, we have evaluated the applications of both methods to study this species. Our results show that (a) camera trapping provided reliable data on several key aspects of its ecology, (b) walking surveys to collect feces for molecular data failed completely, and (c) for footprints, identification problems and the marked effects of the absence of optimal substrates and the prevalence of wind are relevant handicaps. Beyond this evaluation, we provide for the first time some key aspects of the ecology of sand cats in the Sahara Desert, including habitat selection, density, diel activity, and predator–prey relationships.
•A model of local and landscape disturbance effects on seed dispersal is proposed.•The model is tested regionally with a keystone semiarid scrub dispersed by mammals.•Disturbance at each scale ...impacts on seed dispersal via distinct pathways.•Fruit intake is affected by remnant while disperser abundance by landscape features.•Attention to the scale of disturbance is needed to recover seed dispersal functions.
The scale of disturbance is of paramount importance to understand the disruptive effect of anthropogenic perturbation on animal seed dispersal and its consequences for plant species conservation at regional level. However, the intricate ways by which landscape and local-scale disturbances affect seed dispersal remain unclear. We propose a conceptual scheme of the direct and indirect effects that large-scale (landscape) and local-scale (within-habitat remnant) disturbances may have on seed dispersal. We evaluate this scheme regionally with Ziziphus lotus, a mammalian-dispersed keystone scrub of threatened European semiarid habitats dispersed by mammals. Using Structural Equation Modeling we disentangled whether disturbance effects on seed dispersal function happen via landscape/remnant structural changes or by shortage in food provision (fruit and carnivores’ prey abundance) and if such changes cascade on seed dispersal by modifying primarily the fruit consumption rates or the animal-disperser assemblages. Disturbances at both spatial scales impacted on seed dispersal, which collapsed in some localities, especially those without juveniles. Rates of fruit consumption by seed dispersers increased with fruit availability that, in turn, depended on the level of alteration at the local scale of each remnant. However, the abundance and diversity of seed dispersers responded to structural changes in the landscape, like natural habitat cover and complexity. Attention to both scales of disturbance is thus needed to recover the seed dispersal function. Management within remnants to improve their state and enhance food provision will favor fruit consumption rates, while increasing natural habitat cover and landscape complexity will favor the disperser-assemblage abundance and diversity.
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