Conspecific Density Research Articles

Neighbor Density and Post‐Contact Immobility Duration as Antipredator Behavior: Antlion Larvae Do Not Fit the Selfish Prey Hypothesis

ABSTRACTRemaining immobile for an unpredictable period after being touched by a potential predator (post‐contact immobility, PCI) may favor survival. However, the factors that determine variation in PCI duration are poorly understood. We tested whether PCI duration depends on the surrounding conspecific density (the selfish prey hypothesis) in the tropical antlion larvae Myrmeleon crudelis. These insects avoid predation by being immobile or burying themselves. The selfish prey hypothesis predicts a reduction in the PCI duration as conspecific density increases because this high density of conspecifics around can stimulate the redirection of the predator's interest in other nearby potential prey. In the field, we measured PCI and found that its duration was independent of the conspecific density. In the lab, we also measured the PCI of a subset of the same larvae in the absence of neighbors. Using a paired design, we found that PCI duration was lower in the lab in the absence of neighbors than in the field. Our results suggest that the antlion larvae did not follow the selfish prey hypothesis. We propose two alternative explanations. First, the larvae have a limited ability to detect neighbors in the field and keep up with the changing number of surrounding active pits. Second, burying may be more important than PCI as an antipredator strategy. In our lab experiment, larvae had a more accurate idea of the conspecific density around their pit because they explored the area. We propose that knowing the absence of conspecifics triggered a shorter PCI duration. Under a high predation risk (i.e., no other prey to which the predator would redirect its attention), the larvae select the unequivocal antipredator behavior of burying. This work illustrates the relevance of accurate information in deciding how to avoid predation, especially when prey can prioritize between alternative behaviors, with success varying between the contexts.

Impacts of ramet density and herbivory on floral volatile emissions and seed production in Solidago altissima.

Plants produce an array of floral olfactory and visual cues to attract pollinators, including volatile organic compounds (VOC), which mediate plant-pollinator interactions and may be influenced by herbivory and neighboring plants. Consequently, these factors may affect plant fitness by disrupting pollination. However, most evidence comes from controlled experiments, limiting our understanding of how VOCs function in natural populations. This study investigated how herbivory and conspecific ramet density influence floral VOC profile, pollination, and seed production in a naturally occurring population of Solidago altissima. We recorded leaf herbivory and ramet density surrounding one focal ramet in 1-m2 plots. We collected VOCs from the floral headspace and measured ovary fertilization as a proxy for pollination success and the number of seeds produced by the focal ramet. Our findings revealed interactive effects between ramet density and herbivory on floral VOC emission, richness, and diversity. Specifically, at lower ramet densities, herbivory did not affect floral volatile emissions. However, in highly dense stands, herbivory suppressed floral volatile emissions. Despite these changes, floral volatiles did not affect pollination and the number of seeds in S. altissima. Our field-based findings underscore the importance of understanding the complex responses of floral VOCs to environmental stressors and their contributions to plant reproduction within natural communities. Our results suggest that while herbivory and ramet density influence floral scent, these changes do not affect reproduction in our study. Ultimately, generalist-pollinated plants like S. altissima might not rely heavily on chemical signaling during pollination.

Fitness consequences of marine larval dispersal: the role of neighborhood density, arrangement, and genetic relatedness on survival, growth, reproduction, and paternity in a sessile invertebrate.

Dispersal can evolve as an adaptation to escape competition with conspecifics or kin. Locations with a low density of conspecifics, however, may also lead to reduced opportunities for mating, especially in sessile marine invertebrates with proximity-dependent mating success. Since there are few experimental investigations, we performed a series of field experiments using an experimentally tractable species (the bryozoan Bugula neritina) to test the hypothesis that the density, spatial arrangement, and genetic relatedness of neighbors differentially affects survival, growth, reproduction, paternity, and sperm dispersal. We manipulated the density and relatedness of neighbors and found that increased density reduced survival but not growth rate, and that there was no effect of relatedness on survival, growth, or fecundity, in contrast to previous studies. We also manipulated the distances to the nearest neighbor and used genetic markers to assign paternity within known mother-offspring groups to estimate how proximity affects mating success. Distance to the nearest neighbor did not affect the number of settlers produced, the paternity share, or the degree of multiple paternity. Overall, larger than expected sperm dispersal led to high multiple paternity, regardless of the distance to the nearest neighbor. Our results have important implications for understanding selection on dispersal distance: in this system there are few disadvantages to the limited larval dispersal that does occur, and limited advantages for larvae to disperse further than a few 10s of meters.

Navigating neighborhoods: Density, size, and species diversity influences on tree survival in subtropical secondary forests

Neighborhood effects significantly impact individual tree survival through mechanisms of resource competition and species interactions within forest ecosystems. However, the specific impacts of these effects, particularly how biodiversity feedback affects survival across diverse life stages and spatial scales in subtropical secondary forests, remains insufficiently documented. To bridge this gap, we conducted an extensive analysis of neighborhood effects at different life stages and spatial scales in the subtropical secondary forests of the Wuyi Mountains in Southeast China, uncovering key insights into the community structure and dynamics. Our investigation over a five-year period encompassed all individuals within our study plot, quantifying effects of neighborhood density, individual size in resource competition, and species diversity in the neighborhood across various life stages. Employing mixed-effects models, we established quantitative relationships to assess the impact of these factors on tree survival at different spatial scales. Our findings confirmed that density dependence adversely affects sapling survival at smaller scales. As trees mature and spatial test scales expand, the detrimental effects of conspecific resource competition on individual mortality decrease, whereas heterospecific resource competition notably impairs survival probabilities in later successional stages, suggesting a shift from intraspecific to interspecific competition as the dominant influence on mortality during secondary succession. Additionally, we detected consistent patterns in conspecific and heterospecific density effects with increasing spatial scale. These effects transitioned from interspecific differences at smaller scales to more uniform positive effects at larger scales, which may be attributed to the strong spatial dependency of neighborhood density effects, potentially due to increased habitat heterogeneity. Furthermore, our study highlights the crucial role of heterospecific neighborhood effects in enhancing survival. We observed significant positive impacts of species diversity and heterospecific interactions on individual tree survival, particularly at smaller spatial scales during the sapling stage. Importantly, our research unveils significant variability in species sensitivity to different neighborhood effects, which change with life stage and spatial scale. This underscores the necessity of accounting for life stage variations among species and the influence of spatial heterogeneity on neighborhood effects such as density. Our findings delineate distinct competition mechanisms between the earlier and later phases of forest succession, emphasizing the distinctive recovery processes of subtropical secondary forests. These insights are essential for informing forest management and conservation strategies, ensuring a nuanced understanding of forest community dynamics.

Predation Efficiency and Biological Control Potential of Micromus angulatus Against Aphis craccivora

Micromus angulatus (Neuroptera: Hemerobiidae) is a widely distributed and highly effective predator that shows promise as a biological control agent against agricultural pests, particularly Aphis craccivora, the cowpea aphid, which threatens leguminous crops globally. This study aimed to evaluate the predation behaviour, search efficiency, and intraspecific interference of M. angulatus at different developmental stages, including first- to third-instar larvae and adults, in controlling adult A. craccivora populations. The results demonstrated that all developmental stages of M. angulatus exhibited predatory behaviour towards adult aphids, with the functional response fitting the Holling Type II model. The instantaneous attack rates for first-, second-, and third-instar larvae and adults were 1.0017, 1.0448, 0.9581, and 0.9508, respectively; the handling times were 0.0158, 0.0051, 0.0016, and 0.0011 days, respectively; and the theoretical maximum daily predation rates were 63.2911, 196.0784, 625, and 909.0909 aphids, respectively. The pest control efficacies were 63.3989, 204.8672, 598.8311, and 864.3192, respectively. The search efficiency at each developmental stage was negatively correlated with aphid density, which decreased as the prey density increased, with second-instar larvae showing the greatest decrease and adults the least. When the aphid density was fixed, the daily predation rate of individual M. angulatus decreased with increasing conspecific density, indicating that predation was affected by its own density, with the interference effect equation being E = 0.6194P−0.87. These findings indicate that M. angulatus, especially in the third-instar larval and adult stages, has considerable potential as a biological control agent for managing A. craccivora populations in agricultural settings. This study contributes valuable insights for developing sustainable agricultural practices by decreasing reliance on chemical pesticides.

Neighbors affect vocal behavior of tropical wrens: a multispeaker density-manipulation experiment.

For territorial animals, the behavior of conspecific neighbors sets the social context of communication. Despite numerous investigations of vocalizations related to territory defense and mate attraction, the effect of neighbor density on animal vocal behavior has received little attention, particularly in tropical animals and animals where both sexes produce complex acoustic signals. In this study, we used an innovative multispeaker playback experiment to manipulate the apparent density of neighbors in rufous-and-white wrens, Thryophilus rufalbus, living in Costa Rica's tropical dry forest. In this tropical songbird, both males and females defend year-round territories and sing complex, learned songs for territory defense. We recorded the singing behavior of 24 subjects (12 pairs), and then we used an array of 6 loudspeakers to simulate the presence of 6 new territorial neighbors (3 simulated pairs) outside each subject pair's breeding territory. The stimuli persisted for 3 consecutive days, with both male and female songs broadcast at a natural rate from dawn to dusk. We found that the mean male song rate increased by almost 50% in response to the simulated increase in local density. Females showed less frequent song-type switching rates following the simulated increase in local density, although it was a marginal increase. These findings reveal that male and female songbirds' vocal behavior varies with the local density of territorial neighbors. We conclude that birds are sensitive to acoustic signals of conspecific density arising from sounds beyond their territory boundaries, and that they use this public information to guide their vocal behavior.

Low predator and conspecific density lead to larger juveniles

Predation is a key size-selective mechanism structuring juvenile fish populations, given typically greater susceptibility of small juveniles in a population to predation compared to larger individuals. We tested the hypothesis that greater predator abundance selectively removes the smallest age 0 Atlantic cod (Gadus morhua) in nearshore habitat, truncating their size distribution in nursery habitats. We tested this hypothesis using fifteen years of historical data on nearshore fish abundance in Newman Sound, Newfoundland. Using skewness to estimate size-frequency distribution asymmetry, our analyses showed smaller age 0 cod were least prevalent under low predator and low conspecific densities. In contrast, high predator abundances corresponded to weak, size-selective removal of the smallest juveniles. Age 0 cod reached the largest sizes under lower predator and conspecific densities. Our analyses link size of individual juvenile fish in the wild with their survival, where predator abundance modulates the advantages gained by attaining larger size.

Arbuscular mycorrhizal fungi equalize differences in plant fitness and facilitate plant species coexistence through niche differentiation.

Mycorrhizal fungi are essential to the establishment of the vast majority of plant species but are often conceptualized with contradictory roles in plant community assembly. On the one hand, host-specific mycorrhizal fungi may allow a plant to be competitively dominant by enhancing growth. On the other hand, host-specific mycorrhizal fungi with different functional capabilities may increase nutrient niche partitioning, allowing plant species to coexist. Here, to resolve the balance of these two contradictory forces, we used a controlled greenhouse study to manipulate the presence of two main types of mycorrhizal fungus, ectomycorrhizal fungi and arbuscular mycorrhizal fungi, and used a range of conspecific and heterospecific competitor densities to investigate the role of mycorrhizal fungi in plant competition and coexistence. We find that the presence of arbuscular mycorrhizal fungi equalizes fitness differences between plants and stabilizes competition to create conditions for host species coexistence. Our results show how below-ground mutualisms can shift outcomes of plant competition and that a holistic view of plant communities that incorporates their mycorrhizal partners is important in predicting plant community dynamics.

Intense light and conspecific density increase seedling mortality across age groups in a typhoon‐disturbed tropical forest

AbstractQuestionsMaintaining forest species diversity, regenerative function and ecosystem resilience begins with successful seedling establishment. Despite their critical role, seedlings face the highest mortality risks among plant life‐history stages. Our research aims to answer the following questions: In a tropical forest disturbed by typhoons, what is the median survival time for seedlings, to what extent do light levels contribute to mortality risks and what are the crucial mortality risks across seedling age groups?LocationA tropical mountain zonal foothill evergreen broad‐leaved forest in Nanjenshan Nature Reserve, Taiwan, frequently visited by typhoons.MethodsWe investigated woody seedlings in 75 quadrats (each 1 m × 1 m) every 3 months from October 2009 to January 2018, spanning 8.3 years with 34 censuses. We used the Kaplan–Meier method to estimate seedlings’ median survival time and Generalized Linear Models to identify mortality risk factors for all seedlings and those that persisted beyond the median survival time.ResultsThe median survival time for all seedlings was 0.5 years, ranging from 0.25 years for shade‐intolerant species to 1.25 years for shade‐tolerant species. Seedlings germinated in high‐light microhabitats and high conspecific seedling density exhibited higher mortality probabilities, regardless of age.ConclusionsThis study reveals the short survival time and key mortality risks of seedlings in a typhoon‐disturbed forest. The negative impact of light levels on seedling survival highlights the potential consequences of increased light levels resulting from typhoon disturbances in the study region.

Consequences of Local Conspecific Density Effects for Plant Diversity and Community Dynamics.

Conspecific density dependence (CDD) in plant populations is widespread, most likely caused by local-scale biotic interactions, and has potentially important implications for biodiversity, community composition, and ecosystem processes. However, progress in this important area of ecology has been hindered by differing viewpoints on CDD across subfields in ecology, lack of synthesis across CDD-related frameworks, and misunderstandings about how empirical measurements of local CDD fit within the context of broader ecological theories on community assembly and diversity maintenance. Here, we propose a conceptual synthesis of local-scale CDD and its causes, including species-specific antagonistic and mutualistic interactions. First, we compare and clarify different uses of CDD and related concepts across subfields within ecology. We suggest the use of local stabilizing/destabilizing CDD to refer to the scenario where local conspecific density effects are more negative/positive than heterospecific effects. Second, we discuss different mechanisms for local stabilizing and destabilizing CDD, how those mechanisms are interrelated, and how they cut across several fields of study within ecology. Third, we place local stabilizing/destabilizing CDD within the context of broader ecological theories and discuss implications and challenges related to scaling up the effects of local CDD on populations, communities, and metacommunities. The ultimate goal of this synthesis is to provide a conceptual roadmap for researchers studying local CDD and its implications for population and community dynamics.

Setting the stage for plant–soil feedback: Mycorrhizal influences over conspecific recruitment, plant and fungal communities, and coevolution

Abstract Plant–soil feedback (PSF) plays a central role in determining plant community dynamics, yet our understanding of how different combinations of plants and microbes influence PSF remains limited. Plants of different mycorrhizal types often exhibit contrasting PSF outcomes, influencing plant recruitment and spatial structure. Generalizing across plant species based on mycorrhizal type creates the potential to examine broader effects on ecological communities. We review mechanisms contributing to different PSF outcomes between arbuscular mycorrhizal and ectomycorrhizal trees. We focus on how plant and fungal traits that differ between mycorrhizal types interact with pathogenic and saprotrophic microorganisms and nutrient and carbon cycling. Synthesis. Building on this framework, we propose several new research directions. First, mycorrhizal‐induced changes in soils can operate beyond the conspecific level, spilling over from abundant plant species onto less abundant ones. This community‐level ‘mycorrhizal spillover’ is hypothesized to affect PSF in ways that are additive and interactive with conspecific density dependence. Second, we describe how mycorrhizal effects on PSF could structure the way plant communities respond to global change. Third, we discuss how they may influence plant evolution by altering the balance of selection pressures on traits and genes related to pathogen defence and mutualism formation.

Drivers of growth in strong year classes of the deepwater redfish (Sebastes mentella) population from the Gulf of St. Lawrence derived from otolith increment-based growth chronologies.

The case of the deepwater redfish (Sebastes mentella) in the Gulf of St. Lawrence (GSL) is a compelling example of drastic fluctuations in annual recruitment strength, characteristic of spasmodic stocks. After three decades of low abundance, the emergence of three consecutive strong year classes in 2011-2013 resulted in an unprecedented increase in biomass. In spasmodic stocks such as GSL redfish, strong year classes sustain both the biomass and catch for decades. Therefore, understanding the growth dynamics of these cohorts is essential. In the present study, we reconstructed the annual growth rates of redfish using otolith increment-based annual chronology and investigated the drivers of growth variation in redfish strong year classes of the early 2010s and early 1980s. Stock biomass was identified as the main extrinsic driver of redfish growth, suggesting intense competition for food at high conspecific density. Warming of deep waters in the GSL, where adult redfish settle, positively correlated with individual growth. However, recent warming of the cold intermediate layer showed a negative correlation with redfish growth, likely related to the shrinking of the habitat this water mass provides for various redfish cold-water prey rather than to a direct effect of temperature. Reconstruction of redfish annual growth trajectories from birth to capture emphasized the importance of carryover effects in the growth potential of strong year classes. This work provided an important first outlook of the factors driving growth variation in GSL redfish spasmodic stock and explored midterm consequences of density-dependent pressures on biological parameters of the population.

Displaced juvenile and subadult Caribbean spiny lobsters show strong orientation toward home dens

Caribbean spiny lobsters are known to undergo migration as adults, but the dispersal and homing ability of subadults and juveniles is not well characterized. Given that settlement habitat for juveniles is inshore seagrass / hardbottom and reproductive habitat is offshore coral reefs, dispersal during ontogeny serves as a bottleneck potentially limiting adult population density. Previous studies have examined factors associated with movement and den selection by juvenile lobsters such as shelter type, predators, and conspecific density. Their attraction to odors of healthy conspecifics plays a significant role in aggregation of lobsters in casitas and traps. But what is unknown is whether juvenile lobsters possess the map and compass orientation found in adults. To examine the ontogeny of homing ability, we conducted multiple mark / displace tracking studies using acoustic telemetry in juvenile hardbottom and subadult coral patch reef habitats. All lobsters regardless of size tend to relocate to new crevice shelters when handled, even if returned to their original shelter. Thus, for non-displaced lobsters tagged and returned to their point of capture, distance and angle travelled appears to be random with distance increasing as function of body size. However, for juvenile and subadult lobsters tagged and displaced away from their point of capture, the distance and angle travelled when released is significantly directed toward the point of capture. Thus, it appears that the map and compass ability of Caribbean spiny lobsters appears early in ontogeny and may allow for individuals to safely explore unfamiliar locations while retaining knowledge of how to return to known shelter. This ability to expand their known habitat map while maintaining knowledge of critical diurnal shelter locations is expected to facilitate their ontogenetic dispersal to adult habitat.

The effect of natural noise and conspesific sound density on the prevalence of Leptophryne borbonica Tschudi, 1838 displaying visual signals

The main mode of communication in Anura is acoustic signals, but environmental noise can hinder effectiveness signal transmission and reception. The adaptation to noise is by visual signals. This study was conducted to determine the density, the type of visual signals detected, and whether there is an influence of environmental noise and conspecific density on the prevalence of Leptophryne borbonica population displaying visual signals. This study was conducted by descriptive method with purposive sampling technique. The data taken was in the form of the number of individuals with visual signals, the number of individuals vocalizing, and the noise of the surrounding environment. The data was processed using the Solomon Coder and analyzed by Poisson regression. 159 individual frogs were found in 40 plots during observations, with the density of individuals in each plot being 3-8 individuals with noise range of 45-74 dB. Noise significantly affected the display of visual signals in a population, while conspecific density did not affect the output of visual signals.

Drought tolerance and species abundance mediate dry season negative density dependence in a tropical forest.

Conspecific negative density dependence (CNDD) is thought to be a key process in maintaining plant diversity. However, the strength of CNDD is highly variable in space and time as well as among species, and correlates of this variation that might help to understand and explain it remain largely unquantified. Using Bayesian hierarchical models, we took advantage of 10-year seedling monitoring data that were collected annually in every dry and rainy season in a seasonal tropical forest. We quantified the interspecific variation in the strength of CNDD and its temporal variation. We also examined potential correlates of this interspecific and temporal variation, including species functional traits (such as drought-tolerant traits, defense-related traits, and recourse acquisition traits) and species abundances. In the dry season, we found a negative relationship between the density of neighboring conspecific seedlings on seedling survival, while in the rainy season, there was a negative relationship between the density of neighboring conspecific adults on seedling survival. In addition, we found that interspecific variation in CNDD was related to drought-tolerant traits in the dry season but not in the rainy season. Across years, we found that drought-intolerant species suffer less CNDD during the dry seasons that have higher rainfall, whereas drought-tolerant species suffer less CNDD when the dry season has lower rainfall. We also found that rare species suffered stronger CNDD in the dry season. Overall, our study highlights that CNDD is highly variable among species and through time, necessitating a deeper appreciation of the environmental and functional contexts of CNDD and their interactions.

Neighborhood Diversity Promotes Tree Growth in a Secondary Forest: The Interplay of Intraspecific Competition, Interspecific Competition, and Spatial Scale.

Understanding the biodiversity-productivity relationship (BPR) is crucial for biodiversity conservation and ecosystem management. While it is known that diversity enhances forest productivity, the underlying mechanisms at the local neighborhood level remain poorly understood. We established a 9.6 ha dynamic forest plot to study how neighborhood diversity, intraspecific competition, and interspecific competition influence tree growth across spatial scales using linear mixed-effects models. Our analysis reveals a significant positive correlation between neighborhood species richness (NSR) and relative growth rate (RGR). Notably, intraspecific competition, measured by conspecific neighborhood density and resource competition, negatively impacts RGR at finer scales, indicating intense competition among conspecifics for limited resources. In contrast, interspecific competition, measured by heterospecific density and resource competition, has a negligible impact on RGR. The relative importance of diversity and intra/interspecific competition in influencing tree growth varies with scale. At fine scales, intraspecific competition dominates negatively, while at larger scales, the positive effect of NSR on RGR increases, contributing to a positive BPR. These findings highlight the intricate interplay between local interactions and spatial scale in modulating tree growth, emphasizing the importance of considering biotic interactions and spatial variability in studying BPR.

Ants may buffer the Janzen-Connell effect in a tropical forest in Southwest China.

Mutualistic symbioses between ants and plants are widespread in nature. Ants can deter unwanted pests and provide protection for plants in return for food or housing rewards. Using a long-term demographic dataset in a tropical seasonal rain forest in Southwest China, we found that associations with ants positively influenced seedling survival and adult growth, and also, species with extrafloral nectaries experienced weaker conspecific negative density dependence compared with species without extrafloral nectaries. Furthermore, we found strong evidence suggesting that species in our forest experienced conspecific density dependence, which we interpreted as heavy pest pressure that may drive the development of anti-pest symbioses such as the plant-ant relationship. Our findings suggest that ants and conspecific neighbors play important but inverse roles on plant survival and growth and that ants can buffer tree neighborhood interactions in this tropical forest.

A social foraging trade-off in echolocating bats reveals that they benefit from some conspecifics but are impaired when many are around

Social foraging is very common in the animal kingdom. Numerous studies have documented collective foraging in various species and many reported the attraction of various species to foraging conspecifics. It is nonetheless difficult to quantify the benefits and costs of collective foraging, especially in the wild. We examined the benefits and costs of social foraging using on-board microphones mounted on freely foraging Molossus nigricans bats. This allowed us to quantify the bats' attacks on prey and to assess their success as a function of conspecific density. We found that the bats spent most of their time foraging at low conspecific densities, during which their attacks were most successful in terms of prey items captured per time unit. Notably, their capture rate dropped when conspecific density became either too high or too low. Our findings thus demonstrate a clear social foraging trade-off in which the presence of a few conspecifics probably improves foraging success, whereas the presence of too many impairs it.

Positive spatial and temporal density‐dependence drive early reproductive economy‐of‐scale effects of masting in a European old‐growth forest community

Abstract Masting, the spatial synchronization of interannual variation in seed production, can enhance reproductive efficiency through positive density‐dependent processes (DD) that result in economies of scale (EOS), such as decreased pollen limitation and predator satiation in years of high reproduction. While the general occurrence of such EOS effects has been documented for masting species, few studies simultaneously investigated how spatial and temporal variation in reproduction affects pollination and predation. Furthermore, it is unclear whether the same mechanisms apply to co‐occurring species with different levels of conspecific density, pollen limitation, and seed defences. Here, we use a long‐term dataset with high spatial resolution of seed production of European beech (Fagus sylvatica), Norway spruce (Picea abies), and silver fir (Abies alba) in a primeval montane forest to investigate the relationship between reproductive effort, pollination efficiency and predispersal predation by insects. We found that, along the temporal axis, the proportion of sound (fertilized and unpredated) seeds correlated positively with annual seed production over the 14‐year study period in all three species, most strongly in beech and only weakly in silver fir. Moreover, the results show that in beech, spatial seed density interacts with plot‐wide annual seed rain to enhance DD effects on seed predation, suggesting additive effects of synchronous reproduction on fitness benefits. Synthesis: For both pollination and predispersal predation in beech and spruce, the strongest DD effects occur at low levels of reproduction and quickly reach asymptotes at higher levels, suggesting the presence of thresholds in different EOS mechanisms. As variability and synchrony in mast‐seeding are expected to decline with climate change, EOS effects driven by DD may remain stable until the threshold is reached, at which sudden declines would result in devastating effects on the availability of viable seeds for germination and recruitment.

Spatial, social, and environmental factors influencing natal dispersal in the colonial griffon vulture

Abstract Natal dispersal is a critical trait for individual fitness and the viability, structure, and genetic identity of populations. However, there is a pronounced information gap for large and long-lived species due to the difficulty of monitoring individuals at appropriate spatio-temporal scales. Here we study how individual traits and social and environmental characteristics influence natal dispersal decisions of griffon vultures (Gyps fulvus) using long-term (30 years) monitoring of a large number of individuals marked as nestlings in Spain. Our results show a strong philopatry in both sexes, with some individuals recruiting as breeders on the same cliffs, and even the same nests, where they were born. This philopatric tendency was modulated by the effect of conspecific density on individual parameters and emphasized the importance of conspecific attraction and changes in food availability that may have influenced the increment in colony size and the colonization of new areas. Although further research is needed considering smaller colonies and more isolated population nuclei, our results highlight the importance of long-term studies on long-lived species to understand the factors that determine their population dynamics and their relationship with anthropogenic activities, whose effects should be predicted and managed using conservation criteria.