Prey Density Research Articles

The Potential of Arboreal Tiger Beetle (<em>Derocrania scitiscabra</em> Walker) as a Natural Enemy for the Control of Fall Armyworm (<em>Spodoptera frugiperda</em> JE Smith)

Purpose: The fall armyworm, Spodoptera frugiperda, is a serious pest of maize, sugarcane, and other crops in Sri Lanka. Natural predators and parasitoids are considered the best methods to control this insect pest. The present study investigates the possibility of using an endemic tiger beetle, Derocrania scitiscabra, as a natural predator for the larval stages of S. frugiperda.Research Method: The feeding preferences of D. scitiscabra to live prey versus dead prey, live prey types including different instar stages of S. frugiperda were investigated in the laboratory using choice tests. Fresh minced meat was used as dead prey, while red ants, earthworms and the six larval instar stages of S. frugiperda were used as live prey.Findings: Red ants were the most preferred prey type of D. scitiscabra, and dead prey, earthworms and mature S. frugiperda larvae were not consumed. Early larval instar stages of S. frugiperda were selected as prey, and the beetle showed a high feeding preference for the second larval instar stage. This feeding preference was observed irrespective of whether red ants were present or absent in the same environment. D. scitiscabra may have selected the second larval instars of S. frugiperda due to their small size, high prey density, mobility, and being devoid of injury.Research Limitations: The tests were conducted under laboratory conditions in insectary facilities. However, field investigations are essential to understand the ecological dynamics that affect insect behavior and survival.Originality/value: An endemic beetle is introduced to control S. frugiperda infestations in their early stages of development. The finding may provide an environmentally safe and economically beneficial method to control S. frugiperda

Prey-Taxis vs. An External Signal: Short-Wave Asymptotic and Stability Analysis

We consider two models of the predator–prey community with prey-taxis. Both models take into account the capability of the predators to respond to prey density gradients and also to one more signal, the production of which occurs independently of the community state (such a signal can be due to the spatiotemporal inhomogeneity of the environment arising for natural or artificial reasons). We call such a signal external. The models differ to one another through the description of their responses: the first one employs the Patlak–Keller–Segel law for both responses, and the second one employs Cattaneo’s model of heat transfer for both responses following to Dolak and Hillen. Assuming a short-wave external signal, we construct the complete asymptotic expansions of the short-wave solutions to both models. We use them to examine the effect of the short-wave signal on the formation of spatiotemporal patterns. We do so by comparing the stability of equilibria with no signal to that of the quasi-equilibria forced by the external signal. Such an approach refers back to Kapitza’s theory for an upside-down pendulum. The overall conclusion is that the external signal is likely not capable of creating the instability domain in the parametric space from nothing but it can substantially widen the one that is non-empty with no signal.

Effects of Temperature and Extraguild Prey Density on Intraguild Predation of Coccinella septempunctata and Harmonia axyridis

Effects of Temperature and Extraguild Prey Density on Intraguild Predation of Coccinella septempunctata and Harmonia axyridis

Gyrfalcon Prey Abundance and Their Habitat Associations in a Changing Arctic.

Arctic habitats are changing rapidly and altering trophic webs and ecosystem functioning. Understanding how species' abundances and distributions differ among Arctic habitats is important in predicting future species shifts and trophic-web consequences. We aimed to determine the habitat-abundance relationships for three small herbivores on the Seward Peninsula of Alaska, USA by fitting data from 983 point counts (collected during 2019, 2021, and 2022) with N-mixture models that account for imperfect detection. These herbivore species, Willow Ptarmigan (Lagopus lagopus), Rock Ptarmigan (L. muta), and Arctic ground squirrels (Urocitellus parryii), are fundamental to tundra food webs, and primary prey for Arctic raptors including Gyrfalcons (Falco rusticolus). Second, we aimed to map herbivore densities within Gyrfalcon breeding territories. Third, we aimed to evaluate whether Gyrfalcons were more likely to occupy territories with higher prey densities using a multi-season occupancy model coupled with occupancy observations from helicopter surveys conducted during 2016-2022 at 97 Gyrfalcon territories. We found that male Willow Ptarmigan were more abundant in areas with greater cover of tundra, tall shrubs, and tussock tundra. Conversely, male Rock Ptarmigan were more abundant in areas with greater cover of sparse vegetation and tundra. Arctic ground squirrels were more abundant at higher elevations with greater cover of sparse vegetation and low shrubs. Willow Ptarmigan were widespread within Gyrfalcon breeding territories, whereas Rock Ptarmigan and Arctic ground squirrels had patchier distributions with few areas of high abundance. Lastly, Gyrfalcons were more likely to occupy territories with higher densities of Willow Ptarmigan and Arctic ground squirrels. As the Artic continues to warm, Rock Ptarmigan and Arctic ground squirrels may be vulnerable to ongoing shrub encroachment, whereas Willow Ptarmigan may benefit. By tying abundances of three prey to Gyrfalcon occupancy, our results contribute to understanding potential impacts on higher levels of this Arctic trophic web.

Stability analysis of a Filippov Gause predator-prey model with or without hunting cooperation among predators with respect to prey density

Stability analysis of a Filippov Gause predator-prey model with or without hunting cooperation among predators with respect to prey density

Predator–Prey Movement Interactions: Jaguars and Peccaries in the Spotlight

ABSTRACTUnderstanding how landscape structure influences predator–prey dynamics is critical for conservation. This study analyzed jaguar‐peccary interactions, revealing uncommon close distances and prevalent 3–5 km ranges, especially away from grasslands. Low peccary densities increased interactions. Findings inform conservation strategies, highlighting landscape structure and prey density roles in maintaining Pantanal's balance.

Exploitation of a marine subsidy by a terrestrial invader

Intertidal environments receive energy from marine ecosystems in the form of marine wrack, which makes up the base of a food web that includes both intertidal and terrestrial consumers. Consumption of wrack by terrestrial consumers can elevate their abundance and alter how they interact with organisms in adjacent terrestrial environments. Although rarely documented, terrestrial invaders may exploit marine wrack subsides and potentially disrupt intertidal and terrestrial food webs. Here, we examine consumption of marine wrack resources by the introduced Argentine ant (Linepithema humile), which occurs commonly on beaches in southern California. In controlled trials the Argentine ant readily scavenged arthropod detritivores (amphipods and flies) abundant in wrack. In spite of obvious risks (e.g., exposure to tides, desiccation, thermal stress) associated with intertidal foraging, Argentine ant activity on beaches was comparable to that in spatially-paired, scrub environments. Foraging on beaches allowed ants to access higher densities of arthropod prey and carrion compared to those found in scrub environments. Stable isotope analyses provide evidence for extensive assimilation of marine-derived resources. Values of δ15N and δ13C for the Argentine ant were higher at beach sites than at scrub sites, and Argentine ant δ15N values broadly overlapped those of intertidal consumers at beach sites. Although ants are known to forage in intertidal environments, this study provides a novel example of an introduced ant species exploiting a cross-boundary subsidy.

Age-gender-specific functional and age-specific numerical responses of Neoseiulus californicus (Acari: Phytoseiidae) on two-spotted spider mite.

The phytoseiid predatory mite Neoseiulus californicus (McGregor) is one of the most efficient biocontrol agents in integrated pest management (IPM) programs of greenhouse pests, with different feeding habits on pollen, thrips, eriophyiids, and spider mites. This study appraised the effect of the age and gender on functional response and age on numerical response of N. californicus fed on larvae and protonymph of Tetranychus urticae Koch under laboratory conditions at 25 ± 1℃, 70 ± 5% RH and a photoperiod of 16L: 8D h. In the functional response test, the 2, 4, 8, 16, 32, 64, and 128 densities of prey were offered to 3, 5, 7, 10, 15, 20, 25, 30, 35 and 40-day-old ages of female and 7, 10, 15, 20, 25 and 30-day-old ages of male individuals of N. californicus. The logistic regression was used to recognize the type of functional response. Type II functional response was recognized for all ages of the male and female individuals of N. californicus. The highest predation rate, and searching efficiency (a) was observed in the middle ages of the predator. A significant increase in oviposition was shown with increasing T. urticae density and increasing ages of the predator. Furthermore, in the middle age with low prey density, the efficiency of conversion of ingested food (ECI) was the highest. The results of this study showed that the different ages of N. californicus are influencing factors on its predation capacity and oviposition rate.

The Effect of Prey Size and Prey Density on Paralarval Feeding Success of the Common Sydney Octopus, Octopus tetricus

ABSTRACTGlobal demand for octopus seafood has been increasing over the past 30 years. This demand is projected to increase further as coastal communities and seafood consumers seek alternative sources of protein as finfish stocks decline. The establishment of a sustainable octopus aquaculture would have the potential to alleviate fishing pressures from wild populations. Commercial‐scale octopus aquaculture, however, has not been achieved due to the difficulty of successfully rearing octopus paralarvae on an efficacious diet. This study investigated the prey size and density preferences of Octopus tetricus paralarvae to understand the characteristics that improve food acquisition during rearing. Groups of octopus paralarvae from multiple broods were observed for a range of feeding behaviour including positioning, attack, capture loss, successful capture and handling time when given different treatments of Artemia prey. Prey size experiments used treatments of Artemia with total lengths of < 0.5, 0.9–1.0 and 1.4–1.6 mm, while prey density experiments used 0.2, 0.6, 1.0, 1.4, 1.8 and 2.2 Artemia mL−1. Increased numbers of successful feeding behaviours (e.g., positionings, attacks and successful captures) were directly observed with increasing prey size. Octopus paralarvae performed 52% more positionings, 100% more attacks and 175% more successful captures when given large Artemia (1.4–1.6 mm) than when given small Artemia (< 0.5 mm). Likewise, the number of observed successful feeding behaviours tended to increase with increasing Artemia density but sharply decreased at the highest density treatment (2.2 Artemia mL−1). Paralarvae performed up to 109% more positionings, 307% more attacks and 300% more successful captures when given prey densities of 1.0–1.8 Artemia mL−1 than when given lower prey density treatments and 2.2 Artemia mL−1. The results from this study indicate that prey size and density are crucial for the successful feeding of octopus paralarvae. Based on the greatest numbers of successful feeding behaviours, O. tetricus paralarvae prefer prey between 1.4 and 1.6 mm in length and at densities between 1.0 and 1.8 prey mL−1. The use of these optimal prey characteristics can be used to promote efficient paralarval octopus prey capture and feeding to greatly increase food intake in octopus paralarvae when reared in aquaculture.

Cameras or Camus? Comparing Snow Track Surveys and Camera Traps to Estimate Densities of Unmarked Wildlife Populations

ABSTRACTPopulation density is a valuable metric used to manage wildlife populations. In the Russian Far East, managers use the Formozov‐ Malyushev‐Pereleshin (FMP) snow tracking method to estimate densities of ungulates for hunting management. The FMP also informs Amur tiger (Panthera tigris altaica) conservation since estimates of prey density and biomass help inform conservation interventions. Yet, climate change and challenges with survey design call into question the reliability of the FMP. Camera traps offer a promising alternative, but they remain unexplored for monitoring tiger prey density. Over three years (2020‐2022), we used the FMP and camera‐based methods to estimate densities of four prey species of the Amur tiger in the Sikhote‐ Alin Biosphere Reserve, Russian Far East: wild boar (Sus scrofa), red deer (Cervus canadensis), roe deer (Capreolus pygargus), and sika deer (Cervus nippon). We compared FMP results from snow track survey routes either along trails, or along routes representative of the study area, and estimates derived from camera data using the random encounter model (REM), space‐to‐event model (STE), and time‐to‐event model (TTE). We found that density estimates from representative routes were typically lower than routes along trails and indicated different relative densities of prey. Density estimates from camera traps and representative track surveys were generally similar with no significant relative bias, but precision was poor for all methods. Differences between estimates were amplified when converted to prey biomass, particularly with larger, more abundant prey, which poses a challenge for their utility for tiger managers. We conclude camera traps can offer an alternative to snow track surveys when monitoring unmarked prey, but we caution that they require considerably more resources to implement. Tiger managers should be especially cautious when extrapolating density to estimates of prey biomass, and we encourage future research to develop more robust methods for doing so.

Predatory efficiency of six-spotted ladybird beetle, Cheilomenes sexmaculata (Fabricius) against the mixed prey densities: a functional response analysis

Predatory efficiency of six-spotted ladybird beetle, Cheilomenes sexmaculata (Fabricius) against the mixed prey densities: a functional response analysis

Feeding behavior of blue whales (Balaenoptera musculus) during austral summer in northern Chilean Patagonia

Over recent decades, the feeding strategies of the blue whale (Balaenoptera musculus) in the northern Chilean Patagonia have been studied mainly through visual observation and anatomical dissection, with limited direct behavioral analyses and measurements of prey distribution due to the difficulty of sampling. Here, we investigated the foraging ecology of this species during six annual research cruises (2014–2019) in the northern Chilean Patagonia, an important feeding and nursery area. We deployed 28 sound and movement recording tags (DTAGs), attached by suction cups, to measure fine-scale behaviors of this species. In addition, from 2016 to 2019, prey density and distribution were simultaneously recorded with tag data utilizing a scientific echosounder. A total of 949 foraging dives and 3,183 feeding events were detected from movement sensors throughout more than 190 hr of data, during both day and nighttime. Blue whales exhibited both shallow and deep foraging events utilizing different strategies in response to changing conditions of prey depth and density, with foraging dives recorded continuously for the whole duration of the deployments. Whales showed a higher feeding rate at night as they foraged on shallow and dispersed krill, but they exhibited a higher rate of foraging events per dive during the day, as they foraged on deep and dense krill patches. The whales used less energetically costly maneuvers when foraging near the surface, with lower values of pitch and speed. Both strategies are consistent with optimal foraging theory, as the whales minimizing energetic costs associated with feeding while simultaneously maximizing energy intake. These results provide valuable insights into the behavioral and foraging ecology of blue whales to promote specific conservation plans in the northern Chilean Patagonia.

Recovery of tigers (Panthera tigris): Assessing ecological carrying capacity in Bardia-Banke Complex, Nepal

Tigers (Panthera tigris) are endangered wild felids, despite ongoing efforts to recover populations globally. The majority of the global population is concentrated within ∼ 40 “source sites”. Protection and effective management of these populations constitute the cornerstone of global tiger conservation strategies. Reliable population estimates and site specific carrying capacities are important for informed management actions. Here, we estimated the ecological carrying capacity of tigers based on prey densities in the Bardia– Banke Complex in western Nepal embedded within the Terai Arc Landscape, a globally significant tiger conservation landscape. A total of 303.8 km line transects (n=195) were surveyed in the Bardia–Banke Complex. We estimated an overall density of 69.09 (95 % CI=52.32 – 91.23) ungulates/km2 and biomass of 2736.92 (1807.83 – 4830.12) kg/km2 in Bardia National Park (NP), and 25.67 (18.22 – 36.18) ungulates/km2 and biomass of 1356.65 (646.85 – 2994.86) kg/km2 in Banke NP. The available prey base can support 133 (101 – 177) adult tigers in Bardia NP and 28 (20 – 40) in Banke NP. We also carried out systematic camera trap survey across the Complex with a sampling effort of 13,365 trap days (719 camera sites). In core habitats of Bardia and Banke NP, we estimated tiger abundance of 77 (72 – 83) and 12 (9 – 15) at a density of 7.96 and 2.18 tigers per 100 km2 respectively. Our study shows the tiger populations in the national parks are below carrying capacity. We emphasize the need for robust estimates of prey abundance and carrying capacity of tigers in a given landscape for effective conservation planning. We highlight the importance of high prey density and biomass with effective human-tiger conflict mitigation measures to sustain a large tiger source population.

Behavior and developmental consequences of cannibalism in Spodoptera frugiperda

AbstractThe fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a highly destructive agricultural pest. The ability of S. frugiperda to survive and reproduce is widely recognized, but it is also important to consider the role of larval cannibalism as a significant biological trait. Understanding the cannibalistic habits of pests helps to explore the dynamics and evolution of their populations and facilitates the monitoring of insect outbreaks. Therefore, the stages, densities, and intensity of cannibalism in S. frugiperda larvae, as well as the consequences for their development, were investigated under laboratory conditions. Spodoptera frugiperda larvae showed obvious cannibalism after the third instar even in the presence of maize (Zea mays L., Poaceae) leaves; cannibalism was not observed in first instars. In the case of only one cannibal, the percentage of prey consumed by cannibalism decreased with higher prey density, and the predatory functional responses of fourth‐ to sixth‐instar predators to first‐ to third‐instar preys were fitted using the Holling II model. Compared with larvae feeding on maize only, larvae feeding on a diet of maize supplemented with third‐instar conspecifics had a longer developmental duration and a higher body weight, with no significant differences in larval survival, pupation, or eclosion rates. Larvae supplied with conspecifics only, in the absence of maize leaves, generally had a lower body weight than larvae supplied with maize only, although developmental duration was still longer, and longevity and fecundity rates were lower for these larvae. Overall, consuming a small quantity of conspecifics in addition to maize leaves prolonged the developmental duration of larvae and pupae to some extent, increased the body weight, and did not impact the longevity or reproduction of S. frugiperda. However, cannibalism only, without access to maize leaves, had a detrimental effect on adult longevity and reproduction. These findings could serve as a valuable reference for studying the life history of insects that consume agricultural crops and may have potential applications for biological control.

Dynamics of a discrete Rosenzweig–MacArthur predator–prey model with piecewise-constant arguments

This paper investigates the dynamics of a new discrete form of the classical continuous Rosenzweig–MacArthur predator–prey model and the biological implications of the dynamics. The discretization method used here is to modify the continuous model to another with piecewise-constant arguments and then to integrate the modified model, which is quite different from the traditional Euler discretization method. First, the existence and local stability of fixed points have been thoroughly discussed. Then, all codimension-1 bifurcations have been studied, including the transcritical bifurcations at the trivial fixed point and the boundary fixed point, and the Neimark–Sacker bifurcation at the unique positive fixed point. Furthermore, it is proved that there are no codimension-2 bifurcations. Finally, the control of the bifurcations is studied. Regarding the biological significance, we have considered the following four aspects: When no harvesting effort is applied to both predators and prey, it is observed that providing more resources to the prey species leads to predator extinction, causing the ecosystem to lose stability. This implies that the paradox of enrichment occurs. When predators are harvested, the system exhibits the hydra effect, i.e. increasing the harvesting effort on predators will lead to an increase in the mean population density of predators. When the prey is harvested, numerical examples indicate that increasing the harvesting effort initially reduces prey density. Upon reaching the bifurcation point, prey density stabilizes while the predator density continues to decline. When both prey and predators are harvested, the biological significance is similar to the previous case. The outcomes of this paper have significant theoretical meaning in the study of population ecology. By MATLAB, the bifurcation diagrams, maximal Lyapunov exponent diagrams, phase portraits and mean population density curves are plotted. Numerical simulations not only show the correctness of the theoretical findings but also reveal many new and interesting dynamics.

The influence of spatial context on prey manipulation behaviors in the California moray eel (Gymnothorax mordax)

Predation strategies are shaped by multiple factors, such as prey type, prey density, and/or abiotic conditions. However, limited research has investigated the role of spatial constraints on post-capture behaviors. Our aim was to assess the impact of spatial context on prey manipulation in the California moray eel (Gymnothorax mordax), a crevice forager with a diverse prey handling repertoire. We first compared the duration engaged in specific manipulation behaviors between spatially “enclosed” and “open” foraging environments, followed by a comparison of tightly enclosed spaces that were scaled to individual moray diameter. We observed that the durations spent engaged in specific manipulation behaviors varied based on spatial context. Despite these changes, total feeding time, which consists of both manipulating and swallowing prey, did not vary across treatments. These results highlight the behavioral flexibility of morays, suggesting that they can adjust prey manipulation strategies for specific spatial contexts without compromising overall feeding duration. We additionally documented two previously undescribed behaviors (tail and body anchoring) which seem to be used in the narrowest treatments for leverage when knotting behavior was not possible due to spatial constraints. This research provides valuable insight into the foraging ecology of this locally abundant apex predator and aids in furthering our understanding of predator-prey interactions in the benthic community within the kelp forest ecosystem.

A spatially explicit drift foraging model quantifies salmon rearing habitat enhancement

Salmonid rearing habitat restoration is often intended to increase juvenile prey abundance, predator refugia, and physical conditions that enhance growth, development, and survival. A common restoration evaluation approach is to quantify habitat quality via physical metrics such as depth and velocity. However, such an approach does not account for the bioenergetic implications of habitat occupancy. We developed a spatially explicit predictive framework to assess net rate of energy intake (NREI) for juvenile Chinook salmon (Oncorhynchus tshawytscha) experiencing pre-existing and post-project conditions in a restored side channel complex. Energetic submodels from existing juvenile salmonid drift foraging literature are used in combination with site-specific macroinvertebrate drift data and a 2D hydraulic model. We address the following question: does our model predict increased net available energy for foraging juveniles in a restored channel condition compared to pre-existing conditions under varying discharges, thermal conditions, and seasonality? Observed macroinvertebrate drift data was extrapolated to the model domain via random forest models. Modeled post-project conditions showed statistically significant improvements in foraging opportunity compared to existing conditions, with depth ranked as the most important NREI predictor. The novel framework presented here improves upon previous applications that model drift from a single fish perspective and generalize prey density.

Trait responses, nonconsumptive effects, and the physiological basis of Helicoverpa armigera to bat predation risk.

Predation reduces the population density of prey, affecting its fitness and population dynamics. Few studies have connected trait changes with fitness consequences in prey and the molecular basis and metabolic mechanisms of such changes in bat-insect systems. This study focuses on the responses of Helicoverpa armigera to different predation risks, focusing on echolocating bats and their calls. Substantial modifications were observed in the nocturnal and diurnal activities of H. armigera under predation risk, with enhanced evasion behaviors. Accelerated development and decreased fitness were observed under predation risks. Transcriptomic and metabolomic analyses indicated that exposure to bats induced the upregulation of amino acid metabolism- and antioxidant pathway-related genes, reflecting shifts in resource utilization in response to oxidative stress. Exposure to bat predation risks enhanced the activity of DNA damage repair pathways and suppressed energy metabolism, contributing to the observed trait changes and fitness decreases. The current results underscore the complex adaptive strategies that prey species evolve in response to predation risk, enhancing our understanding of the predator-prey dynamic and offering valuable insights for innovative and ecologically informed pest management strategies.

Structuring of particle-associated bacterial communities along the extracellular polymeric substance gradient of sinking and suspended particles in an oligotrophic, subtropical region of the western North Pacific Ocean

Extracellular polymeric substances, such as transparent exopolymer particles (TEP) composed of acidic polysaccharides, are important particulate organic carbon (POC) components of marine environments that affect particle dynamics and ocean carbon export. However, how polymeric substances interact with and shape bacterial communities associated with marine particles is poorly understood. This study investigated whether the composition of particle-associated bacterial communities differs between sinking and suspended particles, which differ in their polymeric substance contents, in the upper water column of the subtropical, oligotrophic Kuroshio region. Bacterial taxa likely involved in polymer degradation (Alphaproteobacteria, Gammaproteobacteria, and Bacteroidia) were enriched on sinking particles with a lower TEP: POC ratio, indicating that bacterial degradation of polymeric substances promotes particle sinking by removing positively buoyant polymers. By contrast, suspended particles were increasingly enriched for Bdellovibrionota and Desulfobacterota as the TEP: POC ratio increased. These taxa, which include predatory microbes, seem to prefer polymer-rich environments with a high density of potential prey. Planctomycetota were not significantly related to the TEP: POC ratio, indicating their broad niche breadth on particles’ polymeric substance contents. The results suggest that the bacterial niche differentiation associated with the particle polymeric-substance gradient shapes bacterial communities in a subtropical ocean.

Human–wildlife interactions on the tidal flats of the Bijagós Archipelago: does shellfishing affect migratory shorebirds?

The Bijagós Archipelago in West Africa is home to an ethnic group with a rich cultural heritage that is tightly linked to nature. The Bijagós people have a shared cultural identity, but management of natural resources varies between islands due to island‐specific context with regards to socio‐political organization and strength of cultural heritage. Across the archipelago, bivalves harvested manually from the mudflats are an important part of the Bijagós people's diet, economy, and culture. Migratory shorebirds share the use of these mudflats during their non‐breeding season, consuming macrobenthos such as crustaceans and bivalves, including those harvested by local people. At the end of their stay in the Bijagós, just before taking off for their migratory flight, it is particularly important that shorebirds have access to undisturbed feeding areas with suitable food resources. In this study we start by exploring shellfishing patterns across different management regimes (via questionnaires to local shellfishers), then assess seasonal variation in the direct impact of shellfishing on shorebirds (through competition for resources and space), and finally quantify the indirect impact of sediment disturbance due to shellfishing upon shorebird prey availability with an experimental approach. Results indicate that bivalve resources are better managed in areas with formal protection, while traditional management based on cultural beliefs results in poorer stock conditions. Interestingly, the high density of shellfishers in mid‐winter (14.4 ind. km−2) decreased markedly towards shorebirds' fuelling period, when they benefit the most from reduced disturbance on the mudflats. Regardless of the season, no direct competition for resources was detected due to differences in targeted sizes. Indirect impacts caused by sediment disturbance during shellfishing were also mostly absent, causing only a small reduction on shorebirds prey density but with no effect on the available biomass.