Patterns Of Predation Research Articles

Body size modulates demographic patterns of top predators and their native and invasive prey: A biomathematical approach

The arrival of invasive species in native communities impacts the structure and functioning of ecosystems, and is considered a critical indicator of loss of biodiversity. Exploring the effects of new species in communities presents challenges addressable through theoretical ecology. Species body size not only shapes trophic relationships, but may also impact predator success and facilitate species coexistence. However, little attention has been paid to the effects of differences in species body size on interactions between native and invasive primary consumers, which could be relevant to their coexistence with higher-level predators. Our aim is to investigate demographic patterns using a dynamic, mechanistic model of two age-structured primary consumers (one invasive and one native) sharing a plant resource and preyed upon by a common predator. In our model, we highlight three crucial phenomena: the structuring of primary consumers into adults and juveniles, reproduction occurring in discrete pulses, and the seasonal addition of new individuals to the population. Hence, the success of one species over the other relies on its reproductive capacity to incorporate individuals in each reproductive cycle. Our simulations reveal that abundance patterns are influenced by body size, suggesting that changes in predator body size could serve as key indicators of shifts in community structure.

Molecular barcoding reveals patterns of egg predation in small pelagic fish

Cannibalism and intraguild predation occur in a vast number of small pelagic fish (SPF) species. Egg and larval predation can have important consequences on mortality, and its accurate assessment is important to estimate the impact on recruitment strength and population dynamics of predators and prey. Such assessments are hampered by limitations in visual species identification of many fish eggs and larvae in the predators’ stomachs. European sardine Sardina pilchardus and Atlantic chub mackerel Scomber colias, the dominant species of the pelagic food web off the Canary Current Upwelling ecosystem, are major predators of fish eggs. Egg predation by these SPF species is particularly high on sardine and anchovy eggs, but many preyed fish eggs are not amenable to visual identification. This study provides a proof-of-concept application of molecular identification of diverse fish eggs from SPF stomach contents not suitable for visual identification, as a way to improve our understanding of the impact of intraguild predation on fish population dynamics. Results show a high diversity of fish species in the eggs ingested by sardines and chub mackerel (18 and 15 families, respectively), mostly comprising locally abundant coastal taxa. Sardine ingested predominantly anchovy, sardine and sparid eggs, while chub mackerel ingested predominantly sparid eggs, followed by serranid (Serranus spp.) and sardine eggs. Sardines also showed higher variability in prey composition compared to chub mackerel. Exploratory analyses also suggested variability in prey composition with sampling area, season and maturity stage for sardine and chub mackerel, highlighting the need for dedicated follow-up studies.

Clay larvae do not accurately measure biogeographic patterns in predation

AbstractAimSpatial variation in predation can shape geographic patterns in ecology and evolution, but testing how predation varies across ecosystems is challenging as differing species compositions and defensive adaptations can mask underlying patterns. Recently, biogeography has borrowed a tool from ecology: clay prey models. But clay models have not been adequately tested for geographic comparisons, and a well‐known problem –that clay prey only appeal to a subset of potential predators– could bias detected geographic patterns whenever the relative importance of predator guilds varies among sites. Here, we test whether clay larvae accurately capture geographic differences in predation on real larvae.Location90° of latitude and >2000 m elevation across the Americas.TaxonVertebrate and invertebrate predation on ‘superworms’ (Zophobas larvae).MethodsAcross six sites that vary dramatically in latitude, elevation, and biome, we quantified predation on live, dead, and clay larvae. We physically excluded vertebrate predators from some larvae to distinguish total predation and invertebrate‐only predation.ResultsPredation on live superworms almost doubled from our high‐elevation high‐latitude site to our low‐elevation tropical site. Geographic patterns were consistent among live and dead larvae, but clay larvae missed extremely high predation at some sites and therefore mis‐measured true geographic patterns. Clay larvae did a particularly bad job at capturing geographic patterns in predation by invertebrates, although sample sizes for invertebrate predation were small.Main ConclusionsClay larvae are inappropriate for comparing predation rates across sites. They should be abandoned for biogeographic studies and reserved for comparisons within, rather than across, predator communities.

Biotic interactions vary across species' ranges and are likely conserved through geological time

AbstractAimThe evolutionary interactions between western spadefoot toads (genus Spea) represent a textbook example of character displacement, facilitated by dietary specialization of one Spea species on fairy shrimp (Anostraca) when all three co‐occur. The aim of this study is to understand the covariation between predator (Spea) and prey (Anostraca) range shifts in response to climate change oscillations, and whether biotic interactions can be used to project species distribution models on different time scales when studying species with dietary specialization. Taxon: Amphibia: Spea spp. and Crustacea: Anostraca.LocationNorth America.MethodsUsing multiple modelling techniques, we first estimated the potential distribution of central and western North American fairy shrimp species (Crustacea: Anostraca) and two western spadefoot toad species (Spea bombifrons and Spea multiplicata). We then created a shrimp species richness map by aggregating individual species estimates. Third, we studied the relationship between the probability of spadefoot toad presence and fairy shrimp species richness during the present and Last Glacial Maximum conditions. Finally, we estimated the strength and direction of the co‐occurrence between spadefoot toads and fairy shrimp sampled at the level of entire predicted range and at the regional level (allopatric and sympatric).ResultsFirst, the same abiotic environmental variables shape spadefoot toad and fairy shrimp species' distributions in central and western North America across time. Second, areas of sympatry of Spea bombifrons and Spea multiplicata correspond with dry conditions and higher shrimp richness. Finally, the spatial patterns of predator–prey co‐occurrence are highly variable across geography, forming a spatial mosaic over the species' ranges.Main ConclusionPredator–prey relationships form a spatial mosaic across geography and species ranges. Including biotic interactions into species distribution estimates for organisms with dietary specialization is highly recommended. Biotic interactions can be projected across different time frames for organisms with dietary specialization as they are likely conserved.

Bifurcation Patterns in a Discrete Predator–Prey Model Incorporating Ratio-Dependent Functional Response and Prey Harvesting

Bifurcation Patterns in a Discrete Predator–Prey Model Incorporating Ratio-Dependent Functional Response and Prey Harvesting

Wildlife activity patterns and encroaching woody vegetation response to bush thinning on farmlands in north-central Namibia

The Namibian savannah ecosystem has experienced considerable anthropogenic pressures, which have resulted in the disruption of key ecological processes, and consequently, the proliferation of a dense vegetation structure, commonly known as bush encroachment. Approximately 45 million hectares of land have been affected, which has caused a significant decline in the grazing capacity, poor economic returns for the farmers, and loss of suitable wildlife habitat. Restoration thinning, a method that involves the selective removal of excess trees/shrubs, has been applied to counteract the negative effects associated with this phenomenon. This thesis aimed to assess the effect of thinning on (a) the activity patterns of local ungulates and predators, (b) the encroaching woody vegetation in terms of (i) regeneration, and (ii) structure, abundance, and habitat sighting lines, in a savannah habitat in the north-central region. Generalised linear mixed-effects models (GLMM) and linear mixed-effects models (LME) were used for statistical analysis. Results showed that thinned areas had overall greater wildlife activity. Thinned areas also had reduced tree/shrub abundance, which was significant for the mature height classes. Natural regeneration was rapid in thinned areas, where the abundance of young cohorts was 34% greater than non-thinned areas. In the thinned areas, red umbrella thorn (Vachellia reficiens) was significantly reduced but umbrella thorn (Vachellia tortilis) numbers increased. Tree/shrub densities in the thinned areas fell within the commonly accepted range for a 400 mm rainfall area (600–750 tree equivalents (TE) ha–1). Thinning significantly modified the dense thornbush to an open vegetation structure with a low woody canopy cover that favours grass growth and provides greater sighting lines for open savannah wildlife. This thesis demonstrated that thinning was effective in controlling bush encroachment and could be used as a method to restore other affected areas. However, periodic post-thinning management is recommended to control the established samplings.

Patterns of gastropod predation on middle Eocene echinoids from the western Eucla Basin, Western Australia

Patterns of gastropod predation on middle Eocene echinoids from the western Eucla Basin, Western Australia

Analysis of patterns in an additional food-provided predator–prey reaction diffusion model using amplitude equations

Analysis of patterns in an additional food-provided predator–prey reaction diffusion model using amplitude equations

An Assessment of the Impact of Climate Change on Pest Infestation and Control Methods

Climate change has pervasive effects on agriculture, impacting various facets of production. The production of agricultural commodities is particularly susceptible to the influence of climate change. This is exemplified by the escalating losses incurred due to pests, which in turn, pose a significant threat to global food security. Notably, for every degree rise in temperature, insect predators are responsible for a substantial 10–25% reduction in production output. Climate change further exacerbates the situation by bolstering the diffusion, longevity, and adaptability of these pests. Alterations in temperature patterns lead to shifts in weather dynamics, while the emission of chemicals into the atmosphere induces noteworthy changes in the distribution, migration, and behavioral patterns of insect predators. Consequently, this exerts a palpable impact on the overall volume of sustenance generated worldwide. The predicament of crop infestations by insects and the resulting production losses is already a pressing concern for major agricultural powerhouses such as China, the United States, and France. This article delves into a comprehensive assessment of the repercussions of climate change on pest infestations, along with an exploration of viable pest control strategies.

Prey body size generates bias for human and avian agents: Cautions for interpreting small game assemblages

Identifying the accumulating agent(s) of small animal assemblages at archaeological sites is challenging given the range of behaviors, skeletal plans, and body sizes of prey species as well as the range of potential predators. Although mammalian carnivores, raptors, and humans are considered typical predators of small game, there are many contexts—especially in island ecosystems—where humans and raptors are the primary agents for small animal assemblages in the absence of mammalian carnivores. Moreover, smaller animals tend to range in body sizes in these geographically restricted ecosystems. This study aims to broadly explore: 1) how small animal body size affects the taphonomic signature(s) of human and avian predation; and 2) how human and avian-generated small game assemblages compare with one another. To investigate these questions, this study compared the resulting taphonomic patterns of small animal predation by raptors and humans using data collected during a controlled-feeding experiment and an observational study, respectively. In the controlled-feeding experiment, deceased laboratory rats (Rattus norvegicus domestica) (50–500 g) were fed to two Milky Eagle Owls (Ketupa lacteus), one King Vulture (Sarcoramphus papa), and two Lappet-Faced Vultures (Torgos tracheliotos). In the observational study, we explored how humans processed various species of small prey ranging in body mass (80–5000 g) by analyzing anthropogenic modifications (i.e., cutmarks, tooth marks, burning). The resulting small animal assemblages were analyzed post-consumption for skeletal element representation, fragmentation and breakage patterns, and bone surface modifications. Results show that small prey body size significantly affects pre-depositional patterning in terms of skeletal element survival, butchering intensities, and cutmark frequencies. Furthermore, our experimentally generated assemblages show that breakage, fragmentation, and element relative abundance patterns can be used to distinguish between human and avian-accumulated assemblages in the archaeological record.

Rhizosphere shapes the associations between protistan predators and bacteria within microbiomes through the deterministic selection on bacterial communities.

The assembly of bacterial communities in the rhizosphere is well-documented and plays a crucial role in supporting plant performance. However, we have limited knowledge of how plant rhizosphere determines the assembly of protistan predators and whether the potential associations between protistan predators and bacterial communities shift due to rhizosphere selection. To address this, we examined bacterial and protistan taxa from 443 agricultural soil samples including bulk and rhizosphere soils. Our results presented distinct patterns of bacteria and protistan predators in rhizosphere microbiome assembly. Community assembly of protistan predators was determined by a stochastic process in the rhizosphere and the diversity of protistan predators was reduced in the rhizosphere compared to bulk soils, these may be attributed to the indirect impacts from the altered bacterial communities that showed deterministic process assembly in the rhizosphere. Interestingly, we observed that the plant rhizosphere facilitates more close interrelationships between protistan predators and bacterial communities, which might promote a healthy rhizosphere microbial community for plant growth. Overall, our findings indicate that the potential predator-prey relationships within the microbiome, mediated by plant rhizosphere, might contribute to plant performance in agricultural ecosystems.

Visual predators and diurnal nest predation provide support for the Skutch Hypothesis and explain evolved incubation behaviors in a montane tropical bird community

Abstract The Skutch (1949) Hypothesis that nest predation risk constrains parental nest activity has important implications for the evolution of parental care strategies, but the required conditions for the hypothesis to operate have been questioned. We found the necessary conditions existed in a montane tropical bird community where 95.4% of predation events (n = 456) occurred during daylight hours and almost all predators (n = 224) were visually oriented. Moreover, incubation strategies for 21 passerine species were explained by nest predation rates as proposed by the Skutch Hypothesis. Hourly rates of visits to the nest were lower among species with higher nest predation rates, and achieved in part by longer on- and off-bouts. Incubation attentiveness (percent of time incubating) does not necessarily affect parental nest activity and was not related to nest predation rates. Nest predation rates were greater in enclosed- than open-nesting species, counter to long-standing views. Moreover, nest predation was usually higher in the nestling period when parents were more actively visiting nests than during incubation for enclosed- but not open-nesting species. This increase in nest predation in the nestling period for enclosed-nesting species might indicate proximate predation responses to parental nest activity that underlie the evolutionary patterns. Adult mortality also can exert selection on evolved strategies. Following life history theory, annual adult mortality probability explained residual variation in incubation behaviors, while accounting for nest predation, with longer-lived species exhibiting lower nest activity and attentiveness. Ultimately, the conditions for the Skutch Hypothesis were clear and evolved behaviors suggest an important influence of natural selection by nest predation in this montane tropical bird community. At the same time, different patterns of nest predation between open- and enclosed-nesting species emphasize a need for further research into how parental nest activity interacts with nest type to affect predator detection of nests.

Kill rates on native ungulates by Mexican gray wolves in Arizona and New Mexico

AbstractMexican gray wolf (Canis lupus baileyi) reintroduction began in 1998 in Arizona, USA, with 11 individuals initially; wolves from this population dispersed into New Mexico, USA, the following year. Numbers of wolves have steadily increased (≥241 individuals in Dec 2022) and the size of the recovery area has expanded in both states. Understanding kill rates is fundamental to the recovery and management of Mexican wolves to properly maintain a healthy and sustainable population of wolves and their prey species. We used global positioning system (GPS) cluster analysis to locate kill sites and estimate kill rates on native ungulate prey taken in the recovery area by 10 Mexican wolf groups during winter (15 Feb–15 Mar) and 8 wolf groups during summer (15 Jun–15 Jul) in 2015–2017. Elk (Cervus canadensis) composed 94% of the native ungulates documented at Mexican wolf kill sites (n = 139); the remaining 6% were mule deer (Odocoileus hemionus; n = 9). Two‐thirds of all wolf‐killed native ungulates were elk calves. We estimated kill rates as ungulate biomass killed/wolf/day. From combined results for all years, we estimated that each Mexican wolf killed on average 9.0 ± 5.4 kg (±95% CI) of ungulate biomass per day during winter and 7.8 ± 6.2 kg during the summer. Our estimates of kill rates could be overestimated if Mexican wolves obtained a substantial amount of their biomass from scavenging, particularly during 4 months of hunting seasons (Sep–Dec) not captured in winter and summer. Using data from the first 2 years of the study (2015, 2016), we developed a logistic regression model to predict probability of an elk kill occurring at a GPS cluster as a function of hours spent by a collared wolf at that GPS cluster and size of the wolf group. Applying this model to the final year of the study (2017) resulted in similar numbers of predicted (n = 16.1 and 27.2 in winter and summer, respectively) and observed numbers (n = 15 and 26) of elk kills. Additionally, the demographic composition of the 2017 elk kills closely matched that of the previous 2 years. The results of this study indicate similar predation patterns of Mexican wolves to those of wolves in northern locations and can help wildlife managers plan for potential effects from a larger population of wolves across a broad area in Arizona and New Mexico.

Predation Patterns and Hunting Behavior of Snow Leopards: Insights from an Ibex Hunt

The hunting behaviours of the snow leopard (Panthera uncia) are poorly understood. In this note, we describe the successful hunt of an adult male ibex (Capra sibirica) by a known male snow leopard. The hunt started in a mountain slope close to three large boulders and progressed downhill for 115 m until it concluded at the bottom of a drainage. By comparing the habitat where the ibex was killed to the kill sites of 158 ibex and 17 argali (Ovis ammon) that were killed by GPS-collared snow leopards, we demonstrate that the majority (62%) of these were kills occurred in drainages. We propose that in successful hunts, snow leopards commonly ambush from above, causing prey individuals to typically flee downhill. Thereby the prey maintain their momentum and it is not until they are slowed down upon reaching the bottom of the drainage that the snow leopards are able to subdue them.

Shedding light on trophic interactions: A field experiment on the effect of human population between latitudes on herbivory and predation patterns.

Interactions between species within an ecosystem (e.g. predation and herbivory) play a vital role in sustaining the ecosystem functionality, which includes aspects like pest control and nutrient cycling. Unfortunately, human activities are progressively disrupting these trophic relationships, thereby contributing to the ongoing biodiversity decline. Additionally, certain human activities like urbanization may further impact the intensity of these trophic interactions, which are already known to be influenced by latitudinal gradients. The aim of this study was to test the hypothesis of whether the impact of human population, used as a proxy for human pressure, differs between latitudes. To test it, we selected 18 study sites at two latitudes (i.e. ~53°N and ~50°N) with varying human population density (HPD). We used artificial caterpillars placed on European beech branches to assess bird predation and took standardized pictures of the leaves to estimate insect herbivory. Remote sensing techniques were used to estimate human pressure. We found that the intensity of bird predation varied in response to HPD, with opposite trends observed depending on the latitude. At our upper latitude, bird predation increased with HPD, while the opposite was observed at the lower latitude. Herbivory was not affected by urbanization and we found higher levels of herbivory in the lower compared to the higher latitude. At the lower latitude, certain species may experience a disadvantage attributed to the urban heat island effect due to their sensitivity to temperature fluctuations. Conversely, at the higher latitude, where minimum temperatures can be a limitation, certain species may benefit from milder winters. Overall, this study highlights the complex and dynamic nature of trophic relationships in the face of human-driven changes to ecosystems. It also emphasizes the importance of considering both human pressure and latitudinal gradients when assessing the ecological consequences of future climate change scenarios, especially in urban environments.

Golf course living leads to a diet shift for American alligators.

Human-driven land use change can fundamentally alter ecological communities, especially the diversity and abundance of large-bodied predators. Yet, despite the important roles large-bodied predators play in structuring communities through feeding, there have been only a few investigations of how the feeding patterns of large-bodied predators change in human-dominated landscapes. One group of large-bodied predators that has been largely overlooked in the context of land use change is the crocodilians. To help fill these gaps, we studied the feeding patterns of juvenile American alligators (Alligator mississippiensis) on neighboring barrier islands on the southeast coast of Georgia, USA. Jekyll Island has multiple golf courses and substantial amounts of human activity, while Sapelo Island does not have any golf courses and a much smaller amount of human activity. We found that juvenile alligator populations on both islands ate the same types of prey but in vastly different quantities. Sapelo Island alligators primarily consumed crustaceans while alligators that lived on Jekyll Island's golf courses ate mostly insects/arachnids. Furthermore, the Jekyll Island alligators exhibited a much more generalist feeding pattern (individuals mostly ate the same types of prey in the same quantities) than the more specialized Sapelo Island alligators (diets were more varied across individuals). The most likely explanation for our results is that alligators living on golf courses have different habitat use patterns and have access to different prey communities relative to alligators in more natural habitats. Thus, land use change can strongly alter the feeding patterns of large-bodied predators and, as a result, may affect their body condition, exposure to human-made chemicals, and role within ecological communities.

Distance to the edge and other landscape features influence nest predation in grey partridges

AbstractPredation and habitat deterioration are the main reasons for the strong decline of ground‐nesting farmland birds such as the grey partridge Perdix perdix in Europe. Grey partridge nests and incubating females are especially vulnerable to predation. We have previously demonstrated that predator activity is much lower inside flower blocks (agri‐environment schemes sown with a flower seed mix) than at their edges and that predator activity in flower blocks depends on the surrounding landscape. Here, we investigate whether these differences in predator activity translate into differences in grey partridge nest predation and assess predation patterns relative to landscape and nest site characteristics. We recorded the success of 56 nests of radio‐tagged grey partridges between 2009 and 2017 in an agricultural landscape in Central Germany. We used Bayesian logistic regression to analyse the effects of nest site and landscape characteristics on nest predation on a subset of 46 nests (21 nests successful, 25 predated). Distance to the edge of the nesting habitat was the most important predictor, reducing predation probability from 66.8% at the edge to 18.5% at 85.5 m. Predation probability decreased with increasing length of habitat borders, habitat diversity and the area of permanent grasslands and fallows. Predation probability was higher further from settlements and increased with increasing woodland area in the agricultural matrix. When considering linear landscape structures, nest predation patterns matched the patterns of predator activity from our previous studies. Results suggest that the distance to the edge of the nesting habitat is most important and that nest predation may be reduced by providing sufficiently broad nesting habitats. Nest predation may further be minimized by increasing habitat diversity and coverage of extensive vegetation types and by establishing conservation measures for grey partridges further away from woodlands. These measures may also benefit other ground‐nesting farmland birds.

Seasonal density and natural mortality of Halyomorpha halys (Stål) and indigenous stink bugs (Hemiptera: Pentatomidae) in a field crop agroecosystem.

Stink bugs (Hemiptera: Pentatomidae), including the exotic Halyomorpha halys (Stål), Nezara viridula (L.), and other indigenous species, are pests that damage a variety of agricultural crops. At a study site in the southeastern United States, we measured the density of stink bug species and patterns of parasitism and predation on corn, cotton, and soybean and host trees in an adjacent woodline. We assessed parasitism and predation of naturally laid egg masses in crops and sentinel egg masses in host trees and used pheromone-baited traps to determine H. halys seasonal development. Overall, H. halys and N. viridula were the dominant bugs observed. Adult H. halys were first detected each year on trees, followed by corn, and then cotton and soybean, suggesting that trees served as a source of H. halys dispersing into crops. For H. halys, more nymphs were captured in soybean than in corn or cotton. For N. viridula, more adults were captured in corn and cotton than in soybean, and more nymphs were captured in corn during 2019 and 2021 than in 2020. Percentage parasitism of N. viridula egg masses (74.2%) was higher than than that for H. halys egg masses (54.3%). Accordingly, conservation biological control has the potential to enhance parasitism of indigenous stink bugs and H. halys in field crop agroecosystems.

A stable isotope analysis of the dietary patterns of the aquatic apex predator, the African tigerfish (Hydrocynus vittatus).

Stable isotope analyses, specifically δ13 C and δ15 N, are useful tools increasingly used to understand ecosystem function, food web structures and consumer diets. Although the iconic tigerfish, Hydrocynus vittatus, is regarded as an apex predator in southern African freshwater systems, little information is available regarding their feeding behaviour and how this may change with growth or differ between ecosystems with most information stemming from stomach content analyses (SCA). The aim of the present study was to address this lack of information through a baseline study of the diet of large and small tigerfish in various lentic and lotic ecosystems in South Africa using stable isotope methods. Fish and various food web components and food sources were collected from two river and two lake ecosystems from the Lower Phongolo River floodplain, SA. The δ13 C and δ15 N values for all samples were determined and multivariate analyses and Bayesian analytical techniques applied to determine the feeding ecology of H. vittatus and how this may differ with size and habitat type. Analyses revealed a substantial difference in the type and abundance of food sources contributing to the diet of H. vittatus between ecosystems, most prominently between the lotic systems, where less dietary specialisation was observed, and lentic systems where more specialisation was observed. Furthermore, there was a distinct difference in diet between small and large tigerfish, especially in the lotic system, indicating an ontogenetic diet shift as tigerfish grow and further supporting previous SCA studies. This is the first study of its kind on the African continent for H. vittatus and the findings illustrate the value of stable isotope analysis in providing in-depth information into the feeding ecology of consumers and how this may differ between size classes and habitat types. This article is protected by copyright. All rights reserved.

Characterizing Antarctic air-breathing predator dive patterns on a common prey base from stationary echosounders

Diving patterns of air-breathing predators were monitored from three moored subsurface upward-looking echosounders. Complete and partial dive profiles were visible on active acoustic records as echoes that started and/or returned to the surface. Dive metrics: maximum dive depths, durations, and wiggle count were measured and angles, distances, and velocities, were calculated at each site. Dive shapes ‘U’, ‘V’ and ‘W’ were derived using the number of wiggles and the percentage of dive bottom time. Dive profiles were classified into four types with type 1 dives being short in total duration and distance, low velocities, small angles, shallow, and linked to ‘U’ and ‘W’ shapes. Type 2 dives were short in distance, had low velocities, shallow depths, and were linked to ‘V’ dives. Dive types 3 and 4 had higher velocities, larger angles, longer total durations, and were deeper than types 1 and 2. Observed dive types could correspond to travelling, exploring, and foraging predator behaviors. Significant predator-prey overlaps occurred with predator dive profile counts correlated with krill aggregation thickness, density, and depth. This study demonstrates the utility of using stationary active acoustics to identify predator dive profiles with a simultaneous characterization of the potential prey field.