Prey Herd Research Articles

Dusky dolphin (Lagenorhynchus obscurus) habitat use in a mussel farming region and changes over time

ABSTRACT Information on marine mammal habitat use in coastal areas can provide a better understanding of anthropogenic effects on species. Admiralty Bay, New Zealand has extensive near-shore mussel farms and is an important dusky dolphin (Lagenorhynchus obscurus) foraging habitat. Prior dusky dolphin research indicated a declining trend in regional abundance from the late 1990s to mid-2000s. We describe dusky dolphin behaviour, habitat patch use and movement patterns in Admiralty Bay in 2011–2012 and compare findings to previous research to capture long-term trends. Sampling methods included small-boat group follows and photo-identification and shore-based theodolite tracking. Dolphin encounter rate, mean group size, and individual resighting rate showed a negative trend from previous years. Coordinated prey ball herding, a foraging technique documented in previous years, was rarely observed during this study. Dolphins were more likely to forage near farms (excluding specialised prey herding), though they seldom entered farms. Near shore, swimming speed was slower, reorientation rate was higher, and linearity was lower in the presence of farms than in their absence. This research builds upon prior studies, suggesting a continued decline in dusky dolphin presence, and highlights differences in habitat patch use in a human-altered ecosystem.

Prey herding and predators’ feeding satiation induce multiple stability

In this paper, we study a predator–prey model assuming that the prey population gathers together in herd and considering feeding satiation for the predator population as well. After analyzing the equilibrium points of the model, their stability and the existence of bifurcations we show the existence of multistability for three different equilibrium points via numerical simulations. This last analysis is performed using the bSTAB software and its extensions. It allows to compute the basin of stability values and to plot bifurcation diagram surfaces with respect to the model parameters.

Bifurcation analysis of a discrete type prey-predator model with Michaelis–Menten harvesting in predator

Abstract A discrete predator–prey model with square root functional response describing prey herd behavior and nonlinear predator harvesting has been considered in the present work. Three equilibria of the system have been found and observed that two equilibrium points always exist and are feasible, but the interior equilibrium point is feasible under a parametric condition. The local stability of the three equilibria has been analyzed. The interior equilibrium point is locally asymptotically stable under a parametric condition. It is examined that a flip and Neimark–Sacker bifurcations have occurred in the system at the axial equilibrium point. The flip and Neimark–Sacker bifurcations have been analyzed by the center manifold theorem and bifurcation theory, considering the harvesting coefficient as the bifurcation parameter. The proposed discrete model with a nonlinear Michaelis–Menten type harvesting effect on the predator population exhibits rich dynamics; for instance, bifurcations, chaos, and more complex dynamical behaviors. The discrete-time model also produced few numerical simulation results that are more accurate than the continuous model. The proposed discrete model will be performed better than the continuous model in populations with non-overlapping generations or smaller densities. The harvesting coefficient’s optimal value has finally been identified, and an optimal harvesting policy has been introduced. To verify the results, further numerical simulations have been performed.

An ecoepidemic model with healthy prey herding and infected prey drifting away

We introduce here a predator–prey model where the prey are affected by a disease. The prey are assumed to gather in herds, while the predators are loose and act on an individualistic basis. Therefore their hunting affects mainly the prey individuals occupying the outermost positions in the herd, which is modeled via a square root functional response. The conditions of boundedness and uniform persistence are established. Stability and bifurcation analysis of all feasible equilibrium are carried out. Conditions on the model parameters for the possible existence of limit cycles are derived, global stability analysis is also shown in proper choice of suitable Lyapunov function. Numerical simulation of the various bifurcations validate the theoretical results. It is found that the system ultimate behavior depends mainly on two crucial parameters, the force of infection and predator average handling time. A discussion of the biological significance of the investigation concludes the paper.

Fear-driven extinction and (de)stabilization in a predator-prey model incorporating prey herd behavior and mutual interference

<abstract><p>The indirect effect of predation due to fear has proven to have adverse effects on the reproductive rate of the prey population. Here, we present a deterministic two-species predator-prey model with prey herd behavior, mutual interference, and the effect of fear. We give conditions for the existence of some local and global bifurcations at the coexistence equilibrium. We also show that fear can induce extinction of the prey population from a coexistence zone in finite time. Our numerical simulations reveal that varying the strength of fear of predators with suitable choice of parameters can stabilize and destabilize the coexistence equilibrium solutions of the model. Further, we discuss the outcome of introducing a constant harvesting effort to the predator population in terms of changing the dynamics of the system, in particular, from finite time extinction to stable coexistence.</p></abstract>

Spatiotemporal patterns in a diffusive predator–prey system with Leslie–Gower term and social behavior for the prey

In this paper, we deal with a new approximation of a diffusive predator–prey model with Leslie–Gower term and social behavior for the prey subject to Neumann boundary conditions. A new approach for a predator–prey interaction in the presence of prey social behavior has been considered. Our main topic in this work is to study the influence of the prey's herd shape on the predator–prey interaction in the presence of Leslie–Gower term. First of all, we examine briefly the system without spatial diffusion. By analyzing the distribution of the eigenvalues associated with the constant equilibria, the local stability of the equilibrium points and the existence of Hopf bifurcation have been investigated. Then, the spatiotemporal dynamics introduced by self‐diffusion was determined, where the existence of the positive solution, Hopf bifurcation, Turing‐driven instability, and Turing–Hopf bifurcation point have been derived. Further, the effect of the prey's herd shape rate on the prey and predator equilibrium densities as well as on the Hopf bifurcating points has been discussed. Finally, by using the normal form theory on the center manifold, the direction and stability of the bifurcating periodic solutions have also been obtained. To illustrate the theoretical results, some graphical representations are given.

New evidence of a fish–bird interspecific feeding association between the European seabass and the European shag in the Mediterranean Sea

Although they have received little attention, interspecific feeding associations are a particular predation behavior in which two or more different species temporary feed simultaneously on the same food sources to obtain greater success in predation. These collaborations can be either mutualistic, commensalistic, or parasitic. One of the best-known examples is the seabird–cetacean associations. Prey herding is the foraging tactic most used in these associations and consists of swimming around and under prey balls to trap them in the water column. Here we reported some new evidence of a fish–bird interspecific feeding association between the European seabass, Dicentrarchus labrax (Linnaeus, 1758) and the European shag, Gulosus aristotelis (Linnaeus, 1761). We analyzed this association through the photograph and video documentation provided by “citizen scientists” in the Mediterranean Sea. We collected reliable proofs of this behavior, at least, in three instances from observations made by recreational fishermen in the Kvarner bay (Croatia, North Adriatic Sea). From the photographs and videos made available, we attempted to reconstruct a predation strategy adopted by these associated species to better understand the advantage this provides during hunting. Although it is not yet clear whether this association is an opportunistic behavior of the European seabass or a mutualistic strategy used by both species to improve their catching success, this feeding association seems to increase the chances to defeat prey defense strategies. Notably, some behavioral imitation of hunting strategies may be put in place by seabasses, which often feed in association with dolphins and other birds using similar prey herding strategies.

Spatiotemporal behavior in a predator–prey model with herd behavior and cross-diffusion and fear effect

In this manuscript, we investigate the fear effect on the spatiotemporal behavior of the predator–prey model with prey social behavior and cross-diffusive. Our main interest is to determine the existence of Turing patterns and the fear effect performed by predators on the prey population and the group defense. The fear can lead to a partition of the prey herd which is known as prey escaping. It is obtained that the system has rich dynamics elaborated by the presence of Turing patterns and Turing–Hopf bifurcation. The nature of Turing patterns is successfully discussed by analyzing the amplitude equations with a multiple-timescale technique. After studying the stability of these amplitude equations, it has been identified various Turing patterns driven by the cross-diffusion. Further, the effect of the fear rate or escaping rate on the behavior of the solution is discussed. The theoretical results are checked numerically.

Mathematical analysis of the influence of prey escaping from prey herd on three species fractional predator-prey interaction model

This research investigates the impact of prey herd dread from the two types of predators using a fractional-order-derivative model. The investigated model considers one type of prey next to predator and super predator. Note that the pray that exhibits herd behavior with the possibility of quitting the group due to the fear generated by the pursuit of predators, it is also considered that there is a predator consumes this prey and a super-predator consumes them both (prey and predator). This dread can be elaborated by the number of the escaped prey from the herd, which influences the evolution of the whole food chain. Our purpose is to study how this fear can affect the existence of the species, where we will discuss it in details through this paper. Indeed, it is obtained that the considered system undergoes an interesting behavior, which is elaborated by the presence of Hopf bifurcation. The obtained mathematical and ecological results are discussed numerically using a numerical scheme used for obtaining the graphical representations.

Spatiotemporal patterns induced by cross-diffusion in predator–prey model with prey herd shape effect

In this paper, we investigate a predator–prey model with herd behavior and cross-diffusion subject to the zero flux boundary conditions. First, the temporal behavior of the model has been investigated, where Hopf bifurcation has been obtained. Then, by analyzing the characteristic equation it has been proved that the cross-diffusion generate a complex dynamics such as Hopf bifurcation, Turing instability, even Turing–Hopf bifurcation. Further, the impact of the prey herd shape on the spatiotemporal patterns has been discussed. Furthermore, by computing and analyzing the normal form associated with the Turing–Hopf bifurcation point, the spatiotemporal dynamics near the Turing–Hopf bifurcation point has been discussed and also justified by some numerical simulations.

Applying the resource dispersion hypothesis to a fission-fusion society: A case study of the African lion (Panthera leo).

The relationship between the spatiotemporal distribution of resources and patterns of sociality is widely discussed. While the resource dispersion hypothesis (RDH) was formulated to explain why animals sometimes live in groups from which they derive no obvious benefits, it has also been successfully applied to species that benefit from group living. Some empirical tests have supported the RDH, but others have not, so conclusions remain equivocal and further research is required to determine the extent to which RDH predictions hold in natural systems. Here, we test four predictions of the RDH in an African lion population in the context of their fission–fusion society. We analyzed data on group composition of GPS‐collared lions and patterns of prey availability. Our results supported the first and second predictions of the RDH: Home range size (a) was independent of group size and (b) increased with distance between encounters with prey herds. Nonetheless, the third and fourth RDH predictions were not supported: (c) The measure of resource heterogeneity and (d) resource patch richness measured through prey herd size and body size had no significant effect on lion group size. However, regarding the fourth prediction, we added an adaptation to account for dynamics of fission–fusion society and found that the frequency of pride fission increased as group size increased. Our data set restricted us from going on to explore the effect of fission–fusion dynamics on the relationship between group size and patch richness. However, this should be investigated in future studies as including fission–fusion dynamics provides a more nuanced, realistic appreciation of lion society. Our study emphasizes the importance of understanding the complexity of a species' behavioral ecology within the framework of resource dispersion. Whatever larger theoretical framework may emerge to explain lion society, incorporating fission–fusion dynamics should allow the RDH to be refined and improved.

Up for grabs: prey herding by penguins facilitates shallow foraging by volant seabirds.

Visual and olfactory signals are commonly used by seabirds to locate prey in the horizontal domain, but foraging success depends on prey depth and the seabird's ability to access it. Facilitation by diving seabirds has long been hypothesized as a mechanism to elevate deep prey to regions more accessible to volant seabirds, but this has never been demonstrated empirically. Footage from animal-borne video loggers deployed on African penguins was analysed to establish if volant seabird encounters involved active cuing by seabirds on penguins to obtain prey and, during mutual prey encounters, if interactions were driven by the vertical displacement of prey by penguins. Independent of prey biomass estimates, we found a strong inverse relationship between penguin group size, a proxy for visibility, and the time elapsed from the start of penguins' dive bouts to their first encounter with other seabirds. Most mutual prey encounters (7 of 10) involved schooling prey elevated from depths greater than 33 m by penguins and only pursued by other seabird species once prey was herded into shallow waters. This is likely to enhance foraging efficiency in volant seabird species. As such, penguins may be integral to important processes that influence the structure and integrity of marine communities.

Impact of prey herd shape on the predator-prey interaction

Abstract In this paper, a delayed predator-prey model with the presence of a social behavior for the prey population has been investigated. A new functional response is obtained. We studied the effect of the herd shape for the prey population on the prey and predator equilibrium densities. The analysis of the system has been also established where the boundedness, stability, Hopf bifurcation, stability of Hopf bifurcation are obtained.

An Ecoepidemic Model with Prey Herd Behavior and Predator Feeding Saturation Response on Both Healthy and Diseased Prey

A predator-prey system is analysed where the transmissible disease can spread into the prey population. This will lead to a three-dimensional ecoepidemic model described by the temporal change of the healthy and diseased prey and the predator populations. The predator-prey interaction is modelled using the square root functional response such that the prey experience group defence: only the healthy individuals at the edge of the herd are consumed while the infected drift behind the herd. The predator feeds on both healthy and diseased prey individuals. The two prey populations are assumed substitutable so that a deficiency in one of the prey populations can be compensated by consuming the other. The resulting model for the trophic interaction is an extension of the classical Holling type II functional response for one prey population. Bifurcation analysis gives long-term dynamics of the boundary and interior equilibria, limit cycles and heteroclinic connections to saddle equilibria. The main goal is to gain insight into the effects of simultaneous predator feeding of both healthy and diseased individuals on the dynamics of the predator-prey system. With simultaneous feeding the feasibility of the system becomes smaller.

A single predator charging a herd of prey: effects of self volume and predator–prey decision-making

We study the degree of success of a single predator hunting a herd of prey on a two-dimensional square lattice landscape. We explicitly consider the self volume of the prey restraining their dynamics on the lattice. The movement of both predator and prey is chosen to include an intelligent, decision making step based on their respective sighting ranges, the radius in which they can detect the other species (prey cannot recognise each other besides the self volume interaction): after spotting each other the motion of prey and predator turns from a nearest neighbour random walk into directed escape or chase, respectively. We consider a large range of prey densities and sighting ranges and compute the mean first passage time for a predator to catch a prey as well as characterise the effective dynamics of the hunted prey. We find that the prey's sighting range dominates their life expectancy and the predator profits more from a bad eyesight of the prey than from his own good eye sight. We characterise the dynamics in terms of the mean distance between the predator and the nearest prey. It turns out that effectively the dynamics of this distance coordinate can be captured in terms of a simple Ornstein–Uhlenbeck picture. Reducing the many-body problem to a simple two-body problem by imagining predator and nearest prey to be connected by an effective Hookean bond, all features of the model such as prey density and sighting ranges merge into the effective binding constant.

Ambush and Active Search in Multistage Predator–Prey Interactions

In this paper, we study a multistage search game. The general situation is described as a predator---prey problem as follows: in a certain region there is a predator and a group of prey. The prey have h different places to go to eat, and every day the group goes to one of these places, but all the days, the herd is forced to go to a certain place, W, say to drink. Simultaneously, the predator has to select a strategy to meet the herd of prey and catch one of them, it can use its ambush strategy, which consists of going to place W, and wait there for the herd, or select a search strategy and go to one of the h different places where the herd goes to eat and search for a prey there. When predator and prey meet each other in one place, predator can catch a prey with a probability depending on the place and on the movement of the predators. Since animals require a minimum consumption of energy over time to survive, we suppose that the predator has to catch a minimum number of prey, K, over a number of days, M. We model this problem as a two-person zero-sum multistage game, which we solve in some situations by giving optimal strategies for prey and for predator and the value of the game.

Dolphin Bait-Balling Behaviors in Relation to Prey Ball Escape Behaviors

Delphinids frequently coordinate behaviors to contain or capture schooling fishes, but we know little about how these behaviors relate to prey escape behaviors, and corresponding costs and benefits. In this study, we described prey ball escape behaviors and investigated how prey ball behaviors related to dusky dolphin, Lagenorhynchus obscurus, prey herding and capturing behaviors using above-water and underwater video methods. Prey balls exhibited horizontal and vertical movements, both of which would have increased feeding costs for dolphins compared with feeding on stationary prey at the surface. The only prey ball behavior that we observed to precede escape was ‘funneling’ or the brief formation of a prey ball shape where the height was at least twice the width. Funneling was observed most often for large prey balls, immediately before they descended. When prey balls ascended, there was an insignificant trend for dolphins to do a greater proportion of herding passes that did not include a prey capture (p = 0.094), and dolphins did a larger proportion of prey-capture attempts on the sides of prey balls (p = 0.017) and a smaller proportion through the edges of prey balls (p = 0.037). When prey balls ascended, dolphins also did a smaller proportion of attempts with a dorsal body orientation (p = 0.037); there were insignificant trends for them to do a smaller proportion with a side orientation (p = 0.100) but a larger proportion with a ventral body orientation (p = 0.081). Thus, funneling is an effective behavior by which large prey balls are able to vertically escape, and dolphins may counter vertical prey escape behaviors by doing herding passes that do not include a prey-attempt, and changing location or body orientation of prey-capture behaviors.

Dolphin prey herding: Prey ball mobility relative to dolphin group and prey ball sizes, multispecies associates, and feeding duration

Dolphin prey herding: Prey ball mobility relative to dolphin group and prey ball sizes, multispecies associates, and feeding duration

Demography of the Serengeti cheetah (Acinonyx jubatus) population: the first 25 years

AbstractData are presented on the demography and reproductive success of cheetahs (Acinonyx jubatus) living on the Serengeti Plains, Tanzania over a 25‐year period. Average age at independence was 17.1 months, females gave birth to their first litter at approximately 2.4 years old, interbirth interval was 20.1 months, and average litter size at independence was 2.1 cubs. Females who survived to independence lived on average 6.2 years while minimum male average longevity was 2.8 years for those born in the study area and 5.3 years for immigrants, with a large proportion of males dispersing out of the Plains population. Females produced on average only 1.7 cubs to independence in their entire lifetime and their average reproductive rates were 0.36 cubs per year or 0.17 litters per year to independence. Variance in lifetime reproductive success in the cheetah is similar to that of other mammals.No significant negative correlations were found between adult cheetah population size and numbers of cubs reaching independence, implying that the Plains population had not reached carrying capacity. Annual numbers of adult female cheetahs only were correlated with rainfall. Adult female cheetah numbers were not correlated with adult female lion numbers on the Plains, however, reproductive rates of cheetahs were negatively correlated with the presence of lions while cheetahs had cubs. Moreover, cheetah reproductive success was lower during the period of high lion abundance (1980‐1994) than during the earlier period of relatively few lions (1969‐1979). Litter size at independence dropped from 2.5 to 2.0, lifetime reproductive success declined from 2.1 to 1.6 cubs reared to independence, and the reproductive rate (cubs/year) decreased from 0.42 to 0.36 from the earlier to the later period.Cheetah reproductive success showed little association with the presence of Thomson's gazelle at sightings except for a negative correlation between large numbers of gazelle (200±500) and reproductive success possibly because hunting success decreases with increasing prey herd size, or because cheetahs always lose in direct competition with other predators which are attracted to large congregations of prey. In addition, cheetah reproductive success was negatively correlated with the presence of Grant's gazelles (11 or more) perhaps because Grant's gazelles were more likely to occur consistently in dry areas.

A Game-theoretic Model of Predator—Prey Signaling

We develop a model of strategic predator—prey interaction in which the latter has a certain range of actions available whose cost is inversely correlated with escape ability ("quality"). Under the assumption that each herd of prey is generated by random independent draws from the whole population, we investigate the issue of whether such actions may become signals of quality in an evolutionarily stable equilibrium. Necessary and sufficient conditions for this are derived, which essentially hinge on the existence of an appropriate size (neither too wide nor too narrow) of the action range. The bounds of such range, which are parameters of our model, would reflect considerations of "surprise", characteristics of the habitat, etc, in terms of which empirical evidence may be evaluated.