scholarly journals Survival of prey growing through gape-limited and apex predators

2019 ◽  
Author(s):  
James J. Anderson
Keyword(s):  
Mechanistic Model ◽  
Model Fit ◽  
Adult Survival ◽  
Apex Predators ◽  
Frequency Distributions ◽  
Predator Prey ◽  
Size Dependent ◽  
Predator Size ◽  
Prey Behavior ◽  
Population Recruitment

ABSTRACTA mechanistic model based on first principles of growth and predator-prey behavior introduces the effects of a predator size distribution on the survival of rapidly growing prey. The model, fit to Chinook salmon data, can explain the observed increase in ocean survival with smolt ocean entrance length using different predator size-frequency distributions. The model introduces new dimensions to theories on predator-prey interactions and population recruitment and suggests the possibility that fish recruitment control can be highly variable; sometimes dominated by juvenile growth and encounters with gape-limited predators and other times dominated by adult encounters with apex predators. Additionally, a sensitivity analysis suggests that scale and otolith circuli spacing are insensitive indicators of size-selective mortality but the profile of adult survival with juvenile length provides information on the balance of size-dependent and size-independent mortality processes.

scholarly journals Prey-predator size-dependent functional response: derivation and rescaling to the real world

2004 ◽  
Vol 73 (2) ◽  
pp. 239-252 ◽  
Author(s):  
Albashir A. Aljetlawi ◽  
Erik Sparrevik ◽  
Kjell Leonardsson
Keyword(s):  
Functional Response ◽  
Real World ◽  
The Real ◽  
Size Dependent ◽  
Predator Size

scholarly journals Reintroduced wolves and hunting limit the abundance of a subordinate apex predator in a multi-use landscape

2020 ◽  
Vol 287 (1938) ◽  
pp. 20202202
Author(s):  
L. Mark Elbroch ◽  
Jake M. Ferguson ◽  
Howard Quigley ◽  
Derek Craighead ◽  
Daniel J. Thompson ◽  
...  
Keyword(s):  
Population Model ◽  
Human Impacts ◽  
Adult Survival ◽  
Apex Predator ◽  
Vital Rates ◽  
Grey Wolf ◽  
Apex Predators ◽  
Negative Effects ◽  
Top Down ◽  
Species Abundances

Top-down effects of apex predators are modulated by human impacts on community composition and species abundances. Consequently, research supporting top-down effects of apex predators occurs almost entirely within protected areas rather than the multi-use landscapes dominating modern ecosystems. Here, we developed an integrated population model to disentangle the concurrent contributions of a reintroduced apex predator, the grey wolf, human hunting and prey abundances on vital rates and abundance of a subordinate apex predator, the puma. Increasing wolf numbers had strong negative effects on puma fecundity, and subadult and adult survival. Puma survival was also influenced by density dependence. Overall, puma dynamics in our multi-use landscape were more strongly influenced by top-down forces exhibited by a reintroduced apex predator, than by human hunting or bottom-up forces (prey abundance) subsidized by humans. Quantitatively, the average annual impact of human hunting on equilibrium puma abundance was equivalent to the effects of 20 wolves. Historically, wolves may have limited pumas across North America and dictated puma scarcity in systems lacking sufficient refugia to mitigate the effects of competition.

Further development of the Spalinger-Hobbs mechanistic foraging model for free-ranging moose

1999 ◽  
Vol 77 (10) ◽  
pp. 1505-1512 ◽  
Author(s):  
John Pastor ◽  
Katie Standke ◽  
Keith Farnsworth ◽  
Ron Moen ◽  
Yosef Cohen
Keyword(s):  
Mechanistic Model ◽  
Sequence Length ◽  
Intake Rate ◽  
Frequency Distributions ◽  
Bite Size ◽  
Bite Rate ◽  
Independent Events ◽  
Epilobium Angustifolium ◽  
Free Ranging ◽  
Further Development

Spalinger and Hobbs proposed a mechanistic model of forage intake based on the mutually exclusive actions of biting and chewing. A necessary consequence of this model is that an animal postpones the intake of more food by biting when it is processing food by chewing. In previous work, the Spalinger-Hobbs model successfully predicted short-term intake in controlled experiments. Application of the model to an entire foraging bout requires the following assumptions: (i) biting and chewing are independent events; (ii) there are no periodicities in the length of consecutive bite or chew sequences; (iii) the average bite size is constant; and (iv) the bite rate does not change with the number of bites in the sequence. To test these assumptions, we videotaped entire foraging bouts of two free-ranging moose (Alces alces) feeding on dense swards of Epilobium angustifolium in midsummer. From these videotapes, we measured the time spent biting and chewing, the rates of biting and chewing, the frequency distributions of consecutive bite and chew sequences, and lengths of E. angustifolium shoots above the point of cropping. Plant samples were collected in order to determine bite mass. A total of 1050 bites and chews were analyzed for moose 1 and 1925 bites and chews for moose 2. For both moose, three chewing events occurred, on average, for each bite event. Given this 1:3 bite:chew ratio, the frequency distributions of consecutive bite and chew sequences were as expected from a geometric distribution of independent events. There were no time-series correlations or dominating frequencies in the lengths of bite and chew sequences. These findings fulfill the first three assumptions required to extend the Spalinger-Hobbs model to entire foraging bouts. However, the fourth assumption was not fulfilled, in that time spent per bite increased asymptotically with bite-sequence length. We therefore incorporated the effect of bite-sequence length on bite rate into the Spalinger-Hobbs model. The new model predicts that to simultaneously maximize the marginal intake rate with respect to both bite rate and bite mass, a moose should take single bites most often and bite mass should be approximately 3.6 g. Eighty-two percent of bite sequences were composed of single bites for both moose, and we and others independently observed a bite size of 3.24-3.75 g for free-ranging moose. These observations lend credibility to our modified model.

Size-dependent predator?prey relationships between pikeperch and their prey fish

2007 ◽  
Vol 16 (3) ◽  
pp. 307-314 ◽  
Author(s):  
H. Dörner ◽  
S. Hülsmann ◽  
F. Hölker ◽  
C. Skov ◽  
A. Wagner
Keyword(s):  
Prey Fish ◽  
Predator Prey ◽  
Size Dependent

Predator–prey mass ratio revisited: does preference of relative prey body size depend on individual predator size?

2016 ◽  
Vol 30 (12) ◽  
pp. 1979-1987 ◽  
Author(s):  
Cheng‐Han Tsai ◽  
Chih‐hao Hsieh ◽  
Takefumi Nakazawa
Keyword(s):  
Body Size ◽  
Mass Ratio ◽  
Predator Prey ◽  
Predator Size ◽  
Prey Mass

A laboratory study of the feeding behavior of the rhabdocoel Mesostoma ehrenbergii on pond Cladocera

1982 ◽  
Vol 60 (6) ◽  
pp. 1305-1307 ◽  
Author(s):  
Steven S. Schwartz ◽  
Paul D. N. Hebert
Keyword(s):  
Feeding Behavior ◽  
Laboratory Study ◽  
Size Dependent ◽  
Prey Behavior ◽  
Cladoceran Species ◽  
Predation Rates

The predation rates of the rhabdocoel Mesostoma ehrenbergii were determined on a number of cladoceran species. Two means of capturing prey are employed by the flatworm but only active predation was explored in these experiments. It was found that this flatworm is a size-dependent predator with a preference for prey of about 1.2 mm. It was also observed that prey behavior was not an important factor in determining susceptibility to predation. M. ehrenbergii is a voracious predator; individuals consume more than 10 prey/day.

scholarly journals Using Bayesian state-space models to understand the population dynamics of the dominant malaria vector, Anopheles funestus in rural Tanzania

2022 ◽  
Author(s):  
Halfan Ngowo ◽  
Fredros Oketch Okumu ◽  
Emmanuel Elirehema Hape ◽  
Issa H Mshani ◽  
Heather M Ferguson ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
State Space ◽  
Malaria Transmission ◽  
Larval Development ◽  
Malaria Vector ◽  
Anopheles Funestus ◽  
Model Fit ◽  
Adult Survival ◽  
Series Data

Abstract Background: It is often assumed that the population dynamics of the malaria vector Anopheles funestus, its role in malaria transmission and the way it responds to interventions are similar to the more elaborately characterized An. gambiae. However, An. funestus has several unique ecological features that could generate distinct transmission dynamics and responsiveness to interventions. The objectives of this work were to develop a model which will; 1) reconstruct the population dynamics, survival, and fecundity of wild An. funestus populations in southern Tanzania, 2) quantify impacts of density dependence on the dynamics, and 3) assess seasonal fluctuations in An. funestus demography. Through quantifying the population dynamics of An. funestus, this model will enable analysis of how their stability and response to interventions may different from that of An. gambiae s.l.Methods: A Bayesian State Space Model (SSM) based on mosquito life history was fit to time series data on the abundance of female An. funestus s.s. collected over 2 years in southern Tanzania. Prior values of fitness and demography were incorporated from empirical data on larval development, adult survival and fecundity from laboratory-reared first generation progeny of wild caught An. funestus. The model was structured to allow larval and adult fitness traits to vary seasonally in response to environmental covariates (i.e. temperature and rainfall), and for density dependency in larvae. We measured the effects of density dependence and seasonality through counterfactual examination of model fit with or without these covariates.Results: The model accurately reconstructed the seasonal population dynamics of An. funestus and generated biologically-plausible values of their survival larval, development and fecundity in the wild. This model suggests that An-funestus survival and fecundity annual pattern was highly variable across the year, but did not show consistent seasonal trends either rainfall or temperature. While the model fit was somewhat improved by inclusion of density dependence, this was a relatively minor effect and suggests that this process is not as important for An. funestus as it is for An. gambiae populations.Conclusion: The model's ability to accurately reconstruct the dynamics and demography of An. funestus could potentially be useful in simulating the response of these populations to vector control techniques deployed separately or in combination. The observed and simulated dynamics also suggests that An. funestus could be playing a role in year-round malaria transmission, with any apparent seasonality attributed to other vector species.

scholarly journals Derivation of predator functional responses using a mechanistic approach in a natural system

2020 ◽  
Author(s):  
Andréanne Beardsell ◽  
Dominique Gravel ◽  
Dominique Berteaux ◽  
Gilles Gauthier ◽  
Jeanne Clermont ◽  
...  
Keyword(s):  
Functional Response ◽  
Prey Species ◽  
Mechanistic Model ◽  
Natural System ◽  
Field Observations ◽  
Functional Responses ◽  
Acquisition Rate ◽  
Predator Prey ◽  
Mechanistic Approach ◽  
Acquisition Rates

AbstractThe functional response is central to our understanding of any predator–prey system as it establishes the link between trophic levels. Most functional responses are evaluated using phenomenological models linking predator acquisition rate and prey density. However, our ability to measure functional responses using such an approach is often limited in natural systems and the use of inaccurate functions can profoundly affect the outcomes of population and community models. Here, we develop a mechanistic model based on extensive data to assess the functional response of a generalist predator, the arctic fox (Vulpes lagopus), to various tundra prey species (lemmings and the nests of geese, passerines and sandpipers). We found that predator acquisition rates derived from the mechanistic model were consistent with field observations. Although sigmoidal functional responses were previously used to model fox-prey population dynamics, none of our simulations resulted in a saturating response in all prey species. Our results highlight the importance of predator searching components in predator-prey interactions, especially predator speed, while predator acquisition rates were not limited by handling processes. By combining theory with field observations, our study provides evidences that predator acquisition rate is not systematically limited at the highest prey densities observed in a natural system. We reinforce the idea that functional response categories, typically types I, II, and III, should be considered as particular cases along a continuum. Specific functions derived with a mechanistic approach for a range of densities observed in natural communities should improve our ability to model and understand predator-prey systems.

HOW DO PARTIALLY HIDING BEHAVIOR AND COMPLETELY HIDING BEHAVIOR IMPACT INTERACTING POPULATIONS?

2020 ◽  
Vol 28 (03) ◽  
pp. 641-679
Author(s):  
ZHIHUI MA ◽  
SHUFAN WANG ◽  
HAOPENG TANG
Keyword(s):  
Sufficient Conditions ◽  
Point Of View ◽  
Predator Prey ◽  
Resource Level ◽  
Prey Behavior ◽  
Special Cases ◽  
Interacting Populations ◽  
Predator Prey Models ◽  
Negative Impacts ◽  
Hiding Behavior

As the two main behaviors of prey populations in ecological systems, the partially hiding behavior (PHB) and the completely hiding behavior (CHB) play a significant role in determining the dynamics of predator–prey models. This work examines to the dynamical consequences of predator–prey systems with the PHB and the CHB. Previous research has independently studied the two behaviors, and the general conclusions are that the two behaviors can have positive and/or negative impacts on the considered population models. However, to our knowledge, no study has combined and compared the two behaviors in studying the dynamical consequences of predation interactions. Motivated by this, we investigated the dynamical consequences induced by the PHB and the CHB. From a mathematical point of view, the dynamical behaviors are studied and the corresponding sufficient conditions are given. Our findings are general and some published models are special cases of ours. From an ecological point of view, we find that the size of the ecological regions is mainly determined by the two behaviors, and which one is ecologically beneficial for the health coexistence of the interacting populations are primarily determined by the functional response and the attack coefficient of predators. Moreover, we conclude that the evolutionary and optimal choices of prey behavior (PHB or CHB) depend on the predators attack coefficient (large or small attack coefficient) and the resource level (abundant or pool resource level).

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