Recruitment Limitation as a Consequence of Natural Selection for Use of Restricted Feeding Habitats and Predation Risk Taking by Juvenile Fishes

1993 ◽  
Vol 50 (10) ◽  
pp. 2058-2070 ◽  
Author(s):  
Carl J. Walters ◽  
Francis Juanes
Keyword(s):  
Predation Risk ◽  
Food Availability ◽  
Spatial Scales ◽  
Food Density ◽  
Additional Time ◽  
Density Dependent ◽  
Competitive Effects ◽  
Survival And Reproduction ◽  
Time Spent Feeding ◽  
Foraging Time

Juvenile fishes generally have spatial refuges from predation, and forage in limited but risky areas near refuges. Models of food density dynamics within such limited foraging areas predict that food availability and consumption per time spent feeding should depend strongly on Juvenile density. Selection should act on the time that Juveniles spend foraging, so as to strike a balance between growth and predation risk; we predict that optimum balance will occur at foraging times proportional to the minimum needed to reach viable sizes for later survival and reproduction plus an additional time inversely proportional to the predation risk per time. Combining the food availability and optimal foraging time predictions leads to stock–recruitment patterns similar to classic Beverton–Holt and Ricker forms, depending on how food organisms respond over time. Very strong density-dependent mortality can occur even without noticeable changes in juvenile growth rates or average food densities over large spatial scales, but intraspecific competitive effects should always be evident through density-dependent changes in foraging time.

Do changes in reef habitats influence relative predation risk on the juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875)?

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 839-856 ◽  
Author(s):  
J. Hesse ◽  
J. A. Stanley ◽  
A. G. Jeffs
Keyword(s):  
Predation Risk ◽  
Spatial Scales ◽  
Spiny Lobster ◽  
Habitat Type ◽  
Small Spatial Scale ◽  
Important Species ◽  
Early Juvenile ◽  
Risk Of Predation ◽  
Jasus Edwardsii ◽  
Commercially Important

Kelp habitats are in decline in many temperate coastal regions of the world due to climate change and expansion of populations of grazing urchins. The loss of kelp habitat may influence the vulnerability to predators of the juveniles of commercially important species. In this study relative predation rates for kelp versus barren reef habitat were measured for early juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875), on the northeastern coast of New Zealand using tethering methods. Variation in assemblages of predators over small spatial scales appeared to be more important for determining the relative predation of lobsters, regardless of habitat type. Therefore, the assessment of relative predation risk to early juvenile lobsters between kelp and barren habitats will require more extensive sampling at a small spatial scale, as well as a specific focus on sampling during crepuscular and nocturnal periods when these lobsters are most at risk of predation.

Hominid carnivory and foraging strategies, and the socio-economic function of early archaeological sites

1991 ◽  
Vol 334 (1270) ◽  
pp. 211-221 ◽  
Keyword(s):  
Predation Risk ◽  
Foraging Strategies ◽  
Archaeological Sites ◽  
Olduvai Gorge ◽  
Marrow Fat ◽  
Density Dependent ◽  
Early Hominids ◽  
Competing Hypotheses ◽  
New Evidence ◽  
Economic Function

New evidence for the tissue types exploited by early hominids from carcasses possibly acquired through scavenging is derived from the larger mammal bone assemblages from FLK I, level 22 ( Zinjanthropus floor), and FLKN levels 1 and 2 from Bed I, Olduvai Gorge, Tanzania. Published skeletal part profiles from the two archaeological sites are evaluated using (i) modern observations on the sequence by which carnivores consume carcass parts in order to assess the timing of hominid access to carcasses, and (ii) measurements of flesh and marrow yields to assess the tissue types sought and acquired. These results suggest that the maximization of marrow (fat) yields, not flesh (protein) yields, was the criterion shaping decisions about carcass processing. Because of evidence for density-dependent destruction of some flesh-bearing parts by scavengers of the hominid-butchered assemblages, however, it is uncertain whether carcass parts were transported and acquired by hominids in a largely defleshed condition. The results on tissue types acquired are combined with a discussion of predation risk, feeding competition and the equipment needs of carcass processing in an attempt to identify archaeological test implications of competing hypotheses for the socio-economic function of the earliest archaeological sites.

scholarly journals Behavioural adaptations of mussels to varying levels of food availability and predation risk

2010 ◽  
Vol 76 (4) ◽  
pp. 348-353 ◽  
Author(s):  
A. A. Robson ◽  
C. Garcia De Leaniz ◽  
R. P. Wilson ◽  
L. G. Halsey
Keyword(s):  
Predation Risk ◽  
Food Availability ◽  
Behavioural Adaptations

scholarly journals Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3333
Author(s):  
Tomás Fernández ◽  
Alex Lancaster ◽  
Claudio A. Moraga ◽  
Sergio Radic-Schilling ◽  
Achaz von Hardenberg ◽  
...  
Keyword(s):  
Food Availability ◽  
Intraspecific Competition ◽  
Management Strategies ◽  
Domestic Sheep ◽  
Movement Rates ◽  
Behavioural Changes ◽  
Bite Rate ◽  
Chilean Patagonia ◽  
Potential Competitor ◽  
Time Spent Feeding

In extensive livestock production, high densities may inhibit regulation processes, maintaining high levels of intraspecific competition over time. During competition, individuals typically modify their behaviours, particularly feeding and bite rates, which can therefore be used as indicators of competition. Over eight consecutive seasons, we investigated if variation in herd density, food availability, and the presence of a potential competitor, the guanaco (Lama guanicoe), was related with behavioural changes in domestic sheep in Chilean Patagonia. Focal sampling, instantaneous scan sampling, measures of bite and movement rates were used to quantify behavioural changes in domestic sheep. We found that food availability increased time spent feeding, while herd density was associated with an increase in vigilant behaviour and a decrease in bite rate, but only when food availability was low. Guanaco presence appeared to have no impact on sheep behaviour. Our results suggest that the observed behavioural changes in domestic sheep are more likely due to intraspecific competition rather than interspecific competition. Consideration of intraspecific competition where guanaco and sheep co-graze on pastures could allow management strategies to focus on herd density, according to rangeland carrying capacity.

Interlake variation in growth and size structure of bluegill (Lepomis macrochirus): inverse analysis of an individual-based model

1998 ◽  
Vol 55 (2) ◽  
pp. 387-396 ◽  
Author(s):  
Nathan P Nibbelink ◽  
Stephen R Carpenter
Keyword(s):  
Predation Risk ◽  
Food Availability ◽  
Inverse Modeling ◽  
Habitat Structure ◽  
Size Structure ◽  
Lepomis Macrochirus ◽  
Habitat Choice ◽  
Selective Predation ◽  
Free Parameters ◽  
Contrasting Habitats

Habitat structure alters food availability and predation risk, thereby directly affecting growth, mortality, and size structure of fish populations. Size structure has often been used to infer patterns of resource abundance and predation. However, food availability and predation risk in contrasting habitats have proven difficult to measure in the field. We use an inverse modeling approach to estimate food availability and habitat choice parameters from changes in length distributions of bluegill (Lepomis macrochirus). The model suggests that dynamics of bluegill length distributions primarily reflect food availability and habitat choice. Bluegill behavior minimized effects of size-selective predation on size structure. Parameters for food availability and habitat choice were correlated. It was therefore not possible to attain unique estimates of food availability and habitat selection when both were free parameters. However, when one parameter was estimated independently, the other could be identified. In five Wisconsin lakes, seining studies were used to estimate the size at which bluegill switched from littoral to pelagic habitats. Using this measure of switch size in the model, we estimated food availability for bluegill in each lake. These estimates were positively correlated with observed growth (r2 = 0.91), demonstrating the model's ability to estimate food availability.

scholarly journals Scales of Food Availability for an Endangered Insectivore, The Hawaii Akepa

The Auk ◽  
2002 ◽  
Vol 119 (1) ◽  
pp. 166-174 ◽  
Author(s):  
J. Scott Fretz
Keyword(s):  
Food Availability ◽  
Prey Availability ◽  
Spatial Scales ◽  
Canopy Cover ◽  
Distribution Patterns ◽  
Prey Population ◽  
Suitable Habitat ◽  
Population Declines ◽  
Loxops Coccineus ◽  
A Site

Abstract The Hawaii Akepa (Loxops coccineus coccineus) is an endangered bird that has declined dramatically in the last 100 years, and is now rare or absent from many areas that appear to support suitable habitat. Food availability may play a role in these distribution patterns, but differences in food between sites may arise from different sources. I compared prey availability between a site supporting a large, stable Hawaii Akepa population, and a site from which Hawaii Akepa have declined in the last 100 years for unknown reasons. I used three spatial scales to compare food between sites to explore the basis of differences in food between sites. At a scale appropriate for comparing prey population dynamics (scale 1), I found that prey population densities are similar between sites, suggesting that introduced (or native) predators or parasitoids have not affected prey populations differently between sites. At two larger scales incorporating habitat structure, I found that food availability is much lower at the site of Hawaii Akepa declines. Differences in canopy density per square meter (scale 2), and in canopy cover per square kilometer (scale 3), result in lower food availability that may have effects on individual foraging birds as well as on potential Hawaii Akepa population density. These findings illustrate the importance of explicitly incorporating spatial scale into inquiries about food for Hawaii Akepa, and suggest that the site of population declines may not be suitable habitat with respect to food for this species.

Ecological drivers of group size in female Alpine chamois, Rupicapra rupicapra

Mammalia ◽  
2015 ◽  
Vol 79 (4) ◽  
Author(s):  
Roberta Chirichella ◽  
Andrea Mustoni ◽  
Marco Apollonio
Keyword(s):  
Predation Risk ◽  
Energy Intake ◽  
Group Size ◽  
Food Availability ◽  
Herd Size ◽  
Rupicapra Rupicapra ◽  
Trade Off ◽  
Mammalian Herbivores ◽  
Alpine Chamois

AbstractIn large mammalian herbivores, an increase in herd size not only reduces predation risk but also energy intake. As a consequence, the size of the groups made up by herbivores is often assumed to be the outcome of a trade-off depending on local predation risk and food availability. We studied Alpine chamois (

scholarly journals Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0138016 ◽  
Author(s):  
Maximilian Drakeley ◽  
Oriol Lapiedra ◽  
Jason J. Kolbe
Keyword(s):  
Risk Perception ◽  
Predation Risk ◽  
Food Density ◽  
Foraging Decisions ◽  
Conspecific Cues

scholarly journals USE OF TRACK PLATES TO QUANTIFY PREDATION RISK AT SMALL SPATIAL SCALES

2005 ◽  
Vol 86 (5) ◽  
pp. 991-996 ◽  
Author(s):  
Matthew J. Connors ◽  
Eric M. Schauber ◽  
Andrew Forbes ◽  
Clive G. Jones ◽  
Brett J. Goodwin ◽  
...  
Keyword(s):  
Predation Risk ◽  
Spatial Scales ◽  
Track Plates

scholarly journals Identification of Factors Affecting Predation Risk for Juvenile Turtles Using 3D Printed Models

Animals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 275
Author(s):  
Sasha J. Tetzlaff ◽  
Alondra Estrada ◽  
Brett A. DeGregorio ◽  
Jinelle H. Sperry
Keyword(s):  
Predation Risk ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Field Trials ◽  
Factors Affecting ◽  
Habitat Features ◽  
Terrapene Carolina ◽  
Vegetation Height ◽  
Management Actions ◽  
Box Turtles

Although it is widely accepted that juvenile turtles experience high levels of predation, such events are rarely observed, providing limited evidence regarding predator identities and how juvenile habitat selection and availability of sensory cues to predators affects predation risk. We placed three-dimensional printed models resembling juvenile box turtles (Terrapene carolina) across habitats commonly utilized by the species at three sites within their geographical range and monitored models with motion-triggered cameras. To explore how the presence or absence of visual and olfactory cues affected predator interactions with models, we employed a factorial design where models were either exposed or concealed and either did or did not have juvenile box turtle scent applied on them. Predators interacted with 18% of models during field trials. Nearly all interactions were by mesopredators (57%) and rodents (37%). Mesopredators were more likely to attack models than rodents; most (76%) attacks occurred by raccoons (Procyon lotor). Interactions by mesopredators were more likely to occur in wetlands than edges, and greater in edges than grasslands. Mesopredators were less likely to interact with models as surrounding vegetation height increased. Rodents were more likely to interact with models that were closer to woody structure and interacted with exposed models more than concealed ones, but model exposure had no effect on interactions by mesopredators. Scent treatment appeared to have no influence on interactions by either predator group. Our results suggest raccoons can pose high predation risk for juvenile turtles (although rodents could also be important predators) and habitat features at multiple spatial scales affect predator-specific predation risk. Factors affecting predation risk for juveniles are important to consider in management actions such as habitat alteration, translocation, or predator control.

Sign in / Sign up

Export Citation Format

Share Document