Is prey predation risk influenced more by increasing predator density or predator species richness in stream enclosures?

Oecologia ◽  
2004 ◽  
Vol 139 (1) ◽  
pp. 117-122 ◽  
Author(s):  
Heather D. Vance-Chalcraft ◽  
Daniel A. Soluk ◽  
Nicholas Ozburn
Keyword(s):  
Species Richness ◽  
Predation Risk ◽  
Predator Density ◽  
Predator Species

scholarly journals Interference competition pressure predicts the number of avian predators that shifted their timing of activity

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180744 ◽  
Author(s):  
Yifan Pei ◽  
Mihai Valcu ◽  
Bart Kempenaers
Keyword(s):  
Species Richness ◽  
Body Size ◽  
Interference Competition ◽  
Relative Importance ◽  
Exploitation Competition ◽  
Predator Species ◽  
Avian Predator ◽  
Avian Predators ◽  
Time Partitioning ◽  
Competition Pressure

Being active at different times facilitates the coexistence of functionally similar species. Hence, time partitioning might be induced by competition. However, the relative importance of direct interference and indirect exploitation competition on time partitioning remains unclear. The aim of this study was to investigate the relative importance of these two forms of competition on the occurrence of time-shifting among avian predator species. As a measure of interference competition pressure, we used the species richness of day-active avian predator species or of night-active avian predator species (i.e. species of Accipitriformes, Falconiformes and Strigiformes) in a particular geographical area (assemblage). As an estimate of exploitation competition pressure, we used the total species richness of avian predators in each assemblage. Estimates of the intensity of interference competition robustly predicted the number of Accipitriformes species that became crepuscular and the number of Strigiformes species that became day-active or strictly crepuscular. Interference competition pressure may depend on body size and on the total duration of the typical active period (day or night length). Our results support—to some extent—that smaller species are more likely to become time-shifters. Day length did not have an effect on the number of time-shifter species in the Accipitriformes. Among the large Strigiformes, more time-shifter species occur in areas where nights are shorter (i.e. where less of the typical time resource is available). However, in the small Strigiformes, we found the opposite, counterintuitive effect: more time-shifters where nights are longer. Exploitation competition may have had an additional positive effect on the number of time-shifters, but only in Accipitriformes, and the effect was not as robust. Our results thus support the interference competition hypothesis, suggesting that animals may have shifted their time of activity, despite phylogenetic constraints on the ability to do so, to reduce the costs of direct interactions. Our findings also highlight the influence of body size as a surrogate of competitive ability during encounters on time partitioning, at least among avian predators.

scholarly journals Reduced predator species richness drives the body gigantism of a frog species on the Zhoushan Archipelago in China

2010 ◽  
Vol 80 (1) ◽  
pp. 171-182 ◽  
Author(s):  
Yiming Li ◽  
Feng Xu ◽  
Zhongwei Guo ◽  
Xuan Liu ◽  
Changnan Jin ◽  
...  
Keyword(s):  
Species Richness ◽  
The Body ◽  
Predator Species ◽  
Frog Species ◽  
Zhoushan Archipelago

scholarly journals Association between predator species richness and human hantavirus infection emergence in Brazil

One Health ◽  
2020 ◽  
Vol 11 ◽  
pp. 100196
Author(s):  
Kyung-Duk Min ◽  
Maria Cristina Schneider ◽  
Sung-il Cho
Keyword(s):  
Species Richness ◽  
Hantavirus Infection ◽  
Predator Species

scholarly journals Testing Whether Camera Presence Influences Habitat Specific Predation Pressure on Artificial Shorebird Nests in the Arctic

ARCTIC ◽  
2021 ◽  
Vol 74 (1) ◽  
pp. 22-29
Author(s):  
Kevin G. Young ◽  
Lisa V. Kennedy ◽  
Paul A. Smith ◽  
Erica Nol
Keyword(s):  
Predation Risk ◽  
Proportional Hazards Model ◽  
Habitat Type ◽  
Cox Proportional Hazards Model ◽  
The Arctic ◽  
Arctic Fox ◽  
Artificial Nests ◽  
Predator Species ◽  
Risk Of Predation ◽  
The Impact

When monitoring the breeding ecology of birds, the causes and times of nest failure can be difficult to determine. Cameras placed near nests allow for accurate monitoring of nest fate, but their presence may increase the risk of predation by attracting predators, leading to biased results. The relative influence of cameras on nest predation risk may also depend on habitat because predator numbers or behaviour can change in response to the availability or accessibility of nests. We evaluated the impact of camera presence on the predation rate of artificial nests placed within mesic tundra habitats used by Arctic-breeding shorebirds. We deployed 94 artificial nests, half with cameras and half without, during the shorebird-nesting season of 2015 in the East Bay Migratory Bird Sanctuary, Nunavut. Artificial nests were distributed evenly across sedge meadow and supratidal habitats typically used by nesting shorebirds. We used the Cox proportional hazards model to assess differential nest survival in relation to camera presence, habitat type, placement date, and all potential interactions. Artificial nests with cameras did not experience higher predation risk than those without cameras. Predation risk of artificial nests was related to an interaction between habitat type and placement date. Nests deployed in sedge meadows and in supratidal habitats later in the season were subject to a higher risk of predation than those deployed in supratidal habitats early in the season. These differences in predation risk are likely driven by the foraging behaviour of Arctic fox (Vulpes lagopus), a species that accounted for 81% of observed predation events in this study. Arctic fox prey primarily on Arvicoline prey and goose eggs at this site and take shorebird nests opportunistically, perhaps more often later in the season when their preferred prey becomes scarcer. This study demonstrates that, at this site, cameras used for nest monitoring do not influence predation risk. Evaluating the impact of cameras on predation risk is critical prior to their use, as individual study areas may differ in terms of predator species and behaviour.

scholarly journals Wildlife-Friendly Livestock Management Promotes Mammalian Biodiversity Recovery on a Semi-Arid Karoo Farm in South Africa

2021 ◽  
Vol 2 ◽  
Author(s):  
Matthew P. E. Schurch ◽  
Jeannine McManus ◽  
Stefan Goets ◽  
Lain E. Pardo ◽  
David Gaynor ◽  
...  
Keyword(s):  
South Africa ◽  
Species Richness ◽  
Relative Abundance ◽  
Positive Impact ◽  
Mammalian Species ◽  
Biodiversity Loss ◽  
Livestock Grazing ◽  
Predator Species ◽  
Livestock Farm ◽  
Number Of Species

Agriculture is an essential production system used to feed the growing human population, but at the same time has become a major driver of biodiversity loss and environmental degradation. Employing production methods that restore degraded landscapes can have a positive impact on biodiversity, whilst improving food production. We assessed how mammalian biodiversity, specifically richness and their relative abundances varied on five Karoo farms in South Africa that had been amalgamated and subjected to a transition from traditional livestock grazing techniques (sporadic rotational grazing and lethal predator control) to wildlife-friendly non-lethal predator management, using human shepherding of livestock under a high-density short-duration grazing regime. We used camera trap data collected over a 4-year period, to measure mammalian species richness, distribution and relative abundance on the wildlife-friendly farm to investigate temporal changes throughout the conversion from traditional farming practices. In the last year of the study (2019) additional cameras were used to provide a spatial comparison of mammalian species on the wildlife-friendly farm to two neighboring farms, a traditional livestock farm using lethal predator controls, and a game farm. We found that mammalian species richness increased year on year resulting in a significant increase of 24% over the duration of the study. Herbivores showed an increase of 33% in the number of species detected over the years, while predator species increased by 8%. The relative abundance and distribution of most species also showed increases as the conversion process took place. For example, 73% of the herbivore species detected throughout the study increased in their relative abundance. Similarly, 67% of all species showed an increase in the number of sites occupied over the years. In the final year of the study the wildlife-friendly farm had more mammalian species compared to the game farm and traditional livestock farm, with the latter two sites having a similar number of species when compared to the commencement of the conversion of the wildlife-friendly site. These broad improvements in mammalian biodiversity demonstrate that livestock production can benefit local mammalian biodiversity through a combination of herder grazing management and wildlife-friendly farming.

How does stocking density affect enhancement success for hatchery-reared red king crab?

2018 ◽  
Vol 75 (11) ◽  
pp. 1940-1948 ◽  
Author(s):  
William Christopher Long ◽  
Peter A. Cummiskey ◽  
J. Eric Munk
Keyword(s):  
Predation Risk ◽  
Wild Population ◽  
Stocking Density ◽  
Mortality Rates ◽  
Red King Crab ◽  
Paralithodes Camtschaticus ◽  
Predator Density ◽  
King Crab ◽  
Crab Density ◽  
Better Than

Stock enhancement of red king crab (Paralithodes camtschaticus (Tilesius, 1815)) could increase the crab population near Kodiak, Alaska, which collapsed in the 1980s and has not recovered. We conducted a field experiment examining the effect of juvenile red king crab density on enhancement success. Hatchery-reared crabs were released in plots near Kodiak at three densities: 25, 50, and 75 m−2. Crab densities were monitored for 6 months after release. Predation risk was measured via tethering experiments and predator density via quadrat and transect surveys. Neither migration nor mortality changed with crab density, but mortality rates decreased over time. Crab density did not affect predator density or predation risk, although predation risk decreased with time. Excluding the high initial mortality rate of 67.5%, the predicted survival after 6 months was 34%, which is better than the survival observed in a wild population. This suggests that red king crab enhancement is not predation limited and can occur at high densities. Further, processes affecting juvenile red king crab may not be strongly density dependent, at least at the scales and habitats tested.

scholarly journals Trophic structure stability and extinction dynamics of beetles (Coleoptera) in tropical forest fragments

1998 ◽  
Vol 353 (1367) ◽  
pp. 437-451 ◽  
Author(s):  
R. K. Didham ◽  
J. H. Lawton ◽  
P. M. Hammond ◽  
P. Eggleton
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Tropical Forest ◽  
Forest Fragmentation ◽  
Trophic Structure ◽  
Forest Edge ◽  
Forest Fragments ◽  
Trophic Groups ◽  
Predator Species ◽  
Extinction Probabilities

A first analysis of the stability of trophic structure following tropical forest fragmentation was performed in an experimentally fragmented tropical forest landscape in Central Amazonia. A taxonomically and trophically diverse assemblage of 993 species of beetles was sampled from 920 m 2 of leaf litter at 46 sites varying in distance from forest edge and fragment area. Beetle density increased significantly towards the forest edge and showed non-linear changes with fragment area, due to the influx of numerous disturbed-area species into 10 ha and 1 ha fragments. There was a marked change in species composition with both decreasing distance from forest edge and decreasing fragment area, but surprisingly this change in composition was not accompanied by a change in species richness. Rarefied species richness did not vary significantly across any of the sites, indicating that local extinctions of deep forest species were balanced by equivalent colonization rates of disturbed-area species. The change in species composition with fragmentation was non-random across trophic groups. Proportions of predator species and xylophage species changed significantly with distance from forest edge, but no area-dependent changes in proportions of species in trophic groups were observed. Trophic structure was also analysed with respect to proportions of abundance in six trophic groups. Proportions of abundance of all trophic groups except xylomycetophages changed markedly with respect to both distance from forest edge and fragment area. Local extinction probabilities calculated for individual beetle species supported theoretical predictions of the differential susceptibility of higher trophic levels to extinction, and of changes in trophic structure following forest fragmentation. To reduce random effects due to sampling error, only abundant species ( n ≥ 46) were analysed for extinction probabilities, as defined by absence from samples. Of these common species, 27% had significantly higher probabilities of local extinction following fragmentation. The majority of these species were predators; 42% of all abundant predator species were significantly more likely to be absent from samples in forest fragments than in undisturbed forest. These figures are regarded as minimum estimates for the entire beetle assemblage because rarer species will inevitably have higher extinction probabilities. Absolute loss of biodiversity will affect ecosystem process rates, but the differential loss of species from trophic groups will have an even greater destabilizing effect on food web structure and ecosystem function.

scholarly journals Host manipulation as a parasite transmission strategy when manipulation is exploited by non-host predators

2008 ◽  
Vol 4 (6) ◽  
pp. 663-666 ◽  
Author(s):  
Otto Seppälä ◽  
Jukka Jokela
Keyword(s):  
Predation Risk ◽  
Transmission Probability ◽  
Parasite Transmission ◽  
Host Manipulation ◽  
Predator Species ◽  
Transmission Strategy ◽  
Adaptive Value ◽  
Parasite Populations ◽  
Manipulation Strategy ◽  
Increased Susceptibility

Trophically transmitted parasites often alter their intermediate host's phenotype, thereby predisposing hosts to increased predation. This is generally considered to be a parasite strategy evolved to enhance transmission to the next host. However, the adaptive value of host manipulation is not clear, as it may be associated with costs, such as increased susceptibility to predator species that are unsuitable next hosts for the parasites. Thus, it has been proposed that, to be adaptive, manipulation should be specific by predisposing hosts more strongly to predation by target hosts (next host in the life cycle) than to non-hosts. Here we formally evaluate this prediction, and show that manipulation does not have to be specific to be adaptive. However, when manipulation is nonspecific, it needs to effectively increase the overall predation risk of infected hosts if it is to increase the parasite transmission probability. Thus, when initial predation risk is low, even highly nonspecific manipulation strategies can be adaptive. However, when initial predation risk is high, manipulation needs to be more specific to increase parasite transmission success. Therefore, nonspecific host manipulation may evolve in nature, but the adaptive value of a certain manipulation strategy can vary among different parasite populations depending on the variation in initial predation risk.

Vulnerability To Predation in Baboon Populations

Behaviour ◽  
1994 ◽  
Vol 131 (3-4) ◽  
pp. 293-304 ◽  
Author(s):  
Guy Cowlishaw
Keyword(s):  
Predation Risk ◽  
Prey Capture ◽  
Prey Selection ◽  
Predator Species ◽  
Sleeping Sites

AbstractThis study investigates patterns of predation in Papio baboon populations across Africa. Using anecdotal reports collated from the primate and predator literature, the following analyses are conducted. First, the primary predators of baboons are identified. These are shown to be the terrestrial carnivores; in order of importance leopards, lions and hyena. Second, patterns of large felid predation on baboons are investigated in detail. In terms of prey selection, leopards are more likely to take (1) adults than juveniles and (2) males than females. While lion attacks are strictly diurnal, leopards will attack during both the day and night. However, both predators are usually limited to conducting attacks when and/or where visibility is limited. Leopards were about twice as successful as lions at hunting baboons. Nocturnal leopard hunts were more successful than diurnal hunts when twilight cases were excluded; in relation to this, leopard attacks at sleeping sites were more likely to end in prey capture than attacks at waterholes. Finally, patterns of baboon retaliation against predators revealed that males are more likely to retaliate than females and that such behaviour effectively deters predators. Males are particularly aggressive towards leopards, where in 4/11 cases the leopard was killed. These results may help to resolve a number of outstanding controversies regarding the nature of predation risk in baboons, indicating that diurnal predation is a substantial threat, that males are effective at deterring several predator species, particularly leopards, and that predators will successfully attack and capture males.

Sign in / Sign up

Export Citation Format

Share Document