The dynamics of prey selection by the trap-building predator Gasteracantha hasselti

2020 ◽  
Vol 36 (3) ◽  
pp. 87-93
Author(s):  
Radek Michalko ◽  
Ondřej Košulič ◽  
Venus Saksongmuang ◽  
Prasit Wongprom ◽  
Prapinya Siripaiboon ◽  
...  
Keyword(s):  
Prey Availability ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predators ◽  
Dynamic Component ◽  
Tropical Lowland ◽  
North Eastern ◽  
Lowland Forests ◽  
Dynamic Components ◽  
Relative Selectivity

AbstractPrey selection by generalist predators can be highly dynamic depending on the prey community structure. However, the dynamics of prey selection at the stage of prey entrapping are rarely investigated in trap-building predators, probably because their traps have been previously considered to intercept mobile prey proportionally to its availability in environment. Here we investigated the dynamics of prey selection by the orb-weaving spider Gasteracantha hasselti (Araneidae) depending on the composition of the available prey in tropical lowland forests located in north-eastern Thailand. We found that Gasteracantha captured a wide variety of prey but selected, on average, mostly Coleoptera and Diptera. The selectivity of Gasteracantha’s webs for Coleoptera was constant across the changes in overall prey availability and prey composition. The web selectivity for Hemiptera decreased rapidly with increasing relative densities of Hemiptera in the environment. The selectivity for Diptera and Hymenoptera increased and decreased, respectively, with their absolute densities in the environment. The relative selectivity of Gasteracantha’s traps for a particular prey type was driven by the presence and density of the highly selected prey rather than overall prey density. The results show that the selectivity of Gasteracantha’s traps for prey had both fixed and dynamic components and the dynamic component was determined by the relative as well as absolute densities of the particular prey types in the environment.

Factors affecting spider prey selection by Sceliphron mud-dauber wasps (Hymenoptera: Sphecidae) in northern Italy

2007 ◽  
Vol 57 (1) ◽  
pp. 11-28 ◽  
Author(s):  
Matteo Federici ◽  
Carlo Polidori ◽  
Carlo Pesarini ◽  
Francesco Andrietti
Keyword(s):  
Prey Availability ◽  
Prey Selection ◽  
Northern Italy ◽  
Generalist Predators ◽  
Factors Affecting ◽  
The Family ◽  
Orb Web ◽  
Males And Females ◽  
Orb Web Spiders ◽  
Wasp Nests

AbstractPredatory habits of apoid wasps are well documented for many species, revealing a choice of prey ranging from generalist to specialised, but few studies tested the degree of specialisation when compared with the availability of prey in the environment. In a study carried out in northern Italy, nests of the mud-dauber wasps Sceliphron spirifex L. and S. caementarium Drury were collected to obtain the spider prey of the wasps, and a survey of the nesting area was performed to ascertain frequency of the available spider prey species in the environment. Wasps preyed preferably upon spiders of the family Araneidae. Adult preferred spider prey size ranged from 4 to 6 mm in length. The factor which most affected prey selection was the ecology of the spiders, with orb-web spiders being the preferred prey despite the fact that terricolous, non-web groups were the most abundant in the locality. Sex (female, male or juvenile) of prey was also important in prey selection: juvenile spiders were the most preferred even though males and females were equally and most abundant (respectively). Sceliphron spp. seem almost to be specialised rather than generalist predators. These results suggest that the terms 'generalist' or 'specialised' should not be applied to predators solely on the basis of prey collected from wasp nests, but should also be related to local prey availability.

Effect of prey availability on the abundance of White-breasted Wood-Wrens, insectivorous birds of tropical lowland forests

2014 ◽  
Vol 85 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Natalie V. Sánchez ◽  
Luis E. Vargas-Castro ◽  
Gerardo Avalos ◽  
Federico Paniagua
Keyword(s):  
Prey Availability ◽  
Insectivorous Birds ◽  
Tropical Lowland ◽  
Lowland Forests

Causes and Consequences of Monodominance in Tropical Lowland Forests

2001 ◽  
Vol 157 (2) ◽  
pp. 141
Author(s):  
Torti ◽  
Coley ◽  
Kursar
Keyword(s):  
Tropical Lowland ◽  
Lowland Forests

scholarly journals Feeding Ecology of Short-Toed Snake-Eagle (Circaetus gallicus [Gmelin, 1788]) in the Montados of Iberian Peninsula

2020 ◽  
Vol 28 (2) ◽  
pp. 155-179
Author(s):  
Nuno Onofre ◽  
Luís Sampaio
Keyword(s):  
Relative Abundance ◽  
Diet Composition ◽  
Prey Species ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predator ◽  
Important Prey ◽  
Psammodromus Algirus ◽  
Circaetus Gallicus ◽  
Water Snakes

The diet of Short-toed Snake-eagle (Circaetus gallicus) during the breeding season in an area dominated by cork and holm oak parkland forests (Montados) was analyzed in this study. As expected, results showed that snakes are the dominant prey in the diet of this eagle, comprising up to 92.5% of the identified items, if potential secondary prey species were excluded. The Montpellier Snake (Malpolon monspessulanus) was the most consumed one (42.2%), followed by the Ladder Snake (Zamenis scalaris) (28.0%), and the water snakes (Natrix spp.) (14.2%). According to the same criteria, lizards (mainly Psammodromus algirus) and mammals represent between 4.8 and 2.2%, respectively. Other animals such as pond turtle and amphibians are irregular prey (<1%), and no bird remains were found at all. Short-toed Snake-eagle is usually referred as a stenophagic predator where snakes are by far its most important prey type, and where within this taxonomic group it behaves as a generalist predator. In this study this premise was then tested comparing the relative abundance of the snake species with their proportion in the diet composition of the eagle in order to know whether or not prey selection exists with regard to the species of snakes in this region. Results point to a quite plausible "preference" for the Ladder Snake and an "avoidance" for the smooth snakes group (Macroprotodon brevis/Coronella girondica), and possibly for the Horseshoe Whip (Hemorrhois hippocrepis). The avoidance to the Horseshoe Whip must be indirect and habitat related, while in relation to the two smooth snakes it may be due in large extend to its small size, in particular.

The Comparative Feeding Ecology of Six Species of Shark and Four Species of Ray (Elasmobranchii) In The North-East Atlantic

1996 ◽  
Vol 76 (1) ◽  
pp. 89-106 ◽  
Author(s):  
J.R. Ellis ◽  
M.G. Pawson ◽  
S.E. Shackley
Keyword(s):  
Feeding Ecology ◽  
Stomach Contents ◽  
Generalist Predators ◽  
Dietary Overlap ◽  
East Atlantic ◽  
Dietary Breadth ◽  
North East ◽  
The North ◽  
North Eastern ◽  
Commercial Species

The stomach contents of ten species of elasmobranch from the north-eastern Atlantic indicate that most are generalist predators, eating a variety of polychaetes, molluscs, crustaceans and teleosts. Two species, Mustelus asterias and Squatina scjuatina were found to be specialist feeders, consuming portunid crabs and pleuronectids, respectively. Measures for both dietary breadth and dietary overlap are given and the implications of elasmobranch predation on the prey communities and on commercial species are discussed.

Managing Centrarchid Fisheries in Rivers and Streams

2019 ◽  
Keyword(s):  
Community Structure ◽  
Stable Isotope ◽  
Prey Availability ◽  
Prey Selection ◽  
Trophic Position ◽  
Trophic Niche ◽  
Smallmouth Bass ◽  
Spatial Differences ◽  
Stream Size ◽  
Diet Analyses

<em>Abstract.</em>—Prey selection and diet are highly plastic and can vary with temporal and spatial differences in competition or prey availability. This study investigated the possibility that the trophic position of Smallmouth Bass <em> Micropterus dolomieu </em>might change in response to systematic, hierarchical variation in community structure in stream networks. We hypothesized that a shift toward increased insectivory and decreased piscivory would be observed in smaller streams, resulting in a lower trophic position of Smallmouth Bass and reflecting differences in community structure and prey availability. We applied a combination of diet analyses and stable isotope methods to compare prey selection and trophic position of Smallmouth Bass across a range of stream sizes. Stable isotope analyses indicated that Smallmouth Bass trophic position was slightly elevated in smaller watersheds, contradicting our initial hypothesis. However, differences in average trophic position in watershed size categories were small (ranging from 3.6 to 3.8) and of limited ecological significance. Isotopic niche width did not vary among stream size categories, and gut content analyses revealed no differences in frequency of occurrence of fish, crayfish, or insects (larvae and adults). Collectively these results indicate that trophic position, and perhaps trophic niche, of Smallmouth Bass are consistent across hierarchical variation in stream size and habitat.

Variation in the diet of the Lataste's viper Vipera latastei in the Iberian Peninsula: seasonal, sexual and size-related effects

2007 ◽  
Vol 57 (1) ◽  
pp. 49-61 ◽  
Author(s):  
Juan Pleguezuelos ◽  
José Brito ◽  
Soumia Fahd ◽  
Xavier Santos ◽  
Gustavo Llorente ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Conservation Management ◽  
Prey Availability ◽  
Feeding Activity ◽  
Prey Type ◽  
Ontogenetic Shift ◽  
Ecological Data ◽  
Opposite Pattern ◽  
Iberian Range ◽  
Ambush Predation

AbstractSeveral life-history traits may increase vulnerability of species to extinction. Among snakes, ambush predation and dietary specialisation are factors that increase this vulnerability. European viper species, genus Vipera, display such traits and are categorised as endangered in several parts of its range. For their conservation management, a deeper knowledge of their ecology and habitat use is highly relevant. One of the species with less ecological data is the Lataste's viper Vipera latastei, a species which lives in the Iberian Peninsula and northwestern Africa. Here, we describe its diet based on the analysis of gut content of 435 museum specimens plus nine bibliographic data from the entire Iberian range. The species showed seasonal and ontogenetic shift in diet but no sexual variations. Feeding activity (percentage of vipers with prey) was low in accordance with its ambush predation tactics, being lower in spring than in summer and autumn. Prey spectrum included two main (reptiles and small mammals), and three sporadic, types of prey (arthropods, amphibians and birds). The consumption of reptiles and mammals was seasonal; the former decreased in occurrence from spring to autumn, whereas the latter showed an opposite pattern. There was an ontogenetic shift in the diet: juveniles fed mainly on reptiles and arthropods, whereas adult vipers progressively substitute this prey with insectivores, and the largest vipers primarily foraged on rodents and birds. Our results suggest that the seasonal variation in prey type was related to prey availability, whereas the ontogenetic shift was linked to gape limitation. The apparently wide prey spectrum of V. latastei must therefore be examined, taking into account that there are seasonal and ontogenetic dietary variations as well as geographic differences, the latter probably driven by climatic contrasts into the Iberian Peninsula. This new data of the endangered Iberian V. latastei can aid the effective conservation management of this species.

Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection

1985 ◽  
Vol 63 (11) ◽  
pp. 2507-2515 ◽  
Author(s):  
Robert M. R. Barclay
Keyword(s):  
Short Range ◽  
Prey Availability ◽  
Prey Selection ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Straight Line ◽  
Lasionycteris Noctivagans ◽  
Selection Of

Habitat use, temporal activity, foraging behaviour, and prey selection of hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) were studied at Delta Marsh, Manitoba. Bat activity was assessed by monitoring echolocation calls with ultrasonic detectors. Prey availability was determined using sticky and Malaise traps and dietary information was obtained from fecal analysis. Both species were active all night and foraged primarily in the lee of a narrow forested ridge. Lasionycteris noctivagans foraged in a manner that indicates that it detects and pursues prey over short distances. These bats fly slowly, are highly manoeuverable, and were commonly observed feeding on swarms of insects in small clearings. They use echolocation calls that support the notion of a short-range foraging strategy and feed opportunistically on whatever insects are available. Lasiurus cinereus, on the other hand, uses a long-range prey detection and pursuit foraging strategy. They fly rapidly along straight line paths in open areas and use echolocation calls designed to detect insects at a distance. The diet consists primarily of large insects (moths, beetles, and dragonflies), but the bats nonetheless feed opportunistically. The foraging strategy likely restricts the availability and profitability of small insects as prey.

Prey selection and food habits of three sympatric large carnivores in a tropical lowland forest of the Eastern Himalayan Biodiversity Hotspot

2013 ◽  
Vol 78 (4) ◽  
pp. 296-303 ◽  
Author(s):  
K. Muthamizh Selvan ◽  
Gopi Govindhan Veeraswami ◽  
Salvador Lyngdoh ◽  
Bilal Habib ◽  
Syed Ainul Hussain
Keyword(s):  
Food Habits ◽  
Prey Selection ◽  
Biodiversity Hotspot ◽  
Large Carnivores ◽  
Lowland Forest ◽  
Tropical Lowland ◽  
Tropical Lowland Forest

scholarly journals Land Cover and Forest Type Classification by Values of Vegetation Indices and Forest Structure of Tropical Lowland Forests in Central Vietnam

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Hung Nguyen Trong ◽  
The Dung Nguyen ◽  
Martin Kappas
Keyword(s):  
Land Cover ◽  
Vegetation Index ◽  
Forest Type ◽  
Vegetation Indices ◽  
Landsat 8 ◽  
Tropical Lowland ◽  
Central Vietnam ◽  
Lowland Forests ◽  
Type Classification ◽  
Sentinel 2

This paper aims to (i) optimize the application of multiple bands of satellite images for land cover classification by using random forest algorithms and (ii) assess correlations and regression of vegetation indices of a better-performed land cover classification image with vertical and horizontal structures of tropical lowland forests in Central Vietnam. In this study, we used Sentinel-2 and Landsat-8 to classify seven land cover classes of which three forest types were substratified as undisturbed, low disturbed, and disturbed forests where forest inventory of 90 plots, as ground-truth, was randomly sampled to measure forest tree parameters. A total of 3226 training points were sampled on seven land cover types. The performance of Landsat-8 showed out-of-bag error of 31.6%, overall accuracy of 68%, kappa of 67.5%, while Sentinel-2 showed out-of-bag error of 14.3% and overall accuracy of 85.7% and kappa of 83%. Ten vegetation indices of the better-performed image were extracted to find out (i) the correlation and regression of horizontal and vertical structures of trees and (ii) assess the variation values between ground-truthing plots and training sample plots in three forest types. The result of the t test on vegetation indices showed that six out of ten vegetation indices were significant at p<0.05. Seven vegetation indices had a correlation with the horizontal structure, but four vegetation indices, namely, Enhanced Vegetation Index, Perpendicular Vegetation Index, Difference Vegetation Index, and Transformed Normalized Difference Vegetation Index, had better correlations r = 0.66, 0.65, 0.65, 0.63 and regression results were of R2 = 0.44, 0.43, 0.43, and 0.40, respectively. The correlations of tree height were r = 0.46, 0.43, 0.43, and 0.49 and its regressions were of R2 = 0.21, 0.19, 0.18, and 0.24, respectively. The results show the possibility of using random forest algorithm with Sentinel-2 in forest type classification in line with vegetation indices application.

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