The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides). III. Searching for different prey types in structurally varied habitats

1998 ◽  
Vol 76 (3) ◽  
pp. 548-555 ◽  
Author(s):  
Stephen J Mullin ◽  
Robert J Cooper ◽  
William HN Gutzke
Keyword(s):  
Prey Capture ◽  
Foraging Ecology ◽  
Structural Complexity ◽  
Prey Type ◽  
Foraging Strategies ◽  
Vegetation Density ◽  
Small Rodents ◽  
Elaphe Obsoleta ◽  
Rat Snake ◽  
Low Levels

Dietary generalists foraging for prey inhabiting different microhabitats may encounter different levels of structural complexity. We examined the effect of variation in prey type on the predation success and behaviors of the semi-arboreal gray rat snake (Elaphe obsoleta spiloides) foraging in structurally varied habitats. Individual snakes searched for contents of arboreal birds' nests or for small rodents in enclosures that simulated a bottomland hardwood forest habitat with one of five levels of vegetation density. Latency to prey capture was lower when the snakes were searching for small rodents than when they were searching for birds' nests, and lower for male snakes than for females. Generally, snakes were most successful when searching for prey in enclosures with low levels of structural complexity, and experienced decreased predation success in barren or highly complex habitats. Habitats with low levels of structural complexity may offer the snakes concealment from predation while not obscuring their perception or pursuit of prey. Of behavior durations measured in the trials, over 95% concerned 6 of the 20 behaviors described, and 3 of these occurred more often than the others, regardless of variation in the structural complexity of the habitat. Foraging gray rat snakes exhibited behaviors characteristic of active and ambush foraging strategies that increased their predation success on different prey types in the varied environments.

The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides). II. Influence of habitat structural complexity when searching for arboreal avian prey

2000 ◽  
Vol 21 (2) ◽  
pp. 211-222 ◽  
Author(s):  
Robert Cooper ◽  
Stephen Mullin
Keyword(s):  
Prey Species ◽  
Foraging Ecology ◽  
Structural Complexity ◽  
The Other ◽  
Vegetation Density ◽  
Field Site ◽  
Elaphe Obsoleta ◽  
Bird Nest ◽  
Rat Snake ◽  
Low Levels

AbstractA predator's behavior and success when foraging can be compromised by a variety of environmental factors. We examined the effect of variation in habitat structural complexity on the predatory success of the semiarboreal gray rat snake (Elaphe obsoleta spiloides) foraging for arboreal bird nest contents. Individual snakes searched for nests in enclosures containing one of five levels of vegetation density that reflected the range of structural complexity measured at a field site where predator and prey species are common. Subjects were most proficient at locating prey in enclosures having low levels of structural complexity, and experienced decreased predatory success in barren or highly-complex habitats. Ten behaviors comprised over 95% of the trial durations, and four of these occurred more often than the other six regardless of variation in structural complexity within the enclosure. We suggest that low levels of structural complexity offer snakes concealment from predation while not obscuring their view of provisioning activity at the nest.

scholarly journals Foraging Behaviour of Three Sympatric Babblers (Family: Timaliidae)

2020 ◽  
Vol 3 (2) ◽  
pp. a26-34
Author(s):  
JONATHON JULIANA ◽  
DENCY FLENNY GAWIN
Keyword(s):  
National Park ◽  
Foraging Behaviour ◽  
Foraging Ecology ◽  
Secondary Forest ◽  
Structural Complexity ◽  
Foraging Strategies ◽  
Dipterocarp Forest ◽  
Fruit Orchard ◽  
Disturbed Forest ◽  
Mixed Dipterocarp Forest

We investigated the foraging ecology of three species of babblers in Kampung Gumbang, Kampung Padang Pan and Dered Krian National Park, Bau. Vegetation in Kampung Gumbang include tall trees, shrubs and patches of kerangas. Dered Kerian National Park consists of mixed dipterocarp forest and limestone forest, which is surrounded by orchards and few villages. In Kampung Padang Pan, the vegetation is a mixed fruit orchard and secondary forest. Foraging data were obtained to compare foraging behaviour in three species. From 133 observations, suspended dead leaves was the most frequently used substrate by the three species. Stachyris maculate showed the most general foraging behavior, and it adopted probing strategy. Cyanoderma erythropterum and Mixnornis gularis obtained food items by gleaning. These three babblers utilize different foraging strategies and substrates, irrespective of their resemblances in other characteristics.  C. erythropterum and S. maculate forage mainly among dead and curled, twisted leaves in understory vegetation at significantly different heights. M. gularis forages on dead and living leaves and this species can be found abundantly in disturbed forest and plantation or farm habitats. All the three areas were observed never lacked falling leaves and structural complexity required as foraging substrates by those three babbler species. All three babblers occupy different foraging niches, and therefore interspecific competitions among themselves are minimized.

Condition-dependent foraging strategies in a coastal seabird: evidence for the rich get richer hypothesis

2018 ◽  
Vol 30 (2) ◽  
pp. 356-363 ◽  
Author(s):  
Brock Geary ◽  
Scott T Walter ◽  
Paul L Leberg ◽  
Jordan Karubian
Keyword(s):  
Individual Variation ◽  
Multiple Scales ◽  
Foraging Ecology ◽  
Population Level ◽  
Foraging Strategies ◽  
Significant Relationships ◽  
Fitness Consequences ◽  
Brown Pelicans ◽  
The Rich ◽  
Foraging Movements

Abstract The degree to which foraging individuals are able to appropriately modify their behaviors in response to dynamic environmental conditions and associated resource availability can have important fitness consequences. Despite an increasingly refined understanding of differences in foraging behavior between individuals, we still lack detailed characterizations of within-individual variation over space and time, and what factors may drive this variability. From 2014 to 2017, we used GPS transmitters and accelerometers to document foraging movements by breeding adult Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico, where the prey landscape is patchy and dynamic at various scales. Assessments of traditional foraging metrics such as trip distance, linearity, or duration did not yield significant relationships between individuals. However, we did observe lower site fidelity and less variation in energy expenditure in birds of higher body condition, despite a population-level trend of increased fidelity as the breeding season progressed. These findings suggest that high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand, consistent with a “rich get richer” scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. This work highlights the importance of considering behavioral variation at multiple scales, with particular reference to within-individual variation, to improve our understanding of foraging ecology in wild populations.

scholarly journals Subcolony Variation in Breeding Success in the Tufted Puffin (Fratercula Cirrhata): Association With Foraging Ecology and Implications

The Auk ◽  
2007 ◽  
Vol 124 (4) ◽  
pp. 1149-1157
Author(s):  
J. Mark Hipfner ◽  
Mathieu R. Charette ◽  
Gwylim S. Blackburn
Keyword(s):  
Stable Isotope ◽  
Breeding Success ◽  
Large Scale ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Egg Yolk ◽  
Foraging Strategies ◽  
Small Scale ◽  
Carbon And Nitrogen ◽  
Tufted Puffin

Abstract Large-scale oceanographic processes are the main drivers of seabird breeding success, but small-scale processes, though not as well understood, can also be important. We compared the success of Tufted Puffins (Fratercula cirrhata) breeding at two subcolonies only 1.5 km apart on Triangle Island, British Columbia, Canada, 2002–2005. In addition, we used stable-isotope analysis to test the hypothesis that parental foraging strategies differed between the two subcolonies, potentially underlying the variation in breeding success. Success was concordant across years at the two sites but, overall, Tufted Puffins bred more successfully at Strata Rock than at Puffin Rock. They raised chicks in all four years at Strata Rock, but in only three years at Puffin Rock; in two of those three years, Strata Rock chicks were, on average, 60 g and 100 g heavier than Puffin Rock chicks just before fledging. Discriminant analysis of carbon and nitrogen stable-isotope ratios in egg yolk and chick blood in 2004 and 2005 indicated that parental foraging differed between the two subcolonies, with both spatial (δ13C) and trophic-level (δ15N) differences involved. Thus, our study demonstrates the existence of foraging asymmetries in a pelagic seabird at a small spatial scale (between subcolonies), complementing patterns found at larger scales (between colonies). Moreover, the foraging asymmetries were associated with inequalities in fitness measures. We conclude that small-scale processes—in this case, systematic differences in the foraging ecology of local groups—can interact with large-scale oceanographic processes to determine seabird breeding success. Variation sous-coloniale du succès de reproduction de Fratercula cirrhata: Association avec l'écologie de la quête alimentaire et implications

scholarly journals Prey type and foraging ecology of SanderlingsCalidris albain different climate zones: are tropical areas more favourable than temperate sites?

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1125 ◽  
Author(s):  
Kirsten Grond ◽  
Yaa Ntiamoa-Baidu ◽  
Theunis Piersma ◽  
Jeroen Reneerkens
Keyword(s):  
Foraging Ecology ◽  
Prey Type ◽  
Climate Zones ◽  
Tropical Areas

scholarly journals Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density

2015 ◽  
Vol 1 (9) ◽  
pp. e1500469 ◽  
Author(s):  
Elliott Lee Hazen ◽  
Ari Seth Friedlaender ◽  
Jeremy Arthur Goldbogen
Keyword(s):  
Energy Intake ◽  
Prey Density ◽  
Prey Capture ◽  
Energy Gain ◽  
Foraging Strategies ◽  
Foraging Efficiency ◽  
Energetic Efficiency ◽  
Breath Hold ◽  
Balaenoptera Musculus ◽  
Blue Whales

Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.

Foraging ecology of the horseshoe bat, Rhinolophus megaphyllus (Rhinolophidae), in eastern Australia

2004 ◽  
Vol 31 (4) ◽  
pp. 403 ◽  
Author(s):  
Chris R. Pavey ◽  
Chris J. Burwell
Keyword(s):  
Prey Capture ◽  
Foraging Ecology ◽  
Light Trap ◽  
Foraging Strategy ◽  
Flying Insects ◽  
Open Forest ◽  
Eastern Australia ◽  
Wide Range ◽  
Horseshoe Bat ◽  
Conservation Concern

The foraging ecology of the eastern horseshoe bat, Rhinolophus megaphyllus, was examined at five sites spread along 2100 km of its Australian distribution in coastal Queensland. Foraging strategy and prey-capture behaviour of light-tagged bats were similar across sites. Bats were observed foraging during continuous flight at all sites, whereas perch hunting was observed (rarely) at only one site. Bats captured insects by aerial hawking, with a single record of gleaning. In rainforest bats spent most time close to vegetation whereas openings were favoured in open forest/woodland. Only flying insects were captured and, although a wide range of taxa was taken, Lepidoptera (all sites) and Coleoptera (all sites except one) were the primary prey. Occurrence in faeces of Lepidoptera, Coleoptera, and other taxa combined, varied across sites and across seasons, but there was no three-way interaction between taxon, site and season. Comparison of insect taxa in faeces with those captured in a light-trap set at foraging grounds indicated that insects were selectively captured by R. megaphyllus. The foraging ecology of R. megaphyllus is similar to that of other horseshoe bats in its relative stability across a large geographic range. Although the species is currently not of conservation concern in Australia, aspects of its foraging ecology suggest that it may become regionally threatened in areas with high levels of vegetation clearance.

scholarly journals Shaped to kill: The evolution of siphonophore tentilla for specialized prey capture in the open ocean

2019 ◽  
Author(s):  
Alejandro Damian-Serrano ◽  
Steven H.D. Haddock ◽  
Casey W. Dunn
Keyword(s):  
Prey Capture ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Genetic Correlations ◽  
Prey Type ◽  
Morphological Characters ◽  
Open Ocean ◽  
Food Web Structure ◽  
Dead End ◽  
Modular Structures

AbstractPredator specialization has often been considered an evolutionary ‘dead-end’ due to the constraints associated with the evolution of morphological and functional optimizations throughout the organism. However, in some predators, these changes are localized in separate structures dedicated to prey capture. One of the most extreme cases of this modularity can be observed in siphonophores, a clade of pelagic colonial cnidarians that use tentilla (tentacle side branches armed with nematocysts) exclusively for prey capture. Here we study how siphonophore specialists and generalists evolve, and what morphological changes are associated with these transitions. To answer these questions, we: (1) measured 29 morphological characters of tentacles from 45 siphonophore species, (2) mapped these data to a phylogenetic tree, and (3) analyzed the evolutionary associations between morphological characters and prey type data from the literature. Instead of a dead-end, we found that siphonophore specialists can evolve into generalists, and that specialists on one prey type have directly evolved into specialists on other prey types. Our results show that siphonophore tentillum morphology has strong evolutionary associations with prey type, and suggest that shifts between prey types are linked to shifts in the morphology, mode of evolution, and genetic correlations of tentilla and their nematocysts. The evolutionary history of siphonophore specialization helps build a broader perspective on predatory niche diversification via morphological innovation and evolution. These findings contribute to understanding how specialization and morphological evolution have shaped present-day food webs.Significance StatementPredatory specialization is often associated with the evolution of modifications in the morphology of the prey capture apparatus. Specialization has been considered an evolutionary ‘dead-end’ due to the constraints associated with these morphological changes. However, in predators like siphonophores, armed with modular structures used exclusively for prey capture, this assumption is challenged. Our results show that siphonophores can evolve generalism and new prey-type specializations by modifying the morphological states, modes of evolution, and genetic correlations between the parts of their prey capture apparatus. These findings demonstrate how studying open-ocean non-bilaterian predators can reveal novel patterns and mechanisms in the evolution of specialization. Understanding these evolutionary processes is fundamental to the study of food-web structure and complexity.

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