Foraging and scavenging behaviour of the prairie rattlesnake (Crotalus viridis): no evidence that envenomation cues facilitate kleptoparasitism of struck prey

2021 ◽  
pp. 1-11
Author(s):  
Mark S. Teshera ◽  
Rulon W. Clark ◽  
Amy E. Wagler ◽  
Eli Greenbaum
Keyword(s):  
Foraging Strategy ◽  
Viable Alternative ◽  
Search Image ◽  
Crotalus Viridis ◽  
Scent Trails ◽  
High Degree ◽  
Ambush Predators ◽  
Hunting Strategy

Abstract Most viperids are ambush predators that primarily use venom to subdue prey, employing a strike-release-trail hunting strategy whereby snakes follow the unique scent of envenomated prey to locate carcasses they have bitten and released. In addition to killing prey, rattlesnakes (like most carnivores) will also opportunistically scavenge carrion. This scavenging strategy likely includes the occasional consumption of carcasses killed by other snakes (i.e., kleptoparasitism). In areas with high densities of other pitvipers, utilizing the unique scent of animals envenomated by other snakes might be a viable alternative foraging strategy. We evaluated this possibility experimentally using a series of captive behavioural trials on prairie rattlesnakes (Crotalus viridis) to determine whether conspecific or heterospecific (C. scutulatus, C. ornatus) envenomation cues might increase the likelihood of kleptoparasitism. Rattlesnakes did not prefer envenomated prey over nonenvenomated prey, nor did they prefer venom cues of one species over another. Although they did frequently scavenge carcasses, in the absence of striking, snakes generally located carcasses using random searching movements instead of scent trails. Additionally, the amount of time rattlesnakes spent investigating carcass trails did not differ significantly among treatments, suggesting that striking, and the resultant formation of a chemical search image of prey, is more crucial to trailing behaviour than venom cues. Moreover, a high degree of behavioural variation among individuals was observed, suggesting that scavenging and kleptoparasitism in rattlesnakes is more complex than previously realized, and making generalizations about these behaviours is challenging.

Reaching, grasping and manipulation of food objects by two tree kangaroo species, Dendrolagus lumholtzi and Dendrolagus matschiei

1998 ◽  
Vol 46 (3) ◽  
pp. 235 ◽  
Author(s):  
A. N. Iwaniuk ◽  
J. E. Nelson ◽  
T. L. Ivanco ◽  
S. M. Pellis ◽  
I. Q. Whishaw
Keyword(s):  
Foraging Strategy ◽  
Manual Dexterity ◽  
Degree Of Freedom ◽  
Limb Movements ◽  
Freedom Of Movement ◽  
Food Items ◽  
Grasping And Manipulation ◽  
High Degree ◽  
Forelimb Movements ◽  
Dendrolagus Lumholtzi

This study examined manual dexterity and skilled limb movements in two species of tree kangaroos (Dendrolagus lumholtzi and D. matschiei) in order to evaluate the claim that claws are detrimental to object handling and the view that all marsupials conform to a ‘typical’ set of movements. The tree kangaroos demonstrated two main differences from previously studied species: (1) a high degree of freedom of movement of the upper forelimb; and (2) in one species (D. matschiei), some independent digital movement. The two species differed from one another in the mode of picking up food items and the type of grasp used. These differences appear to be linked to differences in feeding and foraging strategy between the two species, as well as to anatomical differences. This study indicates that marsupials do not have a common set of skilled forelimb movements and that claws do not impede prehension.

scholarly journals Foraging activity of the snail kite, Rostrhamus sociabilis (Aves: Accipitridae) in wetlands of southern Brazil

2013 ◽  
Vol 73 (2) ◽  
pp. 245-252 ◽  
Author(s):  
FB Bergmann ◽  
HLC Amaral ◽  
DP Pinto ◽  
CC Chivittz ◽  
AM Tozetti
Keyword(s):  
Habitat Heterogeneity ◽  
Prey Availability ◽  
Handling Time ◽  
Foraging Strategy ◽  
Climate Factors ◽  
American Continent ◽  
Snail Kite ◽  
Direct Observations ◽  
Rostrhamus Sociabilis ◽  
Hunting Strategy

The snail kite (Rostrhamus sociabilis) is widely distributed in the American continent. Its specialised diet consists mostly of the gastropod mollusk Pomacea sp and its foraging strategy probably varies depending on the season, prey availability, and climate factors, which can be reflected in its semi-nomad behaviour. This study was aimed at examining the hunting strategy of the snail kite, and its association with climate factors and habitat heterogeneity. Direct observations of birds between January 2010 and March 2011 in southernmost Brazil revealed that hunting was still the predominant foraging strategy (79% of records) to capture mollusks. Despite morphological specialisations to extract mollusks from the shells, the handling time (average = 92.4 s) was twice as much the time between prey search and capture (average = 55 s). The increase in the number of mollusks ingested apparently occurs when the resting time on perches or any other substrates near the hunting sites decreases between successive unsuccessful attempts. The correlation between the number of consumed preys and the climatic variables examined was low. Regarding habitat heterogeneity, our findings suggest that birds forage preferentially in marshes with low vegetation, which may increase the access to mollusks. The hunting efficiency of the snail kite was high (76 % successful attempts) compared to those of other birds of prey.

scholarly journals What’s for dinner? Diet and trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago

2018 ◽  
Author(s):  
Nitya Prakash Mohanty ◽  
John Measey
Keyword(s):  
Prey Availability ◽  
Foraging Strategy ◽  
Amphibian Species ◽  
Predator Prey ◽  
Future Studies ◽  
Hoplobatrachus Tigerinus ◽  
Body Sizes ◽  
Potential Impact ◽  
Trophic Impact ◽  
Ambush Predators

Amphibian invasions have considerable detrimental impacts on recipient ecosystems; however, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We assessed the diet of the invasive Hoplobatrachus tigerinus (n = 358), the native Limnonectes spp. (n = 375) and Fejervarya spp. (n = 65) in three sites, across four habitat types and two seasons, on the Andaman archipelago. We found a significant dietary overlap of H. tigerinus with Limnonectes spp., which may lead to competition. Small vertebrates, including several endemic species, constituted a majority of H. tigerinus diet by volume, suggesting potential impact by predation. Diets of the three species were mostly governed by the positive relationship between predator-prey body sizes. Niche breadth analyses did not indicate any significant changes in diet between seasons. Hoplobatrachus tigerinus and Fejervarya spp. chose evasive prey, suggesting that these two species are mostly ambush predators; Limnonectes spp. elected sedentary prey; although a large portion of its diet consisted of other prey types, such electivity indicates ‘active search’ as its major foraging strategy. All three species of anurans mostly consumed terrestrial prey. This intensive study on a new genus of invasive amphibian contributes to the knowledge on impacts of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We stress on the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians.

scholarly journals What’s for dinner? Diet and trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago

2018 ◽  
Author(s):  
Nitya Prakash Mohanty ◽  
John Measey
Keyword(s):  
Prey Availability ◽  
Foraging Strategy ◽  
Amphibian Species ◽  
Predator Prey ◽  
Future Studies ◽  
Hoplobatrachus Tigerinus ◽  
Body Sizes ◽  
Potential Impact ◽  
Trophic Impact ◽  
Ambush Predators

Amphibian invasions have considerable detrimental impacts on recipient ecosystems; however, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We assessed the diet of the invasive Hoplobatrachus tigerinus (n = 358), the native Limnonectes spp. (n = 375) and Fejervarya spp. (n = 65) in three sites, across four habitat types and two seasons, on the Andaman archipelago. We found a significant dietary overlap of H. tigerinus with Limnonectes spp., which may lead to competition. Small vertebrates, including several endemic species, constituted a majority of H. tigerinus diet by volume, suggesting potential impact by predation. Diets of the three species were mostly governed by the positive relationship between predator-prey body sizes. Niche breadth analyses did not indicate any significant changes in diet between seasons. Hoplobatrachus tigerinus and Fejervarya spp. chose evasive prey, suggesting that these two species are mostly ambush predators; Limnonectes spp. elected sedentary prey; although a large portion of its diet consisted of other prey types, such electivity indicates ‘active search’ as its major foraging strategy. All three species of anurans mostly consumed terrestrial prey. This intensive study on a new genus of invasive amphibian contributes to the knowledge on impacts of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We stress on the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians.

Tissue section lifting for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 86-87
Author(s):  
Adrian F. van Dellen
Keyword(s):  
Infectious Disease ◽  
Electron Microscopy ◽  
Tissue Culture ◽  
Organ System ◽  
Surrounding Tissue ◽  
Paraffin Sections ◽  
Surface Areas ◽  
Specific Determination ◽  
High Degree ◽  
Accuracy And Repeatability

The morphologic pathologist may require information on the ultrastructure of a non-specific lesion seen under the light microscope before he can make a specific determination. Such lesions, when caused by infectious disease agents, may be sparsely distributed in any organ system. Tissue culture systems, too, may only have widely dispersed foci suitable for ultrastructural study. In these situations, when only a few, small foci in large tissue areas are useful for electron microscopy, it is advantageous to employ a methodology which rapidly selects a single tissue focus that is expected to yield beneficial ultrastructural data from amongst the surrounding tissue. This is in essence what "LIFTING" accomplishes. We have developed LIFTING to a high degree of accuracy and repeatability utilizing the Microlift (Fig 1), and have successfully applied it to tissue culture monolayers, histologic paraffin sections, and tissue blocks with large surface areas that had been initially fixed for either light or electron microscopy.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Cytoplasmic Organization in the Receptor Cells of the Crista Ampullaris

1972 ◽  
Vol 30 ◽  
pp. 60-61 ◽  
Author(s):  
Robert F. Dunn
Keyword(s):  
Fine Particles ◽  
Apical Cell ◽  
Apical Region ◽  
Receptor Cells ◽  
Cuticular Plate ◽  
Morphological Organization ◽  
Crista Ampullaris ◽  
Cytoplasmic Organization ◽  
High Degree ◽  
General Appearance

Receptor cells of the cristae in the vestibular labyrinth of the bullfrog, Rana catesbiana, show a high degree of morphological organization. Four specialized regions may be distinguished: the apical region, the supranuclear region, the paranuclear region, and the basilar region.The apical region includes a single kinocilium, approximately 40 stereocilia, and many small microvilli all projecting from the apical cell surface into the lumen of the ampulla. A cuticular plate, located at the base of the stereocilia, contains filamentous attachments of the stereocilia, and has the general appearance of a homogeneous aggregation of fine particles (Fig. 1). An accumulation of mitochondria is located within the cytoplasm basal to the cuticular plate.

Computer Reconstruction of the Cellular Architecture of the Daphnia Magna Optic Ganglion

1975 ◽  
Vol 33 ◽  
pp. 284-285
Author(s):  
E. R. Macagno ◽  
C. Levinthal
Keyword(s):  
Daphnia Magna ◽  
Genetic Background ◽  
Compound Eye ◽  
Synaptic Connectivity ◽  
Serial Sections ◽  
Cross Sectional ◽  
Small Crustacean ◽  
Optic Ganglion ◽  
Structural Invariance ◽  
High Degree

The optic ganglion of Daphnia Magna, a small crustacean that reproduces parthenogenetically contains about three hundred neurons: 110 neurons in the Lamina or anterior region and about 190 neurons in the Medulla or posterior region. The ganglion lies in the midplane of the organism and shows a high degree of left-right symmetry in its structures. The Lamina neurons form the first projection of the visual output from 176 retinula cells in the compound eye. In order to answer questions about structural invariance under constant genetic background, we have begun to reconstruct in detail the morphology and synaptic connectivity of various neurons in this ganglion from electron micrographs of serial sections (1). The ganglion is sectioned in a dorso-ventra1 direction so as to minimize the cross-sectional area photographed in each section. This area is about 60 μm x 120 μm, and hence most of the ganglion fit in a single 70 mm micrograph at the lowest magnification (685x) available on our Zeiss EM9-S.

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