scholarly journals Barking up the wrong tree: climbing performance of rat snakes and its implications for depredation of avian nests

2002 ◽  
Vol 80 (4) ◽  
pp. 591-595 ◽  
Author(s):  
Stephen J Mullin ◽  
Robert J Cooper
Keyword(s):  
Migratory Birds ◽  
Bottomland Hardwood Forest ◽  
Elaphe Obsoleta ◽  
Predator Species ◽  
Empidonax Virescens ◽  
Quercus Nuttallii ◽  
Surface Irregularities ◽  
Declining Populations ◽  
Nest Depredation ◽  
Acadian Flycatchers

Nest depredation is the leading cause of nest failure in Neotropical–Nearctic migratory birds, which are of interest because of their declining populations. In a recent study in a bottomland hardwood forest, Acadian Flycatchers (Empidonax virescens) experienced higher nest success in Nuttall oak (Quercus nuttallii), a tree species with relatively smooth bark at maturity. To determine if variation in bark-surface irregularities may influence the ability of a predator species to access the contents of avian nests, we examined the climbing abilities of rat snakes (Elaphe obsoleta) on trees having three different bark types. None of the subjects was able to ascend large Nuttall oaks in the absence of vines; with vines present, subjects still required more time to climb Nuttall oaks than to climb other species. A few of the subjects successfully climbed smaller Nuttall oaks lacking vines, but ascent time was longer and climbing behavior was modified from that observed in the other trials. Our results indicate that the likelihood of nest predation by rat snakes decreases in this forest when birds nest in trees with smooth bark and without vines. Investigators need to consider differences among nest substrates that are important to both the prey and the predator.

Male Acadian flycatchers, Empidonax virescens, obtain extrapair fertilizations with distant females

2005 ◽  
Vol 69 (4) ◽  
pp. 921-929 ◽  
Author(s):  
Bonnie E. Woolfenden ◽  
Bridget J.M. Stutchbury ◽  
Eugene S. Morton
Keyword(s):  
Empidonax Virescens ◽  
Acadian Flycatchers

scholarly journals Cues used by predators to detect freshwater turtle nests may persist late into incubation

2014 ◽  
Vol 128 (2) ◽  
pp. 179 ◽  
Author(s):  
Julia L. Riley ◽  
Jacqueline D. Litzgus
Keyword(s):  
Incubation Period ◽  
Freshwater Turtle ◽  
Predator Species ◽  
Nest Sites ◽  
Painted Turtles ◽  
Turtle Conservation ◽  
Nesting Sites ◽  
Nest Depredation ◽  
Trail Cameras ◽  
The Relationship

Previous studies have found that turtle nest depredation is concentrated immediately post-oviposition, likely because cues alerting predators to nest presence are most obvious during this time. In Algonquin Provincial Park, Ontario, we examined the frequency of nest depredation during the incubation period for Snapping Turtles (Chelydra serpentina [Linnaeus, 1758]) and Midland Painted Turtles (Chrysemys picta marginata [Agassiz, 1857]). Contrary to most past findings, nest depredation occurred throughout the incubation period for both species. In fact, 83% and 86% of depredation interactions with Snapping and Painted Turtle nests, respectively, occurred more than a week after oviposition at our study site. Peaks in nest depredation (weeks with ≥10% nest depredation) occurred late in incubation and may have coincided with hatching. Trail cameras deployed at four nesting sites revealed six predator species interacting with nests. The presence of predators at nest sites increased late in the incubation period indicating a persistence or renewal (from hatching) of cues; additional research is necessary to determine the nature of these cues. These findings have implications for both research and turtle conservation. Further research should examine the relationship between temporal changes in predator species’ density and patterns of nest depredation. Additionally, in areas where protective nest caging is used as a species recovery action, it may be important to ensure that cages remain in place throughout the incubation period until emergence of hatchlings.

scholarly journals Scale-Dependent Habitat use of Acadian FlyCatcher (Empidonax Virescens) in Central Ohio

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 368-382 ◽  
Author(s):  
Marja H. Bakermans ◽  
Amanda D. Rodewald
Keyword(s):  
Habitat Use ◽  
Vegetation Structure ◽  
Spatial Scales ◽  
Riparian Forests ◽  
Matrix Composition ◽  
Multiscale Approach ◽  
Theoretic Approach ◽  
Landscape Matrix ◽  
Empidonax Virescens ◽  
Acadian Flycatchers

Abstract We used a multiscale approach to examine use of riparian forests by Acadian Flycatchers (Empidonax virescens) at three distinct scales: microsite (nest or territory), local stand (3-ha patch of forest), and landscape (1-km-radius area). We examined the extent to which understory arthropod biomass, vegetation structure, and breeding productivity affected habitat use by Acadian Flycatchers across 36 mature riparian forests along an urbanization gradient in central Ohio, 2001–2002. Using an information-theoretic approach, we found that although vegetation structure and understory arthropod biomass were associated with nest and territory location at small spatial scales, they failed to explain habitat use across stands. Instead, percentage of urban cover in the landscape best explained variation in the abundance of Acadian Flycatchers among stands. In fact, Acadian Flycatchers were >3× more abundant in the most rural (≤1% urban) riparian forests than in the more urban (≥10% urban) riparian forests. Nest survival and productivity also declined as urban development increased within the landscape. We suggest that increased nest predation in urban riparian forests, coupled with either reduced productivity or site fidelity or both, may be an underlying mechanism of landscape-scale patterns. Results suggest that explicit consideration of multiple spatial scales, and especially landscape matrix composition, is critical for understanding habitat use. Uso del Hábitat Dependiente de la Escala por parte de Empidonax virescens en el Centro de Ohio

Trophic position scales positively with body size within but not among four species of rocky reef predators

2020 ◽  
Vol 640 ◽  
pp. 189-200 ◽  
Author(s):  
AM Olson ◽  
A Frid ◽  
JBQ dos Santos ◽  
F Juanes
Keyword(s):  
Body Size ◽  
Trophic Position ◽  
Stomach Contents ◽  
Rocky Reef ◽  
Morphometric Traits ◽  
Predator Species ◽  
Predatory Fishes ◽  
Average Size ◽  
Interspecific Comparisons ◽  
Large Predators

Intra- and interspecifically, larger-bodied predators generally occupy higher trophic positions (TPs). With widespread declines in large predators, there is a need to understand their size-based trophic roles to predict ecosystem-level responses. In British Columbia, Canada, we examined size-based trophic interactions between predatory fishes—3 rockfish species (genus Sebastes) and lingcod Ophiodon elongatus—and their prey, converting predator δ15N signatures to TP and analyzing stomach contents. Intraspecifically, TP scaled positively with predator length and gape width, but the rates of change varied by species. Interspecifically, TP did not scale positively with the observed mean sizes or known maximum sizes of species. Lingcod TP was lower than that of yelloweye and quillback rockfishes, which were 51 and 37%, respectively, smaller than lingcod. Yellowtail rockfish had the smallest average size, yet their mean TP did not differ significantly from that of lingcod. Neither species differences in some morphometric traits known to influence body size-TP relationships nor phylogenetic history explained these results. Most prey consumed were <20% of the predator’s size, which might partially explain the lack of a size-based trophic hierarchy among species. Currently, large size classes of rockfishes are being lost due to fisheries and perhaps climate-driven changes. Our findings on intraspecific size-TP relationships indicate that fishery removals of large individuals may diminish trophic structures. Interspecific comparisons of TP suggest that, along with size, species remain an important factor in understanding trophic dynamics. In addition, smaller-bodied predator species may have significant ecological roles to be considered in ecosystem-based fisheries management.

SURFACE IRREGULARITIES AS A COMPLEX SIGNAL OF TOOL REPRESENTATION TOGETHER WITH UNEVEN DISPLACEMENT IN RESPECT TO THE WORKPIECE

2014 ◽  
Vol 21 (1) ◽  
pp. 133-144 ◽  
Author(s):  
Adam Boryczko ◽  
Wojciech Rytlewski
Keyword(s):  
Machining Process ◽  
Surface Irregularity ◽  
Complex Signal ◽  
Complex Phenomenon ◽  
Tool Profile ◽  
Surface Irregularities ◽  
The Individual ◽  
Frequency Functions

Abstract In a dynamic machining process, distortion in surface irregularity is a very complex phenomenon. Surface irregularities form a periodic representation of the tool profile with various kinds of disturbance in a broad range of changes in the height and length of the profile. To discern these irregularity disturbances, interactions of the tool in the form of changes perpendicular and parallel relative to the workpiece were analyzed and simulated. The individual kinds of displacement of the tool relative to the workpiece introduce distortions in the changes of height and length. These changes are weakly represented in standard height and length irregularity parameters and their discernment has been found through amplitude-frequency functions.

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