Nest predators can adversely affect the viability of songbird populations, and their impact is exacerbated in fragmented habitats. Despite substantial research on this predator-prey interaction, however, almost all of the focus has been on the birds rather than their nest predators, thereby limiting our understanding of the factors that bring predators and nests into contact. We used radiotelem...

Although mercury (Hg) is a well-studied contaminant, knowledge about Hg accumulation in snakes is limited. The authors evaluated Hg bioaccumulation within and among four snake species (northern watersnakes, Nerodia sipedon; queen snakes, Regina septemvittata; common garter snakes, Thamnophis sirtalis; and rat snakes, Elaphe obsoleta [Pantherophis alleghaniensis]) from a contaminated site on the...

Snakes are active contours in the 2d image plane. Starting from an initial estimate of a curve's shape and position they move to salient image features in an iterative process driven by minimization of an energy function. The twin snakes concept is an extension to traditional snakes. Twin snakes are designed for detecting two parallel contours simultaneously and are useful for line extraction i...

SYNOPSIS. Most snakes ingest and transport their prey via a jaw ratcheting mechanism in which the left and right upper jaw arches are advanced over the prey in an alternating, unilateral fashion. This unilateral jaw ratcheting mechanism differs greatly from the hyolingual and inertial transport mechanisms used by lizards, both of which are characterized by bilaterally synchronous jaw movements....

Why humans fear snakes is an old, yet unresolved debate. Its innate origin from evolutionary causes is debated against the powerful influence early experience, culture, media and religion may have on people's aversion to snakes. Here we show that the aversion to snakes in human beings may have been mistaken for an aversion to aposematic signals that are commonly displayed by snakes. A total of ...

In this paper we propose a method for finding people and segmenting their body parts in video image sequences. We propose the use of Genetic Snakes, that are active contour models, also known as snakes, with an energy minimization procedure based on Genetic Algorithms (GA). Genetic Snakes have been proposed to overcome some limits of the classical snakes, as initialization and existence of mult...

There are 4 genera of venomous snakes in Latin America: Bothrops, Crotalus, Lachesis, and Micrurus. Acute kidney injury (AKI) has been reported consistently after Bothrops and Crotalus envenomations. In fact, these 2 genera of snakes are responsible, along with the Russell's viper, for the majority of cases of snakebite-induced AKI reported worldwide. Although the Bothrops snakes are the leadin...

Many animals move using lateral undulations, but snakes are noteworthy for using this type of locomotion in an unusual diversity of environments, including trees in which both the spacing and orientation of branches vary considerably. Despite branches providing discrete locations for snakes to generate propulsive forces during lateral undulation, the consequences of branch spacing for the locom...

Snakes are a remarkably diverse and successful group today, but their evolutionary origins are obscure. The discovery of snakes with two legs has shed light on the transition from lizards to snakes, but no snake has been described with four limbs, and the ecology of early snakes is poorly known. We describe a four-limbed snake from the Early Cretaceous (Aptian) Crato Formation of Brazil. The sn...

Animals moving through arboreal habitats face several functional challenges, including fitting onto and moving on cylindrical branches with variable diameters and inclines. In contrast to lizards and primates, the arboreal locomotion of snakes is poorly understood, despite numerous snake species being arboreal. We quantified the kinematics and performance of corn snakes (Elaphe guttata) moving ...