Does Rattling Deter? The Case of Domestic Dogs.

Although the rattling of rattlesnakes ( and ) is widely accepted as being aposematic, the hypothesis that rattling deters approach from the snake's potentially dangerous adversaries has not been well tested. In a controlled study using rattling recorded from captive rattlesnakes () and a variety of comparison sounds or no-sound controls, domestic dogs () showed no hesitation to approach camouflaged speakers projecting the recorded rattles. The dogs were equally likely to approach speakers projecting rattling as they were to approach speakers playing control sounds, or speakers that were silent.

Preferential snake detection in a simulated ecological experiment.

Objectives: According to Isbell's snake detection theory (SDT), the need to rapidly detect and thus avoid snakes had a major impact on the evolution of the primate visual system, and thus the origin and evolution of the primate lineage, as expansion of the visual sense is a key characteristic of primates. The SDT rests on the assumption that there are both cortical (conscious) and subcortical (unconscious) brain structures and pathways that are responsible for rapid visual detection of and quick avoidance reactions to snakes. Behavioral evidence for the SDT primarily comes from visual search tasks and presentations of images on a computer screen; our aim was to evaluate the SDT under more ecologically valid circumstances.

Scratching under positive and negative arousal in common marmosets (Callithrix jacchus).

Scratching has been widely used as an indicator of anxiety in many primate species. However, a handful of studies have shown no change in scratching under anxiety-provoking circumstances. In addition, the existing literature has investigated scratching only in relation to negative arousal (i.

Social learning in captive African elephants (Loxodonta africana africana).

Social learning is a more efficient method of information acquisition and application than trial and error learning and is prevalent across a variety of animal taxa. Social learning is assumed to be important for elephants, but evidence in support of that claim is mostly anecdotal. Using a herd of six adult female African bush elephants (Loxodonta africana africana) at the San Diego Zoo's Safari Park, we evaluated whether viewing a conspecific's interactions facilitated learning of a novel task.

A foraging advantage for dichromatic marmosets (Callithrix geoffroyi) at low light intensity.

Most New World monkey species have both dichromatic and trichromatic individuals present in the same population. The selective forces acting to maintain the variation are hotly debated and are relevant to the evolution of the 'routine' trichromatic colour vision found in catarrhine primates. While trichromats have a foraging advantage for red food compared with dichromats, visual tasks which dichromats perform better have received less attention.

Hand preference predicts reactions to novel foods and predators in marmosets (Callithrix geoffroyi).

In chimpanzees (Pan troglodytes) and common marmosets (Callithrix jacchus), left-handed individuals are less likely than right-handed individuals to explore new objects and situations, suggesting a relationship between the hemispheric specialization of emotional states and motor function. To further explore this relationship and to test the hypothesis that fearfulness is related to hand preference, we assessed willingness to approach, sniff, and taste novel foods, and the duration of freeze reactions in response to hawk calls, in 18 Geoffroy's marmosets (Callithrix geoffroyi). In accordance with these hypotheses, left-handed marmosets were slower to explore novel foods and slower to emerge from a freeze response than right-handed marmosets.

Following the rules: why small groups of tamarins do not reconcile conflicts.

Reconciliation is the post-conflict friendly reunion between opponents. A series of conditions and rules in order for reconciliation to take place has been recently proposed. One critical condition is that the relationship between opponents must be disrupted.

Pre-retirement predator encounters alter the morning behavior of captive marmosets (Callithrix geoffroyi).

Limited data are available on the long-term effect an encounter with a predator has on its potential prey. Anecdotal reports from field research indicate that even unsuccessful attacks by predators on callitrichids have long-lasting effects. The subjects for this study were two groups of Geoffroy's marmosets (Callithrix geoffroyi) housed outside, off exhibit, at the Center for Reproduction of Endangered Species at the San Diego Wild Animal Park.

Hawk calls elicit alarm and defensive reactions in captive Geoffroy's marmosets (Callithrix geoffroyi).

Most descriptions of callitrichid antipredator behavior have come from observations of visual encounters with predators, but there is also anecdotal evidence suggesting that callitrichids may use auditory cues associated with raptors for the early detection of potential danger. In the present study, Geoffroy's marmosets consistently reacted to the tape-recorded calls of a red-tailed hawk (Buteo jamaicensis) with high-intensity antipredator behaviors. Compared to the taped calls of a raven (Corvus corax) and the taped sound of a power drill, the hawk calls elicited more startle reactions, more alarm calls, longer freeze times, increased use of safe areas of their enclosure and greater disruption in ongoing behavior.

Evidence for a "monitoring call" in red-bellied tamarins.

In addition to a variety of calls whose functions are to increase or decrease space among individuals, many species of primates use one or more vocalizations that are emitted in no one particular context and elicit no one particular response. Although investigators have given this type of vocalization a number of different names (e.g.

Vigilance, vocalizations, and cryptic behavior at retirement in captive groups of red-bellied tamarins (Saguinus labiatus).

Frequent references are made to presumed antipredator adaptations exhibited by callitrichids, but there are very few systematic investigations of these behaviors. One set of untested presumptions stems from observations that callitrichids become especially vigilant and cryptic prior to retirement each evening. This hypothesis was tested in the current study by quantifying the rates of vocalizations and extragroup behavior at various times of the day.

Visual monitoring of threatening objects by captive tamarins (Saguinus labiatus).

Captive social groups of red-bellied tamarins (Saguinus labiatus) were observed in the presence of threatening, inanimate objects. The tamarins monitored the stimuli over the course of the 20-minute trials by conducting brief, periodic visual checks of the objects. The average number of checks per subject per trial was stable both across trials and between groups, and individual differences in rates varied relatively little around the group means.

Personality traits of adolescent pig-tailed monkeys (Macaca nemestrina): An analysis of social rank and early separation experience.

Personality ratings of ten adolescent pig-tailed macaques (Macaca nemestrina) were carried out by three experienced observers who used a simple three-point rating system. A modification of Stevenson-Hinde & Zunz's [1978] procedure, the agreement between raters on each of 21 traits was evaluated. When correlated with social rank, it was shown that dominant animals were rated as being, for example, confident, effective, and opportunistic.