Ecological uncertainty influences vigilance as a marker of fear

We expand on the factors that may shape the predictability of risk and the potential impacts on the links between vigilance and fear, primarily in aquatic prey communities. Uncertainty in predation risks has been shown to induce increased levels of neophobia among prey. As a result of this phenotypically plastic response, prey are faced with risk assessment cues that may vary widely in their reliability. We argue that decomposing predictability may provide useful insights into the relationship between vigilance and fear

Ecological uncertainty influences vigilance as a marker of fear

We expand on the factors that may shape the predictability of risk and the potential impacts on the links between vigilance and fear, primarily in aquatic prey communities. Uncertainty in predation risks has been shown to induce increased levels of neophobia among prey. As a result of this phenotypically plastic response, prey are faced with risk assessment cues that may vary widely in their reliability. We argue that decomposing predictability may provide useful insights into the relationship between vigilance and fear

Do rainbow trout and Atlantic salmon discriminate kin?

The purpose of this study was to determine if juvenile Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) can discriminate kin from non-kin, since other salmonid species (coho salmon (Oncorhynchus kisutch) and Arctic charr (Salvelinus alpinus)) have been shown to possess this ability. When tested in water conditioned by conspecifics (kin and non-kin) and heterospecifics in a two-choice tank, both rainbow trout and Atlantic salmon demonstrated a significant preference for kin over non-kin and heterospecifics, indicating that these species possess kin-discrimination abilities. This ability appears to be widespread among salmonid fishes

An Analysis of Masked Bobwhite Collection Locales and Habitat Characteristics

We evaluated the collecting locales of 251 masked bobwhite (Colinus virginianus ridgwayi) specimens in museum collections. Eighteen were from 4 sites in Arizona—all collected by Herbert Brown. The vast majority (93%) of specimens were from the Mexican State of Sonora. We visited and photographed each of the Arizona collection locations and most of the sites in Sonora. Collector descriptions indicate the bird’s principal habitat affiliations were with tall grass-weed (1⁄4 forb) pastures, savannas, and farm fields. All historic localities visited were either in grass-forb habitats along drainages or in present or former savannas adjacent to woody cover and/or agricultural fields between 240 and 1,060 m elevation. These sites were remarkably similar to other bobwhite habitats in subtropic-tropic South Texas and Oaxaca, Mexico. Masked bobwhite habitat was a diverse tropic-subtropic grassland within or adjacent to dense woody cover (thornscrub) and/or farmland. These habitats experienced alterations and loss of the tall grass-weed component due to livestock husbandry. Some former habitat sites appear to have recovered, however, and restoration of the subspecies might be possible if suitable stock exists. Unfortunately, this bird may now be functionally extinct

Orientation of rainbow trout (Salmo gairdneri) in normal and null magnetic fields

In the absence of distinct visual or olfactory cues, adult and juvenile rainbow trout (Salmo gairdneri) showed preferred orientation in the presence of a normal magnetic field. In contrast, fish tested in a null magnetic field showed no directed orientation. These results were obtained in both the presence and absence of a slight (12-cm/s) circular water current. These findings indicate that nonanadromous salmonids, like anadromous forms, are capable of sensing magnetic cues during certain types of spatial activity

Conspecific skin extracts elicit antipredator responses in juvenile rainbow trout (Oncorhynchus mykiss)

We investigated, under laboratory conditions, the presence of chemical alarm signals in juvenile rainbow trout (Oncorhynchus mykiss). In an initial experiment, we exposed trout to a whole-body extract from conspecifics or a distilled-water control. When exposed to whole-body extract, trout significantly (i) decreased time spent swimming, (ii) increased time taken to resume foraging, and (iii) decreased the number of food items eaten. These data indicate a significant chemically mediated antipredator response. A second experiment was conducted to determine (i) if this is a generalized response to injured fish or a specific response to injured conspecifics, and (ii) if the chemical signal is localized in the skin. We exposed juvenile trout to one of three chemical stimuli: (1) trout skin extract, (2) trout body extract, or (3) swordtail (Xiphophorus helleri) skin extract. Significant antipredator responses were observed in trout exposed to conspecific skin extract, but responses of those exposed to conspecific body extract or swordtail skin extract did not differ from those of distilled-water controls. These data strongly suggest that juvenile rainbow trout possess a chemical alarm signal, localized in the skin, that elicits antipredator behaviour when detected.by conspecifics

Visual and Chemical Prey Cues as Complementary Predator Attractants in a Tropical Stream Fish Assemblage

To date, little attention has been devoted to possible complementary effects of multiple forms of public information similar information on the foraging behaviour of predators. In order to examine how predators may incorporate multiple information sources, we conducted a series of predator attraction trials in the Lower Aripo River, Trinidad. Four combinations of visual (present or absent) and chemical cues (present or absent) from each of two prey species were presented. The occurrences of three locally abundant predatory species present within a 1 m radius of cue introduction sites were recorded. The relative attractiveness of cue type to each predator was directly related to their primary foraging modes, with visual ambush predators demonstrating an attraction to visual cues, benthivores to chemical cues, and active social foragers demonstrating complementary responses to paired cues. Predator species-pair counts were greatest in response to cues from the more abundant prey species, indicating that individuals may adopt riskier foraging strategies when presented with more familiar prey cues. These differences in predator attraction patterns demonstrate complementary effects of multiple sensory cues on the short-term habitat use and foraging behaviour of predators under fully natural conditions