Search results for "Predation"

Fishless-stream mayflies express behavioural flexibility in response to predatory fish

1996

The fish avoidance behaviour of nymphs of the grazing mayfly Baetis rhodani (Ephemerop- tera) was examined. The nymphs originated from a fishless stream. To study their responses to the addition of predator cues, nymphs were exposed to (1) chemical cues from a caged fish, or (2) a freely moving diurnal fish (European minnow, Phoxinus phoxinus). The nymphs immediately increased their refuge use when exposed to a live fish, whereas chemical cues alone did not cause any avoidance responses. In a second experiment, the eVects of (1) fish chemicals and (2) a fish model plus fish chemicals on the diel refuge use patterns of Baetis nymphs were examined. In the presence of a fish model, more nymphs…

Notes: FOOD AND PARASITES FROM TWO HOURGLASS DOLPHINS, LAGENORHYNCHUS CRUCIGER (QUOY AND GAIMARD, 1824), FROM PATAGONIAN WATERS

2003

Combining stable isotope and intestinal parasite information to evaluate dietary differences between individual ringed seals (Phoca hispida botnica)

2006

The diet and foraging behaviour of nine individual Baltic ringed seals ( Phoca hispida botnica Gmelin, 1785) in the Bothnian Bay were studied by combining results from stable isotope analyses (δ13C and δ15N) with data on intestinal parasites whose occurrence varied among the fish hosts. The patterns of infection with three acanthocephalan parasites, Corynosoma semerme (Forssell, 1904), Corynosoma magdaleni Montreuil, 1958, and Corynosoma strumosum (Rudolphi, 1802), and with a cestode larva, Schistocephalus solidus (Müller, 1776), were examined. The ringed seals become infected with these intestinal parasites by feeding on the fish hosts and hence have different parasite species and differe…

Can large branchiopods shape microcrustacean communities in Mediterranean temporary wetlands?

2011

It was recently suggested that large branchiopods may play a keystone role in temporary aquatic habitats. Using a microcosm experiment manipulating microcrustacean communities of Mediterranean temporary wetlands (Camargue, Southern France), we tested the following hypotheses: (i) large branchiopods (the notostracan Triops cancriformis and the anostracan Chirocephalus diaphanus) can limit microcrustacean densities through both competition and predation; (ii) notostracans create high suspended-matter concentrations through bioturbation, which can negatively impact microcrustaceans; and (iii) the outcome of these biotic interactions is more detrimental at high salinities. We found a strong pr…

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

2010

Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis)…

Shoaling behaviour of fish under parasitism and predation risk

2008

Shoaling is a common antipredatory adaptation in several fish species. However, parasite infections may alter shoaling behaviour of fish by impairing fish sensory/motor systems and by reducing the net benefit of shoaling. In an experimental study, we investigated whether Diplostomum spathaceum (Trematoda) eye flukes alter shoaling behaviour of rainbow trout, Oncorhynchus mykiss, and if this has an interaction with predation risk. The parasite reduces the vision of fish by inducing cataract formation, which in previous studies has been shown to alter fish escape responses and crypsis. We found that the shoals of infected fish contained fewer individuals and they divided into separate groups …

Female bank voles ( Clethrionomys glareolus ) prefer dominant males; but what if there is no choice?

1996

Both intra-sexual competition between males and female mate choice have been found to affect mating behaviour in rodents. We studied female choice in the bank vole (Clethrionomys glareolus) under circumstances where male-male competition was excluded and the female could interact and mate freely with the males. Mating behaviour was observed in two situations: (1) the female encountered two males with a clear dominance relationship; and (2) the two males were equal in their social status. In all tests where a female in postpartum oestrus had a choice between males of different social rank she mated with the dominant one. When choosing between an even pair of males there was no difference in …

Predatory behavior in the genusLeptogenys: A comparative study

1997

We studied the predatory behavior of seven species of the genusLeptogenys from Mexico and Cameroon. The ants of this genus are armed with long, thin, curved mandibles articulated at the extreme corners of the anterior margin of the head, permitting them easily to seize oniscoid isopods, the obligate or the principal prey of mostLeptogenys species. Workers hunt these prey, which are able to roll themselves up, solitarily. Foraging behavior comprises sequences of up to eight activities. The prey can be seized by the body (rolled up or not), or alternatively by the edge of the shell, then turned over and stung on the ventral face. A relationship between the mandible size of the workers and the…

WEASELS’ (MUSTELA NIVALIS NIVALIS) PREFERENCE FOR OLFACTORY CUES OF THE VOLE (CLETHRIONOMYS GLAREOLUS)

2003

Many studies on life history strategies of small mammals under predation risk are based on assumptions that mammalian predators use scent marking from prey in searching and hunting. This is especially true for small mustelids hunting in the tunnels and cavities of their prey. It is assumed that weasels use the estrous signs of female voles as hunting cues, which exposes such females to a more pronounced risk of predation. We studied the preferences of 57 least weasels (Mustela nivalis nivalis) toward odor cues from four different reproductive categories of the bank vole (Clethrionomys glareolus). In the first experiment, weasels selected clearly for vole odors over clean bedding in a Y-maze…

Why are wasps so intimidating: field experiments on hunting dragonflies (Odonata: Aeshna grandis)

2003

Abstract The mechanisms of aposematism (unprofitability of prey combined with a conspicuous signal) have mainly been studied with reference to vertebrate predators, especially birds. We investigated whether dragonflies, Aeshna grandis, avoid attacking wasps, Vespula norwegica, which are an unprofitable group of prey for most predators. As a control we used flies that were painted either black or with yellow and black stripes. The dragonflies showed greater aversion to wasps than to flies. Black-and-yellow-striped flies were avoided more than black ones, suggesting that aposematic coloration on a harmless fly provides a selective advantage against invertebrate predators. There was no signifi…