ABS Lay Summeries

Revisiting translocation and reintroduction programmes: the importance of considering stress

lopierce — 2006-10-19T17:01:33Z

In this article we discuss why programmes that release animals back to the wild frequency meet with failure. Specifically, we analyse the role of stress in the fail of animal translocations and reintroductions. Our analysis shows that stress is a poorly understood phenomenon by conservation biologists; for example, few understand that the effects of stress can be accumulative or additive. While the adverse effects of stress on animal health and well-being are known, its adverse effects on important cognitive abilities, such as memory, learning and attention are relatively unknown by conservation biologists. We conclude by making a plea for a greater interchange of information between animal welfare scientists and conservation scientists.

Plasticity of worker reproductive strategies in Bombus terrestris: lessons from artificial mixed-species colonies

lopierce — 2006-10-19T16:56:44Z

In social insects, reproduction is clearly biased in favour of the queen. However, worker sterility is conditional and social-context-dependent. Under normal colony conditions the mechanism and the flexibility level of worker reproductive strategy are often masked to the researcher. We employed a system of mixed colonies of two bumblebee species, Bombus terrestris workers hosted by B. lapidarius colonies which revealed some traits of this reproductive plasticity.
The introduced B. terrestris workers were well integrated into their host B. lapidarius colony in all aspects except for reproduction. Unlike the resident B. lapidarius workers they were not inhibited by the queen and laid eggs from which B. terrestris males emerged. Moreover, workers B. terrestris in mixed species groups exhibited a completely different reproductive strategy from equivalent workers reared in queenless homospecific colonies. Instead of exhibiting a reproductive skew in favour of one or two workers, all of them developed ovaries and laid eggs, behaving as parasites in the presence of heterospecific workers. This finding suggests that the experimental paradigm of artificial mixed colonies may also provide new insights into the evolution of social parasitism in social insects.

Failure to find aversive marking of toxic foods by Norway rats

lopierce — 2006-10-19T16:49:50Z

It has long been known that rats mark foods and feeding sites that they are exploiting with residual cues that make those sites more attractive to other rats than unmarked foods and feeding sites. In the present series of experiments, we asked whether rats that had learned to avoid a food because they had become ill after eating it would mark that food in a way that caused other rats to avoid eating it. Somewhat surprisingly we found that residual cues left by rats in and around a food that they were avoiding eating, were just as attractive to other rats as cues deposited by rats that were eating the same food. Why rats do not seem to be able to signal their fellows to avoid an unprofitable potential feeding site, whereas other species can remains to be determined.

Learning, memory and predator avoidance by freshwater snails: effects of experience on predator recognition and defensive strategy

lopierce — 2006-10-19T16:46:52Z

A number of recent studies show that animals have an impressive ability to detect and avoid predators. The ability to detect predators and employ an appropriate behavioural defense may be innate or it may be learned, but for most taxa the role of experience in shaping predator avoidance behavior is not known. We assessed whether perception of predation risk and choice of defensive strategies by the snail Physa acuta is influenced by experience by performing three experiments in which we manipulated exposure to predators and then assayed behavioural responses to predator cues. Snails responded to both fish and crayfish predators, but the defensive strategy depended on prior exposure to predators, showing that learning plays some role in shaping anti-predator behavior. Overall, however, the effects of experience were small relative to the overall effects of predator cues on snail habitat use, showing that the anti-predator responses of P. acuta are largely innate.

Hiding behaviour in two cricket populations that differ in predation pressure

lopierce — 2006-10-19T16:44:21Z

Despite evidence that predators and parasites influence the evolution of songs in crickets, less is known about the influence of predators and parasites on their hiding behaviour. However, crickets differ in the amount of time spent hiding in refuges. We studied the hiding behaviour of crickets from two populations that differ in predation and parasitism. We tethered crickets overnight in both habitats and found that more crickets were eaten in Arizona than in California. We also found more parasitic flies in Arizona than in California. These flies are attracted to male songs and lay their maggots on male crickets. The maggots burrow into the crickets, feed on their tissues, and eventually kill them. In the laboratory, male Arizona crickets hid longer in a novel environment than male California crickets. Our results suggest that hiding times of crickets are shaped by natural selection acting through predation and/or parasitism.

Infanticide, sexual selection and task specialization in a biparental burying beetle

lopierce — 2006-10-19T18:32:53Z

There are few behaviors for which our perspective has changed so much as for infanticide. Although biologists today accept infanticide as adaptive, there is disagreement in many cases over the causes of infanticide. This study of burying beetles investigated two causes of infanticide, resource competition and sexual selection. When the potentially infanticidal intruder was of a different species, only resource competition was important. When the intruder was of the same species but of opposite sex there was a possibility of sexual selection as well. In sexually selected infanticide, the intruder will kill the resident’s offspring and then pair with the resident to produce a replacement brood. Where both resource competition and sexual selection were operating in burying beetles, infanticide was more common. It is hypothesized that the ability to produce a replacement brood with the intruder reduces the motivation to protect the young and leads to a higher incidence of infanticide.

Increased reliance on socially acquired information while foraging in risky situations?

lopierce — 2006-10-19T16:25:52Z

When choosing foods to eat, rats use both information they acquire as a result of their own sampling and evaluation of available alternatives and information they have acquired previously from others. Formal models (and common sense) suggest that, as potential costs of repeated sampling of alternatives for individual evaluation rises (e.g. in the presence of predators or in environments containing poison foods), dependence on socially acquired information should increase.
We looked at reliance on socially acquired information by rats choosing between two foods both when predators were either present or absent and when subjects had either learned or not learned that some foods in their environment were toxic. We did not find evidence of enhanced reliance on social learning when individual learning was risky. Rather, presence of predators decreased the choosiness of subjects and presence of poison foods had no effect on their use of socially acquired information.

Social foraging in Bufo americanus tadpoles

lopierce — 2006-10-19T16:21:25Z

Animals can find food using information from the food itself or from others that are also looking for food. Social information about food can be actively communicated or based on unavoidable by-products of feeding activities. We present three experiments that explore the relative importance of odour gradients and social information as Bufo americanus tadpoles locate food sources. In the first experiment, tadpoles quickly found food and chose the better quality of two food patches spaced 15 cm apart in the field. In a second experiment, the initial presence of tadpoles on one food patch attracted more tadpoles for a period of an hour, compared to an identical food patch without tadpoles spaced 114 cm apart. In a third experiment, the time required to initial contact with a single food patch did not change over a 16-fold range of food concentration, suggesting that B. americanus tadpoles have a limited ability to locate food from a distance using information from the food itself. However, larger groups were able to locate this resource faster, suggesting that the tadpoles were using information from others. Finding food and discriminating food patch quality from a distance is probably a major adaptive advantage of sociality in B. americanus tadpoles, although the presence or absence of active signalling remains to be determined.

Ornament colour selection, visual contrast and the shape of colour preference functions in great bowerbirds, Chlamydera nuchalis

lopierce — 2006-10-19T16:17:25Z

Male bowerbird visual signals include their own plumage, a structure they construct out of plant material, and coloured objects (ornaments) placed on or near the structure, all of which are used to attract females for mating. Ornaments on bowers are known to contrast with plumage, bower structure and visual backgrounds in seven Australian Bowerbird species. We estimated the colour preferences in a wild population of great bowerbirds (Chlamydera nuchalis) using artificially coloured objects widely spaced in bird colour space. We found that birds prefer colours which contrast with their own plumage, the bower structure, and the visual backgrounds adjacent to the bower, and that they have very strong dislikes for colours which are similar to the plumage and visual backgrounds. The range of disliked colour hues was much narrower than the range of preferred colours, suggesting that the word “preference” may be misleading. Preferences for colour are inherently multidimensional and should be studied in the context of their function.

Interpreting short-term behavioural responses to disturbance within a longitudinal perspective

lopierce — 2006-10-19T16:12:24Z

We conducted experimental vessel approaches to bottlenose dolphins in Shark Bay, Western Australia, to understand effects of vessel traffic on dolphin behaviour. We found that when the vessel was nearby, the dolphins’ swimming patterns became more erratic, their groups became more compact, and group membership was more changeable. We observed these responses in regions of both high and low vessel traffic, but dolphins living with low vessel traffic had responses that were stronger and longer lasting. The less dramatic responses of dolphins in a region of high vessel traffic would typically be taken to mean that they had become accustomed to vessel activity. However, another study – showing that dolphin-watching tourism in Shark Bay contributed to declining dolphin numbers in the region of high vessel traffic (Bejder et al. in press, Conservation Biology) – led us to conclude that we documented moderated responses to vessels because the dolphins sensitive to vessel disturbance had left the region of high vessel traffic before our study began. From this, we concluded that behavioural responses may not be reliable indicators of the effects of human disturbance on wildlife.

Synchrony, social behaviour and alliance affiliation in Indian Ocean bottlenose dolphins, Tursiops aduncus

lopierce — 2006-10-19T16:06:32Z

Male bottlenose dolphins in Shark Bay, Western Australia form complex nested alliances in competition over estrus females. Males cooperate in pairs and trios to guard and herd individual females and teams of two or more such alliances cooperate in mating competition against other alliances. A striking characteristic of male alliance behavior is synchrony; males perform elaborate synchronous displays around females and, more routinely, surface side-by-side synchronously with each other. Not surprisingly, males surface synchronously more often with members of their pair or trio than with other alliances. However, instances of synchrony between males from different but affiliating alliances are more common during group socializing, especially when males are exited around estrus females. The seamless manner in which synchronous surfacing is incorporated into the elaborate male displays suggests a signal function. For example, synchrony between males belonging to different but cooperating alliances may help reduce tension in the company of estrus females. But, whether a signal or an artifact of males swimming close together, synchrony will provide a useful tool for behavioral ecologists interested in dolphin social relationships and mating success. The possible convergence between humans and bottlenose dolphins in the evolution of complex nested male alliances and the use of synchrony in alliance behavior deserves further study.

Name that tune: call discrimination and individual recognition in Magellanic penguins

lopierce — 2006-10-19T16:02:01Z

We explored individual recognition and call discrimination in Magellanic penguins (Spheniscus magellanicus) through several playback experiments and demonstrate that both adults and chicks can discriminate between calls. We played male ecstatic display calls to incubating females and, later, their mates. Females responded more strongly to their mate’s calls than to calls of neighbours and strangers. Males, however, responded similarly to their own calls and those of neighbours and strangers. We also played mutual display calls to pair members during incubation and, later, to their unattended chicks. Adults responded more strongly to their own call than that of a stranger pair. Chicks responded more strongly to their parent’s calls than to strangers’ calls. We found several factors that correlated strongly with response strength: longer-mated females responded less strongly to their mate’s call, males responded more strongly later in the season, and chicks responded less strongly at higher temperatures.

Courtship strategies of male insects: when is learning advantageous?

lopierce — 2006-10-19T15:58:30Z

Research in the past few decades has established that insects rely heavily on learning for a variety of tasks. Recently, it has also been documented that male and female insects learn in the context of sexual behaviour. These findings challenge the traditional views that male insects are either indiscriminate or rely on genetically programmed rules for courtship. It is not intuitively clear when male insects can benefit from learning in the context of courtship. Hence we investigated the conditions favouring learning during courtship in insects by using a model that compared a learning strategy to two alternatives, indiscriminate courtship, which means courting all females encountered, and innate selectivity, implying the adoption of a fixed criterion above which females are courted. Our model identifies the settings under which learning during courtship is most likely to evolve.

Cottontop tamarin, Saguinus oedipus, alarm calls contain sufficient information for recognition of individual identity

lopierce — 2006-10-19T15:51:37Z

Many species vocalize to warn conspecifics of a predatory threat. This vocalization, called an alarm call, plays an important role in predator defense. Here we look at the cotton-top tamarin and its ability to discern changes in identity of alarm callers. If a tamarin hears the alarm calls of one individual, can it detect a change in caller identity? Is that change important? Our results indicate that cotton-top tamarins can detect that change. The alarm calls of one individual are ignored if repeated in the presence of no danger. However, if after this individual’s calls have become unreliable, a different animal alarm calls, subjects do not ignore this new individual. This suggests that these animals have the tools to recognize individuals based on their vocalizations alone. It also shows that an alarm call is not simply a signal of danger, but a signal of danger from a particular individual.

How noisy information and individual asymmetries can make ‘personality’ an adaptation: a simple model

lopierce — 2006-10-19T14:51:37Z

Individual animals sometimes differ across many different contexts of behaviour. There are individuals who behave boldly and others who behave shyly, whether in conflict over food, search for mates, or territory defense. These differences are puzzling, because in many cases it seems an individual would do better to remain entirely flexible across situations. Why should any animal display "personality"? This paper explores the logic of a model in which personality types arise because (1) there is uncertainty about which context an individual is in and (2) there are subtle differences in physical state or experience among individuals that make some situations more profitable or dangerous. As a result, the best thing to do may be to behave inflexibly and in a way that maximizes each individual's own payoffs.