| 1. |
- Alström, Per
(författare)
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Is the Soft Song of the Brownish-Flanked Bush Warbler an Aggressive Signal?
- 2013
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 119, s. 653-661
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Tidskriftsartikel (refereegranskat)abstract
- Soft songs have been detected in many songbirds, but in most species, research on soft songs has lagged behind studies of broadcast songs. In this study, we describe the acoustic features of a soft song in the brownish-flanked bush warbler Cettia fortipes. Compared with the broadcast song, the warbler's soft song was characterized by a lower minimum frequency and longer duration, and it had a higher proportion of rapid frequency modulation notes. Using playback experiments, some in combination with mounted specimens, we found different responses to soft and broadcast songs, and we found that soft song can predict aggressive escalation (attack). We conclude that the soft song is an aggressive signal in this species.
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| 2. |
- Amcoff, Mirjam, et al.
(författare)
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Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin ( Corynopoma riisei)
- 2014
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 120:5, s. 463-470
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Tidskriftsartikel (refereegranskat)abstract
- Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C.riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone-treated females showed lower stress levels compared to the control group. Furthermore, pheromone-treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.
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| 3. |
- Andersson, Malte, 1941
(författare)
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Evolution of classical polyandry: Three steps to female emancipation
- 2005
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 111:1, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- In classical polyandry, sex roles are reversed and a female reproduces with several males, each of whom raises his offspring with little or no help from her. This mating system occurs in some fishes and birds, and it is of great interest in relation to parental investment, sex role and sexual selection theory. The evolution of classical polyandry, however, is debated and not well understood. It is here suggested to generally take place in three main steps. (1) First evolves male care for eggs, for reasons that differ between fishes and birds. (2) Second, a female becomes able to lay more eggs than a male can accommodate. This can happen, for example, by evolution of male pregnancy or smaller body size, or by female production of more or larger eggs, made possible by larger female body size or more food. Polyandry in several taxa is associated with shift to a habitat rich in food during the breeding season, to novel specialised foraging methods, or to both. A favourable food situation may be crucial for evolution of classical polyandry. (3) In step three, females compete to lay two or more clutches in sequence for different males. Successful polyandrous females obtain more offspring, spreading traits that enhance success in competition over males. Step three may be most likely in species with small body size, for reasons of reproductive constraints and seasonality. Evolution of classical polyandry appears to have followed these steps in shorebirds, coucals and pipefishes, but the reasons why certain species differ from their close phylogenetic relatives in being polyandrous are far from clear. Behavioural and ecological studies of additional species, and detailed phylogenies of taxa with diverse mating systems including polyandry, are needed for testing these ideas.
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| 4. |
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| 5. |
- Benson, Scott A., et al.
(författare)
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Graded-risk sensitivity in northern European mixed-species flocks of tit and nuthatch species
- 2022
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 128:5, s. 437-442
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Tidskriftsartikel (refereegranskat)abstract
- Avian species often use anti-predator calls such that the costs and benefits of vigilance are distributed within the group. Some species respond differentially to graded risk by attending to relevant predator cues, such as head orientation and gaze direction. One benefit of graded-risk sensitivity is fewer missed foraging opportunities. It is not known how the makeup of risk response behaviors in mixed-species flocks may relate to the relative nuclearity of each species in the flock. In the current study, predator models were presented to two nuclear and two satellite species of passerines that frequently occur in natural mixed flocks. Predator models either faced toward or away from a nearby stocked feeder to simulate high and low risk of predation, and calling and seed-taking rates of the present flock were recorded. The nuclear species, great tits (Parus major) and crested tits (Lophophanes cristatus), took more seeds when the predator faced away from the feeder than toward it. The satellite species, Eurasian nuthatches (Sitta europaea) and willow tits (Poecile montanus), did not show an effect of predator orientation. No species showed consistent differences in calling behavior relative to predator orientation, although insufficient calling data for great tits prevented analysis for this species. The results of this study suggest that one aspect of nuclearity in mixed-species flocks is a tendency for graded-risk sensitivity, or alternatively, that satellite species are more sensitive to mere predator presence rather than to predator orientation cues.
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| 6. |
- Berdal Anderson, Monica, et al.
(författare)
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Innovation as part of a wider behavioural syndrome in the guppy: : Theeffect of sex and body size
- 2018
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310.
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Tidskriftsartikel (refereegranskat)abstract
- Recent work on animal personalities has shown that individuals within populations often differ consistently in various types of behaviour and that many of these behaviours correlate among individuals to form behavioural syndromes. Individuals of certain species have also been shown to differ in their rate of behavioural innovation in arriving at novel solutions to new and existing problems (e.g., mazes, novel foods). Here, we investigate whether behaviours traditionally studied in personality research are correlated with individual rates of innovation as part of a wider behavioural syndrome. Guppies (Poecilia reticulata) of both sexes from three different wild population sources were assessed: (a) exploration of an open area; (b) speed through a three‐dimensional maze; (c) investigation of a novel object; and (d) attraction to a novel food. The covariance structure (syndrome structure) was examined using structural equation modelling. The best model separated behaviours relating to activity in all contexts from rates of exploration/investigation and innovation. Innovative behaviour (utilizing new food and moving through a novel area) in these fish therefore forms part of the same syndrome as the traditional shy‐bold continuum (exploration of an open area and investigation of a novel object) found in many animal personality studies. There were no clear differences in innovation or syndrome structure between the sexes, or between the three different populations. However, body size was implicated as part of the behavioural syndrome structure, and because body size is highly correlated with age in guppies, this suggests that individual behavioural differences in personality/innovation in guppies may largely be driven by developmental state.
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| 7. |
- Bobrowicz, Katarzyna, et al.
(författare)
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Social context hinders humans but not ravens in a short-term memory task
- 2020
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Ingår i: Ethology. - : Wiley. - 1439-0310 .- 0179-1613. ; 126:2, s. 125-139
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Tidskriftsartikel (refereegranskat)abstract
- Using resources shared within a social group – either in a cooperative or a competitive way - requires keeping track of own and others’ actions, which, in turn, requires well-developed short-term memory. Although short-term memory has been tested in social mammal species, little is known about this capacity in highly social birds, such as ravens. We compared ravens (Corvus corax) with humans in spatial tasks based on caching, which required short-term memory of one’s own and of others’ actions. Human short-term memory has been most extensively tested of all social mammal species, hence providing an informative benchmark for the ravens. A recent study on another corvid species (Corvus corone) suggests their capacity to be similar to the humans’, but short-term memory skills have, to date, not been compared in a social setting. We used spatial set-ups based on caches of foods or objects, divided into individual and social conditions with two different spatial arrangements of caches (in a row or a 3x3 matrix). In each trial, a set of three up to nine caches was presented to an individual that was thereafter allowed to retrieve all items. Humans performed better on average across trials, but their performance dropped, when they had to keep track of partner’s actions. This differed in ravens, as keeping track of such actions did not impair their performance. However, both humans and ravens demonstrated more memory-related mistakes in the social than in the individual conditions. Therefore, whereas both the ravens’ and the humans’ memory suffered in the social conditions, the ravens seemed to deal better with the demands of these conditions. The social conditions had a competitive element, and one might speculate that ravens’ memory strategies are more attuned to such situations, in particular in caching contexts, than is the case for humans.
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| 8. |
- Borg, Åsa A., et al.
(författare)
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Interactions Among Female Guppies (Poecilia reticulata) Affect Growth and Reproduction
- 2012
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 118:8, s. 752-765
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Tidskriftsartikel (refereegranskat)abstract
- Competition among females over resources may have consequences for their resource budgets and thereby the resource allocation between growth and reproduction. In addition, the consequences of femalefemale interactions may differ for dominant and subordinate individuals, with the dominant ones being at an advantage. In this study, we investigated the consequences of femalefemale competition in guppies by manipulating the competitive environment of females. We found that large guppy females dominated smaller females and that interactions between females likely are costly because females exposed to competition grew less. These females compensated by growing at a higher rate when no longer subjected to competition. The higher growth rate might in turn be the cause of the reduced reproductive effort in the more competitive treatments. Furthermore, interactions were more costly for females when they were in the subordinate role than in the dominant role, because the reduction in growth and reproductive effort was highest in females exposed to larger competitors. Whether there was a differential allocation of resources into growth and reproduction depending on dominance status needs further investigation. However, in general, smaller females had a higher growth rate than larger females, independent of competitive level. We also found a negative relationship between reproduction and growth in all treatments, indicating a cost of reproduction.
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| 9. |
- Brodin, Anders, et al.
(författare)
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Memory and brain in food-storing birds: Space oddities or adaptive specializations?
- 2008
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Ingår i: Ethology. - : Wiley. - 1439-0310 .- 0179-1613. ; 114:7, s. 633-645
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Forskningsöversikt (refereegranskat)abstract
- Scatterhoarding birds that cache food items have become an important model system for the study of spatial memory and its correlates in the brain. In particular, it has been suggested that through adaptive specialization, species that cache food have better spatial memory and a relatively larger hippocampus than their non-caching relatives. Critics of this approach, dubbed neuroecology, maintain that neither of these hypotheses has been confirmed. Here, we review the evidence pertaining to a correlation between food-storing capability and the relative volume of the hippocampus. Hippocampal volume has been related to food-storing behaviour in comparisons between species, within species, or within individuals, but the evidence is not consistent. There are several possible reasons for this inconsistency, including: (1) food-hoarding birds may not always use memory for retrieval, (2) there may be systematic differences between data from North American and Eurasian species that affect the analysis, and (3) sample sizes have in many cases been too small. In addition, both the independent variable (degree of food-hoarding specialization) and the dependent variable (relative volume of the hippocampus) are not clearly and consistently defined. Alternatively, it is possible that the neuroecological hypothesis is false. Systematic empirical research is necessary to determine whether or not food-storing birds have evolved adaptive specializations in brain and cognition.
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| 10. |
- Brodin, Tomas
(författare)
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Predator hunting modes and predator-prey space games
- 2020
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 126, s. 476-485
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Tidskriftsartikel (refereegranskat)abstract
- Predators and prey are often engaged in a game where their expected fitnesses are affected by their relative spatial distributions. Game models generally predict that when predators and prey move at similar temporal and spatial scales that predators should distribute themselves to match the distribution of the prey's resources and that prey should be relatively uniformly distributed. These predictions should better apply to sit-and-pursue and sit-and-wait predators, who must anticipate the spatial distributions of their prey, than active predators that search for their prey. We test this with an experiment observing the spatial distributions and estimating the causes of movements between patches for Pacific tree frog tadpoles (Pseudacris regilla), a sit-and-pursue dragonfly larvae predator (Rhionaeschna multicolor), and an active salamander larval predator (Ambystoma tigrinum mavortium) when a single species was in the arena and when the prey was with one of the predators. We find that the sit-and-pursue predator favors patches with more of the prey's algae resources when the prey is not in the experimental arena and that the prey, when in the arena with this predator, do not favor patches with more resources. We also find that the active predator does not favor patches with more algae and that prey, when with an active predator, continue to favor these higher resource patches. These results suggest that the hunting modes of predators impact their spatial distributions and the spatial distributions of their prey, which has potential to have cascading effects on lower trophic levels.
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