We know that animals differ in their behavior. What we do not know is why the study of animal personalities is apparently the only way by which we can understand individual differences among animals. We argue that the field of animal personality does not add anything new. Instead, it appears to be a rebranding of much more rigorous fields of research.

Changes in space and group size for water striders (aquatic bugs) induced striking, reversible changes in mating behaviors within days or even hours. In large groups, no male could dominate the rest. Instead, males harassed females, drove them into hiding, mated frequently, and typically guarded females for several hours after mating. In contrast, in small groups, an alpha male often emerged, driving other males into hiding, mating only occasionally, and rarely harassing or guarding females.

Parasitoid wasps need to measure time to optimize their behavior. Using training with odors, we demonstrated that they are able to measure the time between host encounters. They will fly to the odor associated to the interval of time they just experienced. The way by which they measure time appears to be at least in part through activity during the waiting period. Indeed, restraining movement appears to prevent them from measuring time.

Bird parents that share incubation coordinate their shifts to never leave the eggs alone for too long. In the wild zebra finch, parents produce vocal duets each time they meet at the nest. We measured the acoustic structure of these duets and showed that birds call differently before leaving or staying in the nest. Thus, bird parents may communicate to organize parental care.

We use comparative information on carnivores and bear subspecies to investigate coloration of the giant panda. We find that white fur on the body is for matching white snowy backgrounds, black fur on legs is for camouflage in shade, but that markings on the face are for communication to other pandas or to would-be predators. The giant panda’s extrordinary pelage coloration has several different functions.

To evolve and respond to natural selection behavioural traits must have a genetic component. Quantifying the genetic component of behaviour can thus reveal its evolutionary significance. In a cooperative breeder, we tested if behavioural traits were consistent, heritable and correlated. We found that our measures of exploratory behaviour were consistent and correlated, and that novel environment exploration, was heritable. This behaviour therefore has the greatest capacity to evolve in response to a changing environment.

Many mating signals are multimodal, combining elements that stimulate different sensory systems. How do these different elements affect female choice? We asked female brown headed cowbirds which combinations of male song and visual display they most preferred. We found that the intensity of movement in the visual display can change the female’s ranking of a song. Selection may then favor males that possess a range of different types of songs and visual displays.

Density-dependent differences between dispersing and non-dispersing birds in mass and fledging success were observed in control but not food-supplemented nests. Density-dependent differences in oxidative state were however not altered by the supplementation. Our results support the hypothesis that food availability is responsible for some of the density-dependent differences previously observed in this natural population between dispersing and non-dispersing individuals but other mechanisms are also involved in these differences.

Grasshoppers increase their camouflage when it matters more. Azure Sand Grasshoppers can change their colour so it matches the environment, just like chameleons, only by different means and therefore more slowly. When exposed to a greater risk of predation, they improve their colour match even more, as was known for fast colour changers. This shows that fast and slow colour changers are not that different, apart from how, and how fast, they change.

Many animals possess conspicuous traits that appear to be nonfunctional for survivorship but are used in communication. Such traits often provide information about the quality of the possessors to others. However, although empirical studies have found many signal traits that are associated with individual quality, the underlying mechanisms remain to be understood. In this study, we showed that high-quality individuals could produce colourful plumage without increasing oxidative stress through genetic control.

Early-life conditions have stronger effects on the fitness of male than female collared flycatchers. Male nestlings from experimentally enlarged broods had fewer eggs from their mates during their life than male nestlings from reduced broods, which was a consequence of their shorter breeding lifespan. In females, rearing conditions had no effect on fitness. Together with earlier results, we show that although sex differences in growth disappear by fledging, the greater sensitivity of males had lifelong consequences.

In a world where predators use an array of hunting strategies, prey must adapt their escape responses accordingly or be eaten. The ability of prey to convey information on predator type or its location to other members of social groups has received minimum attention in research regarding avian acoustic communication. Using an array of practical approaches, we present novel evidence that a social bird species possesses 2 distinct alarm calls for aerial versus terrestrial predators that can inform others of both the type of predator and its likely location.

Organisms could treat sudden changes to their environment (novelty) either similarly or uniquely depending on context. We tested this idea in foraging house sparrows. Sparrows responded to several forms of novelty. Individuality existed in the speed to come to the food source and in initial responsiveness to a novel object, but not in the adjustment to objects as they became familiar or novel cues of food. Sparrows are highly flexible, which may explain their ability to coexist with humans.

Males can evolve cheating mating strategies to reduce some of the costs associated with reproduction. Certain spiders court females by offering “cheaper” food gifts, consisting of leftovers from their meals rather than edible prey. We show that these males can afford to produce genuine gifts, but nevertheless cheat: they wrap their gifts in larger silk amounts, possibly to mask worthless contents and keep females engaged in feeding to prolong mating.

Twitter: @CristinaTuni

Killer whales are considered highly social animals, however, social structure has been quantitatively studied in few populations. We show that killer whales at Marion Island (Southern Ocean) have small social modules which are mostly stable over years, but that these can be dynamic over shorter time periods. This may be a response to environmental conditions. The social modules comprise non-kin as well as kin, in contrast to the highly matrifocal structure in some other populations.

We show that in domestic fowl male–male aggression over mating is lower among related compared to unrelated males, and in older males. We experimentally explored factors affecting male interruption of competitor males’ copulations by producing groups of related and unrelated males, and with either young (ca 2 years) or old (ca 6 years) dominant males. This allowed us to test the potential for kin selection and whether male age mediates the magnitude of kin tolerance.

Twitter: @dr_lovlie

A late arriving migrant bird species (wood warbler) are attracted to simulated presence of an earlier arriving species (chiffchaff). This habitat selection strategy was previously only described for migrants attracting to resident species, but we show that using other species as cues for good breeding sites also occurs between migrants. Wood warblers use a combination of personal information, and cues based on individuals of the same and different species to make settlement decisions.

Twitter: @szymkowiakj

Not all predators are created equal. Here we show that Steller’s jays assess the level of risk a predator poses by the interaction between 4 different predator species and whether they heard or saw the predators. Sharp-shinned hawks are threatening regardless of being seen or heard where northern goshawks are more threatening if seen than heard. Furthermore, Steller’s jays alter their alarm calls in subtle ways in response to these differences.

In species where males contribute substantially to parental care, males are expected to be choosy. Males should benefit from selecting a female of high fecundity, but it is unclear to what extent males are able to judge female fecundity before breeding. Here we show that male zebra finches seem to have only limited abilities to identify the better mate when faced with a choice between extremes in terms of female fecundity.

Seasonal organisms use temperature as a cue in reproductive decisions, but the role of climate change is not yet clear. Here, an experimental increase in temperature during laying in a small passerine bird reveals that heated females adjusted their incubation behavior and the number of eggs laid, and produced nestlings of equal condition over the season, unlike control females. A small temperature increase may therefore influence breeding strategy and offspring phenotype.

We provide valuable insights into the evolution of primate brain size by demonstrating that relatively large brains are associated with high levels of social competition. Although overall levels of conflict increase in larger groups, the amount of aggression between each individual pair decreases, suggesting that primates in large groups can somewhat mitigate the damaging social costs of conflict.

This is the first study to survey vocalizations from shorebird eggs in the field and to assess potential costs of vocalization. Embryonic vocalizations only occurred during the 4 days before hatching. Once detected, embryonic vocalizations increased in rate and frequency with age. Acoustic cues did not heighten the risk of egg depredation, suggesting that this potential cost of vocalization may not apply.

The nutritional quality of food during development is known to affect several traits of adult life in most organisms (the silver spoon effect): here we show that in a minute parasitic wasp, memory retention is lower when individuals develop in a low quality host than when they develop in a high quality host. In addition, the content of proteins, lipids, and carbohydrates within the body is higher when developing in a high quality host.

Pipefish females need twice as many males as they get: Females in 2 sex role–reversed species produced twice as many eggs as males could care for. In 1 species, males preferred larger females, in the other not. Thus, although potential reproductive rates were similar between species, mate choice was not. Obviously, costs and benefits of choice were more important than potential reproductive rates to understand mate choice.

Social environment experienced during development shapes female mate choice in guppies. We showed that they modified their preferences depending on the distribution of males’ phenotypes experienced while maturing, favoring unfamiliar phenotypes. This may allow them to avoid inbreeding and could contribute to the maintenance of the polymorphism found in male color patterns. Moreover the length of exposure to adult males also affected their preferences but only when exposed to certain sexual traits.

Information conveyed by the timing and temporal structure of calls embedded in sounds of breeding choruses is necessary for eliciting orientation in treefrogs. In contrast, information based on emergent acoustic properties arising from the collective mixture of calls constituting the chorus is not enough. Orientation based on the timing and temporal properties of the actual calls composing choruses could limit the distances over which female frogs could use sound to orient toward and localize breeding aggregations.

Rapid behavioral shifts allow populations of a predator (the northern quoll) to persist in the presence of toxic cane toads. The northern quoll, a mesopredator from northern Australia, has declined dramatically with the invasion of a toxic prey species, the cane toad. We show that some quoll populations persist because quolls are less likely to attack toads. These individuals are therefore “toad-smart,” a trait that is likely passed down generations.

Twitter: @ecology_ella

We provide experimental evidence to confirm that the common cuckoo (Cuculus canorus) locates its Oriental reed warbler (Acrocephalus orientalis) host nests by monitoring the activities of nest owners. Cuckoos distinguished between nest types of different host species and choose to parasitize nests of the most commonly parasitized host, while cuckoos did not choose to lay eggs in nests matching the appearance of their own eggs.

Bills not only influence what birds eat – they can also influence what birds sound like. Island Scrub-Jays, which only occur on one island, have bills that are adapted to food in their local habitat. Here, we report that females with longer, shallower bills (characteristic of pine habitats) produce calls that differ from females with shorter, deeper bills (characteristic of oak habitats), an association that may have aided the evolution of different bills within the island.

We show that winning or losing a contest change male aggressiveness, and that aggressiveness predicts future social rank better than winner–loser effects. Although aggression is often associated with winning a contest, little is known about how winning or losing predict future aggression. Further, the relative importance of aggression and recent contest experiences for establishment of future dominance relationships is unclear. Our study improves the understanding of factors affecting the outcome of male–male dominance interactions.

Despite the high impact of keystone individuals, such as leaders, on group behavior, their identity appears to be immaterial. By repeatedly replacing the keystone individual in groups of social spiders, we show that it is sufficient to have a keystone individual to improve group performance when attacking prey but the keystone individual does not necessarily have to be a specific or familiar individual to serve its role.

Mud dauber wasp females hunt, sting, paralyze, and pack spider prey into a mud nest for their offspring to eat. Individual female wasps of the same species, in the same population, with access to the same resources have different preferences for the spider prey that they capture. Some females specialize on only one species of spider (prey specialists) while others catch a number of species (prey generalists). Individuals’ preferences remain consistent over time.

The hurry-up hypothesis suggests parents should complete reproduction as soon as possible when the quantity or quality of resources declines over time. However, this would come at a cost if it leads to asynchronous hatching that reduces offspring fitness. Here, we present the first test of this hypothesis in a nonavian system. In contrast to what was predicted, we find no evidence that parents complete reproduction sooner under conditions where this would be favorable.

Rising temperatures impose a behavioral trade-off on Alpine ibex because cooler, higher altitude areas have poorer quality, less abundant vegetation. Many species use behavioral strategies to regulate their temperatures, such as ibex moving upslope when it is hotter. Our study shows that such behaviors can negatively affect other key activities such as foraging. As the climate warms, heat-sensitive species will face a precarious balancing act between thermoregulation and acquiring enough energy to survive and reproduce.

We investigated collective cognition in populations subject to different levels of predation. In a choice experiment, wild guppies had to distinguish an edible from a nonedible but similar-looking object. We found that the guppies under low predation made better decisions when in groups but not those under high predation. This suggests a trade-off in the ability of fish to use collective cognition to detect predators and to detect food, depending on the predation level they face.

Parental duties, observed in the natural lake environment of cichlid fish, were better coordinated when the parents had the same body color. Indeed, individuals that pair up with a mate of other color varieties than their own may be disadvantaged due to behavioral incompatibilities. These findings are important because they show how coordination of parental tasks can be important in the evolution of species that have multiple co-occurring morphologies.

Quantifying mating preferences is essential to understand how sexual selection shapes both mating systems and sexual dimorphisms. We present a new method for detecting and quantifying both stabilizing and directional mating preferences and demonstrate the experimental and statistical advantages of this method over previous approaches. We illustrate the method using data from a mate choice experiment in which female sand crickets were provided a choice of 2 males. Both directional and stabilizing preference are identified for components of the male call song.