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Vigilance is a behavioural tactic that allows individuals to control their surroundings and to assess predation risk. In contrast, sleep is unique behavioural state with widely hypothesized restorative and energy‐saving functions, but reducing attentiveness and increasing susceptibility to predation. Sleeping birds resolve this conflict by interrupting sleep with short periods of eye opening (termed...
How should animals sleep in groups? Because sleeping reduces the ability of an individual to detect potential threats, not all individuals should sleep at the same time. The obvious solution of taking turns to sleep is not documented in animal groups. Individuals can also organize their sleeping bouts independently of each other but this simple strategy can be dangerous if too many individuals happen...
In some biparental mammals, paternal care is important for offspring development and survival. We investigated the influence of the early post‐natal environment on the development of paternal care in the naturally paternal desert‐dwelling African striped mouse (Rhabdomys pumilio). Our aim was to establish whether the expression of paternal care in adult sons is influenced by their experience of paternal...
Alarm calling by parents is widespread among animals and has strong implications for parent and offspring fitness, yet it is virtually unknown whether parental alarm calls can initiate a corticosterone response in offspring. We investigated whether parental alarm calls of the white‐crowned sparrow, Zonotrichia leucophrys, activated the corticosterone response of their nest‐bound young, as such a response...
Salmonids are characterized by alternative reproductive tactics, which can lead to an asymmetry in relatedness among offspring within nests and consequently the benefit of discriminating among nestmates. In this study, we examined the effect of paternal reproductive tactic on juvenile behaviour and kin discrimination in Chinook salmon. We created maternal half‐sibling families by collecting eggs from...
Colony reproduction in honey bees involves complex interactions between sterile workers and reproductive castes. Although worker–queen interactions have been studied in detail, worker–drone interactions are less well understood. We investigated caste interactions in honey bees by determining the age and behavior of workers that perform vibration signals, trophallaxis, and grooming with drones. Workers...
Male and female mating preferences are commonly inferred from association times spent with potential mates in a dichotomous‐choice test. However, this assessment method is rarely validated, particularly so for male mating preferences. Using the Trinidadian guppy (Poecilia reticulata), an important model species in the study of sexual selection, we tested whether a male’s mating preference for either...
Many animals defend territories against conspecific individuals using acoustic signals. In birds, male vocalizations are known to play a critical role in territory defence. Territorial acoustic signals in females have been poorly studied, perhaps because female song is uncommon in north‐temperate ecosystems. In this study, we compare male vs. female territorial singing behaviour in Neotropical rufous‐and‐white...
One prediction from life‐history theory is that males should increase investment in reproductive effort as they age because the opportunity for future reproductive events declines. However, older males may not be able to increase their reproductive effort if condition declines with age. The effect of age‐related changes in condition may be especially important for energetically costly activities such...
Redness of the human eye is produced primarily by vasodilation of blood vessels of the conjunctiva, a membrane positioned over the sclera, the eye’s tough, white outer layer. Reddened eyes are a uniquely human cue because other primates lack the background of white sclera necessary to make the reddened conjunctiva visible. This study evaluates red eyes as a social and biological cue by contrasting...
Multiple signals that convey different messages have been reported in many taxa, but relatively few studies have been made on such signals in invertebrates. In the present study, I investigated four types of claw‐waving display used in the fiddler crab Uca lactea to test whether the displays have different functions. Three males with a sand structure beside their burrows (which can attract females)...
Animals are exposed to different predators over their lifespan. This raises the question of whether exposure to predation risk in an early life stage affects the response to predators in subsequent life stages. In this study, we used wood frogs (Rana sylvatica) to test whether exposure to cues indicating predation risk from dragonfly larvae during the wood frog larval stage affected post‐metamorphic...
Burrow architecture enhances important animal functions such as food storage, predator avoidance, and thermoregulation. Occupants may be able to maximize fitness by remodeling burrows in response to seasonal changes in climate and predation risk. My objective was to examine how banner‐tailed kangaroo rats (Dipodomys spectabilis) modify the number of burrow entrances in response to seasonal conditions...
While the presence of predators can influence female mate choice, few studies have investigated how females respond to quantitative variation in predation risk. In addition, we know little of how females respond to multiple, independent cues of risk. In this study, we investigated the effects of simulated predation risk on mate choice in túngara frogs, Physalaemus pustulosus, using the advertisement...
Environmental conditions experienced early in life have been shown to significantly affect growth trajectories at later stages in many vertebrate species. Amphibians typically have a biphasic life history, with an aquatic larval phase during early development and a subsequent terrestrial adult phase after completed metamorphosis. Thus, the early conditions have an especially strong impact on the future...
Birds may sing from positions in the vegetation (song posts) to allow efficient transmission of sexual and territorial vocal displays while simultaneously minimizing the risk of predation because of avian and mammalian predators. Because urban areas are deficient in specialized avian predators, but have many cats while the opposite is the case for nearby rural areas, urban birds should display higher...
We studied anti‐predator strategies in nine species of tarantulas from Asia, Africa, and the Americas. Tarantulas in the New World possess urticating hairs which induce inflammation when in contact with vertebrate mucus membranes and skin. In contrast, tarantulas from the Old World lack this defense but are observed to exhibit a much greater willingness to escalate to an active defense when provoked...
Urbanization creates challenges for wildlife, most notably through changes in resource availability and the frequent occurrence of sensory disturbance. Some native species, however, have been able to exploit and thrive in urban environments. Research, in this regard, has mostly focused on the ecological conditions that have allowed such species to prosper. In contrast, less attention has been devoted...
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