acta ethologica最新文献

In many animals, vocalizations are necessary for social interactions to occur; however, anthropic noise can pose a problem as it can disrupt acoustic communication. Oscine birds display a variety of strategies to presumably increase the chances of detection in noisy habitats. On the other hand, suboscines, a group of birds with arguably less vocal flexibility, have been less studied, and we have a poor understanding of the strategies that they may use to cope with noise. Anecdotal evidence suggests that vermilion flycatchers (Pyrocephalus rubinus), a suboscine that produces song bouts, interrupts its bouts in the presence of sudden urban noise (SUN, e.g., when a car passes by), avoiding peak noise. To test this idea, we conducted a playback experiment on 27 free-living males. We recorded the song bouts of each individual: before playback, during SUN playback, and after playback. Ambient noise and artificial light at night (ALAN) have been shown to influence bird singing. To evaluate if there is an association between these pollutants and birds’ response to SUN, we also measured mean ambient noise, ambient noise coefficient of variation, and ALAN in the males’ territories. We found that birds sang shorter bouts during the SUN treatment. Song bout length during the SUN treatment was not associated with mean noise levels or coefficient of variation in males’ territories; however, it was positively associated with ALAN. This result was dependent upon an influential point and should be taken cautiously. We found no association between singing recovery (latency to sing and song bout length after SUN relative to before SUN) and mean ambient noise, ambient noise coefficient of variation, and ALAN. Our results show SUN-induced temporal singing flexibility and suggest that vermilion flycatchers are well adapted to acoustically polluted environments, with males living in territories with more light pollution possibly being less affected by traffic noise peaks. A previous study showed that song bout length is an important signal during intra-sexual interactions; interrupting this acoustic component may have important consequences during social interactions.

Abstract

There is growing concern that anthropogenic noise has various deleterious effects on wildlife in urban environments. In humans, it has been suggested that anthropogenic noise exposure during childhood can have long-term effects on cognitive processes in adulthood. Here we tested if urban noise impacts avian cognitive performance by testing adult zebra finches (Taeniopygia guttata) on several cognition tasks in the presence or absence of urban noise playback. We also tested if urban noise impacts growth and cognitive development by testing adult zebra finches on cognition tasks after exposing them to urban noise, pink noise, or no noise during their first 90 days of life. We found that urban noise exposure marginally reduced cognitive performance during tests of a novel motor skill but did not reduce performance during tests of color association learning or spatial memory tasks. We found that urban noise exposure during development marginally affected cognitive performance in adulthood on a color association task. While urban noise exposure during development did not affect adult body size, treated males and females developed less bright bill coloration and redder bills, respectively, than untreated birds. Our results suggest that urban noise exposure may affect morphological traits, such as bill color, that influence social interactions and mate choice. Future studies should examine how noise exposure affects other cognitive behaviors, such as social behavior, and how social behavior in turn might exacerbate or mitigate negative effects of noise.

Abstract

Vasotocin (VT) has been associated with the regulation of different aspects of social behavior (e.g., mating and aggression). Given the fact that androgens are also known to regulate reproductive behavior, we hypothesized that VT and androgens could be interacting, rather than acting independently, in the regulation of reproductive behavior. In the present study, we aimed to understand the effect of VT and its interaction with gonadal hormones (putatively androgens) on different aspects of reproductive behavior of a polygynous and territorial cichlid fish, the Mozambique tilapia (Oreochromis mossambicus). Using a within-subject design, we treated territorial males, that were previously castrated or sham-operated, with different dosages of VT as well as with a V1A receptor antagonist (Manning compound) and subsequently analyzed their behavior towards females and towards an intruder male. Our results showed that VT affected the behavior of territorial males towards females but not towards males. Specifically, VT-treated males interacted less with females (i.e., spent less time touching the transparent partition that allowed visual contact with females) and were less aggressive towards females than saline-treated males. Moreover, in sham-operated males, blocking V1A receptors increased the frequency of bites towards females in comparison to saline-treated males, but not in castrated males. This result suggests that VT down-regulates aggressiveness towards females through the action of V1A receptors in the gonads (putatively decreasing androgen secretion), and that androgens up-regulate this behavior. In summary, our results suggest that VT may modulate social behavior, through an interaction with gonadal hormones.

Abstract

The primary purpose of this study was to examine whether 2D:4D ratios (a putative measure of prenatal androgen exposure) could be determined using participant-submitted hand images. The secondary purpose was to examine whether 2D:4D ratio was associated with pro-environmental behaviors, attitudes, and empathy, given the recent literature linking sex to environmental attitudes and actions. Participants (N = 1065) were asked via an online survey to submit a clear photograph of their right hand, palm side up. Participants also completed a questionnaire to assess (a) demographics, (b) dispositional empathy, and (c) environmental attitudes and behavior. A 2D:4D ratio was calculated for each participant, and the quality of each image was classified as poor, moderate, or good. We then examined the reliability of the 2D:4D image measurements, and the relationship between 2D:4D and our environmental measures. 2D:4D ratios fell somewhat outside of previously reported ranges, but the measurements did show acceptable intra-rater consistency. Although we did not find a sex difference in 2D:4D, we did find a sex by ratio interaction for both empathy and the number of pro-environmental behaviors in which individuals had engaged. Specifically, as 2D:4D ratio increased, males reported lower empathy and less engagement in pro-environmental behaviors, whereas females reported more engagement in pro-environmental behaviors (but no differences in empathy). These findings were contrary to expectations, as we anticipated that greater digit ratios (i.e., feminized) would be associated with greater empathy and pro-environmental behaviors. Overall, the findings of this study present a preliminary examination of the utility of measuring digit ratio with online samples. Furthermore, our results provide information regarding the complex relationship between sex and pro-environmental behaviors.

Global warming and invasive species often act synergistically to threat native communities. The Neotropical Poeciliidae have extensively been introduced to control populations of malaria-transmitting mosquitoes and are now successful invaders around the world. Poecilids introduced to a habitat in the fringe of its thermal tolerance will be increasingly more competitive as temperature increases. This can lead to either local extinction or rapid adaptation of native species. We evaluated if the introduction of two-spot livebearers (Pseudoxiphophorus bimaculatus) has led, after approximately 28 years, to hereditary differences between amarillo fish (Girardinichthys multiradiatus) from an invaded and a non-invaded adjacent temperate mountain lake. Laboratory-born F1 amarillo from the two lakes were raised in either presence or absence of feeding competition with two-spot livebearers. F1 females from Zempoala foraged for shorter periods and were more frequently aggressive than those from Tonatiahua, whereas Zempoala males were quicker to start foraging, did so for shorter periods, and were less likely to fight with their own, than males from Tonatiahua. Similarly, amongst fish from Zempoala reared in the presence of competition with P. bimaculatus, females were slower to start foraging and foraged for shorter periods, and males had reduced foraging and agonistic behaviour, than those reared facing only conspecific competition. We conclude that temperature-dependent behavioural differences have arisen between populations of a native fish, seemingly linked to foraging in a competitive environment and the tendency to be aggressive towards conspecific and heterospecific fish. These differences are the result of both local adaptation and behavioural flexibility.

The current and cascading effects of global change challenges the interactions both between animal individuals (i.e. social and sexual behaviour) and the environment they inhabit. Amphibians are an ecologically diverse class with a wide range of social and sexual behaviours, making them a compelling model to understand the potential adaptations of animals faced with the effects of human-induced rapid environmental changes (HIREC). Poison frogs (Dendrobatoidea) are a particularly interesting system, as they display diverse social behaviours that are shaped by conspecific and environmental interactions, thus offering a tractable system to investigate how closely related species may respond to the impacts of HIREC. Here, we discuss the potential impacts of global change on poison frog behaviour, and the future challenges this group may face in response to such change. We pay special attention to parental care and territoriality, which are emblematic of this clade, and consider how different species may flexibly respond and adapt to increasingly frequent and diverse anthropogenic stress. More specifically, we hypothesise that some parents may increase care (i.e. clutch attendance and distance travelled for tadpole transport) in HIREC scenarios and that species with more generalist oviposition and tadpole deposition behaviours may fare more positively than their less flexible counterparts; we predict that the latter may either face increased competition for resources limited by HIREC or will be forced to adapt and expand their natural preferences. Likewise, we hypothesise that human-driven habitat alteration will disrupt the acoustic and visual communication systems due to increased noise pollution and/or changes in the surrounding light environment. We highlight the need for more empirical research combining behavioural ecology and conservation to better predict species’ vulnerability to global change and efficiently focus conservation efforts.