Black goby territorial males adjust their ejaculate's characteristics in response to the presence of sneakers

In many species, males can rapidly adjust their ejaculate performance in response to changing levels of sperm competition, an ability that is probably mediated by seminal fluid adaptive plasticity. In the black goby, Gobius niger , territorial males attach viscous ejaculate trails to the nest roof, from which sperm are slowly released into the water during the long-lasting spawning events. Sneaker males release their sperm in the vicinity of the nest, and territorial males try to keep them at a distance by patrolling their territory. We show here that territorial males' ejaculate trails released a higher proportion of their sperm in the presence of a single sneaker, but this proportion decreased when there were three sneakers, an effect that is most likely mediated by a change in the seminal fluid composition. Field observations showed that when multiple sneaking attempts occurred, territorial males spent more time outside the nest, suggesting that ejaculation rate and territory defence are traded-off. Altogether, these results suggest that the adjustment of sperm release from the ejaculate may be strategic, guaranteeing a more continuous concentration of the territorial male's sperm in the nest, although at a lower level, when he is engaged in prolonged territory defence outside the nest.

Frequent female song in blue tits: behavioural context suggests a role in intrasexual competition

The blue tit (Cyanistes caeruleus) is an important avian model in evolutionary ecology (> 20,000 published scientific studies). Song, like in other songbird species, is generally described as a male trait and plays an important role in mate attraction and territory defence. Over the decades, there have been recurring reports of anecdotal female song but these have not led to any quantitative study of female song in blue tits. Our systematic sampling over three years revealed prolific female singing in a northern population of colour ringed blue tits. Daytime singing of females occurred throughout the breeding season during agonistic interactions, solo songs and alarm situations, and these contexts are similar to male song. Notably, female song was absent during the dawn chorus; the period around sunrise when males sing intensively just before mating. Female and male song overlapped substantially in acoustic structure (i.e. same song types, peak frequency or trill rates) but there were also significant differences in that females had smaller repertoires, shorter trills and lower vocal consistency. Differential selections pressures related with contextual (functional) differences in the role of male and female song could explain the observed differences in acoustic structure. The new finding of prolific female singing in such a well-studied species suggests we ought to revise our understanding of male and female vocal communication in this (and probably other) species. Identifying the selection pressures associated to the convergence versus divergence of male and female song may provide important insight in understanding birdsong evolution.

Group living facilitates the evolution of duets in barbets

The duets of birds have intrigued biologists for a long time, yet much remains unknown about the evolution of these striking collective displays. This is partly because previous studies on duet evolution have been biased to songbirds and neglected other bird groups. In songbirds, the absence of migration has been found to predict the occurrence of duetting, indirectlysupporting the idea that duet communication is linked with pair bonding. Here, we used phylogenetic comparative analyses in a sedentary clade of non-songbirds, the barbets (Capitonidae), to reveal new correlates of duet evolution. We found (i) that duets evolved several times independently in different barbet lineages and (ii) that duetting evolved in association with group living (i.e. the presence of helpers or non-breeding adults during the breeding period), but not with sexual monochromatism or habitat type. Our findings are consistent with a duet function in mate guarding and dominance against subordinate group members as well as joint territory defence. Altogether, the results highlight the importance of the social environment for the evolution of collective signalling.

Function of a multimodal signal: a multiple-hypotheses test using an electromechanical robot

1. Many animal species communicate using multimodal signals, which are composed of two or more components emitted and interpreted through different sensory modalities. The main types of selective pressures leading to the evolution of multimodal signals are: (1) content-based, when combined components convey information about the signaller, (2) efficacy-based, when combined components increase the efficacy of signal transmission or processing, and (3) inter-signal interaction, when combined components act in concert to elicit a receiver’s response that differs from the response to either components alone.2. We experimentally tested predictions of five competing hypotheses about the selective pressures leading to the evolution of an audiovisual display (aggressive calls + toe flags) emitted during agonistic male-male interactions of the Neotropical frog Crossodactylus schmidti. 3. To simulate these agonistic interactions in the field, we built an electromechanical robot that emitted acoustic and visual stimuli, either combined or in isolation. We assessed male receiver’s responses to the stimuli types in terms of occurrence and frequency of signals emission.4. The hypothesis that received most support was the context hypothesis, which states that one signal provides a context in which a receiver can interpret and respond to a second signal. The main findings supporting this hypothesis are: (1) the receiver’s response to the acoustic and visual stimuli were non-redundant; (2) the multimodal stimulus magnified the receiver’s response; and (3) the frequency of aggressive notes and toe flags covaried in the receiver’s response to the multimodal stimulus.5. We suggest that the addition of toe flags to aggressive calls modulates male-male interactions by providing to the receiver a new context for the interpretation and response to the acoustic signal. This new context may be motivation to fight for territory possession, level of aggressiveness, or intent of territory defence or invasion. Our study provides one of the few evidences of a context function of a multimodal signal with a modulation effect in animal contests. Moreover, our results draw attention to the role of inter-signal selection on the evolution of multimodal signals in species living in heterogeneous habitats, where efficacy-based selection is often considered as a major driver.

Scent marking in wolves Canis lupus inhabiting managed lowland forests in Poland

In wolves Canis lupus, scent marking plays an important role in territory defence. In Europe, studies on patterns of scent marking in wolves have mostly been conducted in mountains or primeval forests, but since these areas are characterised by low human activity, the impact of people on this behaviour has been neglected. We conducted a study that combined genetic methods with an analysis of the spatial distribution of wolf territory markings in lowland managed forests with high human activity. We found that scent markings are deposited by all members of wolf family groups. Wolves most intensively marked crossroads and their vicinity, especially on roads only accessible for four-wheel drive cars. Our study provides further evidence that crossroads of forest roads play a crucial role in wolf scent marking. The results of our study may be useful during inventories of wolf populations based on collecting indirect signs of their presence or non-invasive genetic sampling.

How Birds Behave

Birds are intelligent, sociable creatures that exhibit a wide array of behaviours – from mobbing and mimicking to mating and joint nesting. Why do they behave as they do? Bringing to light the remarkable actions of birds through examples from species around the world, How Birds Behave presents engaging vignettes about the private lives of birds, all explained in an evolutionary context. We discover how birds find food, relying on foraging techniques, tools and thievery. We learn about the courtship rituals through which birds choose, compete for, woo and win mates; the familial conflicts that crop up among parents, offspring and siblings; and the stresses and strains of nesting, including territory defence, nepotism and relationship sabotage. We see how birds respond to threats and danger – through such unique practices as murmurations, specific alarm calls, distraction displays and antipredator nest design. We also read about how birds change certain behaviours – preening, migration, breeding and huddling – based on climate. Richly illustrated, this book explores the increasing focus on how individual birds differ in personality and how big data and citizen scientists are helping to add to what we know about them. Drawing on classic examples and the latest research, How Birds Behave offers a close-up look at the many ways birds conduct themselves in the wild.

Types of convictions concerning coping with pain of the participants of territory defence activities

Introduction: The complexity of physiological, emotional and behavioural reactions is connected with experiencing pain. A few components appear here: sensory, affective, motivational and cognitive. Relatively strongly fixed beliefs, concerning the possibilities of coping with this feeling, make an important cognitive effect in coping with pain. Knowledge about beliefs about controlling pain influence understanding of pain mechanisms. Material and methods: The research covered 48 hospitalised participants of territorial defence (33.94±9.54 years old; range: 21-56 years old), provided treatment in hospitals in Luck and in the region (Ukraine) with the use of standardised questionnaires within psychology of health and documents’ analysis. The patients differed with respect to diagnosis concerning the presence of neuropathic pain: confirmed neuropathic pain and not fully confirmed neuropathic pain, and the lack of pain of a neuropathic character. Results: In the case of pain of a probable, but not fully confirmed neuropathic pain, the value of conviction relying on one's own internal abilities to coping with pain amounted to 20.73 ± 2.35. The values of the indicators of the two remaining types of convictions analysed in the research are lower. The obtained results indicate that neuropathic pain differentiated beliefs referring to the possibility of coping with pain on one’s own (p<0.001). Conclusions: The obtained results indicate that neuropathic pain differentiated beliefs referring to the possibility of copying with pain on one’s own. No significant correlations have been noticed between the level of externalised and extinguished anger and certain types of beliefs concerning coping with pain.

Body mass and territorial defence strategy affect the territory size of odonate species

The territory is a distinct mating place that a male defends against intruding conspecific males. The size of a territory varies between species and most of the variation between species has been found to scale allometrically with body mass. The variation that could not be explained by body mass has been explained with several variables such as habitat productivity, trophic level, locomotion strategy and thermoregulation. All previous interspecific comparative studies have been done on vertebrate species such as birds, mammals, reptiles and fishes, meaning that studies using invertebrate species are missing. Here, we studied the relationship of a species's territory size with its fresh body mass (FBM) in addition to other ecologically relevant traits using 86 damselfly and dragonfly (Odonata) species. We found that territory size is strongly affected by species FBM, following an allometric relationship similar to vertebrates. We also found that the territory size of a species was affected by its territorial defence strategy, constantly flying species having larger territories than species that mostly perch. Breeding habitat or the presence of sexual characters did not affect territory sizes, but lotic species and species without wing spots had steeper allometric slopes. It seems that an increase in a species’s body mass increases its territory size and may force the species to shift its territory defence strategy from a percher to a flier.