Bowers of the Great Bowerbird (Chlamydera nuchalis) remained unburned after fire: is this an adaptation to fire?

Fire plays an important role in the evolution of life-history characteristics of organisms living in fire-prone regions. Although there are many reports of plants exhibiting adaptations to reduce the harmful or lethal effects of fire, little is known about fire-resistance mechanisms among animals, other than fleeing responses. Here, we report observations that may represent a type of fire adaptation in a bird species: bowers in one population of the Great Bowerbird Chlamydera nuchalis remained unburned after fire. If a bower is destroyed by fire or other mechanisms during courtship and breeding season, the male may lose the opportunity to mate with females, thereby reducing his apparent fitness. Therefore, traits that minimise the damage to bowers from fires may be beneficial. By measuring the unburned areas surrounding bowers after fires, we showed that the survival of bowers after fires is unlikely to be solely related to chance. Our observations are consistent with the hypothesis that bower resistance to fire is an adaptation of the Great Bowerbird. However, it is also possible that unburned bowers are by-products of sexual selection.     

Female Mate Preference for Males Having Long and Symmetric Fins in the Bower-holding Cichlid Cyathopharynx furcifer

Female mate preference in a bower-holding cichlid, Cyathopharynx furcifer, was studied in Lake Tanganyika. Most males held territories with crater-shaped bowers in sand, but some males held territories without bowers. Territories were distributed adjacently and females visited them to spawn. After engaging in circling behaviour with the male, a female deposited eggs in the bower. Soon after spawning, the female picked the eggs up into her mouth and brooded them in places away from male territories. Female mate choice appeared to follow three steps: 1) females visited only bower-holding male territories, and more frequently visited territories of males that performed courtship displays at a higher frequency and had longer pelvic fins; 2) females preferred to start circling with males having longer and more symmetrical pelvic fins; 3) females chose males with more symmetrical pelvic fins as their mates. Less than 7% of females that visited male territories spawned eggs in the bowers. In contrast to other bower-holding species, bower size did not correlate with male reproductive success in C. furcifer. Bowers may therefore be essential as spawning sites or may function as a species recognition character for females. Female choice may be dependent instead on males having long and symmetrical pelvic fins apparent during the circling behaviour carried out in the bowers.     

SEQUENTIAL FEMALE ASSESSMENT DRIVES COMPLEX SEXUAL SELECTION ON BOWER SHAPE IN A CICHLID FISH

In many animals, sexual selection on male traits results from female mate choice decisions made during a sequence of courtship behaviors. We use a bower‐building cichlid fish, Nyassachromis cf. microcephalus, to show how applying standard selection analysis to data on sequential female assessment provides new insights into sexual selection by mate choice. We first show that the cumulative selection differentials confirm previous results suggesting female choice favors males holding large volcano‐shaped sand bowers. The sequential assessment analysis reveals these cumulative differentials are the result of selection acting on different bower dimensions during the courtship sequence; females choose to follow males courting from tall bowers, but choose to engage in premating circling with males holding bowers with large diameter platforms. The approach we present extends standard selection analysis by partitioning the variances of increasingly accurate estimates of male reproductive fitness and is applicable to systems in which sequential female assessment drives sexual selection on male traits.     

Patterns of painting in satin bowerbirds Ptilonorhynchus violaceus and males' responses to changes in their paint

Satin bowerbirds Ptilonorhynchus violaceus have an elaborate multi-component sexual display, some components of which have been extensively studied. We describe a relatively unstudied component of this display, bower painting, and birds' responses to manipulations of their paint. Males of this species focus their display around a stick bower constructed on the forest floor which they decorate with a variety of objects and paint. Painting involves a male masticating plant material and wiping the plant-saliva mixture onto the inside walls of the bower; during courtship visits to bowers, females nibble at this paint. We found that 93% of 53 males painted their bowers at our study site and the time males spent painting their bowers accounted for 24% of their time at the bower. We experimentally removed and added paint to bowers to test whether males respond to these changes in their paint. Males gave more advertisement calls and spent less time manipulating sticks at the bower when we added fresh wet paint to their bowers compared to older dried paint or a control treatment. They did not respond to the removal of paint from their bowers, perhaps because it was primarily older dried paint that was removed. We also found that males painted more frequently when there was measurable wind in their bowers, which could have degraded the quality of the signal. Our findings indicate that fresh wet paint is more important to males than older dried paint and, together with previous work at this site, suggest that paint may act as a signal to females. Given that females nibble bower sticks during courtship, we suggest that bower paint may function as a chemical sexual signal rather than a visual signal.     

Feather stealing in the satin bowerbird (Ptilonorhynchus violaceus): male competition and the quality of display

Male satin bowerbirds use feathers to decorate their bowers and often steal feathers and other decorations from the bowers of other males. Decorations are a key element in sexual display and tracking their movement between bowers provides the first detailed information about this unique pattern of sexual competition. For two field seasons the movement of marked feathers was followed. Males varied greatly in stealing activity. The most active feather thieves were often from areas where bowers were close together and they were involved in reciprocal stealing with males at adjacent bowers. The rate of stealing by males was significantly correlated with the number of feathers on their bowers. This suggests that stealing is important in determining the level of bower decoration and mating success. Patterns of stealing behaviour support models of sexual selection which suggest that male interactions are important in influencing female choice through their effect on the quality of male display.     

Multiple male traits interact: attractive bower decorations facilitate attractive behavioural displays in satin bowerbirds

Sexually selected male courtship displays often involve multiple behavioural and physical traits, but little is known about the function of different traits in mate choice. Here, we examine female courtship behaviours to learn how male traits interact to influence female mating decisions. In satin bowerbirds (Ptilonorhynchus violaceus), successful males give highly aggressive, intense behavioural displays without startling females. Males do this by modulating their displays in response to female crouching, which signals the display intensity that females will tolerate without being startled. Females typically visit multiple males for multiple courtships before choosing a mate, and females show differing tolerance for intense displays during their first courtship with each male. We test three hypotheses that may explain this: (i) familiarity with the courting male; (ii) the order of the courtship in mate-searching; and (iii) the attractiveness of the courting male. We found that females are more tolerant of intense displays during first courtships with attractive males; this increased female tolerance may allow attractive males to give higher intensity courtship displays that further enhance their attractiveness. We then examined why this is so, finding evidence that females are less likely to be startled by males with better physical displays (bower decorations), and this reduced startling then contributes to male courtship success. This role of physical displays in facilitating behavioural displays suggests a novel mechanism by which multiple physical and behavioural traits may influence female choice.     

Patterns of painting in satin bowerbirds Ptilonorhynchus violaceus and males’ responses to changes in their paint

Satin bowerbirds Ptilonorhynchus violaceus have an elaborate multi‐component sexual display, some components of which have been extensively studied. We describe a relatively unstudied component of this display, bower painting, and birds’ responses to manipulations of their paint. Males of this species focus their display around a stick bower constructed on the forest floor which they decorate with a variety of objects and paint. Painting involves a male masticating plant material and wiping the plant‐saliva mixture onto the inside walls of the bower; during courtship visits to bowers, females nibble at this paint. We found that 93% of 53 males painted their bowers at our study site and the time males spent painting their bowers accounted for 24% of their time at the bower. We experimentally removed and added paint to bowers to test whether males respond to these changes in their paint. Males gave more advertisement calls and spent less time manipulating sticks at the bower when we added fresh wet paint to their bowers compared to older dried paint or a control treatment. They did not respond to the removal of paint from their bowers, perhaps because it was primarily older dried paint that was removed. We also found that males painted more frequently when there was measurable wind in their bowers, which could have degraded the quality of the signal. Our findings indicate that fresh wet paint is more important to males than older dried paint and, together with previous work at this site, suggest that paint may act as a signal to females. Given that females nibble bower sticks during courtship, we suggest that bower paint may function as a chemical sexual signal rather than a visual signal.     

Redescription of Natalaspis leptocarpi n.comb. (Homoptera: Diaspididae)

Abstract

Cyllobelus rufopictus? a salticid species from equatorial Africa, has a large and complex repertoire of displays. These spiders live on and near the ground in habitats of short grass, and build opaque silk nests on dead leaves. Each male uses one of three different mating tactics depending on the female’s maturity and location (communicatory versatility). Type 1 courtship, involving special movements and postures of the legs, palps, and body, occurs if the female is an adult away from the nest; apparently this type of courtship is vision-dependent. If the male encounters an adult female inside her nest, he uses Type 2 courtship, which consists of movements by the male that cause the silk to vibrate. If the female is a subadult inside her nest, the male initially uses Type 2 courtship, then builds a second chamber on the female’s nest, and cohabits until she moults and matures. Other displays occur during male-male and female-female interactions. Biting and pinching are distinctive Type 2 courtship displays that have not been described previously for salticids, and juddering is the most distinctive Type 1 display.     

Female choice for male motor skills

Sexual selection was proposed by Darwin to explain the evolution of male sexual traits such as ornaments and elaborate courtship displays. Empirical and theoretical studies have traditionally focused on ornaments; the reasons for the evolution of elaborate, acrobatic courtship displays remain unclear. We addressed the hypothesis that females choose males on the basis of subtle differences in display performance, indicating motor skills that facilitate survival. Male golden-collared manakins (Manacus vitellinus) perform elaborate, acrobatic courtship displays. We used high-speed cameras to record the displays of wild males and analysed them in relation to male reproductive success. Females preferred males that performed specific display moves at greater speed, with differences of tens of milliseconds strongly impacting female preference. In additional males, we recorded telemetrically the heart rate during courtship using miniature transmitters and found that courtship is associated with profoundly elevated heart rates, revealing a large metabolic investment. Our study provides evidence that females choose their mates on the basis of subtle differences in motor performance during courtship. We propose that elaborate, acrobatic courtship dances evolve because they reflect motor skills and cardiovascular function of males.     

When less is best: female brown-headed cowbirds prefer less intense male displays

Sexual selection theory predicts that females should prefer males with the most intense courtship displays. However, wing-spread song displays that male brown-headed cowbirds (Molothrus ater) direct at females are generally less intense than versions of this display that are directed at other males. Because male-directed displays are used in aggressive signaling, we hypothesized that females should prefer lower intensity performances of this display. To test this hypothesis, we played audiovisual recordings showing the same males performing both high intensity male-directed and low intensity female-directed displays to females (N?=?8) and recorded the females' copulation solicitation display (CSD) responses. All eight females responded strongly to both categories of playbacks but were more sexually stimulated by the low intensity female-directed displays. Because each pair of high and low intensity playback videos had the exact same audio track, the divergent responses of females must have been based on differences in the visual content of the displays shown in the videos. Preferences female cowbirds show in acoustic CSD studies are correlated with mate choice in field and captivity studies and this is also likely to be true for preferences elucidated by playback of audiovisual displays. Female preferences for low intensity female-directed displays may explain why male cowbirds rarely use high intensity displays when signaling to females. Repetitive high intensity displays may demonstrate a male's current condition and explain why these displays are used in male-male interactions which can escalate into physical fights in which males in poorer condition could be injured or killed. This is the first study in songbirds to use audiovisual playbacks to assess how female sexual behavior varies in response to variation in a male visual display.     

Physiological Costs of Repetitive Courtship Displays in Cockroaches Handicap Locomotor Performance

Courtship displays are typically thought to have evolved via female choice, whereby females select mates based on the characteristics of a display that is expected to honestly reflect some aspect of the male’s quality. Honesty is typically enforced by mechanistic costs and constraints that limit the level at which a display can be performed. It is becoming increasingly apparent that these costs may be energetic costs involved in the production of dynamic, often repetitive displays. A female attending to such a display may thus be assessing the physical fitness of a male as an index of his quality. Such assessment would provide information on his current physical quality as well as his ability to carry out other demanding activities, qualities with which a choosy female should want to provision her offspring. In the current study we use courtship interactions in the Cuban burrowing cockroach, Byrsotria fumigata to directly test whether courtship is associated with a signaler’s performance capacity. Males that had produced courtship displays achieved significantly lower speeds and distances in locomotor trials than non-courting control males. We also found that females mated more readily with males that produced a more vigorous display. Thus, males of this species have developed a strategy where they produce a demanding courtship display, while females choose males based on their ability to produce this display. Courtship displays in many taxa often involve dynamic repetitive actions and as such, signals of stamina in courtship may be more widespread than previously thought.     

Eavesdropping in crabs: an agency for lady detection

Although conspicuous courtship displays are an effective way of attracting the attention of receptive females, they could provide valuable information to rival males on the location of these females. In fiddler crabs, males that see a receptive female wave their single, greatly enlarged claw in a highly conspicuous courtship display. We test whether other males use this courtship display to alert them to the presence of receptive females that they cannot directly see. We show that male fiddler crabs (Uca mjoebergi) eavesdrop on the courtship displays of nearby males to detect mate-searching females. This allows males to begin waving before a female becomes visible. Furthermore, males appear to adjust their waving according to the information available: eavesdropping males wave 12 times faster than non-courting males but only 1.7 times slower than males in full visual contact with the female.     

Sneaky copulations by subordinate males suggest direct fitness benefits from male–male associations in spotted bowerbirds (Ptilonorhynchus maculatus)

Male spotted bowerbirds (Ptilonorhynchus maculatus) build and defend a structure of sticks and straw—the bower—decorated with colourful objects to attract mates during the breeding season. Specific non-territorial, subordinate males are tolerated by resident males at bowers over multiple breeding seasons. Prior research showed that these male–male associations exhibit attributes of coalitionary behaviour and that subordinate males gain delayed benefits from associating with bower owners, namely future bower inheritance. Yet, it remained unclear whether subordinate males may additionally gain direct fitness benefits from attending established bowers. Here, we report on four separate instances of sneaky copulations (or attempts of copulating) by subordinate males at resident males' bowers. Multiple non-resident males disrupted the ongoing copulations between the bower owner and a receptive female, and these events were followed by violent aggressive interactions. These observations shed new light on same-sex social dynamics in spotted bowerbirds and support the hypothesis that subordinate males are sexually mature individuals that occasionally obtain access to females while attending established bowers. We discuss these findings in light of the literature on male courtship coalitions and agonistic behaviour in bowerbirds, and highlight further aspects of subordinate behaviour that require empirical investigation.     

The displays of the White-throated Manakin Corapipo gutturalis in Suriname

The courtship displays of the White-throated Manakin Corapipo gutturalis (Pipridae) were observed in the Brownsberg Nature Preserve, Suriname, for over 50 h on 17 days between 17 October and 17 December 1982, and the display elements and calls are described. Males perform displays from perches in trees, in flight and on mossy fallen logs. The perch displays are performed as preliminaries to the log-approach displays which are given while in flight towards the log. The log-approach displays vary in length and complexity from a short flight from a nearby perch down to the log, to a dramatic flight above the canopy and back to the log. As males land, they perform a series of aerial manoeuvres and give a complex vocal and mechanical display call. Males may also perform a slower silent moth-flight log approach. The log displays are the culminating elements of courtship and copulation is known to take place there (Davis, T.A.W. 1949. Ibis 91: 146–147). All the courtship displays can be performed either solitarily by a single male or by a group of up to seven males which compete simultaneously for access to single display sites at a series of different logs. Fourteen display logs were located dispersed in two areas 250 m wide which were separated by 350 m, but it was not determined whether these areas constituted separate leks with different pools of possible mates. The behaviour of C. gutturalis is compared with that of the White-ruffed Manakin Corapipo leucorrhoa and other manakins. Male Corapipo appear to have abandoned defence of exclusive advertisement territories in favour of simultaneous competition for a series of different display sites. This detached or mobile form of lek is unique among known manakins and a mechanism for its evolution through female choice is discussed.     

Co-option of male courtship signals from aggressive display in bowerbirds

The pre-existing trait hypothesis suggests that females evolve a mating preference for an already existing male trait. This hypothesis poses a simple resolution to Darwin's long-standing question of how elaborate, male display traits evolve. The frequently observed convergence of aggressive and courtship displays across a wide array of species provides the only current support for this hypothesis. Here we provide much more detailed supporting evidence from bowerbird skrraa calls used in aggression and courtship. Consistent with the pre-existing trait hypothesis we show that (i) putatively co-opted skrraa calls used in courtship and aggression are homologous, (ii) skrraa calls were used in aggression in bowerbirds before being used in courtship, (iii) historically, intense, aggressive-like courtship calls were present near the time of co-option, and (iv) bower types contemporaneous with co-option emphasize design features that provide females protection from the adverse effects of intense courtship displays. These results, plus evidence for a female preference for males with intense aggressive-like courtship skrraa calls, suggest that aggressive skrraa calls have been co-opted for use in male courtship display     

Interpopulation differences exhibited by Spotted Bowerbirds Chlamydera maculata across a suite of male traits and female preferences

Male Spotted Bowerbirds Chlamydera maculata build and decorate structures, bowers, that act as targets for female choice. Bower construction, orientation and distribution all differed between two populations, as did rates of intrasexual aggression. Although there was a broad similarity in classes of decorations used on bowers, the exact types and positioning varied between populations. For two intensively studied populations, different decorations appeared to be the best predictors of mating success. In both populations, male owners of high-quality bowers obtained higher mating success. Male display intensity differed dramatically between populations, and females appeared to differ in the attention that they paid to the male's own display movements. Females also differed in the position that they took to observe a male's display. These variations suggest that differing selective forces may be acting on the elaboration of extreme male display traits across populations. I comment on how this variation can be used to illuminate current hypotheses for the evolution of bowers.     

Visual effects in great bowerbird sexual displays and their implications for signal design

It is often assumed that the primary purpose of a male''s sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (Ptilonorhynchus nuchalis) construct bowers that exploit the female''s predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female''s predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female''s eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female''s attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.     

黄腹角雉求偶炫耀行为

黄腹角雉雄鸟的求偶炫耀为典型的正面型。自12月开始炫耀行为即时有出现,至3、4月份达高潮,高峰出现于交配及雌鸟产卵期间。典型正面型根据炫耀程度可分完全及不完全求偶炫耀两种类型。雌鸟的反应是达到完全求偶炫耀的重要因素。完全求偶炫耀由6个动作组成,需时45—48秒。对雄鸟求偶炫耀时的叫声进行了声谱分析,频率范围与红腹角雉相似,但音节多。     

Indirect mate choice, direct mate choice and species recognition in a bower-building cichlid fish lek

Sexual selection arising through female mate choice typically favours males with larger, brighter and louder signals. A critical challenge in sexual selection research is to determine the degree to which this pattern results from direct mate choice, where females select individual males based on variation in signalling traits, or indirect mate choice, where male competition governs access to reproductively active females. We investigated female mate choice in a lekking Lake Malawi cichlid fish, Hemitilapia oxyrhynchus, in which males build and aggressively defend sand 'bowers'. Similar to previous studies, we found that male reproductive success was positively associated with bower height and centrality on the lek. However, this pattern resulted from males holding these territories encountering more females, and thus their greater success was due to indirect mate choice. Following initial male courtship, an increase in the relative mating success of some males was observed, but this relative increase was unrelated to bower size or position. Crucially, experimentally manipulating bowers to resemble those of a co-occurring species had no appreciable effect on direct choice by females or male spawning success. Together, these results suggest indirect mate choice is the dominant force determining male-mating success in this species, and that bowers are not signals used in direct mate choice by females. We propose that, in this species, bowers have a primary function in intraspecific male competition, with the most competitive males maintaining larger and more central bowers that are favoured by sexual selection due to higher female encounter rates.