The Function of Male Agonistic Displays in Ursine Colobus Monkeys (Colobus vellerosus): Male Competition,Female Mate Choice or Sexual Coercion?

Male agonistic displays may allow males to assess competitors, females to assess mates, or could be directed at cycling females to sexually coerce them. We analysed the display output of 26 male ursine colobus monkeys (Colobus vellerosus) in four groups over 13‐mo at the Boabeng‐Fiema Monkey Sanctuary, Ghana. Display indices (including three behaviours, loud calls, stiff‐legs, and jump‐displays) were calculated for males in each group. Males vary in their expression of these behaviours suggesting they are sexually selected signals. We investigated the target of displays and whether display indices varied in relation to male dominance rank, eviction of other males, copulation rate, and proceptive behaviours received from females, to assess the primary function of these behaviours. Male displays decreased in vigour over time and were targeted to other groups and males. High‐ranking males displayed more than low‐ranking males. Alpha male display indices correlated with the number of other males evicted from the group. Display rates were generally higher when cycling females were present in the group. However, neither male display index nor rank correlated with copulation rates. Alpha and non‐alpha males gave cycling females equal rates of sexual solicitations; likewise cycling females showed no difference in the rates of proceptive behaviours directed towards alpha and non‐alpha males. Females mated promiscuously and did not seem to base mating decisions on male display output, although data on female hormones is needed to determine if they mate with strongly displaying males more in the periovulatory period. The male–male competition hypothesis received the greatest support, with some support for the female mate choice hypothesis. Although behaviours that appeared sexually coercive were observed, the function of male displays did not seem to be sexual coercion. Displays were rarely directed at females and males that displayed more did not have greater mating success.     

Effects of forest fragmentation on the lekking behavior of White-throated Manakins in Central Amazonia

Forest fragmentation can affect various aspects of population dynamics, but few investigators have assessed possible effects on the behavior of a species. Loss of habitat may limit population recruitment and abundance, which may alter breeding dynamics in forest remnants. We examined the lekking behavior of White-throated Manakins (Corapipo gutturalis) in a fragmented landscape to determine if forest fragmentation affected the spatial distribution of display courts and male behavior at courts. We captured and observed males at 19 courts located in 11 primary forests of different sizes in forest habitats of the Biological Dynamics of Forest Fragments Project area, an experimentally fragmented landscape located in the central Brazilian Amazon, and estimated their spatial distribution as the distance to the nearest court in the landscape. We quantified habitat loss using the proportion of forest cover surrounding courts and their distances to forest edges. No courts were detected in 1-ha forest fragments, suggesting direct effects from habitat loss following fragmentation that affected connectivity and thus recruitment and persistence of courts in the smallest fragments. The spatial distribution of display courts in forests larger than 10 ha remained unaltered, compared to display courts in continuous forests, but adult males were less numerous on courts with a higher percentage of forest cover and they displayed less on courts closer to forest edges. The spatial distribution of courts also contributed to variation in male social behavior, with more juvenile males present and adult males displaying at lower rates at more isolated courts. Although White-throated Manakins are locally common, the observed behavioral changes in response to habitat loss may affect their population dynamics. Our results show the importance of assessing behavioral changes in conservation programs and, in particular, of including biologically relevant measures of habitat loss in addressing its possible effects on species persistence in fragmented landscapes.     

Patterns of inheritance of mating signals in interspecific hybrids between sailfin and shortfin mollies (Poeciliidae: Poecilia: Mollienesia)

Differences in male morphology and mating behaviors are thought to confer species sexual isolation between sailfin and shortfin species of mollies. This study used interspecific crosses between the sailfin molly, P. latipinna, and the shortfin molly, P. mexicana, to investigate patterns of inheritance of morphological traits and behavioral rates of three mating behaviors in F1 hybrid males. The two parental species showed clear species differences with respect to the length of the dorsal fin and dorsal fin ray number. First generation hybrid males were intermediate between the two parental species for dorsal fin length and fin ray number, suggesting autosomal control of this trait with little effect of dominance by genes from either parental species. Parental species showed clear species differences in their rates of courtship displays. Unlike the pattern for dorsal fin morphology, F1 hybrid males showed a clear distinction in display rates with respect to the direction of the interspecific cross. Male hybrids whose sires were P. latipinna had courtship display rates that were up to three times higher than the rates of displays performed by hybrid males whose fathers were P. mexicana. The distribution of phenotypes between the parental species and that of hybrid males sired by that parental species was nearly identical. Such a pattern suggests the influence of Y-linked genes on the inheritance of courtship display rates in mollies.     

The function of male aggressive displays towards females in mountain gorillas

In groups ofGorilla g. beringei, male aggression towards females regularly takes the form of male display. This paper examines male display towards females in two Karisoke study groups (Group 5 and Group BM) in 1989, a period when none of the females were new immigrants. Results are based on 259 hr of focal observations and 121 hr ofad libitum observations on male behaviors towards females. The goal is to see if the data are compatible with four non-mutually exclusive hypotheses to explain male displays towards females: (1) demonstration of male fighting abilities to influence female long term residence decision; (2) decrease potential competitive inequities between females; (3) provision to females of an occasion to confirm their subordinance to a male; and (4) short term influence on mating. First, male-female proximity was tested against proportion of male displays, to rule out the possibility that males display towards females simply because they happen to be close by. There was no association between proximity and male display. Dominant males were responsible for a higher proportion of displays than subordinate males. This is consistent with the idea that males display to demonstrate their fighting abilities, or their qualities as protector, since dominant males are the ones offering long term protection against infanticide and predators. Females that were in a position to transfer did not receive a higher proportion of male display, however. Long term resident dominant females received a higher proportion of displays from the dominant males, which is consistent with the idea that males attempt to decrease potential competitive inequities between females. There was an association between female appeasement reactions and male displays, which suggests that males display to create occasions for the females to confirm their subordinance to them. Estrous females did not receive a higher proportion of male displays, and there was no association between male display and copulation, suggesting that male displays are not a form of courtship aggression aimed at influencing mating in the short term.     

郑州地区夜鹭的求偶行为

2003年及2004年3~6月在河南郑州市区对夜鹭(Nycticorax nycticorax)的求偶行为进行了观察。结果表明,3月中旬至5月底雄性夜鹭表现出占区及固定的仪式化求偶行为,主要包括伸展炫耀、扬举炫耀、炫耀羽毛和配偶形成后的相互爱抚4个方面,其中前两种行为是夜鹭主要的求偶行为。在营巢地,求偶行为从早上日出之前夜鹭觅食归来开始,一直持续至日落前后。夜鹭的配偶选择包括雄性之间对巢区的竞争、雄鹭与雌鹭的相互选择等一系列过程。     

Female signals enhance the efficiency of mate assessment in satin bowerbirds (Ptilonorhynchus violaceus)

Recent evidence suggests that males adjust their sexually selecteddisplay traits in response to female behaviors during courtships.Little is known, however, about whether females signal to influencemale displays and whether females benefit from this interaction.Male courtship displays in the satin bowerbird (Ptilonorhynchusviolaceus) are highly intense and aggressive. Females may usethese displays as indicators of mating benefits, but these displaysoften startle females and disrupt courtship. Previous studieshave shown that successful males decrease female startling byadjusting their display intensity according to female crouchingbehaviors, suggesting that crouching behaviors function as signals.Here we address whether female crouching is a signal by usingobservations of natural courtship behaviors. In addition, weexamine why females differ in signaling and whether femalesbenefit from signaling. First, we find that female crouchingis related to the likelihood that females will be startled bymale displays, suggesting that crouching signals the degreeof display intensity that females will tolerate from a malewithout being startled. Second, we find that female tolerancefor intense display increases during successive courtships asfemales assess potential mates, and that female tolerance mayalso be affected by age and condition. Third, we find evidencethat females that reduce startling by signaling their intensitytolerance are more efficient in mate searching. These resultssuggest that females signal to influence how males display theirsexually selected traits, and by doing so, females may increasetheir benefits in mate choice.     

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.     

Mate Choice and Spawning Success in the Fighting Fish Betta splendens: the Importance of Body Size, Display Behavior and Nest Size

Courtship displays should be exaggerated enough to attract mates and yet tempered so as not to deter them. We tested this hypothesis in the fighting fish Betta splendens by studying courtship displays and body size and their relationships with male parental quality and female fecundity, as well as the effects of display behavior and body size on mate choice decisions and spawning success. Because of their high degree of parental investment, males are expected to be discriminating in their choice of mates. Males who displayed more frequently built larger nests, a measure of parental quality, but larger males did not. When females were paired with males with high display rates, however, the pair had fewer eggs in their nest, even when accounting for female body mass. In a mate choice test using computer‐generated male stimuli that differed only in display behavior, females showed no preferences for displaying males vs. non‐displaying males, or for males with higher display rates vs. lower display rates. In similar tests in which the computer‐generated males differed only in size, females preferred larger males, but also preferred males that differed with respect to body size (negative assortative mating). Males preferred computer‐generated females that performed courtship displays over non‐displaying females, but showed no preferences for female body size. Neither a female's body size nor her display behavior was a significant predictor of her fecundity as estimated by the number of eggs released during spawning. Thus, our results suggest that female B. splendens must balance male parental quality (nest size) with the risk of potentially disruptive or dangerous behavior during spawning, and that females may minimize these risks through negative size‐assortative mating. Female display behavior, while unrelated to fecundity in our study, may attract males because it indicates reproductive readiness or serves a species‐recognition function.     

Mating games squid play: reproductive behaviour and sexual skin displays in Caribbean reef squid Sepioteuthis sepioidea

Observation of the sexual interactions of Sepioteuthis sepioidea squid during the short reproductive stage of their lives showed a scramble competition system, with both male and female polygyny. Mature females were faithful to a specific location in the daytime, whereas males moved from group to group and formed short-term consortships with females. Males defended females from other males, particularly with an agonistic Zebra display. Male–female pairs exchanged Saddle-Stripe displays, after which males might display an on–off Flicker. There was considerable female choice. Only if a female responded to this display with a parallel Rocking action would she pair and would the male deposit spermatophores at the base of her arms, and only 50% of the time did females move the spermatophores internally to where sperm might be released and stored in the oviducal gland for later fertilization of eggs. This long-term set of interactions and solitary deposition of hidden egg strings contrasts with the attraction of both sexes to a common ‘egg mop’ laid by many females which was a site of competition in other loliginid squid. Since Sepioteuthis is a primitive genus within the family Loliginidae, it may represent a generalist reproductive strategy that evolved into a specialized localization one.     

Males in seemingly female‐like plumage do not mimic females: UV reflectance reveals temporal cryptic dimorphism in a manakin species exhibiting delayed plumage maturation

Manakins (Pipridae) are neotropical birds that usually exhibit delayed plumage maturation (DPM). Thus, while plumage of most adult male manakins is brightly conspicuous, subadult males and females are basically dull‐olive green. Although sexual dichromatism in some bird species may be evident only through UV reflectance, this phenomenon, known as hidden sexual dichromatism, has not been previously studied in manakins to compare subadult males and females. Within this framework, we carried out spectrophotometric analyses in searching for hidden sexual dichromatism in the white‐bearded manakin Manacus manacus, through comparison of UV spectra in females and subadult males in green plumage. Our results revealed UV reflectance in both sexes in green plumage. Moreover, we found UV spectral differences in homologous color patches between sexes, particularly at belly. Since the observed differences may allow intraspecific sex recognition of individuals in green plumage, our results do not support the female‐mimicry hypothesis to explain delayed plumage maturation in the white‐bearded manakin. Although our findings dismiss the female mimicry hypothesis, we cannot state whether these results support the non‐mutually exclusive cryptic and status signaling hypotheses. We propose then, that dull coloration of subadult males may serve both as a cryptic trait and to limit the energetic costs of acquiring the adult plumage before sexual maturity. Meanwhile, differential UV color traits between sexes in green plumage may allow adult males to avoid unnecessary energy expenditures in courtship displays in the presence of males near leks, and to selectively focus their the courtship displays on females. In accordance with the status signaling hypothesis, subadult males can be recognized both as males and subordinates and consequently may practice courtship displays without suffering aggressions by adult males. Our results highlight the importance to include a wider range of spectrophotometric information analyses for testing hypotheses regarding delayed plumage maturation.     

Sex differences in antipredator tail-waving displays of the diurnal yellow-headed gecko Gonatodes albogularis from tropical forests of Colombia

Many vertebrate species show display behaviors when predators are in their vicinity. Some of these displays may inform the predator of the improbability of capturing the prey (i.e., pursuit-deterrent displays) and are potentially advantageous to both predator and prey. Here we present data on a tail display performed by Gonatodes albogularis, a diurnal tropical gecko. We performed transect surveys in three habitats near Bogotá in Colombia. Geckos detected during transects were approached by the observer in a standardized way, and details of their tail-waving displays were recorded. In control recordings animals were watched from a distant site without approaching them. Results showed sexual differences in tail-waving display: when approached by the observer, males performed this behavior more frequently than females. We found no significant differences between males and females in flight-initiation distances and height above the substratum when they were initially located. Results also showed that males displayed more frequently when approached than when the simulated predator remained stationary. We interpret these results as evidence that the display functions as a pursuit-deterrent signal to potential predators. However, as some tail displays were performed in the presence of conspecifics, the display may also have a social function.     

Testosterone and its effects on courtship in golden-collared manakins (Manacus vitellinus): seasonal, sex, and age differences

Male golden-collared manakins gather on leks and perform an acrobatic display to attract females. In temperate breeding species, testosterone (T) activation of courtship displays has been well studied. Few studies have examined T activation of displays in tropical species; even fewer have explored the activational role of T in elaborate courtship displays such as in the manakin. In some tropical species, including manakins, territorial aggression or song behavior are uncoupled from T. We have previously shown that T activates display behavior in manakin males when endogenous T levels are low in the non-courtship season. To understand how T functions in breeding birds, we examined T levels in a large group of manakins sampled during the courtship and non-courtship season. In addition, during the courtship season, we gave T implants to adult males, juvenile males, and females. We found that T levels were low during the non-courtship season and comparatively higher on average during the courtship season. However, T levels were low in many adult males during the courtship season, especially when compared to temperate breeding species. Regardless of initial endogenous T levels during the courtship season, T implants did not increase the display frequency of adult males. T-treated females and juvenile males did display under similar conditions. Our data suggest that the effects of T on manakin display vary with season, sex, and age and that high T is not necessary for display.     

Red anemone guild flowers as focal places for mating and feeding by Levant glaphyrid beetles

Several species of glaphyrid (Scarabaeoidea: Glaphyridae) beetles forage and mate on Mediterranean red bowl‐shaped flowers. In red anemones and poppies in Israel, female beetles occupy only a subset of the flowers, do not aggregate, and are hidden below the petals. This raises the question of how males find their mates. In the present study, we investigated the hypothesis that males and females orient to similar plant‐generated cues, thereby increasing their mate encounter prospects. Previous studies have demonstrated that beetle attraction to red models increases with display area. Choice tests with flowers and with models indicate that both male and female beetles prefer large displays. In anemones, beetles rest, feed, and mate mainly on male‐phase flowers, which are larger than female‐phase flowers. Poppies that contain beetles are larger than the population average. These findings support the hypothesis that males and females meet by orienting to large red displays. Corolla size correlates with pollen reward in both plant species, suggesting that visits to large flowers also yield foraging benefits. Male beetles often jump rapidly among adjacent flowers. By contrast to the preference for large flowers by stationary individuals, these jump sequences are random with respect to flower sex‐phase (in anemone) and size (in poppy). They may enable males to detect females at close range. We hypothesize that males employ a mixed mate‐searching strategy, combining orientation to floral signals and to female‐produced cues. The glaphyrids' preference for large flowers may have selected for extraordinarily large displays within the ‘red anemone’ pollination guild of the Levant. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 808–817.     

Plasticity in courtship and sneaking behaviors depending on tail length in the male guppy, <Emphasis Type="Italic">Poecilia reticulata</Emphasis>

Male guppies Poecilia reticulata exhibit two types of mating behavior, i.e., courtship displays for cooperative copulation and sneaking attempts for forced copulation. The frequencies of the two male mating behaviors are influenced by tail length. Males possessing long tails exhibit courtship displays less frequently and sneaking attempts more frequently than those possessing short tails, even though they have similar total lengths. To examine whether these male behavioral tendencies depending on tail length are genetically controlled or are determined by tail length per se, tail length manipulation was conducted. The tail lengths of males that had previously possessed longer tails were surgically shortened to a greater degree than those of their counterparts that had previously possessed shorter tails. Although the frequencies of the mating behaviors exhibited by the latter males did not apparently change, the former males clearly increased the frequency of courtship displays and decreased that of sneaking attempts following tail shortening. These results indicate that males adjust the frequencies of the two mating behaviors according to their tail length. Since females avoid cooperative mating with males possessing long tails, the change in mating behavioral patterns by males depending on their tail length may increase their mating opportunities.     

Homosexual Mating Displays in Penguins

More than 50 yr ago, field studies recorded the same‐sex pairs (and trios) of penguins displaying to each other during the mating season, using behavior patterns typical of heterosexual mating displays. Such observations led to a hypothesis that due to a lack of sex recognition pairing occurs at random with respect to sex, an idea countered by the argument that sex recognition is highly accurate. No quantification of same‐sex mating displays has tested the frequency of such displays in penguins or tested the hypothesis of random display partners with respect to sex. During their mating season, we studied displaying and paired king penguins, Apenodytes patagonicus, at Kerguelen Island and sexed them using a DNA marker, to quantify any occurrence of this behavior. Indeed, same‐sex courtship displays were common (28.3% of 53 displaying pairs), the great majority of which were between males. Some homosexually displaying males eventually paired with females, but such males were significantly slower in heterosexual pairing than males that did not display homosexually. In two extraordinary cases, same‐sex pairs learned each other’s calls, an essential step in the pairing process. The frequency of such pairs was much lower than among displaying couples, significantly so for males. Finally, the frequency of homosexually displaying pairs was significantly lower than expected from random assortment of displaying birds, for both males and females. We examined possible explanations for same‐sex display and its biological significance. A population sex‐ratio bias in favor of males and high concentration of male sex hormones may help to explain non‐reproductive homosexually displaying pairs.     

Cage design attenuates display patterns of male chimpanzees

Chimpanzee (Pan troglodytes) males are well known for their frequent displays toward viewers who approach and stand in front of their cages. If the front of the chimpanzees' cage is vertical and is constructed of bars or chain link framed by steel, the display includes “pant-hooting,” then lunging onto the cage's front, followed by a series of vigorous attempts to shake the entire structure. The display is intimidating and can include spitting and throwing of materials. Also, displays can incur substantial damage to the cage over time. By sloping the front of the cage toward the center of the cage, the display pattern is profoundly attenuated both in frequency and form. Additionally, it serves to make the males more tranquil. No adverse effects on their health and well-being over a 2-year period have been noted.     

Courtship behaviour in a lekking species: individual variations and settlement tactics in male little bustard

We analysed the display behaviour of male little bustard Tetrax tetrax to identify displays that are used in the context of male-male competition and those that are used for attracting females. Courtship was the main activity of males during the breeding season. Calling activity occurred throughout the day, and leks were attended for more than 4 months. Male sexual displays included snort call, wing-flash, and jump display. Snort call was performed throughout the day and mainly involved male-male interactions. In contrast, the wing-flash display was given only at twilight, and was performed most commonly when a female was present, supporting an inter-sexual function for this display. The jump display was performed only in the presence of female at anytime of the day. Analysis of individual variations in display behaviour revealed that intra-individual variation was low compared to inter-individual variation, especially for the jump display. It is, therefore, possible that display rates provide information on male quality. Four male settlement patterns could be defined, singles, paired, lekking and satellite lekking, but only wing-flash display and stamped snort call differed among those categories. We suggest that satellite males are attempting to benefit from proximity to higher status males, in accordance with the hotshot hypothesis of lek evolution.     

Pillar Function in the Fiddler Crab Uca beebei (II): Competitive Courtship Signaling

Male Uca beebei court and attract females into burrows they defend on muddy sand flats in the intertidal zone on the Pacific coast of the tropical Americas. Mating, oviposition and incubation (breeding) occur underground in males' burrows. Some courting males build mud pillars (2 cm high) at the entrance of their burrow. The purpose of this field study was to assess the role of pillars in competitive courtship signaling among males. I studied the effect of pillars on female behavior by recording the responses of wandering females to courtship from males resident at burrows with and without pillars. I also caught females, released them individually in a circular arena with an equal number of empty burrows with and without pillars around its circumference, and chased the females with a simulated avian predator. Females moved to burrows of both types more often when they were courted (82%) than when they were chased (67%). Receptive females were attracted to the burrows of the males that courted them significantly more often (97%) when these burrows had pillars than when they lacked pillars (66%). However, once females entered males' burrows they were equally likely to remain, mate and breed in both types of burrows. Females also more often moved to burrows with pillars (66%) than to burrows without pillars when they ran from the simulated predator. Both male courtship displays and pillars probably provide cues females use to locate males' burrows. The visual similarity between pillars and a display courting males give immediately before they enter their burrows suggests that pillars are icons of the display. The effect of pillars on female behavior, the timing of pillar building relative to when females choose mates, and contrasts in the behavior of males that do and those that do not build pillars suggest that pillar building has evolved due to competition among males to attract females into their burrows.     

Seasonal Changes of Vocal Rates and Their Relation to Territorial Status in Male Galápagos Sea Lions (Zalophus wollebaeki)

Male vocal displays play an important role in sexual selection through both male–male competition and female choice. While this is supported by numerous studies in birds, much less attention has been paid to the role of such displays in mammals. We investigated the function of vocal displays in a polygynous mammal, the Galápagos sea lion (Zalophus wollebaeki). In our study population a large proportion of mature males are unable to establish a territory, providing the opportunity to compare the vocal behaviour between territorial and non‐territorial males. We examined how seasonal patterns of vocalizations differed between territorial and non‐territorial males and how the number of females present in a territory influenced behaviour of territorial males. We found that territorial males vocalized at higher rates than non‐territorial males, and territorial males vocalized more at the onset than towards the end of territory tenure. During the onset of territory‐tenure vocalizations of territorial males were directed more often towards other males than females. Furthermore, we found that vocalizations of territorial males were not only given in male–male interactions, but were also actively directed towards females. Territorial males vocalized at higher rates when more females were present in their territory. Our results suggest that vocalizations are important in male–male interactions, are relevant in territorial disputes and are used as a proxy for females to assess a male’s quality.