Courtship Tactics Research Articles

Female-female aggression in the Gila monster (Heloderma suspectum).

Historically, the role of aggression in the social lives of animals overwhelmingly focused on males. In recent years, however, female-female aggression in vertebrates, particularly lizards, has received increasing attention. This growing body of literature shows both similarities and differences to aggressive behaviours between males. Here, we document female-female aggression in captive Gila monsters (Heloderma suspectum). Based on four unique dyadic trials (eight adult female subjects), we developed a qualitative ethogram. Unexpected and most intriguing were the prevalence and intensity of aggressive acts that included brief and sustained biting, envenomation, and lateral rotation (i.e. rolling of body while holding onto opponent with closed jaws). Given specific behavioural acts (i.e. biting) and the results of bite-force experiments, we postulate that osteoderms (bony deposits in the skin) offer some degree of protection and reduce the likelihood of serious injury during female-female fights. Male-male contests in H. suspectum, in contrast, are more ritualized, and biting is rarely reported. Female-female aggression in other lizards has a role in territoriality, courtship tactics, and nest and offspring guarding. Future behavioural research on aggression in female Gila monsters is warranted to test these and other hypotheses in the laboratory and field.

Male size and alternative mating tactics in white-tailed deer and mule deer

Abstract Within populations, individual males adopt different courtship tactics due to differences in their competitive ability, which may vary depending on the animal’s age and size. To test the hypothesis that mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) males vary their courtship behavior based on their size, we conducted focal observations of 144 mule deer and 85 white-tailed males that varied in size, at a large grassland site in southern Alberta. The smallest mule deer males devoted more time to feeding, were less likely to engage in late-stage courtship than larger males and were less likely to move among female groups. Other males, including small white-tailed males, appeared to use a roving strategy to search for estrous females in different groups, which is consistent with recent research on male movements. Both medium and large males increased the time they spent in one-male groups, and specifically isolated pairs, as courtship advanced, presumably to reduce competition with other males. However, this trend was most pronounced for medium mule deer males, and for all size classes of white-tailed deer. In contrast, large mule deer males spent a similar proportion of time tending females in all group types. Our results identified potential size-dependent tactics for mule deer males. In contrast, white-tailed males of all sizes appeared to rely on a tactic of finding and tending estrous females in isolation from other males.

Courtship strategies of white-tailed deer and mule deer males when living in sympatry

Abstract Courtship behaviour reflects characteristics of an animal’s general biology, while also reflecting selective pressures specific to reproduction. Mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) are sister species that differ in antipredator behaviour and sociality. We observed sympatric mule deer and white-tailed males to document their grouping patterns, courtship tactics, and aggressive interactions during the breeding season. Consistent with the hypothesis that courtship strategies reflect species differences in antipredator tactics and sociality, mule deer males were more likely than white-tailed males to tend females in multi male–multi female groups. White-tailed males almost exclusively tended females in isolated pairs and prevented other males from joining their groups. However, both species spent more time in isolated pairs as courtship advanced, likely to reduce competition. Our results enabled us to distinguish courtship behaviours that reflect contrasting antipredator tactics and sociality from courtship behaviours that reflect reproductive selective pressures that the species share.

Alternative reproductive tactics and inverse size-assortment in a high-density fish spawning aggregation

BackgroundAt high densities, terrestrial and marine species often employ alternate reproductive tactics (ARTs) to maximize reproductive benefits. We describe ARTs in a high-density and unfished spawning aggregation of the squaretail grouper (Plectropomus areolatus) in Lakshadweep, India.ResultsAs previously reported for this species, territorial males engage in pair-courtship, which is associated with a pair-spawning tactic. Here, we document a previously unreported school-courtship tactic; where territorial males court multiple females in mid-water schools, which appears to culminate in a unique ‘school-spawning’ tactic. Courtship tactics were conditional on body size, local mate density and habitat, likely associated with changing trade-offs between potential mating opportunities and intra-sexual competition. Counter-intuitively, the aggregation showed a habitat-specific inverse size-assortment: large males courted small females on the reef slope while small males courted equal-sized or larger females on the shelf. These patterns remained stable across two years of observation at high, unfished densities.ConclusionsThese unique density-dependent behaviours may disappear from this aggregation as overall densities decline due to increasing commercial fishing pressure, with potentially large consequences for demographics and fitness.

The Role of the Arts in Male Courtship Display: Billy Collins’s “Serenade”

The importance of masculine display in courtship and mate selection has been well established by research in the fields of evolutionary psychology and anthropology. Men advertise qualities women find desirable: ambition, intelligence, or strength, for example, including specialized talents fueling accomplishment in music, literature, or graphic design. The role played by artistic virtuosity in sexual selection provides incontrovertible evidence for the adaptive value of the arts, a topic currently inspiring cross-disciplinary research and theoretical debate. The poem “Serenade” by former Poet Laureate Billy Collins speaks to this issue, introducing an ardent male whose courtship tactics emphasize aesthetic excellence and novelty.

Fluctuating sexual selection and the evolution of a courtship strategy

Fluctuating sexual selection caused by environmental heterogeneity can maintain variation in sexual signals. Sexual selection can also shape correlations among behavioral traits (behavioral syndromes) when certain behavioral combinations enjoy greater fitness than other combinations (i.e., under correlational sexual selection). Here, we tested the hypothesis that environmental heterogeneity in predation risk shapes the evolution of courtship tactics and behavioral syndromes of male water striders Gerris gracilicornis. Male G. gracilicornis use an intimidating form of courtship that depends on predation risk, and we predict that male courtship and related behavioral syndromes will be associated with the form of sexual selection under predation. We assayed 4 male behaviors: sex recognition sensitivity, exploration in a novel environment, intimidation, and boldness toward predators. We also estimated males' reproductive success in both the absence and presence of a predator. We found no predation-risk induced differences in linear (i.e., directional) sexual selection. Both treatments experienced directional selection favoring more intimidating courtship by males. Nonlinear sexual selection, however, varied with predation risk. Additionally, we found that sexual selection was not related to the behavioral syndrome structure. Overall, we demonstrate that sexual selection varies with predation risk in ways that might favor the spread of a novel courtship strategy (intimidating courtship) and the maintenance of alternative mating tactics in G. gracilicornis.

Courtship tactics by male Ilyoplax pusilla (Brachyura, Dotillidae)

Mating in the dotillid crab Ilyoplax pusilla occurs after the female enters the male’s burrow in the tidal flat. Males use two tactics to cause females to enter their burrows for mating: the male either directs claw waving to the female (courting-wave display), to which the females responds by following the male to his burrow, or the male runs rapidly away from, then back toward, his burrow (dash-out-back display), which startles the female into his burrow. Males more often used the courting-wave than the dash-out-back display, but mating success did not differ between the two tactics. Male use of either tactic was influenced by date, female density and male size; the courting-wave display was used by larger males, later in the breeding period, and under higher female density.

The interval between sexual encounters affects male courtship tactics in a desert-dwelling fish

Courtship displays are often important in determining male mating success but can also be costly. Thus, instead of courting females indiscriminately, males might be expected to adjust their signalling effort strategically. Theory, however, predicts that such adjustments should depend on the rate with which males encounter females, a prediction that has been subject to very little empirical testing. Here, we investigate the effects of female encounter rate on male courtship intensity by manipulating the time interval between sequential presentations of large (high quality) and small (low quality) females in a fish, the Australian desert goby Chlamydogobius eremius. Males that were presented with a small female immediately after a large female reduced their courtship intensity significantly. However, males courted large and small females with equal intensity if the interval between the sequential presentations was longer. Our results suggest that mate encounter rate is an important factor shaping male reproductive decisions and, consequently, the evolutionary potential of sexual selection.

When Courtship Persistence Becomes Intrusive Pursuit: Comparing Rejecter and Pursuer Perspectives of Unrequited Attraction

Two hundred forty-one undergraduates described their experiences with unrequited love, both as pursuers (actors) and love interests (targets). As expected, targets and actors perspectives differed. As targets, participants reported being on the receiving end of more unwanted courtship tactics, violent and nonviolent, than they reported using as pursuers. Further, participants in the actor role—particularly men—tended to overreport receiving signals that their love interest was reciprocating, and to underreport receiving rejections. Meanwhile, targets—particularly women—claimed numerous attempts to reject, including explicitly stating “I am definitely not interested in you,” and indicated minimal positive reactions to the unwanted pursuit. Implications of these differences, and others, in perspectives for understanding difficulties in differentiating persistence from stalking are discussed.

Snakes in search of sex: the relation between mate-locating ability and mating success in male garter snakes

Is a male’s ability to find fertilizable females an important determinant of his mating success? We exploited unique logistical advantages offered by courting aggregations of garter snakes, Thamnophis sirtalis parietalis, in Manitoba, Canada, to ask: (1) does the order at which a male arrives at a solitary female affect either his courtship tactics or his chances of inseminating her; and (2) does a male’s body size affect his probability of arriving before his rivals? Experimental trials in the field and in outdoor arenas (to control group size and arrival intervals) suggested that, in the area near the main den, being the first to find a solitary female conveys limited or no fitness benefits to a male snake. Other males were likely to arrive before the male could achieve copulation; and early arrival did not guarantee optimal positioning within the mating ball. Thus, late-arriving males were as likely to obtain copulations as were early arrivers. Male body size enhanced mating success more in early arrivers than latecomers, but did not affect arrival times. However, although mate-finding ability was unimportant for male garter snakes competing near the den, it was critical in surrounding woodland where densities of rivals were much lower.

Courtship tactics in garter snakes: how do a male's morphology and behaviour influence his mating success?

The behavioural determinants of male mating success play a pivotal role in sexual selection, but remain poorly known for most kinds of organisms, including most reptiles. In Manitoba, Canada, large numbers of red-sided garter snakes, Thamnophis sirtalis parietalis, court and mate in early spring near communal overwintering dens. To understand how a male's morphology and behaviour might influence his mating success, we videotaped 21 groups of snakes each comprising four males of varying body sizes plus a female. All males engaged in courtship, and mating occurred in all groups. Males with better body condition courted more vigorously and successfully than their smaller rivals did. The males that obtained matings were those that maintained their own cloaca closest to that of the female, aligned most of their body with the female, showed high rates of caudocephalic waving, chin pressing and tail searching, and did not allow other males to insert their body beside the female's. These behavioural differences between ‘winners’ and ‘losers’ were apparent from the beginning of each trial. Thus, male mating success in this ‘scramble’ system is determined not by chaotic, stochastic struggle (as has often been inferred) but instead is strongly linked to male courtship tactics. Energy stores (as evidenced by good body condition) may be critical determinants of mating success in these vigorous courtship episodes.

Cryptic forcible insemination: male snakes exploit female physiology, anatomy, and behavior to obtain coercive matings.

Whether males can inseminate uncooperative females is a central determinant of mating system evolution that profoundly affects the interpretation of phenomena such as multiple mating by females, mate choice, reproductive seasonality, and courtship tactics. Forcible insemination is usually inferred from direct physical battles between the sexes and has been dismissed on intuitive grounds for many kinds of animals. For example, snakes have elongate flexible bodies (making it difficult for a male to restrain a female physically), males are typically smaller than females, and copulation requires female cloacal gaping to enable intromission. Male garter snakes (Thamnophis sirtalis) do not display any overt aggression during courtship and simply lie over the female and exhibit rhythmic pulsating caudocephalic waves of muscular contraction; previous studies have interpreted this behavior as a mechanism for eliciting female receptivity. In contrast, we show that male garter snakes forcibly inseminate females. They do so by taking advantage of specific features of snake physiology, respiratory anatomy, and antipredator behavior. The snake lung extends along most of the body, with the large posterior section (the saccular lung) lacking any respiratory exchange surface. Rhythmic caudocephalic waves by courting male garter snakes push anoxic air from the saccular lung forward and across the respiratory surfaces such that females cannot obtain oxygen. Their stress response involves cloacal gaping, which functions in other contexts to repel predators by extruding feces and musk but in this situation permits male intromission. Thus, superficially benign courtship behaviors may involve cryptic coercion even in species for which intuition dismisses any possibility of forcible insemination.

The Opportunistic Serpent: Male Garter Snakes Adjust Courtship Tactics to Mating Opportunities

Reproductive males encounter potential mates under a range of circumstances that influence the costs, benefits or feasibility of alternative courtship tactics. Thus, males may be under strong selection to flexibly modify their behaviour. Red-sided garter snakes (Thamnophis sirtalis parietalis) in Manitoba overwinter in communal dens, and court and mate in large aggregations in early spring. The number of males within a courting group varies considerably, as do the body sizes of both males and females. We manipulated these factors to set up replicated courtship groups in outdoor arenas, and analysed videotapes of 82 courtship trials to quantify courting behaviours of male snakes. Larger and more heavy-bodied males courted more vigorously than did their smaller, thinner-bodied rivals, and large females attracted more intense courtship. The major effect, however, involved the number of rival males competing for copulation. Males in large groups not only reduced their overall vigour of courtship, but also modified their tactics in such a way as to benefit from the courtship activities of rival males. That is, they devoted less energy to inducing female receptivity (which requires energy-expensive caudocephalic waving) and more effort to behaviour (tail-searching) that enhanced their own probability of mating if the female gaped her cloaca. This social parasitism reveals an unsuspected plasticity and complexity in the behavioural tactics of reproducing male snakes.

Do Male Veiled Chameleons, Chamaeleo calyptratus, Adjust their Courtship Displays in Response to Female Reproductive Status?

Variation in male courtship behavior may be due to inherent differences among males or may arise from males adjusting their courtship displays according to female responsiveness. Female veiled chameleons, Chamaeleo calyptratus, exhibit two distinctive suites of body coloration and behavior patterns that vary according to receptive and non‐receptive stages of their reproductive cycle. We presented male chameleons with both receptive and non‐receptive females, and recorded differences in their mating frequency, courtship intensity and courtship behavior patterns. As expected, males were more likely to court and attempt mating with receptive females. Although fewer males courted non‐receptive females, their courtship displays were significantly longer than those directed towards receptive females. Males also adjusted the contents of their displays according to female reproductive condition. Certain behavior patterns were unique to courtship displays directed towards each class of females. Males exhibited the behavior pattern `head roll' only when paired with receptive females, and `chin rub' was displayed only during courtship of non‐receptive females. We hypothesize that these differences in male courtship frequency, intensity and content reflect differences in female reproductive value. Although males may benefit from mating with both receptive and non‐receptive females, the costs associated with courtship may depend on female responsiveness. Thus, males adjust their courtship tactics accordingly.

Determinants of mating frequency in the spiny orbweaving spider, Micrathena gracilis (Araneae: Araneidae)

Male Micrathena gracilis require two copulations, separated by a dismount, in order to inseminate both reproductive tracts of the female. We examined several factors that might influence a male's copulatory success. Web structure influenced male courtship and dismount tactics, but not copulatory frequency. The presence of another male reduced the likelihood of a given male copulating with both tracts, a limitation mediated by sexual responsiveness of the female. Mating status of the female did influence copulatory frequency; males were less likely to copulate a second time with nonvirgin females. In summary, males modify mating activities to reduce predation by females, to reduce intermale competition, and to avoid expending gametes when there is little chance of fertilization. Females influence males by predatory activities, mediated through web structure, and enhancing sperm competition among males.

Habitat‐adapted communication in Trite planiceps, a New Zealand jumping spider (Araneae, Salticidae)

The natural history and intraspecific interactions of Trite planiceps, a common New Zealand jumping spider (Salticidae), are described for the first time and discussed in relation to this salticid's unusual microhabitat ‐ the rolled‐up leaves of New Zealand flax (Phormium tenax) and similar plants. In many respects, T. planiceps’ display and mating behaviour resembles other salticids. Males have conditional courtship and mating tactics, and the tactics used depend on the female's maturity and location. If in the light, the male uses vision‐based courtship and mates in the open; if at a nest (inside a rolled‐up leaf), the male uses vibratory courtship and mates inside the rolled‐up leaf; if the female is immature but within c. 10 days of maturing, the male cohabits until the female matures and then mates inside the rolled‐up leaf. Regardless of which mating tactic is used, after males mount females there is a phase during which the pair are in physical contact and communicate using tactile signals ('post‐mount courtship'). Other sex and age classes of T. planiceps also communicate using visual displays when in light, away from rolled‐up leaves, and also sometimes employ tactile signals when at nests or during escalated contests in the light. In addition to these typical salticid characteristics, T. planiceps has some atypical display behaviours that appear to be adapted for communicating in its unusual habitat. Even when no conspecific has been encountered, T. planiceps males sometimes display when approaching openings of rolled‐up leaves occupied by conspecific females. These displays closely resemble visual displays used while facing a conspecific in the light. Later, while entering the cavites within rolled‐up leaves and while moving about inside simulated rolled‐up leaves (glass tubes kept away from visible light and observed using infra‐red video), males and females use vibratory displays, tapping the leaf surface with Legs I and vibrating their abdomens, even when no conspecific has been encountered. Finally, when spiders interact within simulated rolled‐up leaves, they appear to communicate using both tactile signals and vibratory signals that are transmitted through nests or leaf surfaces. Many other salticids use nests as a medium for transmission of vibratory signals. However, T. planiceps’ use of the leaves forming its nesting microhabitat for this function is unusual. This is the first study in which infra‐red video has been used to observe interactions between salticids under conditions of total darkness for the spider, and also the first report of a salticid possessing a display repertoire for use in darkness but away from nests. We emphasise adaptation for typical habitat as a partial explanation for species differences in salticid communication systems.

Human male mating strategies: I. Courtship tactics of the “quality” and “quantity” alternatives

Human males may adopt the “quality” strategy, a long-term pair bond with considerable paternal investment, or the “quantity” reproductive strategy, short-term pair bonds with little paternal investment. We hypothesized that (1) the two strategies require different courtship tactics, which can be derived from their different goals, and (2) the behavior used by quality courters is perceived as honest while the quantity strategist is often exploitative. Act nominations of 79 subjects and the investigators generated a set of 71 dating behaviors. Sixty-four other subjects classified each behavior by the theoretically derived tactics. Fifty-four males rated the likelihood of usage of each behavior by a man interested in marriage (quality courter) and by men interested in sexual relationships (quantity courters) who typically deceive, manipulate, or coerce women. Fifty-three other males rated each behavior on ethical scales of honesty, deception, manipulation, and coercion. Both kinds of ratings indicated that (1) tactics of quality courtship involve honest advertisement through mutual assessment, resource expenditure, and a delay in sexual relations, and (2) tactics of quantity courtship involve indirect or direct threats, psychological pressure, and talking about sex. Ethical ratings and the range of behaviors likely to be used by quality and quantity courters confirmed the hypothesis about ethical perceptions of the two strategies and suggested that quantity courters are opportunistic as well as exploitative.

Female cannibalism and male courtship tactics in threespine sticklebacks

Female threespine sticklebacks (Gasterosteus aculeatus) frequently raid male nests and eat all the eggs therein. We tested the hypothesis of Vickery et al. (1988) that females prefer to raid nests containing large numbers of eggs than ones with smaller numbers of eggs. This hypothesis is based on the finding that females spawning in nests containing many eggs will have reduced hatching success because of egg crowding. By consuming the male's eggs and forcing him to rebuild his nest, raiding females might obtain a new opportunity to spawn under better conditions. Our results were consistent with the first prediction of this hypothesis that females were more likely to spawn in nests containing fewer eggs than in nests with many eggs. However, this may be the result of males becoming less receptive to females as the number of eggs in their nests increases. Prediction 2 was that females should raid those nests containing the most eggs. Contrary to this prediction, males defending only one clutch were as likely to have their nests raided by groups of females as males defending several clutches of eggs. Female cannibalism is therefore unlikely to have evolved as a means of gaining access to a male defending a small number of eggs. We also examined the tactics used by males to counter female raids. Most raids occur when the male is courting, and nests are more vulnerable to shoals of females than to single females. Therefore, we hypothesized that males with eggs preferentially court a single female rather than large groups of females, and that males without eggs court both groups indiscriminately. We also predicted that males restrict the number of females they mate with when risk of having their nest raided is high. Our results indicate that: (1) both males with eggs and those without eggs minimize the risk of female cannibalism by courting solitary females rather than groups of females and (2) males limit the number of females that lay eggs in their nest when several potentially raiding females are present.