Lekking Species Research Articles

Cognitive flexibility in a Tanganyikan bower-building cichlid, Aulonocranus dewindti

Cognitive flexibility, the ability to modify one’s decision rules to adapt to a new situation, has been extensively studied in many species. In fish, though, data on cognitive flexibility are scarce, especially in the wild. We studied a lekking species of cichlid fish in Lake Tanganyika, Aulonocranus dewindti. Males create sand bowers as spawning sites and maintain them by removing any objects falling into it. In the first part of our experiment, we investigated the existence of spontaneous decision rules for the maintenance of the bowers. We showed that if a snail shell and a stone are placed in their bower, fish prefer to remove the shell first. In the second phase of our experiment, we took advantage of this spontaneous decision rule to investigate whether this rule was flexible. We tested five individuals in a choice against preference task, in which the fish had to modify their preference rule and remove the stone first to be allowed to then remove the shell and have a clean bower. While there was no overall trend towards flexibility in this task, there was variation at an individual level. Some individuals increased their preference for removing the shell first, deciding quickly and with little exploration of the objects. Others were more successful at choosing against preference and showed behaviours suggesting self-regulatory inhibition abilities. Bower-building cichlids could therefore be a promising model to study cognitive flexibility, and other aspects of animal cognition in the wild.

Circulating Hormones and Dominance Status Predict Female Behavior during Courtship in a Lekking Species.

Female competitive behaviors during courtship can have substantial fitness consequences, yet we know little about the physiological and social mechanisms underlying these behaviors-particularly for females of polygynous lek mating species. We explored the hormonal and social drivers of female intersexual and intrasexual behavior during courtship by males in a captive population of Indian peafowl. We investigated whether (1) female non-stress induced circulating estradiol (E2) and corticosterone (CORT) levels or (2) female dominance status in a dyad predicts female solicitation behavior. We also tested whether female circulating E2 and CORT predict dominant females' aggressive behaviors toward subordinate females in the courtship context. Our findings demonstrate that females with higher levels of circulating E2 as well as higher levels of circulating CORT solicit more courtships from males. Dominant females also solicit more courtships from males than subordinate females. Female intrasexual aggressive behaviors during courtship, however, were not associated with circulating levels of E2 or CORT. Overall, we conclude that circulating steroid hormones in conjunction with social dominance might play a role in mediating female behaviors associated with competition for mates. Experimental manipulation and measures of hormonal flexibility throughout the breeding season in relation to competitive and sexual behaviors will be necessary to further examine the link between hormonal mechanisms and female behavior in polygynous lekking systems.

Dominant females have brighter ornamentation in a sexually dimorphic lekking species

AbstractMales often exhibit elaborate ornamentation that contributes to their fitness. Similarly, females can also exhibit elaborate ornamentation, but we have a relatively limited understanding of its function. Recent studies have demonstrated that female ornamentation can function in both intrasexual competition and male mate choice, but few studies have been conducted on lekking species. We therefore investigated the possibility that female ornamentation provides information about the dominance status of the bearer, which could mediate intrasexual competition. We examined this possibility using Indian peafowl (Pavo cristatus), a sexually dimorphic lekking species in which females exhibit elaborate ornamentation in the form of iridescent green neck plumage. We tested whether female ornamentation predicts dominance status using an information theoretic model averaging approach. We found that females with brighter ornamentation are more socially dominant than females with darker ornamentation. These results suggest that female ornamentation in this species provides social information about the dominance status of the bearer. This study provides insight into the evolution of conspicuous female traits by suggesting a potential role for female ornamentation in intrasexual competition in a lekking species.

Behavioural flexibility in the courtship dance of golden-collared manakins, Manacus vitellinus

Courtship displays have been traditionally considered stereotyped behaviours. Many elaborate courtships are displayed in specific locations or in courts prepared by the displaying individuals. Sudden environmental events may alter the spatial structure of the displaying site, and individuals should be able to cope with such disruptions. In some mating systems, courtship is the only or main trait used in mate choice. This is the case in lek mating systems where male mating success is highly skewed and intense sexual selection may drive the evolution of elaborate courtship. The golden-collared manakin is a lekking species of the Neotropical forests. Males have an elaborate courtship display that includes a series of acrobatic jumps within a court delimited by small saplings. The courtship ends with a jump on one of the saplings, called the mating sapling, which invites the female to copulate. The display of each male follows a consistent routine that males establish at the beginning of the reproductive season. We hypothesized that males possess behavioural flexibility to adapt their courtship behaviour to unpredictable environmental changes. We investigated the effects of a sudden disruption of the court configuration by placing a piece of bark on the mating sapling. Males gradually established a new display sequence with an alternative mating sapling, demonstrating a high level of behavioural flexibility that suggests the involvement of motor learning. When the bark was removed, some males reverted to the original sequence, showing retention of the original display sequence. Our study provides evidence for the involvement of motor learning in the establishment and adjustment of elaborate courtship displays.

Why do females of a lekking species mate with multiple males?

In Focus: Rivers, P. R., & DuVal, E. H. (2020). Multiple paternity in a lek mating system: Females mate multiply when they choose inexperienced sires. Journal of Animal Ecology, 89, 1142-1152. In many socially monogamous species with biparental care, some females engage in extra-pair copulations, despite the apparent risk of losing male help in raising their brood. Why females mate with multiple males remains the focus of intense debate, but may be linked to constraints in social mate choice. If so, multiple mating is not expected in a lekking mating system, where females receive no resources from the male other than sperm and are free to choose the 'best' mate to sire their offspring. Rivers and DuVal (2020) report on the occurrence of multiple paternity in lekking lance-tailed manakins and test several hypotheses to explain it. Their study shows that lower-ranked males and males with less experience were more likely to share paternity. However, the process underlying this pattern remains puzzling. The authors suggest female choice related to male characteristics that change with experience as an explanation, but alternative scenarios cannot be excluded.

Sexual differences in oxidative stress in two species of Neotropical manakins (Pipridae)

Because of differences in energetic investments in reproduction, natural and sexual selection are expected to impact males and females differentially, driving the evolution of sexual dimorphism. Thus, males and females are predicted to also differ in how they respond to environmental stressors and how they restore and maintain body homeostasis. Oxidative stress has been suggested to be one potential indicator of the impact of environmental stressors on wildlife. In this paper, we evaluate, for the first time, the oxidative stress in two sympatric lekking species of Neotropical manakins: the Red-headed Manakin (Ceratopipra rubrocapilla) and the White-crowned Manakin (Pseudopipra pipra). Specifically, we test the hypothesis that females of these two species have higher levels of oxidative stress than males because, among Neotropical manakins, only females provide parental care. We found no support for this hypothesis. In fact, males had higher levels of oxidative stress than females. All three hypotheses (predation stress, oxidation handicap, and aerobic activity) available to explain our results have limitations, so further field and laboratory studies on oxidative stress in manakins are required.

A mobile tool for capturing greater sage‐grouse

ABSTRACTCapturing greater sage‐grouse (Centrocercus urophasianus) using standard approaches can be challenging and inefficient, particularly in areas with relatively small populations and patchy habitat. In areas with low population densities, traditional trapping techniques such as drop‐netting and spotlighting have been largely ineffective. To increase trapping efficiency in such situations, we developed a new method to capture greater sage‐grouse in Wyoming, USA, during spring and autumn 2008–2011. We captured 92 sage‐grouse (30 adult females, 57 yearling females, 3 hatch‐year females, and 2 adult males) using a CODA net launcher modified to mount on a front receiver of a truck or all‐terrain vehicle. We had 71% success (82 successful captures of ≥ 1 grouse in 115 attempts). We captured grouse during spring on the periphery of leks, to reduce disturbance of lekking behavior, and during autumn along gravel roads. Capture mortality was <1.0%. We recorded low mortality (4.6%) up to 2 weeks postcapture that may have been attributed to capture and handling stress. This technique proved effective at capturing greater sage‐grouse and we believe this method can be effective at capturing other lekking species of prairie grouse with similar behavioral traits. © 2018 The Wildlife Society.

No behavioural response to kin competition in a lekking species

The processes of kin selection and competition may occur simultaneously if limited individual dispersal, i.e. population viscosity, is the only cause of the interactions between kin. Therefore, the net indirect benefits of a specific behaviour may largely depend on the existence of mechanisms dampening the fitness costs of competing with kin. Because of female preference for large aggregations, males in lekking species may gain indirect fitness benefits by displaying with close relatives. At the same time, kin selection may also lead to the evolution of mechanisms that dampen the costs of kin competition. As this mechanism has largely been ignored to date, we used detailed behavioural and genetic data collected in the black grouse Lyrurus tetrix to test whether males mitigate the costs of kin competition through the modulation of their fighting behaviours according to kinship and the avoidance of close relatives when establishing a lek territory. We found that neighbouring males’ fighting behaviour was unrelated to kinship and males did not avoid settling with close relatives on leks. As males’ current and future mating success are strongly related to their behaviour on the lek (including fighting behaviour and territory position), the costs of kin competition may be negligible relative to the direct benefits of successful male-male contests. As we previously showed that the indirect fitness benefits of group membership were very limited in this black grouse population, these behavioural data support the idea that direct fitness benefits gained by successful male-male encounters likely outbalance any indirect fitness benefits. Kin selection might be involved in the formation of groups because the fitness benefits of increasing group size can be accrued when groups hold close relatives. However, the fitness costs of competing with kin could counter-balance these indirect fitness benefits unless mechanisms enabling individuals to limit kin competition. Here we show in a lekking species that males do not modulate their fight frequency and intensity according to their kinship and do not avoid establishing territories with closely related neighbours. As the indirect fitness benefits of group display were very small in this system and as this study shows that males do not show any sign of kin competition avoidance, the indirect effects associated with male group display are likely to be very small.

Simultaneous age-dependent and age-independent sexual selection in the lekking black grouse (Lyrurus tetrix).

Individuals' reproductive success is often strongly associated with their age, with typical patterns of early-life reproductive improvement and late-life senescence. These age-related patterns are due to the inherent trade-offs between life-history traits competing for a limited amount of resources available to the organisms. In males, such trade-offs are exacerbated by the resource requirements associated with the expression of costly sexual traits, leading to dynamic changes in trait expression throughout their life span. Due to the age dependency of male phenotypes, the relationship between the expression of male traits and mating success can also vary with male age. Hence, using longitudinal data in a lekking species with strong sexual selection - the black grouse Lyrurus tetrix - we quantified the effects of age, life span and age of first lek attendance (AFL) on male annual mating success (AMS) to separate the effects of within-individual improvement and senescence on AMS from selective (dis)appearance of certain phenotypes. Then, we used male AMS to quantify univariate and multivariate sexual selection gradients on male morphological and behavioural traits with and without accounting for age and age-related effects of other traits. Male AMS increased with age, and there was no significant reproductive senescence. Most males never copulated, and of the ones that did, the majority had only one successful year. Life span was unrelated to AMS, but early AFL tended to lead to higher AMS at ages 1-3. AMS was related to most morphological and behavioural traits when male age was ignored. Accounting for age and age-specific trait effects (i.e. the interaction between a trait and age) reduced the magnitude of the selection gradients and revealed that behavioural traits are under consistent sexual selection, while sexual selection on morphological traits is stronger in old males. Therefore, sexual selection in black grouse operates primarily on male behaviour and morphological traits may act as additional cues to supplement female choice. These results demonstrate the multifaceted influence of age on both fitness and sexual traits and highlight the importance of accounting for such effects when quantifying sexual selection.

Limited indirect fitness benefits of male group membership in a lekking species.

In group living species, individuals may gain the indirect fitness benefits characterizing kin selection when groups contain close relatives. However, tests of kin selection have primarily focused on cooperatively breeding and eusocial species, whereas its importance in other forms of group living remains to be fully understood. Lekking is a form of grouping where males display on small aggregated territories, which females then visit to mate. As females prefer larger aggregations, territorial males might gain indirect fitness benefits if their presence increases the fitness of close relatives. Previous studies have tested specific predictions of kin selection models using measures such as group-level relatedness. However, a full understanding of the contribution of kin selection in the evolution of group living requires estimating individuals' indirect fitness benefits across multiple sites and years. Using behavioural and genetic data from the black grouse (Tetrao tetrix), we show that the indirect fitness benefits of group membership were very small because newcomers joined leks containing few close relatives who had limited mating success. Males' indirect fitness benefits were higher in yearlings during increasing population density but marginally changed the variation in male mating success. Kin selection acting through increasing group size is therefore unlikely to contribute substantially to the evolution and maintenance of lekking in this black grouse population.

Genetic variation in nuclear and mitochondrial markers supports a large sex difference in lifetime reproductive skew in a lekking species.

Sex differences in skews of vertebrate lifetime reproductive success are difficult to measure directly. Evolutionary histories of differential skew should be detectable in the genome. For example, male-biased skew should reduce variation in the biparentally inherited genome relative to the maternally inherited genome. We tested this approach in lek-breeding ruff (Class Aves, Philomachus pugnax) by comparing genetic variation of nuclear microsatellites (θn; biparental) versus mitochondrial D-loop sequences (θm; maternal), and conversion to comparable nuclear (Ne) and female (Nef) effective population size using published ranges of mutation rates for each marker (μ). We provide a Bayesian method to calculate Ne (θn = 4Neμn) and Nef (θm = 2Nefμm) using 95% credible intervals (CI) of θn and θm as informative priors, and accounting for uncertainty in μ. In 96 male ruffs from one population, Ne was 97% (79–100%) lower than expected under random mating in an ideal population, where Ne:Nef = 2. This substantially lower autosomal variation represents the first genomic support of strong male reproductive skew in a lekking species.

Density dependence and habitat quality modulate the intensity of display territory defence in an exploded lekking species

We evaluated the effect of conspecific abundance and habitat quality of leks on the territorial behaviour of males in an exploded lekking species, the Little Bustard (Tetrax tetrax). The hypothesis that males more intensely defend territories with higher conspecific abundance and better habitat quality was evaluated experimentally analysing the agonistic response of experimental males to male decoys placed on their displaying areas. Decoy experiments showed that the intensity of display territory defence by little bustard males is density dependent. The time experimental males took to return to their display sites after decoy placement decreased with abundance of both males and females. The strength of their final response was positively associated to local male and female abundance in the vicinity of their display sites. Habitat quality also influenced males’ display territory defence since the intensity of male response increased with the degree of natural vegetation cover. Habitat quality was particularly relevant in explaining variation of experimental males’ snort call rate, which decreased with the degree in plough cover and increased with the number of fields in the lekking area. Snort call rate decreased with the level of male aggregation and was lowest in males exhibiting the strongest aggressive response to decoys. These results add new evidence for the density dependence of species’ breeding territorial behaviour, supporting density-dependent models of lek formation and reinforcing the role of resources defence in exploded lek mating systems.

Individual Signature in a Lekking Species: Visual and Acoustic Courtship Parameters May Help Discriminating Conspecifics in the Houbara Bustard

AbstractSelection pressures acting on both intrasexual competition and intersexual relationships may lead to the emphasis of individual variation and might thus lead to the expression of individual signature. This is particularly true in lek mating systems, where providing information on identity and/or quality to potential mates or congeners of the same sex can be essential for individuals to optimize their reproductive success. Visual and acoustic signals produced during the courtship of the lekking North African Houbara bustard (Chlamydotis undulata undulata), based on field data from wild birds, are investigated here for the first time. Results show that the vocal signals, called booms, are characterized by a very low frequency, a rare phenomenon in birds which should allow booms to propagate over long distances. Results also show that both visual and acoustic signals are individualized and stereotyped between males. Using three methods of analysis, we highlight the acoustic parameters likely to support vocal individual signature and show that such information mainly relies on frequency parameters.

Tests of the kin selection model of mate choice and inbreeding avoidance in satin bowerbirds

In typically outbreeding species, females can avoid a reduction in offspring fitness by choosing unrelated sires. However, the kin selection model of mate choice suggests that it may be adaptive to mate with relatives to gain inclusive fitness benefits, especially in lekking species. Several studies have shown that females tend to mate with relatives, but the detailed behavioral data necessary to determine whether this reflects an active preference is difficult to acquire. We test the hypotheses that females actively preferred or avoided relatives in mate choice in satin bowerbirds (Ptilonorhynchus violaceus), a lekking species in which comprehensive observations of natural mate choice were obtained using automated video cameras positioned at bowers. We identified specific males that were sampled by individual females and assessed whether relatedness influenced their acceptance or rejection as mates. We found no consistent effect of relatedness on mate choice across years or among multiple stages of mate choice. In 2 of 6 years, females copulated with relatives at or above the half-sibling level significantly more often than expected, but this was attributed to females searching for mates in areas populated by relatives, and not to an active preference for relatives. Furthermore, we found no evidence for inbreeding avoidance through mate choice discrimination or sex-biased dispersal.

Quantitative genetics of sexual display, ejaculate quality and size in a lekking species

The investment into extravagant sexual display and competitive sperm are two essential components of pre- and post-copulatory sexual selection. Even though the selective forces acting on sexual display and sperm characteristics have been extensively studied in recent years, the genetic architecture underlying the expression of these traits has been rarely explored. Here, we estimated the genetic variances and covariances of traits linked with ejaculate size and quality, and sexual display in the houbara bustard (Chlamydotis undulata undulata, Jacquin 1784). Using a very large pedigree-based data set, we show that sexual signalling and ejaculate size (but not ejaculate quality) are heritable and genetically positively correlated. The matrix of genetic covariances also provided support for some across-sex correlations: male and female gamete numbers are positively correlated, and more surprisingly, male display and female gamete numbers are also positively correlated. These results can have important implications for the understanding of the evolution of sperm traits and sexual display in animals.

Determinants and costs of natal dispersal in a lekking species

Avoidance of competition and inbreeding have been invoked as the major ultimate causes of natal dispersal, but proximate factors such as sex, body condition or birth date can also be important. Natal dispersal is expected to be of particular importance to understanding the ecological and evolutionary implications of dispersal strategies, since 1) numerous evidences suggest that individual differences in dispersal strategies are expressed early in life (i.e. at the onset of dispersal movement), 2) ultimate and proximate factors are more likely to act during this stage and 3) this stage is associated with the highest mortality rates in most vertebrates. We analysed the natal dispersal (hereafter, dispersal) behaviour in 100 marked individuals of a lekking species, the North African houbara bustardsChlamydotis undulata undulata, during four years. We investigated the effects of proximate factors on dispersal pattern and distance, as well as the mortality cost associated with movement using multievent models, allowing uncertainty in sex assignment and mixture of live recaptures and dead recoveries. Overall, males exhibited longer dispersal distances than females, contrary to the common pattern in birds. Moreover, males in poorer body condition moved further than those in better condition, whereas distance was independent of body condition in females. Finally, survival rates during dispersal were lower for females than for males and were negatively correlated with the distances covered with a similar distance‐survival slope in the two sexes. Collectively, our results suggest that 1) there is substantial dispersal cost in both sexes, 2) dispersal is strongly male‐biased, 3) this bias is unlikely to be explained by differential movement costs of each sex, and 4) dispersal differences found across different categories of individuals are in broad agreement with both the inbreeding avoidance and intraspecific competition mechanisms for dispersal.

The dynamics of alternative male mating tactics in a population of Black Grouse Tetrao tetrix in the Italian Alps

The Black Grouse Tetrao tetrix is primarily a lekking species, although in some populations solitary display is also common. We analysed data from a 25-year-long survey of an increasing Black Grouse population in the western Italian Alps in order to test whether the numbers of males adopting different tactics conformed to patterns expected, based on the hypothesis that dominant birds occupy the leks and solitary displaying birds are subordinate, and that the tendency for birds to be excluded from leks increases with lek size. Four predictions were made to test this hypothesis: (1) the proportion of solitary males would increase as the overall population increases, (2) there would be a threshold at which there is little or no increase in the size of the lekking population, but continued increase in the population of solitary displaying birds, (3) available lek habitat would be occupied prior to an increase in solitary displaying males, and (4) there would be an increase in the use of less preferred habitat by solitary displaying males as the total population increases. Population trends varied according to display status, in that the lekking population reached an apparent threshold while the number of solitary males continued to increase, and there was an expansion of the range of solitary males into higher altitudes in years when the population was larger. However, there was no increase in the proportion of solitary males as the total population increased. Furthermore, there was no suggestion that suitable lek habitat was limiting, as the number of leks and the mean size of those leks continued to increase throughout the study period. Although two predictions were supported, the precise patterns of trends, and results of additional analyses, suggested that solitary display is more likely to be an alternative rather than a subordinate tactic. Several factors may promote this apparent dual display tactic in Black Grouse, but habitat structure in this and other Alpine populations is likely to be a key influence.

Determinants of yearling male lekking effort and mating success in black grouse (Tetrao tetrix)

Age at first reproduction is a crucial component of individual fitness as it often determines the length of reproductive lifespan. The reproductive success of males generally varies more than that of females, but it is challenging to study because the genetic data or proper surrogate measure needed to investigate reproductive success are usually not available. In black grouse (Tetrao tetrix), a lekking species with strong male mating skew and female preference for older males, there is a strong relationship between observed matings and genetic paternity. Using this relationship, we studied the effects of morphological, and behavioral traits on probability of being territorial, mating success, and survival of yearling males. Heavier yearling males were more likely to be territorial, and higher population density increased the frequency of yearling male territoriality. Mating success was positively related to population density, lek attendance, and fighting rate, but not to morphological traits. Overwinter survival did not differ between territorial and nonterritorial yearling males. Our results show that yearling male black grouse in good condition can establish territories and have some limited mating success, especially during increasing population density. In black grouse, the direct fitness benefits gained as yearlings undoubtedly contribute substantially to individual fitness, as the high reproductive skew means few males successfully copulate during their lifetime. For other species, early reproduction may relate to individual lifetime mating success but depends both on the direction and magnitude of the relationship between age-specific mating success and survival, and, as our results also demonstrate, on extrinsic factors such as population density.

Dual reproductive cost of aging in male medflies: Dramatic decrease in mating competitiveness and gradual reduction in mating performance

Although age-based effects on the reproductive success of males have been reported in several animal taxa the cost of aging on male mating success in lekking species has not been fully explored. We used the Mediterranean fruit fly, a lekking species, to investigate possible cost of aging on male reproductive success. We performed no choice and choice mating tests to test the hypothesis that aging does not affect the mating performance (mating success in conditions lacking competition) or the mating competitiveness (mating success against younger rivals) of males. The mating probability of older males decreased significantly when competing with younger males. Aging gradually reduced the mating performance of males but older males were still accepted as mating partners in conditions lacking competition. Therefore, older males are capable of performing the complete repertoire of sexual performance but fail to be chosen by females in the presence of young rivals. Older males achieved shorter copulations than younger ones, and female readiness to mate was negatively affected by male age. Older and younger males transferred similar amount of spermatozoids to female spermathecae. Females stored spermatozoids asymmetrically in the two spermathecae regardless the age of their mating partner. Aging positively affected the amount of spermatozoids in testes of both mated and nonmated males. No significant differences were observed on the amount of spermatozoids between mated and nonmated males.

Population Estimation Techniques for Lekking Species

With the decline of many lekking species, the need to develop a rigorous population estimation technique is critical for successful conservation and management. We employed mark–resight methods to estimate population size for 2 lekking species: greater sage-grouse (Centrocercus urophasianus) and Gunnison sage-grouse (Centrocercus minimus). We evaluated 2 different estimators: Bowden's estimator and the mixed logit-normal mark–resight model. We captured and marked 75 greater sage-grouse. We counted marked and unmarked birds as they attended 15 known leks. We used 36 and 37 marked Gunnison sage-grouse to estimate population size in 2003 and 2004, respectively. We observed marked and unmarked Gunnison sage-grouse daily as they attended 6 leks in 2003 and 3 leks in 2004. Based on our examination of the assumptions of each mark–resight estimator, relative to behavior and biology of these species, we concluded the mixed logit-normal mark–resight model is preferred. We recommend wildlife managers employ mark–resight approaches when statistically rigorous population estimates are required for management and conservation of lekking species.