Assessing lek attendance of male greater sage-grouse using fine-resolution GPS data: Implications for population monitoring of lek mating grouse

Counts of males displaying on breeding grounds are the primary management tool used to assess population trends in lekking grouse species. Despite the importance of male lek attendance (i.e., proportion of males on leks available for detection) influencing lek counts, patterns of within season and between season variability in attendance rates are not well understood. We used high-frequency global positioning system (GPS) telemetry data from male greater sage-grouse (Centrocercus urophasianus; n = 67) over five lekking seasons (2013–2017) at eight study sites in Nevada to estimate lek attendance rates. Specifically, we recorded daily locations of sage-grouse in relation to mapped lek boundaries and used generalized additive models to assess temporal variation in attendance rates by age class (subadult vs. adult). Average timing of peak attendance occurred on 16 April but varied from March 16, 2014 to April 21 , 2016. Overall, adult males attended leks at higher rates (0.683 at peak) and earlier in the season (19 March) than subadults (0.421 at peak on April 19). Peak attendance probability was positively related to cumulative winter precipitation. Daily probabilities of lek switching differed between adults (0.019 at peak on March 3) and subadults (0.046 at peak on March 22), and lek switching was negatively related to distance to nearest lek. Our results indicate variable patterns in lek attendance through time, and that lek switching may occur at higher rates than previously thought. We demonstrate the use of generalizable daily attendance curves to date-correct lek counts and derive estimates of male abundance, although such an approach will likely require the incorporation of information on age structure to produce robust results that are useful for population monitoring.     

Sharp-tailed grouse lek attendance and fidelity in upper Michigan

To assess and improve existing monitoring protocols for sharp-tailed grouse (Tympanuchus phasianellus) in the eastern Upper Peninsula of Michigan, we used data from 58 radio-collared grouse (46 M, 12 F) monitored within 3 openland landscape types: a xeric, conifer-dominated site, a wetland-dominated site, and a site dominated by low-intensity agriculture. We used lek counts and radio telemetry to determine lek attendance rates, factors affecting lek attendance rates, lek fidelity, and inter-sexual variation in these parameters. Our analysis indicated lek attendance varied with respect to sex of bird, day of year, time after sunrise, and wind speed. Peak male lek attendance rates exceeded those of females by up to 40%, and peak lekking activity for both males and females occurred during the second and third weeks of April. Male lekking activity occurred earlier and was sustained longer than that of females. Lekking activity was negatively related to time of day and wind speed. We observed strong lek fidelity as radio-collared birds attended a primary lek 94% of the time, indicating a low probability of multiple counting of individual birds. We also proposed a method to adjust lek count data for the probability that birds are on a lek during lek counts. Our proposed method can be used by researchers and managers to improve estimates of the number of birds attending a lek by reducing the negative bias associated with observed counts. © 2011 The Wildlife Society.     

How predation risk affects the temporal dynamics of avian leks: greater sage grouse versus golden eagles

Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner and leave later than subordinates, especially if mating skew is high, predation risk is low, or the relationship between lek size and female arrival rate is weak. Both high mean levels of predation risk and small lek size should reduce lek attendance, but the relative tendency of predators to attack large versus small leks has little influence on predicted lekking behavior. Field observations confirmed the predicted effects of female arrival rate, lek size, male dominance, and weather-dependent predator arrival rates on lek departure times. Predicted effects of female arrival rates and male dominance on seasonal lek attendance were also supported. Our model provides an empirically supported adaptive explanation for short-term lek dynamics. It also suggests alternative interpretations for phenomena previously invoked to support the hotshot and skew models of lek formation.     

Aural and Visual Detection of Greater Sage-Grouse Leks: Implications for Population Trend Estimates

Counts of greater sage-grouse (Centrocercus urophasianus) at leks have been used in harvest management, Endangered Species Act listing decisions, and land management policies for over half a century. Lek count sampling methods focus on counting male sage-grouse at known leks, primarily those observed visually from roads or vantage points, but leks are likely missed that are unknown prior to the survey and are difficult to detect while driving between known lek sites. One way to ameliorate this shortfall may be to conduct short point-count surveys at multiple stops along lek-survey routes or while driving between lek counts, thereby detecting newly established or unknown leks. To evaluate the feasibility of this approach, we estimated aural and visual detection probability of active sage-grouse leks during 1-minute point-count surveys at known distances and examined the effects of environmental factors on aural lek detection in southern Idaho, USA, 2016–2017. Our results demonstrate that field observers can aurally detect sage-grouse leks at approximately 3 times greater distances compared to detecting leks visually. The probability of hearing an active lek was highest near the peak of male and female attendance (8 Apr), within an hour of sunrise, on relatively calm and cold days, when the observer was at a higher elevation relative to the lek, and during conditions with no background noise. Detection probability declined with distance and the probability of aural detection was 0.59 at 1 km from a lek when other variables were held at their means. Hence, conducting ≥3 1-minute surveys along a lek route would be expected to detect ≥93% of all leks within 1.5 km of each survey under the average environmental conditions in our study. Our results suggest that surveys could greatly improve detection of unknown or newly established leks and can facilitate a more accurate assessment of sage-grouse population trends through lek counts. Moreover, our results demonstrate how environmental factors influence the detection of leks during surveys, and therefore which variables should be considered for inclusion in any future revisions of lek count protocols or in analyses of lek count data. © 2021 The Wildlife Society.     

Non-defendable resources affect peafowl lek organization: a male removal experiment

A lekking mating system is typically thought to be non-resource based with male providing nothing to females but genes. However, males are thought to clump their display sites on areas where they are more likely to encounter females, which may depend on non-defendable resource location. We tested this hypothesis on a feral population of peacocks. In agreement, we found that, within the lek, display site proximity to food resources had an effect on female visitation rate and male mating success. The attractiveness of display sites to male intruders was explained by the distance to the feeding place and by the female visitation rate. We randomly removed 29 territorial males from their display sites. Display sites that were more attractive to male intruders before removal remained highly attractive after removal and display sites closer to the feeding area attracted the attention of intruders significantly more after removal. Similarly, display sites that were more visited by females before removal remained more visited after removal, suggesting again that the likelihood of encountering females is determined by the display site location. Overall, these results are in agreement with non-defendable resources affecting lek spatial organization in the peafowl.     

Queuing in space and time reduces the lek paradox on an antelope lek

Lek systems, where females often use centrality to assess male quality, highlight a general paradox in evolutionary biology: how can female preferences for males providing good genes persist when consequential strong directional selection is predicted to deplete additive genetic variance in male quality and thereby obliterate benefits of choosiness? An explanation contributing to the resolution of this lek paradox may be that genetic variance is retained when an indirect mate choice cue, such as centrality on a lek, is an imperfect indicator of male genetic quality. Here I investigate whether the presence of alternative male mating tactics limits the reliability of centrality as a quality indicator in lek-breeding topi antelopes. Whereas males establishing territories directly on the central lek were relatively large, smaller peripheral males regularly shifted their territories centripetally and in this way also occasionally obtained central territories. By such opportunistic queuing, small males could increase their mating success drastically; however, their territorial tenure in the lek centre was relatively short, consistent with moderate competitive ability. These results suggest that male topi antelopes can obtain central lek territories through alternative mating tactics, providing scope for variance in male quality on the central lek. In a separate finding, the mating success of central males was found to increase during territorial tenure, independent of estimated age. The demonstration of queuing in both space and time on a mammalian lek highlights the importance of considering male tactical dynamics over time in order to avoid an inflated appearance of the lek paradox.     

Male killing can select for male mate choice: a novel solution to the paradox of the lek

In lekking species, intense directional selection is applied to aspects of the male genotype by female choice. Under conventional quantitative genetics theory, the expectation is that this will lead to a rapid loss in additive genetic variance for the trait in question. However, despite female choice, male variation is maintained and hence it pays females to continue choosing. This has been termed the ''paradox of the lek''. Here we present a theoretical analysis of a putative sex-role-reversed lek in the butterfly Acraea encedon. Sex-role reversal appears to have come about because of infection with a male-killing Wolbachia. The bacterium is highly prevalent in some populations, such that there is a dearth of males. Receptive females form dense aggregations, and it has been suggested that males preferentially select females uninfected with the bacterium. As with more conventional systems, this presents a theoretical problem exactly analogous to the lek paradox, namely what maintains female variation and hence why do males continue to choose? We model the evolution of a male choice gene that allows discrimination between infected and uninfected females, and show that the stable maintenance of both female variation and male choice is likely, so long as males make mistakes when discriminating between females. Furthermore, our model allows the maintenance, in a panmictic population, of a male killer that is perfectly transmitted. This is the first model to allow this result, and may explain the long-term persistence of a male killer in Hypolimnas bolina.     

Absence of male reproductive skew,along with high frequency of polyandry and conspecific brood parasitism in the lekking Houbara bustard Chlamydotis undulata undulata

Behavioural studies have led to the perception that lekking species experience a high male reproductive skew as a consequence of females’ selective mate choice. In addition, observations suggest that females copulate only once and therefore polyandry seems unlikely as females are supposed to choose the best male available. In order to analyse the mating strategy of the Houbara bustard, an endangered lekking species under reinforcement in eastern Morocco, we used microsatellite data to perform paternity analyses. None of our observations followed common expectations under a lek mating system: we found no male reproductive skew suggesting no apparent selective female mate choice and no apparent male benefit from lekking. In contrast, a high level of polyandry (60 % of the nests) was recorded suggesting that sperm competition may operate. In addition, we present another case of conspecific brood parasitism in a lekking species and this was an unexpected alternative strategy for a species presenting high parental cost and low fecundity. The increasing number of studies contradicting common assumptions on lekking species suggests that alternative breeding strategies such as males pursuing an off‐lek mating strategy, female polyandry and even conspecific brood parasitism might be more widespread in lekking species than previously thought.     

Indirect Effects of an Existing Wind Energy Facility on Lekking Behavior of Greater Prairie‐Chickens

Rapid expansion of the wind energy industry has raised concerns about the potential effects of anthropogenic disturbance on prairie grouse. While efforts have been made to address the effects of wind energy facilities on measures of fitness, their effect on the behaviors of prairie grouse has been largely neglected. To address these concerns, we investigated the effects of an existing wind energy facility in Nebraska that became operational in 2005 on the lekking behavior of male greater prairie‐chickens Tympanuchus cupido pinnatus between March and May 2013. Given the potential for disturbance caused by wind turbine noise to disrupt acoustic communication and thus behavior, we predicted that males at leks close to, compared to far from, the wind energy facility would spend more time in agonistic behaviors, and less in booming displays. Given the potential for wind turbine noise to reduce the number of females attending leks (hereafter ‘female lek attendance’), we also predicted that males at leks close to the wind energy facility would spend more time in non‐breeding behaviors and less time in breeding behaviors than males farther from the facility. Although we found no effect of the wind energy facility on female lek attendance, males at leks closer to the wind energy facility spent less time in non‐breeding behaviors than those at leks farther away. However, distance from the wind energy facility had no effect on time spent performing booming displays, flutter jumps, or in agonistic behaviors. Given that lekking behaviors of males influence mating success, our results may have consequences for the fitness of prairie grouse breeding in the vicinity of wind energy facilities.     

Weather conditions and date influence male Sage Grouse attendance rates at leks

For lek‐breeding birds, lek attendance can be correlated with mating success. Variability in lek attendance could confound interpretation of male reproductive effort and complicate the use of lek counts as an index to monitor abundance. We assessed the daily probability of male Sage Grouse Centrocercus urophasianus lek attendance and explored implications of attendance on lek counts. We fitted 145 males with global positioning system (GPS) transmitters over 4 years in Carbon County, Wyoming. We evaluated influences of lek size and topography, date, weather, and bird characteristics such as age on daily morning lek attendance. The daily probability of attendance ranged considerably each year, from 0.120 (, 95% CI 0.051–0.259) in 2012 to 0.917 (95% CI 0.844–0.957) in 2013 with peak attendance dates ranging from 8 April (2012) to 11 May (2011). Attendance decreased with increasing precipitation on the observation day. Only 44–79% of lek counts occurred on days without precipitation and with high attendance (i.e. within 0.1 probability of peak predicted attendance). Although lek counts and population abundance, predicted using attendance rates, followed a similar trend, the relationship was not significantly correlated. We provide empirical evidence supporting current lek‐count protocols: managers should avoid counting leks on days with precipitation because attendance is reduced. Although managers sometimes only complete one to two lek counts per year on active leks, completing at least three lek counts as recommended in protocols increases chances for higher male counts and improves the relationship between counts and abundance. Attendance varies annually, making it challenging to use lek counts to assess regional population trends over short time periods unless attendance is accounted for.     

The lek mating system of the worm pipefish (Nerophis lumbriciformis): a molecular maternity analysis and test of the phenotype‐linked fertility hypothesis

The origin and maintenance of mating preferences continues to be an important and controversial topic in sexual selection research. Leks and lek‐like mating systems, where individuals gather in particular spots for the sole purpose of mate choice, are particularly puzzling, because the strong directional selection imposed by mate choice should erode genetic variation among competing individuals and negate any benefit for the choosing sex. Here, we take advantage of the lek‐like mating system of the worm pipefish (Nerophis lumbriciformis) to test the phenotype‐linked fertility hypothesis for the maintenance of mating preferences. We use microsatellite markers to perform a parentage analysis, along with a mark–recapture study, to confirm that the worm pipefish has an unusual mating system that strongly resembles a female lek, where females display and males visit the lek to choose mates. Our results show that the most highly ornamented females occupy positions near the centre of the breeding area, and males mating with these females receive fuller broods with larger eggs compared to males mating with less‐ornamented females. We also conduct a laboratory experiment to show that female ornaments are condition‐dependent and honestly signal reproductive potential. Overall, these results are consistent with the predictions of a sex‐independent version of the phenotype‐linked fertility hypothesis, as male preference for female ornaments correlates with fertility benefits.     

Non-random mating in classical lekking grouse species: seasonal and diurnal trends

This paper is the first to integrate both field and theoretical approaches to demonstrate that fertility benefits can be a direct benefit to females mating on the classical lek. Field data collected for male sharp-tailed grouse (Tympanuchus phasianellus), a classical lekking species, revealed potential fertility benefits for selective females. Adult males and individuals occupying centrally located territories on the lek were found to have significantly larger testes than juveniles and peripheral individuals. Further, using empirical data from previously published studies of classical lekking grouse species, time-series analysis was employed to illustrate that female mating patterns, seasonal and daily, were non-random. We are the first to show that these patterns coincide with times when male fertility is at its peak. Received: 26 February 1999 / Revised: 13 December 1999 / Accepted: 15 March 2000     

Physiological costs enforce the honesty of lek display in the black grouse (Tetrao tetrix)

Females may use condition-dependent sexual traits as reliable cues of male “quality” if the costs of the expression of such traits vary with male “quality”, and if there is positive genetic correlation between male traits and condition. However, there are multiple ways of measuring the changes in body condition which reflect physiological costs meaning that the multifaceted nature of the physiological costs associated with the expression of sexual traits has rarely been thoroughly examined. In the lekking black grouse (Tetrao tetrix), mating success is highly skewed towards males defending central territories and having high survival rates to the following year, but the mechanisms underpinning such superior performance remain unclear. In this study, we quantified the changes in five measures of body condition before and after the mating season and related these changes to male lek performance (fighting rate, territory centrality and mating success) to understand the physiological costs of male reproductive effort. Between the two capture sessions, male body mass decreased significantly, blood parasite counts and plasma carotenoid concentration increased substantially while the total immunoglobulin concentration tended to increase. There was no overall impairment of individual body condition as the changes in the five measures of body condition were unrelated. Male fighting rate was unrelated to changes in the condition measures but males losing more body mass defended central territories and had high mating success. Therefore, females preferring central, dominant males may select males better able to afford the energetic costs of lek performance thereby effectively enforcing the honesty of male display.     

Testing predictions for the evolution of lekking in the sandfly, Lutzomyia longipalpis

We carried out a combination of field and laboratory experiments to investigate two possible mechanisms promoting the evolution of lekking in the sandfly, Lutzomyia longipalpis. Males in this species lek on or near hosts that females visit to mate and feed. To test whether the distribution of resources, lek size and female number were positively correlated (a prediction of hotspot models) we manipulated the availability of potential lek sites by varying the numbers of chickens, Gallus gallus domesticus, held in field cages. We then investigated the distribution of males and females across leks formed within these cages and measured males to assess the relationship between male size and lek size. The number of males attracted to a lek increased with the number of hosts present and on average males on larger leks had longer abdomens. The number of females was positively correlated with the number of males present, but the average number of females per male decreased with increasing lek size. In a second experiment, we introduced single females to laboratory leks of different sizes, and compared female latency to mate. Contrary to an explicit prediction of the black hole model, lek size had a direct effect on a female's latency to mate. Females at larger leks encountered and copulated with males sooner than those at smaller aggregations, but the length of time a pair spent courting did not vary with lek size. Our results suggest that the black hole model is unlikely to explain the evolution of lekking in this species. The data instead support the hotspot model as a possible mechanism promoting lekking in L. longipalpis but suggest that female preference for larger leks may need to be invoked to obtain the degree of aggregation observed.     

Male rank and optimal lek size

Widemo and Owens presented a model that calculates the expectedcopulation rates of males on leks of a range of sizes. Theyclaim that a negative relationship between lek size and malemating skew will result in low-ranking males having greateroptimal lek sizes than higher ranking rivals. Widemo and Owensoffered no proof of their claim, and their model assumes thatthe rank of a male does not change as lek size increases, whereasin reality, rank may change as more males arrive. We presenta general model that allows rank to change as lek size increases.We show that the crucial determinant of whether optimal leksize increases with male rank is whether relative competitive differencesincrease with lek size. Contrary to the claim of Widemo andOwens, the relationship between skew and lek size has no directbearing on the optimal levels of aggregation of males of differentrank. We show that a negative relationship between skew andlek size can exist even when high-ranking males have the greatestoptimal lek sizes.     

Condition-dependence,genotype-by-environment interactions and the lek paradox

The lek paradox states that maintaining genetic variation necessary for 'indirect benefit' models of female choice is difficult, and two interrelated solutions have been proposed. 'Genic capture' assumes condition-dependence of sexual traits, while genotype-by-environment interactions (GEIs) offer an additional way to maintain diversity. However, condition-dependence, particularly with GEIs, implies that environmental variation can blur the relationship between male displays and offspring fitness. These issues have been treated separately in the past. Here we combine them in a population genetic model, and show that predictions change not only in magnitude but also in direction when the timing of dispersal between environments relative to the life cycle is changed. GEIs can dramatically improve the evolution of costly female preferences, but also hamper it if much dispersal occurs between the life history stage where condition is determined and mating. This situation also arises if selection or mutation rates are too high. In general, our results highlight that when evaluating any mechanism promoted as a potential resolution of the lek paradox, it is not sufficient to focus on its effects on genetic variation. It also has to be assessed to what extent the proposed mechanism blurs the association between male attractiveness and offspring fitness; the net balance of these two effects can be positive or negative, and often strongly context-dependent.     

Condition-dependence, genotype-by-environment interactions and the lek paradox

The lek paradox states that maintaining genetic variation necessary for ‘indirect benefit’ models of female choice is difficult, and two interrelated solutions have been proposed. ‘Genic capture’ assumes condition-dependence of sexual traits, while genotype-by-environment interactions (GEIs) offer an additional way to maintain diversity. However, condition-dependence, particularly with GEIs, implies that environmental variation can blur the relationship between male displays and offspring fitness. These issues have been treated separately in the past. Here we combine them in a population genetic model, and show that predictions change not only in magnitude but also in direction when the timing of dispersal between environments relative to the life cycle is changed. GEIs can dramatically improve the evolution of costly female preferences, but also hamper it if much dispersal occurs between the life history stage where condition is determined and mating. This situation also arises if selection or mutation rates are too high. In general, our results highlight that when evaluating any mechanism promoted as a potential resolution of the lek paradox, it is not sufficient to focus on its effects on genetic variation. It also has to be assessed to what extent the proposed mechanism blurs the association between male attractiveness and offspring fitness; the net balance of these two effects can be positive or negative, and often strongly context-dependent.     

Lek mating systems: a case study in the Little Bustard Tetrax tetrax

Leks have recently been defined as male display aggregations that females attend primarily for the purpose of mating. This is an extended version of previous definitions, as a clear-cut definition of leks is difficult to obtain. Four criteria should be verified to identify a lekking species: (i) there is no male parental investment beyond the sperm; (ii) males aggregate at specific sites for display; (iii) the only resource females find on the lek is the male, i.e. the male genes; (iv) females can select her mate(s), although the necessity of this latter condition for lekking species has been highly debated. We applied these criteria to the endangered little bustard Tetrax tetrax, a species that is claimed to show an exploded lek mating system, but for which this has never been fully investigated. We monitored a population of little bustards in western France during 2 years to investigate the two central criteria in the assessment of their mating system: male aggregation in arenas and lack of consistent resources in male territories. We analysed the spatial distribution of little bustard male territories, the individual variation in size, and the land use characteristics of male territories, with particular attention to the habitats that may be considered as defensible resources. Displaying males showed an aggregated spatial distribution over the study area during the 2 years of survey. Male territories were rather large (19+/-16 ha), but a large among-male variability in territory size was observed. Land use within the territories included mainly permanent and semi-permanent crops. The variability in land use among territories suggests also that resources found within male territories were selected according to male needs (food and display) rather than to female needs (permanent crops that are more appropriate for reproduction). The mating system of the little bustard seems to match the general (and extended) definition of leks, at least in some populations. However, limits between resource defence polygyny and extreme exploded or resource-based leks are thin and unclear, and the little bustard is a good example of how lek definitions may be difficult to apply in non clear-cut empirical situations.     

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.     

To lek or not to lek: mating strategies of male fallow deer

We studied the mating system of fallow deer (Dama dama) for6 years in central Italy. Males in this population could defendterritories that were either single, clumped in leks, or satelliteto leks. The most highly successful males in our study werein leks. When we considered all males, there were no significantdifferences in average copulatory success according to territorytype because many lek males did not achieve any copulations,which were seen in only a few lek territories. The variancein copulatory success, however, was much greater for leks thanelsewhere. Single territories were occupied for shorter timesduring the rut than lek territories. Fighting among males wasmore frequent in the lek, even when we excluded highly successfullek males from the analysis. Chases of nonterritorial malesand harem size were correlated with the number of copulationsachieved by individual males, but did not vary according toterritory type. Copulatory success of some individuals increasedwith age, but there were no age differences among males holdingdifferent types of territories. Satellite males switched tolek territoriality in the course of one rut, but switches fromsingle territory to lek territory were rare. We suggest thatmales in single territories are inferior competitors that selecta low-risk, lowbenefit strategy, whereas those in lek territorieswhere no copulations were seen may be attempting to establishthemselves on the lek to increase their copulatory success infuture years.