Lek Attendance Research Articles

Survival, Movements, and Reproduction of Translocated Greater Sage‐Grouse in Strawberry Valley, Utah

Abstract Translocations of greater sage‐grouse (Centrocercus urophasianus) have been attempted in 7 states and one Canadian province with very little success. To recover a small remnant population and test the efficacy of sage‐grouse translocations, we captured and transported 137 adult female sage‐grouse from 2 source populations to a release site in Strawberry Valley, Utah, USA, during March‐April 2003–2005. The resident population of sage‐grouse in Strawberry Valley was approximately 150 breeding birds prior to the release. We radiomarked each female and documented survival, movements, reproductive effort, flocking with resident grouse, and lek attendance. We used Program MARK to calculate annual survival of translocated females in the first year after release, which averaged 0.60 (95% CI = 0.515‐0.681). Movements of translocated females were within current and historic sage‐grouse habitat in Strawberry Valley, and we detected no grouse outside of the study area. Nesting propensity for first (newly translocated) and second (surviving) year females was 39% and 73%, respectively. Observed nest success of all translocated females during the study was 67%. By the end of their first year in Strawberry Valley, 100% of the living translocated sage‐grouse were in flocks with resident sage‐grouse. The translocated grouse attended the same lek as the birds with which they were grouped. In 2006, the peak male count for the only remaining active lek in Strawberry Valley was almost 4 times (135 M) the 6‐year pretranslocation (1998–2003) average peak attendance of 36 males (range 24–50 M). Translocations can be an effective management tool to increase small populations of greater sage‐grouse when conducted during the breeding season and before target populations have been extirpated.

Lek area characteristics of capercaillie (Tetrao urogallus) in eastern Finland as analysed from satellite-based forest inventory data

Lek area characteristics of capercaillie were studied in eastern Finland. Lekking site data of 42 leks were collected in spring 2000. Satellite images and the Geographical Information System were used to divide the landscape into eight classes and described by means of circles of 11 different sizes (radius 250–4000 m) around the leks. The leks were compared with the average landscape, represented by 50 random points, and studied according to male lek attendance. Mature forests and thinning forests were more abundant and advanced seedling stands less abundant around the leks than in an average landscape. Most of these differences extended up to 750 m distance from the lek. The number of males per lek was best explained by the proportion and patch size of the thinning forests. The effects of landscape structure on the number of cocks were detectable over a wide range, but were strongest within a radius of 1–2 km. The results are discussed in relation to landscape ecology and management applications.

Outbreak of West Nile virus in greater sagegrouse and guidelines for monitoring, handling, and submitting dead birds

West Nile virus (WNV) resulted in a 25% decline in survival in four populations of radiomarked greater sage-grouse (Centrocercus urophasianus) across Alberta, Wyoming, and Montana in 2003. Unexpected impacts of WNV are disturbing because range-wide habitat loss and degradation already threaten sage-grouse populations. In the Powder River Basin of Wyoming and Montana, late-summer survival of sage-grouse was lower at a site with confirmed WNV mortalities (20%) than at two sites without (76%). Dramatic declines in both male and female lek attendance at the WNV site the following spring suggest that outbreaks may threaten some local populations with extirpation. The key to understanding broader impacts of WNV on sage-grouse is to monitor additional populations and to determine whether populations infected in 2003 are again impacted this year. To facilitate this process, we describe a strategy for monitoring WNV mortality in the field and provide information on how to handle, store, and submit dead birds for testing.

Influence of landscape composition on sharp-tailed grouse lek location and attendance in Wisconsin pine barrens

:Populations of sharp-tailed grouse (Tympanuchus phasianellus) in the upper Midwest are in danger of extirpation due to habitat loss caused by succession, tree planting, and control of wildfire. Sharp-tailed grouse in Wisconsin have persisted primarily on reserves maintained in early succession using prescribed burning and mechanical disturbance. However, during the late 1990s the highest and densest populations of sharp-tailed grouse in Wisconsin were found in a complex of clearcuts in southeastern Douglas County. We compared landcover composition and fragmentation at multiple scales within 2.4 km of 36 sharp-tailed grouse leks and 213 unused locations in a 1,350-km2 study area in the pine barrens of northwestern Wisconsin. Leks were located on managed reserves (n = 11) and habitats recently created by timber harvest (n = 23) and wildfire (n = 2). Leks were clustered in the landscape, with distance to nearest neighbour lek shorter for leks than unused points. Leks were characterized by higher proportions of grass and shrub cover classes, lower proportions of forest, fewer forest patches, and greater distances to forest edge relative to unused points. Proportions of grass and shrub cover classes, distance to nearest lek, and distance to forest edge were strong predictors of lek presence in a logistic regression model. Differences between leks and unused points varied with scale of sampling. Response of sharp-tailed grouse to indices of fragmentation varied among scales and metrics. Number of sharp-tailed grouse attending leks was positively associated with recently created habitat and proportion of grass cover in the landscape.

Measuring the Mating Skew

Charles Darwin (1871) defined sexual selection as a difference inreproductive success due to competition over mates, a definition that is still valid today. Being able to quantify such differences is thus essential for explaining the consequences of sexual selection, say, the ornamentation rdisplay behavior of males. In the specific ase of lekking (aggregated, non-resource-based display of males), attempts to do so have proven difficult. Any measure that does not take into account the possibility of random mating to produce the observed pattern of mating success is unsatisfactory as a measure of the intensity of sexual selection (Sutherland 1987; Mackenzie et al. 1995b). That variation in male mating success on leks is systematically higher than expected from pure random mating has been verified by Bradbury et al. (1985) and Mackenzie et al. (1995a). However, these studies do not yet provide means to estimate the expected mating success of individuals displaying together. Since a lek is not itself a trait but an assemblage of several males, each trying to optimize their own fitness (Hoglund and Alatalo 1995), fitness considerations of single individuals are required in explaining the evolution of lekking. The skew index, defined as the ratio of observed to maximum skew (Keller and Vargo 1993; Reeve and Ratnieks 1993), has been gaining popularity as a measure of skewed reproductive success (e.g., Bourke and Heinze 1994; Keller and Reeve 1994; Reeve and Keller 1995), and it has also been used to estimate the expected fitness of lekking individuals (Widemo and Owens 1995). However, this measure has been shown to have undesirable discontinuities (Pamilo and Crozier 1996). Moreover, it interprets random variation as real differences in mating success. This is most clearly seen in models of pure random mating, which nevertheless lead to positive values of the skew measure (Mackenzie et al. 1995b). Recently, Keller and Krieger (1996) proposed a method for correcting the skew index for random variation. We shall show, however, that the corrected measure still is not satisfactory, and we suggest a novel, statistically rigorous method. We give two criteria for a proper measure of skewed mating success. First, it should allow determining the most probable underlying distribution of mating

A structural-equations model for the mating behaviour of bucks in a lek of fallow deer

In many studies, the causal factors of male copulatory success in leks cannot be experimentally analysed under natural conditions. Information is based on the analysis of correlation and on multiple regression models. However, these methods are often flawed or unsuitable for conclusive results. By contrast, an explicit model of the breeding behaviour of male fallow deer (Dama dama L.) has been formulated using structural (regression) equations. The model describes with outstanding precision the network of short-term determinants of male copulatory success. Harem size is identified as the most important indirect cause of male copulatory success and, in its turn, it is a function of (i) lek attendance, (ii) intensity of herding, (iii) aggressive behaviour towards other bucks and (iv) courtship. Comparing the results of the structural-equations model with those of a partial correlation analysis and of a multiple regression study, we conclude that the statistical method presented here better describes the com...

Seasonal variation in lek attendance and lekking behaviour by male Black Grouse Tetrao tetrix

Eleven Black Grouse Tetrao tetrix leks in the Scottish Highlands were visited at dawn once every week for a year. Apart from July and three leks which were unoccupied in winter, males visited leks throughout the year. Total numbers of males attending leks peaked in March in one study area (six leks) and in April in the second (five leks). The number of males present and the proportion of leks occupied varied seasonally. The proportion of males at leks was at a maximum in April (80% of males) when all leks were attended, with a secondary peak in September when 60% of leks had males present. Males spent the most time displaying in April. The optimal conditions for attendance were calm, dry mornings just after dawn. Most reliable counts of numbers of males were those made between the last week of March and the end of the first week of May.

Light Patterns as Cues for Mate Choice in the Lekking White-Throated Manakin (Corapipo gutturalis)

We explored in an exploded lek species the relationships between three alternatives hypotheses for typical skewed male mating success: (1) female preference for display-site characteristics; (2) female preference for male phenotypic traits; and (3) mate choice determined by the outcome of male dominance interactions. The possible role of these mechanisms of female choice was examined in the White-throated Manakin (Corapipo gutturalis), a species in which males display on the top of mossy fallen logs lying on the primary forest floor. Data on light intensity at the display site, lek attendance, male calling and display rates, visits by males and females, and mating success were collected on six males at a single lek. The two males with the brightest two arenas received high rates of female visitation and performed 71% of the mating attempts. However, only one of them successfully copulated because the other male was always disrupted by visiting males. The results suggest that light properties of the display site and attendance of the male determine the attractiveness of male display to females, whereas male interactions subsequently mediate copulatory success. Brightness of the display site appears as the primary cue for mate choice in C. gutturalis, but this is not used by females as an indicator of the males' relative dominance because the dominance status of males is not correlated with the brightness of their display sites.

Female preference for long tails in lekking Jackson's widowbirds: experimental evidence

Jackson's widowbird, Euplectes jacksoni, is a lek-breeding weaverbird (Ploceidae) of East African grassland. Each male displays on his own display court: a cleaned circular track around a grass tuft. The male performs a jump display that attracts females, and a ground display directed at visiting females. Breeding males are black with a tail 20 cm long, which is conspicuously exhibited during display. Females and non-breeding males are streaky brown with a short tail. Tail length was the single most important predictor of male mating success in a previous study, suggesting that the tail is a cue for female mate choice. In the present experiment, males with shortened tails received fewer visits by females than control males, in 11 of 13 test pairs of neighbouring males. The rate of visits by females was correlated with male copulatory success. Display rate and lek attendance were not affected by tail manipulations. The results suggest that female Jackson's widowbirds prefer males with long tails. The experimentally produced difference in tail length roughly spans the standard deviation of a large sample of displaying males. This implies that cue assessment by females is accurate enough to impose sexual selection on male tail length. A previously found positive relationship between tail length and an index of body condition was strengthened by the increased sample size. The results are discussed in relation to current sexual selection theory.

Male-Biased Dispersal in the Great Bustard Otis tarda

We studied dispersal and seasonal movements of Great Bustards marked as young in Villafifila, NW Spain, between 1983 and 1990. This study documented male-biased dispersal in a sexually dimorphic, lekking species; one of the very few documented examples outside the Anatidae. Females nested outside the display area after visiting leks for mating. Males abandoned breeding activities after mating and dispersed during summer to moult. Young stayed with hens until a new breeding cycle was initiated in the next spring. Males dispersed significantly earlier and further from natal sites than females. Home ranges of males were significantly larger during their first two years of life than later, and those of females were significantly smaller than those of males. Average age of first lek attendance was 2.7 yr for males and 1.9 yr for females. Females attended leks closer to natal sites than males, and adult males attended the same leks year after year. Age of first successful breeding was 4-5 yr in females. These results support the hypothesis that sex-biased dispersal is determined by the different value of philopatry for the two sexes.

Correlates of male mating success in the ruff Philomachus pugnax, a lekking shorebird

Male ruffs (Philomachus pugnax), a lekking shorebird, can generally be divided into two morphs according to behavior and plumage coloration. Predominantly dark-colored, “independent” male ruffs defend small territories on a lek, whereas lighter colored “satellite” males are non-territorial and less site-faithful to a particular lek. The traits associated with the mating success of independent male ruffs were studied at two leks during two seasons on the island of Oland, Sweden in May and June of 1985 and 1987. Using multivariate analyses, three characteristics were found to be significantly related to mating success: high frequency of visits by satellites to an independent male's residence, consistency of lek attendance, and low rates of aggressive behavior. In contrast, mating success was unrelated to the degree of darkness of the independent male nuptial plumage, territory location on the lek, or rate of courtship displays. The use of multivariate analyses helped to resolve conflicting conclusions from previous studies which employed simple statistical analyses, or none at all. Experimental manipulations are suggested which will help to further determine the influence of female mate choice in this lekking system.

Bowers on the savanna: display courts and mate choice in a lekking widowbird

Individual display courts, constructed by lekking male Jackson's widowbirds, Euplectes jacksoni, were studied with respect to female mate choice. The court is a shaped tuft of grass, surrounded by a circular track on which displays and mating are performed. At the base of the tuft there are two cup-shaped recesses. Females sit in front of, and often pluck at, one ofthese recesses while males display at the opposite side for about 1 min before they approach and attempt to copulate. The vast majority of females visiting courts with experimentally destroyed or impaired recesses stayed shorter than the average time of male approach, whereas visits to improved courts lasted longer than visits to intact courts. All recorded copulations occurred at intact or improved courts. The display court is a weak predictor of male mating success compared to other choice cues such as display rate and tail length, but females may require the court quality to exceed a certain stimulus threshold to accept the male. Court quality correlates positively with male lek attendance and tail length. This paper discusses the implications of the results for sexual selection and considers the possibility that display courts are ‘external sexual ornaments.’ From comparative data on breeding behavior in related species, the display court and its associated behaviors are suggested to originate from male nest-initiation and female nest-inspection within an ancestral state of resource-defense polygyny.

The Red Queen Visits Sage Grouse Leks

Coevolution between parasites and host is a sufficient although not necessary condition for the evolution of secondary sexual characteristics. I review evidence supporting the role of parasites in the maintenance of lek behavior in Sage Grouse ( Centrocercus urophasianus ). Males bearing avianmalaria ( Plasmodium pediocetii ) or lice ( Lagopoecus gibsoni or Goniodes centrocerci ) have significantly lower reproductive success than noninfected males. Malaria-infected males attend leks significantly less frequently and lek attendance is highly correlated with male reproductive success. Inaddition, males with malaria secured copulations later in the breeding season with hens that wereyounger, in poorer condition, and less successful than mates of malaria-free males. Lice create hematomas on the air sacs of males which females can detect to avoid lousy males. Results of our field studies are reinforced by experiments; captive males given antibiotics to reduce parasite loads are chosen more often by females in arena trials. Our results lend empirical support for Hamilton and Zuk's (1982) interpretation of the RedQueen's hypothesis, although many unknowns remain in our understanding of the interaction between parasites and Sage Grouse.

Relationships between Blood Parasites, Mating Success and Phenotypic Cues in Male Sage GrouseCentrocercus urophasianus

In lek breeding Sage Grouse Centrocercus urophasianus in eastern California, male mating success is strongly correlated with individual differences in lek attendance, and in the rate and acoustic quality of courtship display, suggesting that these provide cues by which females choose mates. Increased lek attendance and high display rates are also associated with elevated metabolic expenditure. This paper examines the hypothesis that the ability to commit energy to display is related to the incidence of blood parasites. A single hematozoan genus, Haemoproteus, was found in 37.5% of 184 Sage Grouse sampled over a five year period. Parasitism varied across years and increased through the breeding season. However, no measure of display performance or mating success was significantly correlated with decreased parasite load among adult males. Several additional lines of evidence, including numerically low infection intensities, the absence of detectable effects of parasites on hematocrit and erythrocyte production, and the seasonal distribution of parasite incidenceall suggested that infections were unlikely to impact male courtship display. Alternative factors maintaining individual variation in male display performance in this population are also evaluated.

Sexual selection and cues for female choice in leks of Jackson's widowbird Euplectes jacksoni

Sexual selection through female mate choice was investigated in the lekking Jackson's widowbird by applying multivariate selection analysis to observational data from four leks. Males perform a stereotyped jump display on small display courts (“dance rings”) constructed by the males in open grassland. Females visit the lek solely for mating and nest on their own, away from the lek area. Few cases of interference during courtship and absence of position effects on mating success indicated that female choice within the leks was not pre-empted by male-male competition. In a set of 11 male traits with mating success as the dependent fitness measure, significant selection differentials (covariances) were found for the length of the conspicuous tail and the rate of the jump display, suggesting sexual selection of these traits. They also showed the largest selection gradients (partial effects) and thereby seem to be the cues on which females base their choice. The success of males in obtaining copulations appears to depend on two components: display rate and lek attendance affect the number of female visits, whereas tail length seems to primarily influence the chance of copulating with a visiting female. Tail length was positively related to a measure of body condition, which is of interest with regard to the suggestions that sexual ornaments may serve as indicators of male viability.

Correlates of copulatory success in a fallow deer lek

We studied the behavior and copulatory success of fallow deer (Cervus dama) males at a lek. We recorded 471 copulations in 3 years. Most males did not copulate. The top three males accounted for between 60 and 90% of copulations each year. Lek attendance time was the major determinant of male copulatory success, but territory location also affected the number of copulations achieved. Copulatory success was correlated with the number of females in a male's territory and possibly with dominance status, but not with fighting success or fighting rate. All males that defended lek territories were 5 years of age or older. Copulatory success may improve with age. Body condition appears to be an important determinant of male copulatory success, because only males in superior condition could defend a lek territory for up to 2 weeks. Males do not feed while defending lek territories. Foraging ability during the year probably determines condition at the onset of the rut. Females appear to choose mates at least partially on the basis of location, preferring males located near traditional routes. Females may ultimately select mates in the best body condition.

Sexual selection in lekking sage grouse: phenotypic correlates of male mating success

Mate choice cues in sage grouse were reinvestigated by analyzing relationships between male mating success and a range of suggested cues. Display cues were implicated by significant relationships between mating status (whether or not a male mated) and lek attendance, display rate (corrected for effects of female proximity and time of day) and an acoustic component related to temporal and frequency measure of a whistle emltted during the strut display. Although display rate and the acoustic component were intercorrelated, both exerted significant partial effects on mating success in mutivariate analyses. These display measures also differed significantly between males. In contrast, mating success was not significantly related to measures of territory characteristics, including size and proximity to the lek center, or to body size. These results resolve discrepancies between previous studies and provide a basis for experimental analysis of the role of female choice in this lek system.

Natal Dispersal and Lek Fidelity of Sage Grouse

Abstract Natal dispersal and lek fidelity (attendance within and between years) of Sage Grouse (Centrocercus urophasianus) were studied on Cold Spring Mountain, northwestern Colorado, from July 1981 through May 1984. Female Sage Grouse followed the typical avian pattern of dispersing farther than males. However, there was no difference between proportions of male and female yearling grouse attending the lek closest to their juvenile banding location. Fifteen percent of all individually marked juveniles (24/157 birds) were known to have attended leks as yearlings. There was no difference between yearling and adult lek attendance rates for either sex; however, females attended leks less often than males. Yearling females, but not yearling males, visited 2 or more leks more often than adults. These differences may be related to yearlings' inexperience with breeding or to a strategy to enhance reproductive success.

Lek Attendance of Male Sage Grouse

Le comptage des mâles sur les sites de reproduction est utilise pour estimer les tendances de la population en vue d'une bonne gestion de ce gibier (Centrocercus urophasianus). On precise ici la presence quotidienne des mâles sur les leks