The Red Queen Visits Sage Grouse Leks

Coevolution between parasites and host is a sufficient althoughnot necessary condition for the evolution of secondary sexualcharacteristics. I review evidence supporting the role of parasitesin the maintenance of lek behavior in Sage Grouse (Centrocercusurophasianus). Males bearing avianmalaria (Plasmodium pediocetii)or lice (Lagopoecus gibsoni or Goniodes centrocerci) have significantlylower reproductive success than noninfected males. Malaria-infectedmales attend leks significantly less frequently and lek attendanceis highly correlated with male reproductive success. Inaddition,males with malaria secured copulations later in the breedingseason with hens that wereyounger, in poorer condition, andless successful than mates of malaria-free males. Lice createhematomas on the air sacs of males which females can detectto avoid lousy males. Results of our field studies are reinforcedby experiments; captive males given antibiotics to reduce parasiteloads are chosen more often by females in arena trials. Ourresults lend empirical support for Hamilton and Zuk's (1982)interpretation of the RedQueen's hypothesis, although many unknownsremain in our understanding of the interaction between parasitesand Sage Grouse.     

Genetic mark-recapture analysis of winter faecal pellets allows estimation of population size in Sage Grouse Centrocercus urophasianus

The Sage Grouse Centrocercus urophasianus is a species of conservation concern throughout its range in western North America. Since the 1950s, the high count of males at leks has been used as an index for monitoring populations. However, the relationship between this lek-count index and population size is unclear, and its reliability for assessing population trends has been questioned. We used non-invasive genetic mark-recapture analysis of faecal and feather samples to estimate pre-breeding population size for the Parachute-Piceance-Roan, a small, geographically isolated population of Sage Grouse in western Colorado, during two consecutive winters from 2012 to 2014. We estimated total pre-breeding population size as 335 (95% confidence interval (CI): 287–382) in the first winter and 745 (95% CI: 627–864) in the second, an approximate doubling in abundance between years. Although we also observed a large increase in the spring lek-count index between those years, high male count data poorly represented mark-recapture estimates of male abundance in each year. Our data suggest that lek counts are useful for detecting the direction and magnitude of large changes in Sage Grouse abundance over time but they may not reliably reflect small changes in abundance that may be relevant to small populations of conservation concern.     

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.     

Evolution of black grouse leks: female preferences benefit males in larger leks

Leks, communal display grounds in which males display and femalesonly attend to mate, represent one of the most remarkable outcomesof sexual selection. There have been no detailed studies thatcompare the behavior of males and females between leks of differentsizes to test if there is any benefit for male clumping andto test the many hypotheses suggested to explain lekking. Inthe black grouse, Tetrao tetrix, larger leks have many morefemale visits and copulations, leading to a higher average malemating success. Females visiting larger leks are also more likelyto mate, indicating that female preferences of males are importantfor the evolution of leks. Yearling males seldom copulate, buttheir presence on the lek increases the mating success of adultmales, suggesting that lek size per se and not only male qualityaffects female preferences for larger leks. The distributionof males over lek sizes agrees with a game theory model of idealfree distribution with unequal competitors, in which less competitivemales go to smaller leks.     

The role of forest maturation in causing the decline of Black Grouse Tetrao tetrix

Black Grouse Tetrao tetrix in Britain have declined through the 20th century, and most birds are now in Scotland. Many causes for this decline have been suggested, notably agricultural intensification, increased grazing levels and moorland afforestation. We examine habitat correlates of Black Grouse distribution and population change from a 700-km² area in the core of the Scottish range, where the numbers of lekking male Black Grouse declined by an estimated 70% to 270 between 1990 and 2002. Habitat data were derived from satellite imagery, in combination with map and field-collected data. Lek occurrence, lek size and changes in lek size were all correlated with forest structure, either positively with the amount of pre-thicket forest cover, or negatively with closed canopy cover. Additional effects of the cover of grass moor and dry heath suggest that Black Grouse are most likely to occur where moorland comprises Heather Calluna vulgaris and grass mosaics. Analysis of the change in Black Grouse abundance within 1.5 km of discrete forest blocks suggests that forest maturation, which has been the dominant habitat change during the course of the study, alone accounts for 58–78% of the decline. Given the close association of Black Grouse and the occurrence of woodland (and particularly conifer plantation) throughout much of their British range, these findings can be used to inform the design of management schemes for the recovery of Black Grouse.     

Lek size variation and its consequences in the ochre-bellied flycatcher, Mionectes oleagineus

Several hypotheses suggest that the costs and benefits of displayin aggregations of different sizes play a major role in boththe evolution of leks and in the distribution of males acrossleks of different sizes. We examined the consequences of variationin lek size for both males and females in a study of the ochre-belliedflycatcher, Mionectes oleagineus. We observed 41 solitary displaysites and leks, ranging in size from 1 to 5 mates, over 3 breedingseasons. Although mean visitation rate by females was positivelycorrelated with lek size, female visitation rate per male remainedconstant across lek sizes. The rate at which females visitedthe male who had the highest female visitation rate at eachlek was positively correlated with lek size as predicted bythe hotshot hypothesis. Neither mean nor per capita intrusionrates were correlated with lek size. For the top-ranked male,however, there was a significant correlation between intrusionrates and the size of the lek at which he displayed. Intrusionat leks may be costly, as 28% of female visits were interruptedby intruders. Solitary mates suffered no such interference.Females show no preferences for larger leks, visiting and matingat solitary sites as well as at leks. However, females preferentiallyvisit males with high singing rates, and this male trait maydetermine visitation patterns. Our data argue that preferencesfor larger leks are not important in the evolution of lekkingin this species, nor do they affect lek size. Instead, the dataare in accordance with the predictions of both the hotshot andhot-spot models. These processes may be operating simultaneouslyin this species     

Predators of Greater Sage‐Grouse nests identified by video monitoring

ABSTRACT Nest predation is the primary cause of nest failure for Greater Sage‐Grouse (Centrocercus urophasianus), but the identity of their nest predators is often uncertain. Confirming the identity of these predators may be useful in enhancing management strategies designed to increase nest success. From 2002 to 2005, we monitored 87 Greater Sage‐Grouse nests (camera, N= 55; no camera, N= 32) in northeastern Nevada and south‐central Idaho and identified predators at 17 nests, with Common Ravens (Corvus corax) preying on eggs at 10 nests and American badgers (Taxidea taxis) at seven. Rodents were frequently observed at grouse nests, but did not prey on grouse eggs. Because sign left by ravens and badgers was often indistinguishable following nest predation, identifying nest predators based on egg removal, the presence of egg shells, or other sign was not possible. Most predation occurred when females were on nests. Active nest defense by grouse was rare and always unsuccessful. Continuous video monitoring of Sage‐Grouse nests permitted unambiguous identification of nest predators. Additional monitoring studies could help improve our understanding of the causes of Sage‐Grouse nest failure in the face of land‐use changes in the Intermountain West.     

Native woodland creation is associated with increase in a Black Grouse Lyrurus tetrix population

Capsule: Black Grouse population increases were greatest where new native woodland (NNW) within 1500?m of leks comprised approximately 30% of land area and averaged 5 years old.

Aims: To examine whether change in a population of Black Grouse Lyrurus tetrix in Scotland was associated with the creation of native woodland.

Methods: We examined whether lek location, size and change in size were associated with habitat and topography surrounding leks. We also examined vegetation differences in NNW and adjacent unplanted moorland.

Results: From 2002 to 2012 the number of lekking male Black Grouse increased by 90%. Lek occurrence was positively associated with the amount of NNW edge habitat. Leks were larger where there was more adjacent NNW. Lek increases were greatest where NNW plots comprised approximately 30% land area, and were 5 years old, within a 1500?m radius. Plots aged more than approximately 20 years old were associated with Black Grouse population declines. NNW supported taller and denser important field-layer vegetation than adjacent moorland, likely due to grazing exclusion.

Conclusions: Subject to longer-term management commitments to stimulate continued regrowth of the important field layer and maintain benefits for Black Grouse, expansion of native woodland could contribute to landscape-scale recovery of Black Grouse after decades of decline.     

Movements of female Sage Grouse Centrocercus urophasianus during incubation recess

We combined GPS data‐loggers, VHF transmitters and DVR video‐monitoring to measure fine‐scale movement patterns during daily incubation recesses by female Sage Grouse Centrocercus urophasianus, a species with uniparental incubation that has experienced widespread population decline and distributional contraction. Most (69.6%) Sage Grouse recess activity was highly localized within a core recess area averaging 2.58 ± 0.64 ha, and females remained within 242.3 ± 30.0 m from the nest during recesses (total recess areas were 11.06 ± 2.27 ha). Visually conspicuous Sage Grouse movements near nests at the start and end of recesses and consistent occupation of core recess areas point to a mechanism for newly abundant predators such as the Northern Raven Corvus corax to detect and depredate Sage Grouse nests. Our methods apply to other avian species of scientific interest and conservation concern.     

Queuing for territory positions in the lekking black grouse (Tetrao tetrix)

The importance of a central territory position as a determinantof male mating success in lekking species has been debated.The process by which a male can obtain a central territory hasbeen especially lacking a quantitative analysis. We presenta stochastic queuing model describing territory succession towardthe lek center and apply it to a 8-year sequence of territorycentrality measures on a black grouse Tetrao tetrix lek. Thelek shows a value of intermediate queue discipline, which deviatessignificantly both from strict orderly queuing and from randomranking of males. Thus, high-ranking males are partly able tomaintain their superior position over years, but queue-jumpingis not excluded; especially because highly succesful males donot attempt to change their territory position toward the lekcenter. As a result of stochastic queuing, a central territoryindicates an older than average male, as well as a male witha history of high fighting rates. These results are consistentwith the hypotheses that territory position is an honest signalof male quality and that the long-term fighting effort and survivalrequired to acquire a central territory may increase the reliabilityof the signal over that of short-term display effort. The impartialqueue discipline, however, also leaves room for other male characteristicsto play a role in determining individual mating success.     

Are Centrally Displaying Males Always the Centre of Female Attention? Acoustic Display Position and Female Choice in a Lek Mating Subterranean Insect

Several conceptual models seek to explain patterns of male display and factors that influence female mate choice in lek mating systems. The central advantage model predicts that males displaying at or near the lek centre should be more attractive to females than are males positioned along the lek periphery. Females may exhibit biases toward these centrally displaying males based on either spatial or display‐related cues. We tested the prediction of the central advantage model in investigating the importance of male display position in the subterranean and lek mating prairie mole cricket (Gryllotalpa major). Gryllotalpa major males form mating aggregations in the early spring and produce an acoustic advertisement signal from a constructed calling chamber at the soil surface. Pair formation occurs in the calling chamber, and males typically maintain these structures for the duration of the reproductive season. To assess whether G. major females exhibit a preference for males calling from centrally located acoustic burrows, we documented the spatial position and number of female attractions for all advertising males across the focal lek. Six spatial attributes related to display position were reduced using principal component analysis and examined for an association with male attractiveness. We found that in general, female attractions were distributed randomly across the lek; male attractiveness was not related to proximity to the lek centre nor to any factor associated with display position. The most highly attractive males, however, were located further from the lek centre and from nearest calling neighbours than other attractive males. Advertising males that segregate themselves within the aggregation and locate nearer the lek margin may gain a geometric advantage resulting in the increased probability of attracting a searching female.     

Correlates of male mating success and female choice in a lek-breeding antelope

We investigated factors underlying variation in male matingsuccess in Uganda kob (Kobus kob thomasi), a lek-breeding antelope.We found that only heavy (and, possibly, relatively old) malesheld lek territories and that female choice was an importantdeterminant of nonrandom mating patterns at leks. Our measureof male mating success was closely related to the historicalpopularity of the territory that a male defended, and individualfemales showed consistent preferences for particular lek territories,despite changes in territory ownership. Male success increasedwith body weight and declined independently of territory effectsduring each bout of lek territory tenure. We also found someevidence that female kob copied one another's choice of matesbecause females arriving at a lek tended to join territoriesthat already had relatively large harems on them. When comparedacross leks, average male mating success increased with leksize. Our results suggest that female kob may use a suite ofmale- and territory-based cues in mate choice at leks and, asa result, mate with particularly large males. However, we wereunable to determine whether female kob gain any direct or indirectbenefits through mate choice at leks.     

Dispersion of greater prairie chicken nests in relation to lek location: evaluation of the hot-spot hypothesis of lek evolution

The hot-spot hypothesis suggests that males should establishleks in areas where they are more likely to encounter females;these areas are determined, in part, by overlap in home rangesof females. We examined this hypothesis using data on movementof greater prairie chickens (Tympanuchus cupido) in northeasternColorado during 1986–1988. The relative quality of variouslocations as potential lek sites was estimated using nest-to-lekdistances of females; quality (male breeding potential) wasevaluated on a scale of 0 to 1 and was positively correlatedwith proximity to nest sites of females. Monte Carlo simulationswere conducted to examine male breeding potential under varyingconditions of observed and random lek locations. Male breedingpotential was higher at actual lek sites than at random leksites. Distributions of leks and nests supported predictionsof the hot-spot hypothesis.     

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

Individual display courts, constructed by lekking male Jackson'swidowbirds, Euplectes jacksoni, were studied with respect tofemale mate choice. The court is a shaped tuft of grass, surroundedby a circular track on which displays and mating are performed.At the base of the tuft there are two cup-shaped recesses. Femalessit in front of, and often pluck at, one ofthese recesses whilemales display at the opposite side for about 1 min before theyapproach and attempt to copulate. The vast majority of femalesvisiting courts with experimentally destroyed or impaired recessesstayed shorter than the average time of male approach, whereasvisits to improved courts lasted longer than visits to intactcourts. All recorded copulations occurred at intact or improvedcourts. The display court is a weak predictor of male matingsuccess compared to other choice cues such as display rate andtail length, but females may require the court quality to exceeda certain stimulus threshold to accept the male. Court qualitycorrelates positively with male lek attendance and tail length.This paper discusses the implications of the results for sexualselection and considers the possibility that display courtsare ‘external sexual ornaments.’ From comparativedata on breeding behavior in related species, the display courtand its associated behaviors are suggested to originate frommale nest-initiation and female nest-inspection within an ancestralstate of resource-defense polygyny.     

Designing mosaic landscapes for Black Grouse Tetrao tetrix using multi‐scaled models

With increasing pressures on land for human use, it is important to identify the habitat requirements of key species, not just in terms of a correlation with a given habitat feature, but also the relationship between species presence and its coverage, proximity to other habitat types, and importance at different spatial scales. We used maximum entropy to estimate the optimal proportions of 18 habitat types, plus elevation and habitat richness associated with the presence of leks of Black Grouse Tetrao tetrix within an 800‐km² study area in Perthshire, Scotland. We repeated the analysis at several radii (0.2–3 km) to assess how the importance of different habitats changed with proximity to lek and scale. We then examined habitat features or combinations of features that were associated with large leks or positive lek growth. Models at all radii had satisfactory predictive power. Using response curves from maxent , we constructed ideal habitat mixes for leks at each radius. At the 2‐km radius, suitability was highest with around 20% each of three moorland types and open/mixed forestry, whereas close to leks (0.2 km), higher proportions of grouse moor and lower proportions of closed‐canopy woodland were optimal. The relationship between habitat and lek size or direction of lek growth was complex, indicating that a landscape containing large or productive leks can be the result of more than one combination of habitats. This demonstrates a degree of flexibility in designing landscapes for Black Grouse conservation, so landowners can prioritize combinations of habitats that are the most practical and/or economical, while still serving the requirements of the target species.     

Lek fidelity and movement among leks by male Greater Sage‐grouse Centrocercus urophasianus: a capture‐mark‐recapture approach

Males in lek mating systems tend to exhibit high fidelity to breeding leks despite substantial evidence of skewed mating success among males. Although movements between leks are often reported to be rare, such movements provide a mechanism for an individual to improve lifetime fitness in response to heterogeneity in reproductive conditions. Additionally, estimates of apparent movements among leks are potentially biased due to unaccounted variation in detection probability across time and space. We monitored breeding male Greater Sage‐grouse Centrocercus urophasianus on 13 leks in eastern Nevada over a 10‐year period, and estimated movement rates among leks using capture‐mark‐recapture methods. We expected that male movement rates among leks would be low, despite predictions of low breeding success for most males, and that detection rates would be highly variable among leks and years. We used a robust design multistate analysis in Program mark to estimate probability of movements among leks, while accounting for imperfect detection of males. Male Sage‐grouse were extremely faithful to their leks; the annual probability of a male moving away from its original lek of capture was approximately 3% (se = 0.01). Detection probabilities varied substantially among leks (range = 0.21–0.95), and among years (range = 0.30–0.76), but remained relatively constant within years at each lek. These results suggest that male Sage‐grouse dispersal is either rare, or consists primarily of dispersal of sub‐adults from their natal areas prior to the breeding season. The study highlights the benefits of robust design multistate models over standard ‘live‐encounter’ analyses, as they not only permit estimation of additional parameters, such as movement rates, but also allow for more precise parameter estimates that are less sensitive to heterogeneity in detection rates. Additionally, as these data were collected using capture‐mark‐recapture methods, our approach to estimating movement rates would be beneficial in systems where radiotagging is detrimental to the study organism.     

Ruffed Grouse Bonasa umbellus habitat selection in a spatially complex forest: evidence for spatial constraints on patch selection

Drumming display sites of male Ruffed Grouse Bonasa umbellus serve as activity centres and occur in a variety of forest types and age classes. We used a case‐control study design and model selection to evaluate a set of predictions about habitat constraints placed upon Grouse given the habitat where their breeding season activity centres were located. We located 110 individual Grouse activity centres near Cloquet, Minnesota, between 2002 and 2005, and 40 activity centres at two other sites in northern Minnesota in 2005. Our most parsimonious model indicated that Ruffed Grouse used logs more than other potential drumming structures (e.g. stumps, dirt mounds or roots) and sites with a higher density of shrubs as compared with unused sites. Predicted values from this model correlated with observed values from independently sampled areas. Structures used by Grouse for their drumming display were characterized by a greater density of aspen stems than unused sites when in young aspen and mature pine, but not when in other forest types. The patterns of habitat selection that we observed supported predictions (1) that the differences in habitats at larger spatial scales (e.g. forest stands or breeding territories) may impose certain constraints on specific sites selected for their drumming display, and (2) that some of these constraints may vary by forest type.     

No peace for estrous topi cows on leks

Male coercion, such as harassment, may be considered the thirdmain component in sexual selection alongside male competitionand female choice. In this study on lek-breeding topi antelopes(Damaliscus lunatus), I investigate whether female mating preferenceshave consequences for male investment in harassment and whetherharassing males are more likely to succeed in mating. I thenaddress the question of whether lek evolution in topi can beexplained by harassment avoidance. Judging from mating rate,I found that female topi antelopes in estrus preferred lek malesto resource defenders. In contrast to lek males, resource defendersdemonstrated significantly higher harassment rates before theysucceeded in mating than when they did not, and the precopulatoryharassment rate was significantly higher on resource territoriesthan on lek territories. After mating on resource territories,harassment dropped to low levels. Thus, resource defenders,but not lek males, seem to employ harassment as a strategy tocoerce females to mate against their preference. However, byusing various measures of harassment intensity, overall estrousfemales were found to experience higher harassment levels onlek, and chases by intruders were relatively rare on all territorytypes. These findings suggest that harassment avoidance is unlikelyas an explanation for lek evolution.     

Correlates of male mating success in a lekking bird with male-male cooperation

Correlates of male mating success were examined in a population of long-tailed manakins, Chiroxiphia linearis, that included 270 colour-banded individuals. Long-tailed manakins have a lek mating system and male-male cooperation in courtship display. Multivariate analysis of behavioural variables indicated that female visitation correlated with the number of unison ‘toledo’ calls given by male partners. Given a female vist, copulatory success was correlated with the ‘butterfly’ display component of the dual-male dance. Both ‘toledo’ output and dance display differed significantly between perch-zones. Only six to eight partnerships in a local population of as many as 55 males per season performed call displays at a level (75–335 toledos per h) that was correlated with any female visitation. Data on crown plumage of female visitors suggested that younger females may have been less discriminating than were older females. The relationship between variance in mating success and the evolution of cooperative male display is discussed.     

Mate retention, harassment, and the evolution of ungulate leks

Current models of lek breeding mostly suggest that males defendclustered mating territories because females show a preferencefor mating on leks. Here we argue that, in lek-breeding ungulates,males may also gain benefits from holding clustered mating territoriesbecause clusters retain does in estrus. We show that in fallowdeer (Dama dama) harems are commonly disrupted by young males.Bucks that hold territories on the lek that lose their haremsquickly regain does as other harems are disrupted, whereas bucksdefending isolated, single territories rarely regain does thesame day. The risk of harassment may also help to explain whydoes in estrus leave the large, unstable herds that they usuallylive in. Does in estrus are frequently chased by young maleswhen outside male mating territories. Benefits of moving tothe lek (versus moving to single territories) include reducedrisks of long chases. Though intrusions by young bucks are thecommonest cause of does leaving male territories in our studypopulation, other factors that cause does to move between neighboringharems (including disturbance by predators and persistent courtshipby males) may generate benefits to males holding clustered matingterritories. Once clustered mating territories have developed,the additional costs of mate choice are likely to be low, andfemale preferences for particular male characteristics may belikely to develop.