Resource Dispersion Research Articles

Markov fracture models of inhomogeneous media and design of layered structures synthesized by additive technology

We consider the problem of studying the fracture of a composite macrolayer synthesized by additive technology on a solid substrate, to which the boundary of the lower microlayer is rigidly bonded. The materials of the microlayers are homogeneous and isotropic. The thicknesses of microlayers and the total thickness of the macrolayer are the control parameters of synthesis. The physical and mechanical characteristics of the microlayers and their combination in the macrolayer are also controlling parameters. The layer is fractured by a crack, which may appear in the top layer (or any other layer) and move toward the substrate or free surface, perpendicular to the boundaries of the microlayers. The crack can stop at the boundaries between the layers (then it is treated as a separate state) or pass through the boundaries without stopping. Based on the theory of Markov chains, the average lifetime of a stratified layer synthesized on a substrate using additive technology and the variance of the number of cycles (lifetime) characterizing the quality of the synthesized structure are calculated. On the basis of the materials available for the synthesis of the layered coating, the problems of optimal design of the composite body with maximum average resource, minimum resource dispersion, maximum specific strength for given geometric and physical-mathematical constraints on the composite parameters are solved. To find optimal solutions, dynamic programming algorithms are used, implemented on circuits (graphs) of sequential selection of a combination of layer materials according to their synergistic properties.

Investigating the effects of landscape productivity on the spatial ecology of a threatened marsupial inside feral predator exclosures

AbstractLandscape productivity and resource dispersion are key drivers of the movement patterns of many species. In less productive environments, home ranges are generally larger as individuals travel further to access resources. The greater bilby (Macrotis lagotis) has been reintroduced to several feral predator exclosures to reduce their extinction risk. Understanding how landscape productivity and resource dispersion influence bilby space use is critical to enable effective management of populations in exclosures. At two exclosures, we tested three hypotheses: 1. Bilbies would preferentially utilize habitats with sandy substrates (<20% clay content), as they are suitable for digging burrows and foraging pits; 2. Home ranges would be larger at the arid site compared to the semi‐arid site due to lower productivity and patchier distribution of preferred habitats; and 3. Bilbies would travel further each night at the arid site to access preferred habitats. Rainfall was used as an indicator of productivity, and dispersion of preferred habitats as an indicator of resource dispersion. The study was undertaken during average rainfall conditions and under similar bilby population densities at both sites. GPS loggers recorded home ranges and movements of 10 bilbies at the arid site, and 11 bilbies at the semi‐arid site. Seventeen of the 21 bilbies preferentially utilized habitats with sandy substrates, which were less abundant at the arid site. There were no significant differences in home range size or nightly movements between the sites for either sex. We suggest the average rainfall conditions at both sites, and the dietary flexibility of bilbies, supported the maintenance of relatively small and stable home ranges (particularly for females). The effects of landscape productivity and resource dispersion on bilby space use are more likely to be evident during extended periods of below average rainfall. Bilby home range studies during low rainfall conditions (e.g. drought) are required for the effective, long‐term management of exclosure populations.

Population density and ranging behaviour of a generalist carnivore varies with human population.

Canid species are highly adaptable, including to urban and peri-urban areas, where they can come into close contact with people. Understanding the mechanisms of wild canid population persistence in these areas is key to managing any negative impacts. The resource dispersion hypothesis predicts that animal density increases and home range size decreases as resource concentration increases, and may help to explain how canids are distributed in environments with an urban-natural gradient. In Australia, dingoes have adapted to human presence, sometimes living in close proximity to towns. Using a targeted camera trap survey and spatial capture-recapture models, we estimated spatial variation in the population density and detection rates of dingoes on Worimi Country in the Great Lakes region of the NSW coast. We tested whether dingo home range and population densities varied across a gradient of human population density, in a mixed-use landscape including, urban, peri-urban, and National Park environs. We found human population density to be a strong driver of dingo density (ranging from 0.025 to 0.433 dingoes/km2 across the natural-urban gradient), and to have a negative effect on dingo home range size. The spatial scale parameter changed depending on survey period, being smaller in the peak tourism period, when human population increases in the area, than in adjacent survey periods, potentially indicating reduced home range size when additional resources are available. Our study highlights the potential value of managing anthropogenic resource availability to manage carnivore densities and potential risk of human-carnivore interactions.

Spatial behaviors and seasonal habitat use of the increasingly endangered thick-billed parrot (Rhynchopsitta pachyrhyncha)

The thick-billed parrot (Rhynchopsitta pachyrhyncha) inhabits highland pine forests in the Sierra Madre Occidental ranges of northwestern Mexico. Their populations have declined significantly to < 2000 individuals due to habitat loss, illegal hunting and increasing predation. Despite their ecological and cultural importance and increasingly endangered status, the species is data deficient. Our study aimed to inform and enhance conservation management strategies for thick-billed parrots with information on their spatial ecology, habitat use, migratory behaviors and social associations. We deployed biotelemetry devices to conduct the first tracking study of wild thick-billed parrots. Our study revealed that thick-billed parrots are seasonal migrators, departing their breeding habitats around October and returning from southern habitats around April. Our research also identified previously unknown overwintering sites and migratory stopover locations, as well as a new nesting site. The parrots exhibited high spatial variability in range shifting behavior, but all tracked parrots exhibited range shifts during migration, with durations of 3–181 days and distances of 173–765 km. They traveled in close social groups and migratory routes primarily followed high-elevation forests along the Sierra Madre Occidental ranges. Home range analysis indicated smaller breeding site ranges and larger overwintering ranges, possibly reflecting nesting constraints and winter food resource dispersion. Parrot spatial associations favored high-elevation forest landscapes with tall and wide-trunked trees, underscoring the importance of preserving old-growth forests for nesting and foraging. Less than 20% of parrot habitats have formal regulatory protections. Conservation management efforts must focus on increasing protections for nesting areas, overwintering habitats, and key migratory stopover sites. As climate change exacerbates regional threats, integrated management plans involving local stakeholders and communities are essential for the parrots' long-term survival and the preservation of their old-growth forest habitats.

S-Band WDM Transmission Using PPLN-Based Wavelength Converters and 400-Gb/s C-Band Real-Time Transceivers

Multi-band WDM transmission beyond the C+L-band is a promising technology for achieving larger capacity transmission by a limited number of installed fibers. In addition to the C- and L-band, we can expect use the S-band as the next band. Although the development of optical components for new bands, particularly transceivers, entails resource dispersion, which is one of the barriers to the realization of multi-band systems, wavelength conversion by transparent all-optical signal processing enables new wavelength band transmission using existing components. Therefore, we proposed a transmission system including a new wavelength band such as the S-band and made it possible to use a transceiver for the existing band by performing the whole-band wavelength conversion without using a transceiver for the new band. As a preliminary verification to demonstrate multi-band WDM transmission including S-band, we investigated the application of a novel wavelength converter between C-band and S-band, which consists of periodically poled lithium niobate waveguide, to the proposed system. We first characterized the conversion efficiency and noise figure of the wavelength converter and estimated the transmission performance of the system through the wavelength converter. Using the evaluated wavelength converters and test signals of 64 channels arranged in the C-band at 75-GHz intervals, we constructed an experimental setup for S-band transmission through an 80-km standard single-mode fiber. We then demonstrated error-free transmission of real-time 400-Gb/s DP-16QAM signals after forward error correction decoding. From the experimental results, it was clarified that thewavelength converter which realizes the uniformlossless conversion covering the whole C-band effectively achieves the S-band WDM transmission, and it was verified that the capacity improvement of the multi-band WDM system including the S-band can be expected by applying it in combination with the C+L-band WDM system.

Using Simple Design Features to Recapture the Essence of Real-Time Strategy Games

Real-time strategy (RTS) games simulate battlefield leadership and tactical and strategic operations. Most overemphasize the number of actions per minute (APM), which encourages players to click rapidly and constantly rather than apply deliberate and finely tuned strategies or tactics. New RTS games featuring resource dispersion game mechanics aimed at reducing APM demand and promoting strategic planning are being released. We created three versions of a single RTS game, recruited players, recorded their game control data, and asked them to complete a simple after-game questionnaire. Data were used to analyze tactical and strategic applications. Player actions were observed and player opinions analyzed in an attempt to identify an optimal game structure as measured by strategic and tactical play.

NICKEL ORE RESOURCES MODELING USING GEOSTATISTICAL METHOD AT BONI VILLAGE, RAJA AMPAT REGENCY, WEST PAPUA

Estimating of nickel resource in block WN-01 PT. Karunia Alam Waigeo, West Papua aims to understand the number of metal tonnages and the direction of the resource dispersion. The study has been done with phases which are literature study, retrieval of drill data (49 boreholes), data processing with Ordinary Kriging (OK) method using GS+ version 70 software, in as much, estimating the resources using block method kriging and point kriging. To understand the estimation correlation of grade to composite grade the scatter diagram analysis was used. Based on the scatter diagram (scatter plot) for the block kriging method correlation coefficient of 0,8843 is obtained while for the point kriging method is 0,8935. With a standard deviation of 0,3280, the point block kriging method has obtained 18.630,08 tons of nickel while for the point kriging method with 0,4060 of the standard deviation the nickel obtained is 18.875,41 tons.

Resources and predation: drivers of sociality in a cyclic mesopredator

In socially flexible species, the tendency to live in groups is expected to vary through a trade-off between costs and benefits, determined by ecological conditions. The Resource Dispersion Hypothesis predicts that group size changes in response to patterns in resource availability. An additional dimension is described in Hersteinsson’s model positing that sociality is further affected by a cost–benefit trade-off related to predation pressure. In the arctic fox (Vulpes lagopus), group-living follows a regional trade-off in resources’ availability and intra-guild predation pressure. However, the effect of local fluctuations is poorly known, but offers an unusual opportunity to test predictions that differ between the two hypotheses in systems where prey availability is linked to intra-guild predation. Based on 17-year monitoring of arctic fox and cyclic rodent prey populations, we addressed the Resource Dispersion Hypothesis and discuss the results in relation to the impact of predation in Hersteinsson’s model. Group-living increased with prey density, from 7.7% (low density) to 28% (high density). However, it remained high (44%) despite a rodent crash and this could be explained by increased benefits from cooperative defence against prey switching by top predators. We conclude that both resource abundance and predation pressure are factors underpinning the formation of social groups in fluctuating ecosystems.

Inferences on mobility and subsistence patterns from degenerative joint disease and entheseal changes. Trends in the farmer/forager border (Central-Western Argentina).

This study tests the hypothesis that the incorporation of cultigens about ca. 2000 years BP substantially changed hunter-gatherer subsistence and mobility in the Atuel River valley (Central-Western Argentina), where the frontier of pre-Hispanic domesticated resource dispersion was defined. Degenerative joint disease and entheseal change markers were analyzed on skeletal remains from Cañada Seca-1, a burial archaeological site with commingled skeletal remains dated about ca. 1500 years BP (MNI = 24). The results show lower mobility in comparison with hunter-gatherer remains from the neighboring Pampa region and quite different manual activities compared to low-level producers. These trends are explained as a result of a mixed subsistence strategy and mobility in an area where the incorporation of domesticated plants was neither a linear nor a fast process, and a stereotypical view proves to be insufficient to understand it. Although further information is required for future discussions, the present research highlights the potential of commingled skeletal remains for this kind of study.

Variable intraspecific space use supports optimality in an apex predator

Within optimality theory, an animal’s home range can be considered a fitness-driven attempt to obtain resources for survival and reproduction while minimizing costs. We assessed whether brown bears (Ursus arctos) in two island populations maximized resource patches within home ranges (Resource Dispersion Hypothesis [RDH]) or occupied only areas necessary to meet their biological requirements (Temporal Resource Variability Hypothesis [TRVH]) at annual and seasonal scales. We further examined how intrinsic factors (age, reproductive status) affected optimal choices. We found dynamic patterns of space use between populations, with support for RDH and TRVH at both scales. The RDH was likely supported seasonally as a result of bears maximizing space use to obtain a mix of nutritional resources for weight gain. Annually, support for RDH likely reflected changing abundances and distributions of foods within different timber stand classes. TRVH was supported at both scales, with bears minimizing space use when food resources were temporally concentrated. Range sizes and optimal strategies varied among sex and reproductive classes, with males occupying larger ranges, supporting mate seeking behavior and increased metabolic demands of larger body sizes. This work emphasizes the importance of scale when examining animal movement ecology, as optimal behavioral decisions are scale dependent.

Group density, disease, and season shape territory size and overlap of social carnivores.

The spatial organization of a population can influence the spread of information, behaviour and pathogens. Group territory size and territory overlap and components of spatial organization, provide key information as these metrics may be indicators of habitat quality, resource dispersion, contact rates and environmental risk (e.g. indirectly transmitted pathogens). Furthermore, sociality and behaviour can also shape space use, and subsequently, how space use and habitat quality together impact demography. Our study aims to identify factors shaping the spatial organization of wildlife populations and assess the impact of epizootics on space use. We further aim to explore the mechanisms by which disease perturbations could cause changes in spatial organization. Here we assessed the seasonal spatial organization of Serengeti lions and Yellowstone wolves at the group level. We use network analysis to describe spatial organization and connectivity of social groups. We then examine the factors predicting mean territory size and mean territory overlap for each population using generalized additive models. We demonstrate that lions and wolves were similar in that group-level factors, such as number of groups and shaped spatial organization more than population-level factors, such as population density. Factors shaping territory size were slightly different than factors shaping territory overlap; for example, wolf pack size was an important predictor of territory overlap, but not territory size. Lion spatial networks were more highly connected, while wolf spatial networks varied seasonally. We found that resource dispersion may be more important for driving territory size and overlap for wolves than for lions. Additionally, canine distemper epizootics may have altered lion spatial organization, highlighting the importance of including infectious disease epizootics in studies of behavioural and movement ecology. We provide insight about when we might expect to observe the impacts of resource dispersion, disease perturbations, and other ecological factors on spatial organization. Our work highlights the importance of monitoring and managing social carnivore populations at the group level. Future research should elucidate the complex relationships between demographics, social and spatial structure, abiotic and biotic conditions and pathogen infections.

Spatial Aspects of Gardens Drive Ranging in Urban Foxes (Vulpes vulpes): The Resource Dispersion Hypothesis Revisited.

Red foxes are a well-established species of urban ecosystems in the UK and worldwide. Understanding the spatial ecology of foxes in urban landscapes is important for enhancement of urban biodiversity and effective disease management. The Resource Dispersion Hypothesis (RDH) holds that territory (home range) size is linked to distribution and richness of habitat patches such that aggregation of rich resources should be negatively associated with range size. Here, we tested the RDH on a sample of 20 red foxes (Vulpes vulpes) in the city of Brighton and Hove. We focused on residential garden areas, as foxes were associated with these in previous studies. We equipped 12 male and 8 female foxes with GPS collars recording at 15 min intervals during discrete seasons over four years. We regressed fox core area size against garden size, number of garden patches, and edge density within and between patches as extracted from GIS in a series of bivariate linear mixed models. We found that foxes used smaller core areas where gardens were large and well-connected and larger core areas where numerous, smaller gardens were fragmented by internal barriers (e.g., fences, walls) or bisected by other habitats such as managed grassland or built-up areas. Our findings confirm the RDH and help to inform future urban planning for wildlife.

Resource dispersion and relatedness interact to explain space use in a solitary predator

Resource dispersion or kin selection are commonly used to explain animal spatial and social organization. Despite this, studies examining how these factors interact in wild populations of solitary animals are rare. We used 16 years of individual‐level spatial and genetic data to disentangle how resources and relatedness influence spatial organization of a solitary predator, the Eurasian lynx Lynx lynx. As expected, space‐use overlap between neighbouring individuals increased when food resources were heterogeneous and unpredictably distributed (as predicted from resource dispersion) or when neighbours were closely related (as predicted from kin selection). However, these patterns were highly dependent on each other. Increased spatial overlap was restricted to mother–daughter dyads, with this effect only occurring in areas and during seasons when prey was clumped and irregularly distributed in the landscape. Additionally, full‐siblings with similar levels of genetic relatedness did not show these patterns, suggesting that kin selection is mediated through mother–daughter recognition, and is only beneficial under specific resource dispersion circumstances. Our results provide key insights into the flexibility of spatial organization of solitary animals, and clearly show the importance of considering the interaction between resources and kinship when assessing animal space use patterns.

Movement barriers, habitat heterogeneity or both? Testing hypothesized effects of landscape features on home range sizes in eastern indigo snakes

AbstractAnimal home ranges are influenced by diverse intrinsic and extrinsic factors. For example, habitat heterogeneity may affect the spatial distribution of resources leading to larger home ranges where resources are spatially dispersed or, conversely, smaller home ranges where resources are concentrated or abundant. Other landscape features may lead to smaller home ranges by constraining or restricting animal movements. Understanding the relative importance of these two processes is increasingly important given the prevalence of anthropogenic features across contemporary landscapes. We test the relative importance of habitat heterogeneity and movement restriction on the home range size of a wide‐ranging, habitat and dietary generalist, the federally threatened eastern indigo snake (Drymarchon couperi). We used data from 83 radio‐tracked individuals in a multi‐scale analysis of home range size as a function of multiple landscape features representing land cover and habitat heterogeneity. We found that home range size was negatively correlated to habitat heterogeneity (i.e., the standard deviation of normalized difference vegetation index [NDVI]) and urban intensity. Smaller home ranges in areas with high habitat heterogeneity and low urban intensity likely reflected reduced resource dispersion through the concentration of diverse foraging habitats. Home ranges were smallest in urban landscapes which, combined with previously documented avoidance of urban habitats by eastern indigo snakes, suggests that urban land cover restricts home range size. Our results demonstrate the importance of considering both the influence of resource dispersion and movement barriers in understanding animal space use. Moreover, we highlight the need to consider the potential role of anthropogenically subsidized resources (e.g., prey, shelter sites) to understand variation in eastern indigo snake home range sizes within urban areas.

Who and How: Exploring the Preferred Senders and Channels of Mental Health Information for Wisconsin Farmers.

Unfavorable economic and environmental conditions have fueled the development of mental health resources and services for farmers. However, it is unclear who farmers want mental health information from (senders) and how they want mental health information delivered (channels). A self-administered questionnaire was used to determine the preferred senders of mental health information and the preferred channels of mental health information. Farmers were most receptive to receiving mental health information from medical providers, spouses/family members, and friends. Among the channels of information, respondents were interested in receiving mental health information from farm newspapers/magazines and one-on-one in person. Our findings have pragmatic implications for agricultural safety and health and public health organizations working to disseminate mental health information to farmers. Receptiveness to specific senders and channels of information among farmers should inform resource dispersion and future intervention.

Spatial partitioning by a subordinate carnivore is mediated by conspecific overlap.

There are several hypotheses that could explain territory size in mammals, including the resource dispersion hypothesis (RDH), the intruder pressure hypothesis (IPH), and the intraguild predation hypothesis (IGPH). In this study, we tested predictions of these three hypotheses regarding territories of 19 packs of endangered African wild dogs (Lycaon pictus) over 2years in the Kruger National Park, South Africa. If territory size was supported by the RDH, then we would observe (1) wild dog territories would be larger when resource patches were more dispersed, (2) pack sizes would be larger when resource patches were rich, and (3) pack size would not affect territory size. If supported by the IPH, then we would observe (4) larger territories would experience less intrusions, and (5) there would be an increase in territory overlap in areas of low resource dispersion. Finally, if supported by the IGPH, we would observe (6) territories would be larger in areas of higher lion (Panthera leo) density, as evidence of a spatial avoidance strategy. We found that the IGPH was fully supported (6), the IPH half supported (5), and the RDH partially supported (1 and 3), where we found spatial partitioning of wild dogs with lions, potentially mediated by resources and territory overlap with conspecifics. Ultimately, our results show that subordinate carnivores must balance a trade-off between dominant interspecific competitors and conspecifics to successfully coexist in areas with dominant carnivores.

Breeding Behavior of Mara [Dolichotis patagonum (Zimmermann, 1780)] in the Monte-Chaco Ecotone of Argentina

Phylogenetic constraints and ecological factors have been suggested as alternative key factors in the evolution of animal sociality. The mara (Dolichotis patagonum) is a cavid rodent endemic to Argentina that has the particularity of being monogamous with a communal breeding system. Researches on reproductive behavior of mara in its natural habitat have been restricted to Peninsula de Valdes (PV). In this work, we studied the breeding behavior of the mara in Sierra de las Quijadas National Park (SQNP). A census to locate mara's dens in 230 ha, was conducted through adjacent line transects of five meters width. After locating the dens, we followed their reproductive activity using camera traps. A density of 4.34 randomly distributed dens/ha was found. No communal breeding was observed. Breeding season extended from October to June. Estimated density was from 0.16 to 0.24 reproductive adults/ha. The survival rate of juveniles was 31.3%. These observations differ from those reported for the species. Resource dispersion hypothesis could explain both reproductive strategies prevailing in the extremes of its distribution, SQNP (solitary breeding) and PV (communal breeding). The intraspecific variability registered enhances the importance of ecological factors in determining sociality traits for the mara.

Applying the resource dispersion hypothesis to a fission-fusion society: A case study of the African lion (Panthera leo).

The relationship between the spatiotemporal distribution of resources and patterns of sociality is widely discussed. While the resource dispersion hypothesis (RDH) was formulated to explain why animals sometimes live in groups from which they derive no obvious benefits, it has also been successfully applied to species that benefit from group living. Some empirical tests have supported the RDH, but others have not, so conclusions remain equivocal and further research is required to determine the extent to which RDH predictions hold in natural systems. Here, we test four predictions of the RDH in an African lion population in the context of their fission–fusion society. We analyzed data on group composition of GPS‐collared lions and patterns of prey availability. Our results supported the first and second predictions of the RDH: Home range size (a) was independent of group size and (b) increased with distance between encounters with prey herds. Nonetheless, the third and fourth RDH predictions were not supported: (c) The measure of resource heterogeneity and (d) resource patch richness measured through prey herd size and body size had no significant effect on lion group size. However, regarding the fourth prediction, we added an adaptation to account for dynamics of fission–fusion society and found that the frequency of pride fission increased as group size increased. Our data set restricted us from going on to explore the effect of fission–fusion dynamics on the relationship between group size and patch richness. However, this should be investigated in future studies as including fission–fusion dynamics provides a more nuanced, realistic appreciation of lion society. Our study emphasizes the importance of understanding the complexity of a species' behavioral ecology within the framework of resource dispersion. Whatever larger theoretical framework may emerge to explain lion society, incorporating fission–fusion dynamics should allow the RDH to be refined and improved.

Space use and social association in a gregarious ungulate: Testing the conspecific attraction and resource dispersion hypotheses.

Animals use a variety of proximate cues to assess habitat quality when resources vary spatiotemporally. Two nonmutually exclusive strategies to assess habitat quality involve either direct assessment of landscape features or observation of social cues from conspecifics as a form of information transfer about forage resources. The conspecific attraction hypothesis proposes that individual space use is dependent on the distribution of conspecifics rather than the location of resource patches, whereas the resource dispersion hypothesis proposes that individual space use and social association are driven by the abundance and distribution of resources. We tested the conspecific attraction and the resource dispersion hypotheses as two nonmutually exclusive hypotheses explaining social association and of adult female caribou (Rangifer tarandus). We used location data from GPS collars to estimate interannual site fidelity and networks representing home range overlap and social associations among individual caribou. We found that home range overlap and social associations were correlated with resource distribution in summer and conspecific attraction in winter. In summer, when resources were distributed relatively homogeneously, interannual site fidelity was high and home range overlap and social associations were low. Conversely, in winter when resources were distributed relatively heterogeneously, interannual site fidelity was low and home range overlap and social associations were high. As access to resources changes across seasons, caribou appear to alter social behavior and space use. In summer, caribou may use cues associated with the distribution of forage, and in winter caribou may use cues from conspecifics to access forage. Our results have broad implications for our understanding of caribou socioecology, suggesting that caribou use season‐specific strategies to locate forage. Caribou populations continue to decline globally, and our finding that conspecific attraction is likely related to access to forage suggests that further fragmentation of caribou habitat could limit social association among caribou, particularly in winter when access to resources may be limited.

Environmental and demographic drivers of male mating success vary across sequential reproductive episodes in a polygynous breeder.

Ecological and social factors underpinning the inequality of male mating success in animal societies can be related to sex ratio, sexual conflict between breeders, effects of nonbreeders, resource dispersion, climatic conditions, and the various sequential stages of mating competition that constitute the sexual selection process. Here, we conducted an individual‐based study to investigate how local resource availability and demography interact with annual climate conditions to determine the degree of male mating inequality, and thus opportunity for sexual selection across two sequential reproductive episodes (harem and subsequent mate acquisition) in a naturally regulated (feral) horse population in Sable Island National Park Preserve, Canada. Using a 5‐year, spatially explicit, mark‐resight dataset and hierarchical mixed‐effects linear modeling, we evaluated the influence of adult sex ratio (ASR) on mating success and then tested for effects of freshwater availability, density, unpaired male abundance, and precipitation during each breeding season. Unpaired male abundance, freshwater availability, and ASR differed in their effects on male mating success according to year and selection episode. Opportunity for sexual selection in males associated with harem acquisition increased with ASR, and unpaired male abundance further explained weather‐related interannual variation after accounting for ASR. In contrast, once a harem was secured, ASR had little effect on male mating inequality in regard to acquiring additional females, while interannual variation in mating inequality increased with decreasing freshwater availability. Our findings show that local demography, resource availability, and weather effect opportunity for sexual selection in males differently depending on selection episode, and can attenuate or accentuate effects of ASR.