Rapid expansion of energy development in some portions of the Intermountain West, USA, has prompted concern regarding impacts to declining greater sage‐grouse (Centrocercus urophasianus) populations. We used retrospective analyses of public data to explicitly investigate potential thresholds in the relationship between lek attendance by male greater sage‐grouse, the presence of oil or gas wells near leks (surface occupancy), and landscape‐level density of well pads. We used generalized linear models and generalized estimating equations to analyze data on peak male attendance at 704 leks over 12 years in Wyoming, USA. Within this framework we also tested for time‐lag effects between development activity and changes in lek attendance. Surface occupancy of oil or gas wells adjacent to leks was negatively associated with male lek attendance in 5 of 7 study areas. For example, leks that had ≥ 1 oil or gas well within a 0.4‐km (0.25‐mile) radius encircling the lek had 35–91% fewer attending males than leks with no well within this radius. In 2 of these 5 study areas, negative effects of well surface occupancy were present out to 4.8 km, the largest radius we investigated. Declining lek attendance was also associated with a higher landscape‐level density of well pads; lek attendance at well‐pad densities of 1.54 well pads/km2 (4 well pads/mile2) ranged from 13% to 74% lower than attendance at unimpacted leks (leks with zero well pads within 8.5 km). Lek attendance at a well‐pad density of 3.09 well pads/km2 (8 well pads/mile2) ranged from 77% to 79% lower than attendance at leks with no well pad within 8.5 km. Further, our analysis of time‐lag effects suggested that there is a delay of 2–10 years between activity associated with energy development and its measurable effects on lek attendance. These results offer new information for consideration by land managers on spatial and temporal associations between human activity and lek attendance in sage‐grouse, and suggest that regional variation is an important consideration in refining existing management strategies.

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The adsorption of 13 C-labeled benzene on imogolite has been studied on samples which had been evacuated and then heated to remove water below their decomposition point. After adsorption of labeled benzene, the samples were studied by nuclear magnetic resonance using non-spinning techniques. The results show that benzene can occupy more than one pore type and that water does not displace benzene from the intra-tube pores at atmospheric pressure. A further finding is that there are at least two types of adsorbed benzene in so called inter-tube pores, one of which is more rigidly held than that in intratube pores. The presence of disordered materials at the edge of pores could also play a role in altering the pore mouth thereby creating new types of pores. Moreover, where two tubes do not pack properly, space might be created where an adsorbed molecule may bind more tightly than expected in a conventional pore.

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