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The decline of woodland caribou (Rangifer tarandus caribou) has been attributed to anthropogenic landscape disturbances, but critical distance thresholds and time lags between disturbance and extirpation are unknown. Using a database of caribou presence and extirpation for northern Ontario, Canada, geo‐coded to 10 times 10‐km cells, we constructed logistic regression models to predict caribou extirpation based on distance to the nearest of each of 9 disturbance types: forest cutovers, fires, roads, utility corridors, mines, pits and quarries, lakes, trails, and rail lines. We used Akaike's Information Criterion to select parsimonious models and Receiver‐Operating Characteristic curves to derive optimal thresholds. To deal with the effects of spatial autocorrelation on estimates of model significance, we used subsampling and restricted randomizations. Forest cutovers were the best predictor of caribou occupancy, with a tolerance threshold of 13 km to nearest cutover and a time lag of 2 decades between disturbance by cutting and caribou extirpation. Management of woodland caribou should incorporate buffers around habitat and requires long‐term monitoring of range occupancy.

14The Red Sea Rift, an archetype of a newly formed ocean basin, is an ideal environment in 15 which to study the controversial processes associated with continental rifting. Different models 16 have been proposed to explain how rifting in the Red Sea evolved; however, accurate constraints 17 on lithospheric structure have not been available to discriminate rifting models. We use the S-18 wave receiver function technique to produce the first images of the lithosphere-asthenosphere 19 boundary (LAB) structure along the Red Sea and throughout the Arabian Peninsula. 20Lithospheric thickness varies considerably, with thin lithosphere centered on the rift axis, 21 thickening toward the Arabian interior. Gravity data are well fit by our structural model and 22indicate that high surface topography along the rift flank is not in isostatic equilibrium, requiring 23 2 dynamic compensation for its support. While our derived structure is consistent with active 24 rifting processes, previous studies demonstrated that the Red Sea initiated as a passive rift. 25 Therefore, our results suggest a two-stage rifting history, where extension and erosion by flow in 26 the underlying asthenosphere are responsible for variations in LAB depth. LAB topography 27 guides asthenospheric flow beneath western Arabia and the Red Sea, demonstrating the 28 important role lithospheric variations play in the thermal modification of tectonic environments. 29

Movement patterns offer a rich source of information on animal behaviour and the ecological significance of landscape attributes. This is especially useful for species occupying remote landscapes where direct behavioural observations are limited. In this study, we fit a mechanistic model of animal cognition and movement to GPS positional data of woodland caribou (Rangifer tarandus caribou; Gmelin 1788) collected over a wide range of ecological conditions. The model explicitly tracks individual animal informational state over space and time, with resulting parameter estimates that have direct cognitive and ecological meaning. Three biotic landscape attributes were hypothesized to motivate caribou movement: forage abundance (dietary digestible biomass), wolf (Canis lupus; Linnaeus, 1758) density and moose (Alces alces; Linnaeus, 1758) habitat. Wolves are the main predator of caribou in this system and moose are their primary prey. Resulting parameter estimates clearly indicated that forage abundance is an important driver of caribou movement patterns, with predator and moose avoidance often having a strong effect, but not for all individuals. From the cognitive perspective, our results support the notion that caribou rely on limited sensory inputs from their surroundings, as well as on long-term spatial memory, to make informed movement decisions. Our study demonstrates how sensory, memory and motion capacities may interact with ecological fitness covariates to influence movement decisions by free-ranging animals.

[1] Group and phase velocities of fundamental mode Rayleigh waves, in the period range of 10 to 70 s, are obtained for southern and northern Tibet. Significant variations in crustal velocity structure are found. The group velocity minimum for Tibet occurs at $33 s and the minimum is $0.12 km/s lower for southern Tibet than for northern Tibet. At periods greater than 50 s, however, group velocities are up to 0.2 km/s faster in southern Tibet. The group and phase velocities are inverted for layered S wave models. The dispersion observations in southern Tibet can only be fit with a low-velocity layer in the middle crust. In contrast, the velocity models for northern Tibet do not require any lowvelocity zone in the crust. The S wave velocity of the lower crust of southern Tibet is $0.2 km/s faster than the lower crust of northern Tibet. In southern Tibet the sub-Moho velocity increases with a positive gradient that is similar to a shield, while there is no velocity gradient beneath northern Tibet. The high-velocity lower crust of southern Tibet is consistent with the underthrusting of Indian continental lithosphere. The most plausible explanation of the mid-crustal low velocity zone is the presence of crustal melt resulting from H 2 O-saturated melting of the interplate shear zone between the underthrusting Indian crust and overflowing Asian crust. The lack of a pronounced crustal low-velocity zone in northern Tibet is an indication of a relatively dry crust. The low S wave velocity in the lower crust of northern Tibet is interpreted to be due to a combination of compositional differences, high temperatures, presumably caused by a high mantle heat flux, and possibly small amounts of partial melt. Combined with all available observations in Tibet, the new surface wave results are consistent with a hot and weak upper mantle beneath northern Tibet.INDEX TERMS: 7205 Seismology: Continental crust (1242); 7218 Seismology: Lithosphere and upper mantle; 7255 Seismology: Surface waves and free oscillations; 8102 Tectonophysics: Continental contractional orogenic belts; KEYWORDS: Tibet, crustal velocity structure, surface wave, Rayleigh waves, continental collision Citation: Rapine, R., F. Tilmann, M. West, J. Ni, and A. Rodgers, Crustal structure of northern and southern Tibet from surface wave dispersion analysis,