Behavioral responses associated with a human-mediated predator shelter

Human activities in protected areas can affect wildlife populations in a similar manner to predation risk, causing increases in movement and vigilance, shifts in habitat use and changes in group size. Nevertheless, recent evidence indicates that in certain situations ungulate species may actually utilize areas associated with higher levels of human presence as a potential refuge from disturbance-sensitive predators. We now use four-years of behavioral activity budget data collected from pronghorn (Antilocapra americana) and elk (Cervus elephus) in Grand Teton National Park, USA to test whether predictable patterns of human presence can provide a shelter from predatory risk. Daily behavioral scans were conducted along two parallel sections of road that differed in traffic volume - with the main Teton Park Road experiencing vehicle use that was approximately thirty-fold greater than the River Road. At the busier Teton Park Road, both species of ungulate engaged in higher levels of feeding (27% increase in the proportion of pronghorn feeding and 21% increase for elk), lower levels of alert behavior (18% decrease for pronghorn and 9% decrease for elk) and formed smaller groups. These responses are commonly associated with reduced predatory threat. Pronghorn also exhibited a 30% increase in the proportion of individuals moving at the River Road as would be expected under greater exposure to predation risk. Our findings concur with the �predator shelter hypothesis�, suggesting that ungulates in GTNP use human presence as a potential refuge from predation risk, adjusting their behavior accordingly. Human activity has the potential to alter predator-prey interactions and drive trophic-mediated effects that could ultimately impact ecosystem function and biodiversity

Photon and positive ion production from collisions of superthermal hydrogen atoms with lithium atoms and molecules. [1 to 10 eV, cross sections, emission spectra]

Photon and positive ion production from superthermal collisions of hydrogen atoms with lithium atoms and molecules is reported. These are the first results in the difficult 1 to 10 eV collision regime obtained with recently developed high intensity plasma-arc source of H atoms. These superthermal H atoms (approximately 5 eV average kinetic energy but not velocity selected in these experiments) have been collided with an intense supersonic lithium beam (approximately 10 percent Li/sub 2/; Li/sub 3/ undetectable) with cold internal degrees of freedom (T/sub vib/ = 195/sup 0/K, T/sub rot/ = 70/sup 0/K). The other aspects of the apparatus have been given previously. Low resolution photon and positive ion production in the collision chamber scattering center and also medium resolution; photon production in the magnet chamber between the skimmer and the magnet were detected

Li/Li/sub 2/ supersonic nozzle beam

The characterization of a lithium supersonic nozzle beam was made using spectroscopic techniques. It is found that at a stagnation pressure of 5.3 kPa (40 torr) and a nozzle throat diameter of 0.4 mm the ground state vibrational population of Li/sub 2/ can be described by a Boltzmann distribution with T/sub v/ = 195 +- 30/sup 0/K. The rotational temperature is found to be T/sub r/ = 70 +- 20/sup 0/K by band shape analysis. Measurements by quadrupole mass spectrometer indicates that approximately 10 mole per cent Li/sub 2/ dimers are formed at an oven body temperature of 1370/sup 0/K n the supersonic nozzle expansion. This measured mole fraction is in good agreement with the existing dimerization theory