ABSTRACT. The effect of ice con ten t a nd normal load on the shear strength charac te rist ics ora frozen coarse g ra nul a r debris was in ves ti g ated . 3 1 shear tests were carr ied out in a modified shea rbox all owing a sampl e te mperat ure of t -1. 0 ± 0.2 j" C and a load rate of 9.63 x 10 -4 cm/min . Th e tes ts showed tha t as the ice co nten t of the frozen d eb ris was increased from 0 % (undersaturated ) to 25 % (saturated), sample shear strength was ma rkedl y increased. In contrast, sample shea r stre ng th was red uced as ice content was increased from 25 % (satu rated ) to 100% (supersaturated ). Th e cha nges in shear stre ng th w ith in creasin g ice conten t we re attributed di rec tl y to changes in in te rn al fri ction and the cohesive effec ts orthe po re ice. The shear tests also ind icate th at shear strengt h inc reases with increasing no rmal load up to a critical limit. Above lhis limit, dilatancy is suppressed causing the shea r strength to decrease or remain relati vely constan t w ith in creased no rmal load .T he stress-strain curves of the 3 1 tests ind icated that samples wit h higher ice contents tended to reach pea k stre ngth (Tp) with less displacement during shear. M o reover, the difference between Tp and -r, (residual strength ) was lowes t for p ure polyc rystalli ne ice a nd highest for ice-sa tura ted samples. The Mo hr-Coulomb fa il ure envelopes displayed ve ry d istin ctive parabolic curvilinea rity. T he degree of curva ture is thought to be a fun ction of ice creep a t low normal loads and pa rticle fracture and crushing a t hig h no rmal loads.R ESUME . Caraetiristiqu,s d, la limit, de rupture decisail/,ment des debris granul,ux grossi"s gelis. Les effets de la q uantite de glace et de la cha rge no rmale sur les caraclcTisti ques de li mite de cisa illement de de bris g ran ule ux grossiers geles ont Cte examines. 3 1 tests de c isaill ement ont ete effectues dans une boile de cisaillement mod ifi ee perm e tlant une tempe ra ture de ( -1,0 ± 0,2j" C et une vitesse de dCfo nnation d e 9,63 x 10 -4 cm /mi n. Les tests ant mo n tre qu ' avec la croissance de la q ua nti te de glace da ns les d ebris geles de 0% (sous-sat uration ) a 25 % (satu ra tio n), la li mite de cisaillemen t ctait nettement accrue . A I'inverse, la li mi te de cisai llemen t di m inuait avec I' augmen tation de la quantite de g la ce de 25 % (saturation ) a 100% (su rsaturation) . Les changements de la li m ile de cisaillemen t avec I'a ugmentation de la te ne ur en glace ant ete atl ribues di rectement aux modi fication du rro tt ement inte rn e et aux effets sur la cohes ion de la glace po re use. Les essa is de cisaillernent indiquent au ss i q u'avec I'augmenta ti on d e la charge norma le la limi te de cisaillement es t portee a une li mi te cri tiq ue. Au-dela de I NTRODUCTI ON Over the past decade there has been a growing interest in the rheology of frozen soils in both North America and the Soviet Union. Much of this interest, espe cially in North Jlmerica, has stemmed from pip...

The growing rate of wildlife underpass use for the mitigation of road-induced wildlife mortality necessitates the development of low-cost monitoring tools for determination of mitigation success. Trail cameras are one such tool that can provide valuable insight into the usage patterns and effectiveness of wildlife underpasses. We deployed trail cameras in wildlife underpasses in Guelph, ON, to develop recommendations for camera monitoring protocols. The trail cameras used high interval time lapse and motion sensors from April to October of 2016 to capture crossing by a variety of species through two slotted, small animal underpasses. Daily and seasonal underpass usage patterns of 21 species and species groups suggest that to comprehensively monitor underpass usage, cameras must be active continuously and utilize high frequency time lapse and motion sensors simultaneously to capture crossing events by both endothermic and ectothermic species. Although these recommendations are dependent on the specific objectives and target conservation species, these results can be used to guide a range of underpass monitoring programs.

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The effect of ice content and normal load on the shear strength characteristics of a frozen coarse granular debris was investigated. 31 shear tests were carried out in a modified shearbox allowing a sample temperature of (–1.0 ± 0.2)° C and a load rate of 9.63 × 10−4 cm/min. The tests showed that as the ice content of the frozen debris was increased from 0% (under-saturated) to 25% (saturated), sample shear strength was markedly increased. In contrast, sample shear strength was reduced as ice content was increased from 25% (saturated) to 100% (supersaturated). The changes in shear strength with increasing ice content were attributed directly to changes in internal friction and the cohesive effects of the pore ice. The shear tests also indicate that shear strength increases with increasing normal load up to a critical limit. Above this limit, dilatancy is suppressed causing the shear strength to decrease or remain relatively constant with increased normal load. The stress-strain curves of the 31 tests indicated that samples with higher ice contents tended to reach peak strength (τP) with less displacement during shear. Moreover, the difference between τp and τr (residual strength) was lowest for pure polycrystalline ice and highest for ice-saturated samples. The Mohr-Coulomb failure envelopes displayed very distinctive parabolic curvilinearity. The degree of curvature is thought to be a function of ice creep at low normal loads and particle fracture and crushing at high normal loads.

Anuran populations are sensitive to changing environmental conditions and act as useful indicators. Presently, much information collected concerning frog populations comes from volunteers following the North American Amphibian Monitoring Protocol. Does weather variability allowed within protocol affect the abundance of calling frogs? For 10 years, Credit Valley Conservation (Ontario, Canada) has been collecting anuran data concerning nine frog species employing three frog monitoring runs. Records include frog abundance by protocol code and five weather variables. Antecedent precipitation and temperature were determined from the nearest weather station. Locations with large source populations of two Hylidae species were selected (spring peeper calling in April and gray tree frog in May). Spearman correlations suggested there were no significant relationships between calling abundance of Hylidae species and ambient wind speed or humidity. However, gray tree frogs were temperature sensitive and calling was significantly related to increased water and air temperatures as well as day time high temperatures over the previous 2 weeks. Both species of calling Hylidae were affected by the volume and timing of precipitation (though, in different ways). Gray tree frogs seem to prefer drier conditions (when temperatures are significantly warmer) while spring peepers prefer to call during, or closely following, precipitation. Monitors targeting gray tree frog should track local weather conditions and focus on evenings when it is (a) warmer than the minimum temperatures and (b) drier than suggested by the protocol. It is recommended that an additional monitoring run could be added to reduce detection variability of this species.