Elk resource selection patterns in a semiarid riparian corridor

Risk assessment of soil heavy metals associated with land use variations in the riparian zones of a typical urban river gradient

Urbanization-induced land use changes in riparian area alter soil and water regimes in complex ways, which may also affect the migration and transformation of soil heavy metals and increase the risk of release. In this study, soil samples from the riparian zone of Beiyun River, which located in the rapidly urbanized Beijing metropolis, were collected and analyzed for heavy metals (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn). Then their zoning distribution pattern along river (section 1 to section 4 from upper to low reaches) and the correlation of heavy metals between riparian soils and riverine sediments were investigated. Results showed that the average soil heavy metal concentrations of Cd, Cr, Cu and Zn in riparian zone were approximately 2.2, 1.7, 1.9 and 2.0 times higher than the background values. Sectionally, the concentrations of Cd, Ni, Pb and Zn displayed a decreasing order with section 2 > section 3 > section 4 > section 1, while the highest values of Cr and Cu were found in section 3. The concentrations of all heavy metals except Cr in artificial garden land were higher than those in other land use types, and the concentrations of Cr among five land use types were in the order of grass land > farmland > artificial garden land > forest land > forest-grass land. Generally, most of the heavy metals in the riverine sediments had higher contents than those in riparian zones, especially Cu and Zn. There was a decreasing order for the average geo-accumulation index (I_geo) of measured heavy metals in the soils of riparian zone: Zn (0.15) > Cr (0.08) > Cu (0.07) > Cd (-0.08) > As (-0.57) > Pb (-0.67) > Mn (-0.75) > Ni (-0.86), whereas they had different "high-low" orders in different land use types. The I_geo index indicated most regions of riparian zone were moderately polluted with Cd, Cr, Cu and Zn, especially in grass land and forest land. Also, Cd, Cr and Zn in riparian zone have positive relationships with the concentrations in riverine sediments. Health risk assessment showed that the contribution of ingestion HQ to HI was the highest among the three exposure pathways (ingestion, inhalation and dermal contact), and children had higher non-carcinogenic risk and carcinogenic risk index than adult. Our findings suggest that land use and soil in riparian zone should be protected and managed scientifically to control the riverine pollution and ensure human health.

Seasonal home ranges and habitat selection of three elk (Cervus elaphus) herds in North Dakota

Changes in land use have resulted in range shifts of many wildlife species, including those entering novel environments, resulting in the critical need to understand their spatial ecology to inform ecosystem effects and management decisions. Dispersing elk (Cervus elaphus) were colonizing areas of suitable habitat in the Northern Great Plains, USA, resulting in crop depredation complaints in these areas. Although state resource managers had little information on these elk herds, limited evidence suggested temporal movements into Canada. We collected and analyzed essential information on home range and habitat selection for 3 elk herds residing in North Dakota. We captured 5 adult female elk in each study area, affixed global positioning system collars, and monitored them for 1 year (2016-2017). We estimated diel period, seasonal, and hunting season home ranges using Brownian Bridge Movement Models for each individual. We analyzed habitat selection using multinomial logit models to test for differences in use of land classes, and for departures from proportionate use based on random sampling; our predictor variables included individual elk, diel period, and season. Home ranges differed between the 3 herds, seasons, and diel period; gun and winter season home ranges were both larger than in summer, as was night when compared with day. Female elk generally restricted themselves to cover during the day and entered open areas at night and during winter months. Our results also suggest that elk in our study areas tended to seek more cover, and in the case of our Turtle Mountain study area, some cross into Canada during gun season. Our study provides a better understanding of the spatial ecology of elk in the Northern Great Plains while highlighting the need for enhanced international cooperative management efforts.

Population Dynamics Model to Inform Harvest Management of a Small Elk Herd in Central New Mexico

Crop depredation by wildlife is a frequent concern for natural resource managers and mitigation of this issue is often an important task for wildlife agencies. Elk Cervus elaphus and other ungulate species have depredated corn Zea mays at Bosque del Apache National Wildlife Refuge, New Mexico, USA, interfering with the ability of the Refuge to provide sufficient supplemental nutrition to overwintering sandhill cranes Antigone canadensis and geese (Anatidae). We estimated annual adult survival and calf recruitment rates of elk from 2011 to 2013 at Bosque del Apache National Wildlife Refuge. Natural adult survival (excludes human-related mortalities) was high (mean = 98.3%; 95% CI = 95.0–100.0%). Calf recruitment was lower than in some populations, and ranged from 13.0 to 36.7 calves : 100 cows at time of recruitment (March and April) with a mean of 21.9 (SD =12.9). Using this information, we constructed a harvest management model to determine annual harvest quotas required to stabilize the growth of the elk herd on the Refuge. The female segment of the herd is growing at an annual rate of 9.0% (95% CI = −1.1–24.1%). To stabilize the growth rate of the female elk population, 8.0% (95% CI = −1.1–19.4%) of the cows would need to be harvested annually. We estimated an adult elk abundance of 40.0 (SE = 4.57; 95% CI = 33.8–52.6) in 2012 and 61.1 (SE = 7.21; 95% CI = 49.9–78.8) in 2013. Our harvest management model provides Refuge staff, who ultimately intend to improve corn yield, with valuable information needed to stabilize the elk herd. Further, our approach outlines a simple, easily implemented modeling technique that can be used for the management of other ungulate herds.