Does Human Predation Risk Affect Harvest Susceptibility of White-Tailed Deer During Hunting Season?

Large carnivores are considered a primary source of mortality for many ungulate populations, but harvest by hunters is the primary means of population management. However, research is needed to evaluate how human predation risk influences observability (a surrogate to harvest susceptibility) of ungulates. We determined how hunting intensity and duration influence observation rates of white-tailed deer (Odocoileus virginianus) and how deer behavior (i.e., movement rate and resource selection) affects observation rates. We sampled 37 adult (≥2 yr) male deer at 2 levels of risk (i.e., low-risk = 1 hunter/101 ha; and high-risk = 1 hunter/30 ha) during 3 exposure periods (i.e., first, second, and third weekend of hunting) on a 1,861-ha property in Oklahoma, USA, during the 2008 and 2009 rifle deer-seasons. Observation rates (collared deer/hunter-hr/day) were greatest during the first weekend in both the low- and high-risk treatments, but declined each weekend thereafter in both treatments. Immediately prior to hunter observation, movement rate of observed collared deer was greater than that of unobserved collared deer, but only when hunting risk was high. Greater movement rates of deer in the high-risk treatment also led to a greater probability of observation. Hunters also had a greater probability of observing collared deer at higher elevations. Overall, deer modified their behavior to avoid detection by hunters. These results can be used to explain decreased observation rates to hunters and to modify harvest rates by altering timing and intensity of human predation risk during the recreational hunting season to help achieve population management goals through harvest

Design of an Underwater Telemetry Antenna for Locating and Retrieving Submerged Radiocollars

Radiocollars represent a significant investment of financial resources, particularly global positioning system (GPS) collars, and loss of data imposes analytical limitations from reduced sample sizes. Radiocollars on large, terrestrial mammals are seldom lost in the water. However, several instances in Oklahoma, USA necessitated a reliable and cost-effective technique for retrieving GPS collars from underwater to salvage the financial investment and data. We designed an underwater telemetry antenna to find and retrieve collars in ≤ 3 m of water. We describe field simulations under varying environmental and water conditions, and provide a list of materials along with instructions and considerations for building and using an underwater telemetry antenna. We successfully used our underwater antenna to locate and retrieve our submerged collar that was disposed of in a pond after illegal harvest; we also located and retrieved all collars used for field simulation (n = 11). On average, search time for collars was 30 min. The design of our underwater antenna was inexpensive (US$30), easy to build, and effective at locating submerged collars in 0.6–3.0 m of water, with varying water turbidity and substrates. Although our underwater telemetry antenna was designed to meet our needs, it could be modified for more specific or alternative circumstances

Damage caused to rangelands by wild pig rooting activity is mitigated with intensive trapping

The wild pig (Sus scrofa), an exotic and invasive species, has caused great concern at a global scale, particularly within agricultural landscapes. The objective of this study was to determine whether intensive trapping and wild pig removal resulted in a concomitant decrease in damage to rangelands. Removal of 356 wild pigs over 2 years showed an immediate reduction in rooting damage that carried over after trapping ceased. After only one trap session, rooting damage across the three sites was reduced 43–82% and total damage reduction from the beginning to the end of the project was 90%. With intensive trapping (1 pig/22.7 ha/year), damage may also be reduced on neighboring areas that are not being trapped, as indicated by data from our non-trapped units. Although we reduced rooting damage locally, and on nearby areas, large-scale, intensive control will be needed for the long-term effective reduction in damage and wild pig numbers because wild pigs have high reproductive rates, high survival, and can recolonize areas rapidly