Human activities and weather drive contact rates of wintering elk

Abstract

Wildlife aggregation patterns can influence disease transmission. However, limited research evaluates the influence of anthropogenic and natural factors on aggregation. Many managers would like to reduce wildlife contact rates, driven by aggregation, to limit disease transmission. We develop a novel analytical framework to quantify how management activities such as supplemental feeding and hunting versus weather drive contact rates while accounting for correlated contacts. We apply the framework to the National Elk Refuge (NER), Wyoming, USA, where the probable arrival of chronic wasting disease (CWD) has magnified concerns. We used a daily proximity index to measure contact rates among 68 global positioning system collared elk from 2016 to 2019. We modelled contact rates as a function of abiotic weather‐related effects, anthropogenic effects and aggregation from the prior day. The winter of 2017–2018 had greater natural forage availability and little snow, which led to a rare non‐feeding year on the NER and provided a unique opportunity to evaluate the effect of feeding on contact rates relative to other conditions. Supplemental feeding was the strongest predictor of aggregation, and contact rates were 2.6 times larger while feeding occurred compared to the baseline rate (0.34 and 0.13, respectively). Snow‐covered area was the second strongest predictor of contact rates highlighting the importance of abiotic factors to elk aggregation, but this effect had half the strength of feeding. These results are the first to show, even in animals that congregate naturally, how greatly supplemental feeding amplifies aggregation. Contact rates were also 23% lower during times when elk hunting was active (0.10) compared to the baseline. Synthesis and applications. Supplemental feeding increased contacts between elk well above the natural effects of weather, even after accounting for correlated movement expected in wintering ungulates. Similarly, differences in hunting season timing with adjacent areas led to an increase in contacts, suggesting an additional management option for reducing aggregation. The analytical framework presented supports the evaluation of temporally varying management actions that influence aggregation broadly and can be easily implemented whether the interest in changing aggregation is related to reduction of disease transmission, human–wildlife conflict or inter‐species competition.

Review on PRNP genetics and susceptibility to chronic wasting disease of Cervidae

“…Thus, human activities, like supplemental feedings, can increase the rate of aggregation and the likelihood of disease transmission. A recent study estimated that the contact rates in Elk population from Wyoming were 2.6 times larger when feeding occurred [21].…”

Eyes on the herd: Quantifying ungulate density from satellite, unmanned aerial systems, and GPScollar data

“…Furthermore, kernel density contours can highlight areas of intensive use, which may be important for identifying areas of protection from disturbances, prioritizing locations of activities to reduce human–wildlife conflict, such as fencing or harvest, targeting collaring or other sampling programs, or optimizing soil or other treatments in areas where infectious agents for environmentally transmitted diseases may be concentrated. We expect the guidelines provided here (Table 5) will assist others who are considering how to quantify animal density in open areas, for other density‐dependent and environmentally transmitted diseases, at other winter ranges, and across a range of adaptive management options, including hunting, irrigation, fire, forestry, weed, or range treatments (Janousek et al, 2021). Following these guidelines, we conclude that GPS collars will provide the NER with the best information to evaluate how animal densities change with population size and planned changes in management, especially in spring when elk are more difficult to distinguish in satellite imagery with patchy snow cover.…”

“…We grouped elk in satellite imagery by feed ground and compared the total number of elk marked in satellite imagery to ground or helicopter counts. The time between satellite images and traditional counts ranged from zero to 2 days; although some elk moved between counts, we considered this reasonable based on available data and size of the survey area (~223 km 2 ) (Janousek et al, 2021). We conducted all analyses in the statistical computing environment R, version 3.5.3 (R Core Team, 2019).…”

“…Thus, when the goal is to characterize density at fine spatiotemporal scales, we need additional options that are consistent enough for comparisons that are useful for research and management. For example, measurements of density across a season or between years with the locations and timing of hunting seasons could help managers assess options for reducing maximum density (Dougherty et al, 2018; Janousek et al, 2021). For such a purpose, as with the use of minimum counts, approaches that measure densities at specific points in time concurrent with specific management activities or stressors of interest could provide needed information for a number of questions.…”

“…For many wildlife species, human activities alter the timing and abundance of food resources, sometimes increasing wildlife aggregations and potential disease transmission (Becker & Hall, 2014; Janousek et al, 2021). The U.S.…”