Association between weather and Dall's sheep Ovis dalli dalli harvest success in Alaska

Scott Leorna,Brad Wendling,Todd Brinkman,Julie McIntyre,Laura Prugh

doi:10.2981/wlb.00660

Abstract

Although extensive research has been conducted on a variety of factors that influence wildlife harvest rates, few studies have quantified the impact of weather on harvest success. As global warming continues to contribute to unprecedented changes in local weather regimes, particularly in arctic and alpine ecosystems, understanding how these changes impact human–wildlife interactions will become increasingly important and relevant for wildlife managers. Therefore, we used a long-term dataset (1999–2015) on Dall's sheep Ovis dalli dalli, an alpine species in Alaska, USA, as a case study to explore how changes in local daily weather has affected hunter harvest success. We used generalized linear mixed models to estimate relationships between daily harvest count and weather variables using three separate models; all hunters, resident hunters and non-resident hunters. Weather variables included daily mean relative humidity, precipitation, air temperature and wind speed. For our model including all hunters, which excluded wind, we estimated that a mean increase in relative humidity, precipitation and temperature from one day to the next resulted in an 11.7, 4.3 and 2.9% decrease in daily harvest, respectively. The effect of relative humidity influenced harvest count two to three times more than all other weather variables across models. This study contributes to a limited body of knowledge on quantifying the impact of weather on harvest success and about how changes in weather affect hunter and wildlife behavior. Advancing knowledge on how weather influences variation in harvest may facilitate effective strategies for adapting hunting regulations to meet harvest and population goals.

Highlights

Hunting has been used as a wildlife management tool to regulate and conserve game populations in North America since the beginning of the twentieth century (Heffelfinger et al 2013)
Extensive research has been conducted on the effects of hunting on game population dynamics (Leopold 1933), and a growing body of research has assessed factors that influence harvest success (Bhandari et al 2006)
Despite decades of the wildlife studies implying that weather conditions influence harvest opportunity (Fobes 1945, Hansen et al 1986, Brinkman et al 2016), few studies have quantified the impact of weather on harvest success and

Summary

Introduction

Hunting has been used as a wildlife management tool to regulate and conserve game populations in North America since the beginning of the twentieth century (Heffelfinger et al 2013). With amplified climate change (Winton 2006, Serreze et al 2009, Stuecker et al 2018), it is plausible that unseasonable and irregular weather conditions will have an increasingly important influence on hunter success by altering either or both hunter and wildlife behavior. We assess the effects of daily weather conditions on harvest success using a long-term dataset on Dall’s sheep Ovis dalli dalli hunter harvests in Alaska, USA. Dall’s sheep populations migrate seasonally between summer and winter ranges following forage availability (Bowyer et al 2000) These high-elevation habitats are gradually being impacted by shrubification and upward advancement of the tree line due to a warming climate (Pauli et al 1996, Dirnböck et al 2003, Ernakovich et al 2014, Greenwood and Jump 2014, Dial et al 2016). Changes in winter and spring snow conditions are thought to be affecting Dall’s sheep population dynamics (Mahoney et al 2018, Rattenbury et al 2018)

Methods

Results

Conclusion