Increased overwinter mortalities of white-tailed deer (Odocoileus virginianus) fawns during a drought year

Abstract

mortality events. In order of importance, survival rates were affected by days since capture, year of drought, age at capture, week post-capture (1/0 indicator), and region. Estimated overwinter (fall through spring) survival rate (± SE) of fawns in both regions during 2010-14 was 0.83 ± 0.04. However, estimated overwinter survival rates were depressed during 2012-13, following the severe drought of 2012 (0.63 ± 0.11 or 0.66 ± 0.11 depending on model). Main causes of mortality were capture-related and predation, though some dead deer also showed signs of hemorrhagic disease. We suspect that the extreme drought of 2012 created favorable conditions for fall-spring mortality of fawns, due to elevated disease transmission and lower forage quality and quantity for deer. In addition, drought may have contributed to predation by reducing abundance of alternative prey. Our results suggest that severe weather conditions during summer can substantially impact overwinter fawn survival.

Importance of spatio–temporal connectivity to maintain species experiencing range shifts

“…Then, we ran a principal component analysis (PCA) on the nineteen bioclimatic variables using the 'ade4' package (Dray and Dufour 2007) to avoid potential collinearity problems. We retained the ones potentially most relevant to the species distribution among highly correlated bioclimatic variables, based on the biological knowledge of the focal species: as the white-tailed deer is sensitive to drought events (Tosa et al 2018), Bio12 (annual precipitation) and Bio17 (precipitation of the driest quarter) were retained; as snowshoe hare and Canada lynx are sensitive to snowfall and snow cover (Hoving et al 2005), Bio11 (mean temperature of the coldest quarter) and Bio19 (rain precipitation of the coldest quarter) were retained; and given that the grey wolf is sensitive to prey distributional changes, the same variables as the ones retained for the white-tailed deer were selected as they also displayed great importance and low correlation for grey wolf (Supplementary material Appendix 1 Fig. A1).…”

Interannual Variability in Survival Rates for Adult Female White‐Tailed Deer

“…A causal relationship between the relatively severe winter of 2009–2010 and subsequent high rates of hunter harvest in fall of 2010 is speculative; however, delayed increases in white‐tailed deer mortality and morbidity following severe weather conditions is documented (Mech et al 1987, Garroway and Broders 2007, Tosa et al 2017). Nixon et al (1991) reported persistent snow depth of ≥15 cm in Illinois limited access to ground forage and reduced the availability of metabolizable energy for deer.…”

Changes to Health Parameters of White-Tailed Deer during a Drought in the US Virgin Islands

“…In addition, deer consumed fewer plants, and plants of lower forage quality, and often did not meet their nutritional requirements, which had the potential to limit lactation [12]. Reduced lactation can decrease deer numbers either because of neonate starvation or result in smaller and weaker fawns [13]. Bucks responded to reduced food quantity and quality by displaying smaller body size and antler growth, particularly in young males that were still growing [12].…”