Wolf denning dates stay constant as the climate warms

Wolf denning has not shifted as spring onset has become earlier in the year. This suggests that wolves may be resilient to changes in climate while still sensitive to seasonal weather conditions that impact their prey.

Arctic and boreal ecosystems are experiencing rapid changes in temperature and precipitation. These weather changes can shift the timing of plant growth and the species that rely on them. Sometimes this causes a misalignment between the timing of important foods and when they are needed most by an animal, such as when animals give birth and need to have abundant food sources to raise their young. Denali National Park and Preserve, Lake Clark National Park and Preserve, and Yukon-Charley Rivers National Preserve, contributed to a study that looked at how wolves in North America were affected by the changes in season onset and recent climatic conditions. We evaluated how changes in temperature and precipitation and spring onset dates affected when wolves den and reproductive success in eight populations across northwestern North America between 2000 and 2017. We found that the onset of spring shifted 14.2 days earlier, but the average denning date did not change, indicating a potential misalignment. So far, this shift has not affected the reproductive success of wolves, but reproductive success did improve during cooler summers and following relatively dry autumns. These weather patterns may improve habitat conditions for ungulates, thereby increasing the availability of important prey for wolves during the pup-rearing season. This suggests that wolves may be able to adapt to some shifts in climate trends, but are still sensitive to seasonal weather conditions that affect their prey at both local and regional scales.

Denning phenology and reproductive success of wolves in response to climate signals

Abstract

Arctic and boreal ecosystems are experiencing rapid changes in temperature and precipitation regimes. Subsequent shifts in seasonality can lead to a mismatch between the timing of resource availability and species' life-history events, known as phenological or trophic mismatch. Although mismatch has been shown to negatively affect some northern animal populations, longer-term impacts across large regions remain unknown. In addition, animals may rely on climate cues during preceding seasons to time key life history events such as reproduction, but the reliability of these cues as indicators of subsequent resource availability has not been examined. We used remote sensing and gridded spatial data to evaluate the effect of climate factors on the reproductive phenology and success of a wide-ranging carnivore, the gray wolf (Canis lupus). We used global positioning system (GPS) location data from 388 wolves to estimate den initiation dates (n = 227 dens within 106 packs) and reproductive success in eight populations across northwestern North America from 2000 to 2017. Spring onset shifted 14.2 days earlier, on average, during the 18-year period, but the regional mean date of denning did not change. Preceding winter temperature was the strongest climatic predictor of denning phenology, with higher temperatures advancing the timing of denning. Winter temperature was also one the strongest and most reliable indicators of the timing of spring onset. Reproductive success was not affected by timing of denning or synchrony with spring onset, but improved during cooler summers and following relatively dry autumns. Our findings highlight a disconnect between climate factors that affect phenology and those that affect demography, suggesting that carnivores may be resilient to shifts in seasonality and yet sensitive to weather conditions affecting their prey at both local and regional scales. These insights regarding the relationship between climate and carnivore demography should improve predictions of climate warming effects on the highest trophic levels.

Mahoney, P. J. K. Joly, B. L. Borg, M. S. Sorum, T. A. Rinaldi, … B. Mangipane, et al. 2020. Denning phenology and reproductive success of wolves in response to climate signals. Environmental Research Letters 15(12): 125001.