Gray Fox (Urocyon cinereoargenteus)
Influence of Weather on Movement and Activity
Using multiple linear regression to model movement rates as a function of seasonal weather conditions, during breeding-denning movement rates were most related to temperature, relative humidity, dewpoint, and barometric pressure. Movement rates generally increased with decreasing humidity, dewpoint, temperature, and barometric pressure.
During fall-winter, movement rates were most related to barometric pressure and barometric trend. Gray fox movement rates increased with changes in barometric pressure of > 0.02. During parturition-young rearing, movement rates most related to relative humidity and barometric trend. Movement rates generally increased with decreasing relative humidity and barometric trend.
Using logistic regression to model seasonal activity as a function of weather conditions, barometric trend and temperature were significant predictor variables during breeding-denning. Gray fox activity increased with declining barometric trends and increasing temperatures. During fall-winter, wind direction was a significant predictor variable. Gray fox activity generally increased with wind directions from the south. During whelping-pup rearing temperature, relative humidity, wind direction, and barometric trend. Gray fox activity increased with decreasing relative humidity, temperature, and barometric trend. Gray fox activity decreased with wind direction from the south. Model classification rates ranged from 53% to 89% of locations correctly classified as active or inactive based on weather conditions.
Information detailing the effects of weather conditions on gray fox movements is unavailable in the current literature. On TWMA and GP, barometric pressure and relative humidity generally had the greatest effect on movement rates across seasons. Gray fox generally moved at greater rates when barometric was either rising or falling, sharply. Decreasing barometric pressure usually indicate the approach of storm fronts. Perhaps prey species become active during these periods, hence gray fox increase movements to search for prey. Results from our study suggest that weather conditions do influence gray fox activity patterns seasonally. Our models provided variable classification rates; however, several models correctly classified >60% of active and inactive locations. Little research has examined the influence of weather on gray fox activity patterns and is unavailable in the literature. For comparison purposes, research examining the influence of weather on other species has noted decreases in activity for raccoons during cold weather. We documented a similar relationship between increasing activity and temperatures during breeding-denning. However, activity increased during whelping-pup rearing with decreasing temperatures. This is not surprising given the extreme daytime temperatures during whelping-pup rearing (1 June - 30 September) on our study areas. Gray fox seldom became active during midday, when temperatures often ranged from 90-100 F. Similarly, during fall-winter, activity generally increased when winds prevailed out of the south, suggesting the approach of warm fronts. This relationship reversed during whelping-pup rearing, when hot winds from the south generally resulted in decreased activity.