Why might deer abandon a drainage after rain or wind?

Water Pressure and Drainage Safety

Deer often avoid flooded drainages because the water pressure and current can be overwhelming, especially for young or weakened animals. When rain or wind causes a drainage to overflow, deer will typically seek higher ground or alternative routes. For example, a 3-inch rainfall event can increase water flow by 10-20 times in a matter of hours, making it difficult for deer to navigate.

Thermal Breaks and Deer Movement

In mountainous terrain, deer often use thermals – areas where cold air sinks and warm air rises – to move through the landscape. After a rain or wind event, thermals can become disrupted, making it harder for deer to read the landscape and detect potential threats. This disruption can cause deer to change their movement patterns and avoid areas where thermals are unstable. For example, a wind event can create a thermal break by blocking the sun’s warmth and creating a cold pocket, making it more challenging for deer to detect.

Deer Migration Patterns and Habitat Selection

Deer are opportunistic feeders and will often move to areas with abundant food and suitable habitat. After a rain or wind event, deer may seek out drainages with calmer water, such as those with slower currents or wider channels. However, they may also avoid areas with standing water, which can be a breeding ground for insects and parasites. For example, deer may prefer areas with 30-50% canopy cover, which provides shelter from wind and rain, and allows them to move through the landscape with greater ease.