March and April are critical months
As they do every winter, biologists with the Division of Wildlife Resources have been watching Utah's deer herds closely.
Photo by Ron Stewart
And so far, biologists have good news: Deer across Utah are doing well during what's always their toughest time of the year.
But even though a lack of snow and mild temperatures has treated the deer well, Anis Aoude, big game coordinator for the DWR, says part of the deer population isn't out of the woods yet.
"Adult deer should come through the winter just fine," Aoude says. "Fawns, however, are still at risk."
Shrubs to green vegetation—making the switch
The green vegetation that becomes available in the spring is a major challenge for deer.
Deer have a complex digestive system. Because it's complex, it takes time for their system to switch from digesting a winter diet of mostly shrubs to a diet that consists mostly of green plants.
Switching to a spring diet is especially challenging for fawns—this is the first time their digestive system has had to make the switch.
If deer eat the green vegetation gradually, they do great. But if they ingest large amounts of green vegetation before their digestive system is ready to receive it, the deer can develop scours (diarrhea).
Scours causes the deer to become dehydrated. If they lose too much moisture, the deer can die.
Areas in Utah that have poor winter range are usually the areas where deer eat large amounts of green vegetation in the spring.
"Areas with poor winter range don't have many shrubs," Aoude says. "As soon as green vegetation appears, the hungry deer start eating it. They can eat a lot of vegetation in a short period of time."
A spring and early summer that isn't too cold or wet, and green vegetation that becomes available to the deer gradually, will increase the number of fawns that survive into the summer.
"If we have those types of conditions this year," Aoude says, "the deer should do really well moving into the summer."
You can learn more about mule deer biology and the challenges deer face in the "Mule Deer: Changing Landscapes, Changing Perspectives" publication.
The free publication is available online .
Watching deer in the winter
In addition to determining the condition of the deer as they entered the winter, DWR biologists watch for the following things during the winter: