Magic Valley Mule Deer Numbers Encouraging

April 5, 2005

Mule deer numbers in the Magic Valley Region continue to increase or remain stable across the region.

Early spring and late summer rains in 2004 improved habitat, which is boding well for mule deer.

"We are having excellence fawn recruitment in many parts of the region this year," said Randy Smith, Idaho Fish and Game Magic Valley Region Wildlife Manager. "The most dramatic increase this year has been in hunting Units 55 and 56, south and east of Burley."

To help track mule deer populations, Idaho Fish and Game biologists conduct aerial surveys twice a year on mule deer winter ranges. The post-hunting season composition counts help biologists determine the number of bucks per hundred does and number of fawns per hundred does. The post-winter survey allows biologists to enumerate deer in a trend area and helps them determine the number of fawns and adult deer that survive the winter.

A comparison of fawn ratios before and after winter helps biologists estimate winter fawn survival. The proportion of fawns in the herd at the end of winter helps biologists understand whether a population is declining or increasing and provides the best indicator of reproductive performance during the previous year.

Because funding is limited, biologists can't afford to count all of the deer in a given unit. However, counting a segment of the population allows wildlife managers to compare the composition of the total population to that of previous years.

In the Magic Valley Region, biologists focus on winter range in four management Units: 45, 54, 55, and 56.

Here are the results from three years of counting in those units:

• Unit 45: Total trend area counts: in 2003, biologists counted 5,419 deer; 2004 - 7,144 deer; 2005 - 6,267 deer. In the post-hunting season count they observed 37 bucks per 100 does. The number of fawns counted in the pre-winter count was 61 fawns per 100 adults and in the post-season count was 50 fawns per 100 adult deer.
  
  "Deer observed in the Bennett Hills (Unit 45) trend area declined by 12 percent from the 2004 levels, but was 16 percent higher than in 2003," said Smith. "Comparison of the pre- and post-winter fawn to adult deer ratios suggests excellent winter fawn survival or around 75 percent and a recruitment rate of 33 percent."
• Unit 54: Total trend area counts: in 2003, biologists counted 1,133 deer; 2004 - 1,832 deer; 2005 - 1,817 deer. In the post-hunting season count they observed 29 bucks per 100 does. The number of fawns counted in the pre-winter count was 53 fawns per 100 adults and in the post-season count was 42 fawns per 100 adult deer.
  
  "The trend area count in Unit 54 was similar to last year and 60 percent higher than in 2003," Smith said. "A comparison of pre- and post-winter fawn to adult deer ratios suggests that fawn survival was higher than 75 percent. Of the four survey areas, Unit 54 had the lowest ratio of fawns entering the winter, and even with excellent fawn survival, the lowest recruitment rate of 30 percent."
• Unit 55: Total trend area counts: in 2003, biologists counted 607 deer; 2004 - 1,100 deer; 2005 - 1,941 deer. During the post-hunting season fawn survey, biologists counted 68 fawns per 100 adult deer.
• Unit 56: Total trend area counts: in 2003, biologists counted 556 deer; 2004 - 996 deer; 2005 - 1,284 deer. In the post-hunting season count they observed 13 bucks per 100 does. The number of fawns counted in the pre-winter survey was 64 fawns per 100 adults and in the post-season count, 59 fawns per 100 adult deer.
  
  "The deer populations in Units 55 and 56 have shown dramatic growth since 2003," Smith said. "Observed post-winter fawn ratios suggest recruitment rates of 40 percent in Unit 55 and 37 percent in Unit 56; indicative of population increases. The buck to doe ratio in Unit 56, following the general any-buck hunting in 2004, was 13 bucks per hundred does compared to an average of 15 bucks per 100 does from 1998-2002."

For more information on mule deer in the Magic Valley Region, contact Randy Smith at 324-4359.