Fawn Recruitment Rates
Kip Adams, QDMA Director of Education and Outreach, Northern Region
because they’re not sure how to use
it for management purposes. With a little help in analysis
and interpretation, managers can
use the data they collect to assess the status of their management program within their respective state, as well as compare how well
they stack up to other states and/or regions. To provide a comparison among states, QDMA surveyed state agencies and collected
information from 1998 and 2008 on four important management program indices. This article focuses solely on one of those indices,
fawn recruitment rates, and future articles will cover the others. With respect to our survey, all states didn’t provide the requested
information, but most did and the data provided for meaningful comparisons among states and between years.
Fawn recruitment rate is a measure of the number of fawns per adult doe (1.5 years and older) alive in the fall pre-hunt population.
Basically, this index records the number of fawns that survive to approximately six months of age and expresses that number in relation
to the number of adult does in the population. The fawn recruitment rate is lower than the number of fetuses per doe and the number
of fawns born in the spring, since not all fetuses survive to become fawns and not all fawns survive until fall. This rate is a good
measure of a deer herd’s productivity, and it is an important factor when determining the biologically appropriate number of does to
harvest. Monitoring the fawn recruitment rate also provides insight into herd health, and it alerts managers to potential problems such
as high fawn predation rates.
Our survey revealed several states do not calculate this valuable index. For those that do calculate it, most states’ recruitment rates
remained similar or declined slightly from an average of 0.88 fawns per adult doe in 1998 to 0.83 in 2008. This means less than one
fawn was recruited for every adult doe in both years, and it explains why the old adage, “When you shoot a doe you’re really killing three
deer” is a myth. The fact that actual recruitment rates are lower than many hunters envision can be a difficult concept to grasp because
we know healthy, mature does tend to have twins, and they can even have triplets in high-quality habitats. However, some fawns will
die before they’re recruited into the fall population. They may succumb to disease, be abandoned by their mother, get hit by a car, or be
killed by a predator.
Also, the definition of fawn recruitment rate is the number of fawns per adult doe (1.5 years and older). Yearling does are included in
this figure, but many yearlings do not have any fawns. Obviously, yearlings with fawns were bred as fawns. In areas such as Iowa, the
majority of doe fawns breed and can have fawns as yearlings. Some fawns in Iowa even give birth to twins! However, in other areas
such as Delaware or South Carolina, less than 10% of the doe fawns breed. That means over 90% of the yearling does in Delaware and
South Carolina have zero fawns, and that dramatically reduces the fawn recruitment rate. Let’s use the following hypothetical data as an
In this realistic example, Deer Herd B has a higher recruitment rate simply because a higher percentage of its yearlings had
fawns. Notice the 2.5 years and older does recruited the same number of fawns in both herds. If you expand this recruitment
rate to larger herds, the difference between 0.87 and 1.0 fawns per adult doe will have significant implications in the rate at
which a deer herd will grow and/or for the number of deer that you can harvest annually.
Getting back to the survey; many states have worked to balance deer herds with their habitat and to improve habitat quality
during the past decade, so you would expect the 2008 average recruitment rate to be higher than it was in 1998. Since it was
lower, it begs the question, “What impact are predators having on fawn recruitment rates?” In some areas predators may have
little impact, but recent research in Alabama, Georgia and South Carolina confirms that bobcats and coyotes can significantly
reduce fawn recruitment rates.
We asked for statewide averages in our survey, but it is important to remember the average recruitment rate can vary widely
within a state. This is especially true for large states with diverse habitats, deer management programs, and snow or rainfall
rates. Our survey revealed there is much variation in recruitment rates across the whitetail’s range. In 2008, fawn recruitment
rates varied from less than 0.5 in Arizona and Oklahoma to 1.2 fawns per adult doe in Illinois and Iowa. That means the
average doe in Illinois and Iowa recruits nearly 2.5 times as many fawns per year as the average doe in Arizona and Oklahoma!
Given this information, it is not surprising the productive Midwest grows so many bucks and requires such high antlerless
harvest rates to keep deer herds in balance with their habitat.
Sportsmen and women can estimate the fawn recruitment rate on the property they hunt/manage with observation data,
spotlight counts, and/or scouting camera surveys. Each technique has biases associated with it, but it’s more important to
estimate this index in the same manner each year so you can monitor trends in the data over time. Compare your estimate
to the range reported above, and then closely examine the direction your trend is moving. Increasing fawn recruitment rates
suggest herd health is improving and may permit higher harvest rates. Decreasing recruitment rates suggest herd health is
declining and/or fawn mortality is increasing. These figures can help fine tune your annual target doe harvest and help you
achieve success in your management program.
Kip’s Korner is written by Kip Adams, a Certified Wildlife Biologist and Northern Director of Education and Outreach for the Quality Deer Management Association (QDMA). The QDMA is an international nonprofit wildlife conservation organization dedicated to ethical hunting, sound deer management and preservation of the deer-hunting heritage. The QDMA can be reached at 1-800-209-DEER or www.QDMA.com.