Here is the Colorado DOW info on deer survival, as an indication of
what a natural or wild population will do:
"The decline in Colorado's deer populations in the 1990's appeared to
result primarily from reduced early fawn survival. During this
period, posthunt fawn:doe ratios steadily declined in most of the
state with the exception of the eastern plains. Radio-telemetry
studies of early fawn mortality in western Colorado indicated that
disease and malnutrition were at least as important as predation in
reducing early fawn survival. Another study showed that improved
nutrition and condition of does during the winter resulted in higher
survival of fawns the following summer. Improved nutrition and
condition of fawns during the winter resulted in highly significant
increases in survival. The predation rate on fawns was inversely
related to fawn nutritional status and condition. A study is
currently underway to evaluate the effects of habitat manipulation on
fawn survival and deer density.
Although a full analysis is still pending, there does not appear to
be a clear relationship between reduced buck harvest and posthunt
fawn:doe ratios (i.e., fawns/100 does) in Colorado. In some units
where major reductions in hunter numbers resulted in large increases
in buck:doe ratios, fawn:doe ratios have remained low. Conversely,
in some units with only minor reductions in hunter numbers and small
increases in buck:doe ratios, fawn:doe ratios have increased
considerably. In many units, observed fawn:doe ratios went from
being consistently low in the late 1990's to showing considerable
year to year variation since 2000. In 2004, the mean, posthunt
statewide fawn:doe ratio was 58 calculated by weighting observed
ratios by estimated posthunt population size.
Colorado estimates posthunt deer populations each year. Estimates
are derived using spreadsheet population models on the basis of Data
Analysis Units (DAUs) that represent relatively discrete deer herds.
The population models use probabilistic harvest data (estimated using
random phone surveys) and observed posthunt sex and age ratios
(estimated using helicopter flights) as the primary inputs. In
addition, in 4 representative DAUs, annual doe survival rates and
winter fawn survival rates are estimated each year using
radio-collared animals and stratified, random quadrat surveys are
periodically used to derive probabilistic population estimates.
Kaplan-Meier survival rates from these DAUs are used as the basis
for calculating survival rates in other DAUs with similar habitat.
In 2004, 62,173 deer were classified by sex and age, annual doe
survival rates averaged 81.5%, and winter fawn survival rates
averaged 77%."
Can you survive as a farmer if 18.5% of your adults die over winter
and 33% of your young stock die over winter and you only produce 58
offspring per every 100 females bred?
--
Eugenie (Oogie) McGuire - oogiem@desertweyr.com
Weyr Associates - Consulting Services
Desert Weyr - CMK Arabian Horses, Black Welsh Mountain Sheep and Pilgrim Geese
http://www.desertweyr.com/
Paonia, CO USA
