September 27, 2023

Sustaining a Deer Herd

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twoyoungdeerblog*Editor’s Note* – This article first appeared in the Bethel Citizen.

Open Air
With Tom Remington

Sustaining a Deer Herd

Nature does not balance itself; at least not in the idealistic sense that many of us have been taught in schools and read about in environmental and wildlife biology books. In nature, or within our ecosystems as the popular term is used today, nothing is in balance. It is always changing. My good friend, Dr. Valerius Geist, a professor emeritus at the University of Calgary, has explained to me, “Thinking nature is in balance is intellectual garbage.” (I have lots more information on this subject on my website if you are interested.)

With that in mind, Maine is struggling to sustain a whitetail deer herd in much of the state. Because Nature does not “balance” itself, if we, as citizens, wish to have a healthy population of varied species throughout the state, humans must participate in making that happen. This becomes one of the functions of a fish and game department but is our responsibility as well.

To maintain a deer herd at present levels, simple math tells us that we must have an equal number of newborn deer survive to replace those that are killed throughout the year by various means. Sounds simple enough but it’s not. If the total mortality of deer is 40%, then newborn and surviving deer must be 40% in order to maintain current population numbers. Should biologists wish to increase deer populations, they must implement ways of decreasing mortality and/or increasing survival of newborns. The opposite is required to reduce populations.

Many people believe that control of a deer population can only be done by how many deer get taken during hunting season. This is not true. Deer die each year in a number of ways: old age, disease, auto collisions, hunting, predators, etc. There often is one factor that goes overlooked – fawn recruitment.

Fawn recruitment is a term used to describe when a newborn deer lives throughout their first year of life. Born mostly in June in Maine, if a fawn makes it through their first winter, that is considered one recruited fawn to the deer herd. Recalling the math earlier, if fawn recruitment drops too low and remains that way for too long, it isn’t long before a deer population begins shrinking very fast. If that number gets too low, recovery can become next to impossible.

Many believe that fawn recruitment must meet 30% to 40% in order to maintain a present deer population. In parts of Maine, recruitment barely makes 20%.

Fawns are a target of many predators such as: black bears, bobcats, coyotes, red fox, Canada lynx, fisher, even domestic dogs. We must also bear in mind that there are recorded events of eagles snatching newborn deer from the field.

This predation is a normal and natural event but what happens if any one or all of the above mentioned predator populations becomes too high? Logic tells us that too many predators can kill too many fawns, bringing the recruitment rate below the necessary level to maintain and even sustain a healthy deer herd.

The reality of life in the forest and fields is not a pretty picture when it comes to surviving. The idea that nature is in balance brings many to believe that if man just left these animals alone, everything would be fine. That is idealistic thinking.

Dr. David Mech, considered the foremost expert on wolves, once also believed that having all the indigenous predators in an ecosystem would “balance” things out. He has since discovered that to not be the case and believes that predators need to be “controlled” in order to achieve the population levels desired by us humans.

The next time you read or hear about people wanting to pass laws to prohibit the scientific control of predators, understand that while few want those predators gone, they do need to be kept in check in order to sustain a healthy ecosystem.