Stories from the NFCCA Newsletter, the “Northwood News”

Northwood News ♦ February 2010

Part One of a Series

Oh, Deer!  The Reasons Behind All The Deer

By Carole A. Barth

If you spend any time in the parks, you’re probably aware of the skyrocketing deer population.  In fact, you can see them everywhere:  from small suburban backyards to roadsides, and even in urban areas.  It’s astonishing to see a group of such large, gangly looking animals leap effortlessly over obstacles and disappear into the tiniest patch of cover in an instant.

When I was a child, it was an extremely rare treat to actually see any of the deer that lived in the woods in our neighborhood.  Even today, the sudden sight of a deer can still put a catch in my breath.  However, I know that these frequent sitings are the symptoms of an ecological disaster.

Deer are most evident during breeding season (October through December).  They are also most unpredictable at this time of year.  A few years ago, a deer wandered into a Metro station, hopped the turnstile and proceeded to the platform.  Recently, a deer actually jumped into the lion enclosure at the National Zoo.  So it’s not surprising that 1,841 deer-car collisions were reported in Montgomery County in 2008.

The Reason for the Problem

Why are there so many deer?  To begin with, deer are an “edge” species.  They thrive on the variety of food found in the interface of forest and field.  Before European colonization, most of the region was covered in dense woods.  So deer habitat was quite limited.  As forests were cut, the balance shifted.  More deer habitat equaled more deer. In addition, large predators (wolves and mountain lions) were eliminated, so there was little to stop expanding deer numbers except for hunting.

As suburban development became widespread, the landscape became almost all edge, and hunting was banned or heavily regulated in the newly developed areas.  Deer breed quickly; in fact, they can have as many as three young a year.  Populations can more than double in two years’ time. So, in hindsight, it’s not surprising that deer populations have rapidly soared in the wake of recent land-use changes.

Just how much has the deer population grown in the eastern U.S.?  New Jersey provides an interesting example.  Estimates are that in 1500, New Jersey’s deer population density was about nine deer per square mile, spread across the state.  Today, the average population density is 50 per square mile.  In some natural areas, the density is over 100 animals per square mile.

An average deer eats six to eight pounds of plants a day or 1.25 tons per year.  So it’s easy to see how even a few deer can wipe out a garden or significantly damage a farmer’s crops.  But the lasting damage is to our remaining forests.

Forests heavily browsed by deer have little or no understory.  With no saplings and seedlings, there are no replacements for trees that die.  With no shrubs and wildflowers, there’s no nesting area for shrub or ground-nesting birds.  There’s no safe place on the forest floor for amphibians and small mammals.  In fact, deer some times consume baby birds in the nest and rare butterfly eggs along with the plants they’re on.  And because deer usually prefer native plants, deer overpopulation also helps exotic invasive plants spread.  The result is a forest missing both its structural complexity and its species diversity.

Eventually, with no population controls, food becomes scarce and the deer begin to suffer.  Starving, diseased, and suffering from parasites, deer can no longer be selective about what they eat.  This has already happened in many areas.

[Part two of this article (link below) will look at what management options are available and what is currently being done to manage deer in the parks.]   ■

Some Useful Contacts

Emergency Contacts

Read Part 2: Deer Repellent Read Part 3: Population Control

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