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The Spice of Life

Posted: May 10, 2016

What is the ideal habitat type for deer?
What is ideal deer habitat? Photo credit: D. Diefenbach

What is ideal deer habitat? Photo credit: D. Diefenbach

I have been asked many times to define deer habitat.  It’s easier to define what deer habitat isn’t.  

Deer have the amazing capacity to scratch out a living in almost any environment.  The forest – absolutely; the plains – of course; the coast – who wouldn’t; the mountains – sure; downtown Pittsburgh – why not!

The only place deer cannot make it work is a paved parking lot.  They have yet to overcome the constraints of asphalt.  But I’m sure they are working on that…in secret meetings.

But what people really want to know is what is IDEAL deer habitat.  To that I respond, what do you mean by ideal?

Is ideal habitat one that generates the maximum amount of deer “food”?

Is ideal habitat one that provides for critical life needs?

Is ideal habitat one that produces the “healthiest” (fattest) deer?

If you’re looking for a well-stocked buffet, early successional habitat (regenerating forest stands less than 6-8 years old) provides 1,000-2,000 lbs/acre of hoof-licking goodness in the form of woody browse, forbs, and soft mast.  Early successional habitat can support about 60 deer/sq mile during the winter.  This far surpasses other forest age classes: Mid-successional habitat (forests dominated by a high density of pole-sized, full-canopied trees) can overwinter 5 deer/ sq mile and mature forests (forest dominated by multi-aged and sized tree species, a well-developed shrub and small tree layer, and a well-developed understory) can overwinter 21 deer/sq mile.

So if your definition of ideal is maximum food output, then fire-up the chainsaws.  Or you could save yourself some trouble and just open a history book and see how well that worked out.

If your definition of ideal is to provide for all seasons and life-stages of deer, then you’re going to need to put your eggs in more than the early successional basket.  Deer like to eat and a full belly goes a long way but there’s a lot to be said for a warm bed and a place to hide.  

All species require water, food, and cover to survive.  Water is pretty standard regarding its definition for a species.  Food and cover are, of course, specific.

The list of food items for a deer is long and varied and includes browse, forbs, grasses, mast, fungi, algae, and even mosses.  With such a wide menu, it’s easy to understand why deer are so adaptable.  

It is no secret that acorns are a favorite on the list.  If they are available, it dominates their diet in fall and winter.  Deer ate about 1.5 lbs of acorns daily per hundred pounds of body weight in a feeding experiment.  Deer can sustain a maximum of 30% weight loss during winter.  More than that and they die of malnutrition.  Deer given basic starvation rations of browse could survive a 90-day winter period if given 0.5 lb of acorns per hundred pounds of body weight.   It’s easy to see why they are so important.

Cover is the other critical habitat component.  Deer use cover for protection from predators and temperature.  Security cover is vegetation thick enough to hide 90% of a deer from observation at a distance of 200 feet or less.  That’s pretty thick.  Saplings and shrubs can do the job very well.  Thermal cover is needed in the summer and winter.  It is most effective when the canopy is 70% or more closed.  In the winter, large tree diameter helps as well.  Everybody needs a safe, comfortable place to sleep. Even deer!

While mature forests only produce 50-100 lbs of browse/acre, it provides other perks not found in early successional habitat like acorns and cover. Also, mature forests are where you are mostly likely to find those spring ephemerals that are so nutritious! 

Obesity may be an American plight but we could use it as a way to judge ideal deer habitat.  Weight and fat deposits are easy to collect and sensitive to habitat conditions particularly for deer under 2 years old.  They are good indicators of forage availability and quality.  If those deer are fat and happy, then the habitat (no matter what it looks like) is the reason.

Ok, so where does that leave us?

Deer can live just about anywhere and do.  Food is of major importance but so is cover.  In particular, the way food and cover are distributed.  Deer, generally speaking, won’t use forage areas more than 600 feet from security cover.  A 100 acre clearcut may provide thousands of pound of deer food but only a fraction of it will be utilized.  

Pennsylvania is also a state with 4 seasons – half of which are not actively producing forage.  Older forests generally provide the best forage conditions for deer in fall and winter.  They are the primary source of mast (acorns!) and produce the about the same quantity of foliage as early successional habitats in winter.  

It seems that for deer variety is the spice of life.  Mature forests and early successional habitat are the yin and yang of ideal deer habitat.  If distributed properly in space and time, deer will have no worries.  

BUT…

There is always a “but,” isn’t there?  While mid-successional habitats contribute the least to deer habitat, you can’t get mature forests unless you pass through this stage of habitat.  It’s the classic “you can’t get there from here.”  Mowing down mid-successional habitat to “make more deer habitat” is setting the clock back decades from reaching mast producing forests.  It’s a stage that must be endured.  That’s where the “distributed properly in space and time” comes in.  

And here is the big one.  The very best habitat is bad if there are too many deer.  Habitat does not stand alone.  It is well documented that deer can and do eat themselves out of house and home.  Great habitat with too many deer soon becomes poor habitat with fewer but still too many deer.  Even less than ideal (poor!) habitat can support healthy (fat!) deer if they do not overwhelm available resources.

So if you're throwing a habitat bash for your favorite state animal, provide an array of options and don’t invite too many to the party.

-Jeannine Fleegle
PGC Deer and Elk Section

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