Preserving plants, animals and ecosystems takes more than preserving land

In a May 19th article by Ike Wilson, entitled “41-year study shows drastic orchid species decline in Catoctin Mountains,” the Frederick News Post conveyed the bad news about the “precipitous” decline of 19 of the 21 species of orchids that have been observed in the mountains here over the last few decades.

The plight of the orchids in Frederick County received the attention because of a recently published study, authored by Wesley M. Knapp and Richard Wiegand, under the title “Orchid (Orchidaceae) decline in the Catoctin Mountains,Frederick County, Maryland as documented by a long-term dataset.” You can read the study in its entirety here, or download it as a pdf file here.

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Here is the abstract:

A 41-year study (1968–2008) of the orchids of the Catoctin Mountains, Frederick County, Maryland reveals that 19 of 21 species have experienced precipitous declines. Four of these species are currently considered Threatened or Endangered by the State of Maryland and another two are considered Rare. Annual census data at 167 sites from throughout the Catoctin Mountains on protected and unprotected lands (private and public) show a loss of three species from the study area, a decline of >90 % (ranging from 99 to 91 %) in seven species, and a decline of <90 % (ranging from 51 to 87 %) for nine species. Each species was analyzed using Ordinary Least Squares Analysis to show trends and document corresponding R2 and p values. We tested the hypothesis that this decline is due to intensified herbivory by white-tailed deer. The overall orchid census data is significantly inversely-correlated (R = −0.93) to the white-tailed deer harvest data of Frederick County (a surrogate for population size), which includes the entirety of the study area. Platanthera ciliaris showed a huge expansion at a single site explicitly managed for this species otherwise this orchid showed a decline similar to the other species. Proper management is critical for the continuation of the orchid species in this study, be it control of the white-tailed deer herd or combating woody plant succession in the case of P. ciliaris.

The entire study is not very long (barely eight pages of text, with tables), and is very readable.

While it mentions a few factors that could affect the population of some or all of the orchids (not to mention other plants), the key finding of the study was that “the main cause of this decline is most likely herbivory by white-tailed deer.”

“The impact of white-tailed deer herbivory was an obvious potential cause of this decline and an independent dataset existed to examine this factor. Studies on the impacts of herbivory to understory herbs are numerous and show herbivory represents a significant threat (Whigham 1990; Anderson 1994; Augustine and Frelich 1998; Ruhren and Handel 2000, 2003; Fletcher et al. 2001; Knight 2004). Regionally, deer herbivory is believed to be so intense it may cause the extinction of American ginseng (Panax quinquefolius L.), a now rare herbaceous plant (McGraw and Furedi 2005).

The inverse correlation argues that the white-tailed deer population of Frederick County is the most likely cause of this decline.”

As valuable as the research is, the conclusion is not surprising, as it confirms the well-known fact that the unnatural overabundance of white-tailed deer has a widespread and dramatic effect on many native plants, and, by extension, on native animals, and even entire ecosystems.

As the authors say:

“This study also challenges the underlying idea that an area is protected just because it is publicly owned. Proper natural resource management is a prerequisite for species survival.”

This is an important point, and one we would be wise to remember when we purchase and/or manage public lands to preserve natural areas. The subject is too broad to get into the weeds here and now, but besides the serious concerns about chronic over-browsing by a much too large deer population, there are other threats to the biological integrity of the habitat, such as invasive, non-native plants, insects and other animals, air pollution, certain recreational uses that fail to adequately consider the ecology of the area in their management plan, and more.

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Below is a column I wrote for the Frederick News Post more than a decade ago, delving a bit into the issue of our deer population. Unfortunately, it’s as relevant today as it was then. Deer are often managed as much or more for the benefit of maintaining a sizable population for hunting than primarily for the benefit of the overall ecological community of native plants and animals.

They are beautiful and graceful native creatures that belong here. But…


Hunting may be best deer solution

Frederick News Post
November 29, 2002

by Kai Hagen

The day after Thanksgiving may be the busiest shopping day of the year, but for many in Maryland it is more noteworthy as the beginning of the white-tailed deer firearms season.

While others are spending the day in stores and malls, a few thousand hunters have been out in the woods and fields around the county, many before the sun came up.

Deer hunters are determined folks, not easily deterred by inclement weather. But rain, fog, wind and unusually warm temperatures contributed to a 13 percent decline in Maryland’s firearm season’s harvest numbers last year. Maryland’s bow and muzzleloader hunters made up the difference, however, with record deer harvests. Altogether, Frederick County hunters took 8,054 deer, more than any other county in the state.

Numbers like that make it hard to believe there was a time when the near complete clearing of Maryland’s original forest and the unrestricted killing of deer led to their elimination from all but the most remote areas of far western Maryland.

Imagine that. No deer in Frederick County.

There weren’t a lot of people here then. But there weren’t a lot of trees, either. And things were seriously out of balance.

Today there are a lot more people in Frederick County. And trees. And, of course, a lot more deer. Too many deer. Things are still out of balance.

The deer population in Maryland has been growing for decades, reaching about 150,000 in 1991, and roughly 250,000 today. Incredibly, some projections suggest it could reach 500,000 before long if nothing is done to control the rate of growth.

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You don’t have to be a wildlife biologist to understand how this has happened. The recipe we’ve used for cooking up a landscape to suit our needs and desires contains all the ingredients necessary to support far more deer than nature intended.

Most significantly, our suburban neighborhoods, pastoral farmland, woodlots and fragmented forests do not support either solitary mountain lions or packs of wolves. More than anything else, these predators kept the deer population in check, maintaining a healthy balance for millennia.

As if removing the large predators wasn’t enough, we’ve also been kind enough to provide ample cover and an abundance of nutritious food. Deer may be fearful and skittish creatures, but the benefits of living near people clearly outweigh the drawbacks.

The white tailed deer is a graceful and beautiful animal, one of the few large mammals that still thrives in Maryland. Without an effective way to reduce the population, however, it won’t be long before they are primarily seen as unwelcome pests.

The burgeoning deer population is having a growing impact on the people of Maryland. Vehicle collisions continue to increase, with thousands of deer being struck each year. Farmers are experiencing more crop damage throughout the state. Orchard and nursery owners constantly battle to reduce damage from browsing and rubbing. Homeowners are experiencing damage to their vegetable gardens, flowerbeds and landscape plantings. Lyme disease, which is spread by ticks found on deer, is increasing.

Any one or two of those problems is enough to convince many people that we have to do more to reduce the number of deer.

For others, the most convincing reason to take more aggressive action is that our seriously out of balance deer population is having a disastrous effect on the health and diversity of our remaining forests and other ecosystems. Hungry deer are eating the food and shelter that a great many other animals depend on.

Too many deer doesn’t just mean sick and hungry deer. It means greatly impoverished forests and reduced biological diversity.

It is a problem of our own making. And it is our responsibility to deal with it. There are all sorts of problems affecting our environment that have nothing to do with deer, of course. But reducing the number of deer is one solution we can’t afford to ignore. Without natural predators, regulated hunting is the only realistic way to achieve this goal in many areas.

In our changing social climate, however, hunting is becoming less acceptable. More people are resisting hunting on the grounds that it is unnecessary, or that it is morally wrong. The number of hunters is in steady and serious decline. And the U.S. Fish and Wildlife Service recently reported a seven percent decline in the number of American hunters over a five year period.

As population growth and suburban sprawl continue to make hunting impractical or impossible in many areas, other measures may be required. There are other options available, such as relocation, contraception, repellants, and fencing, but they are all much more costly and generally less efficient.

In contrast, hunters pay for the privilege of hunting and trapping by purchasing licenses from the state and federal government. The use of hunters and trappers to harvest animals is often the most cost-effective way to manage wildlife populations. Spending substantial tax dollars to do the job less effectively doesn’t make much sense.

It is true that some land management practices and hunting regulations have contributed to our deer problem, prioritizing the maintenance of an unnaturally high population for the benefit of hunters. But that has been changing. Hunters are allowed, even encouraged, to take more does, for example. Hunting seasons have been expanded. It probably isn’t enough. But it’s a start.

I wish them good hunting.


Frederick News Post
41-year study shows drastic orchid species decline in Catoctin Mountains
Monday, May 19, 2014

Orchid (Orchidaceae) decline in the Catoctin Mountains,Frederick County, Maryland as documented by a long-term dataset
on the web
as a pdf file
Wesley M. Knapp • Richard Wiegand

The rest of the columns by Kai from the Frederick News Post and the Gazette (2002 – 2005)