The Swamp Stomp

Volume 16, Issue 27

Many of us are have become familiar with the work of criminal investigators, because this subject has infiltrated television and movies.  For instance, we are familiar with many of the activities required to solve a crime: collecting evidence, interviewing witnesses, conducting surveillance, planning raids, and helping prepare cases for court.  But what most of us don’t realize is that the victims in some of these cases are not people, but rather wildlife.  Special agents of the Fish and Wildlife Service investigate crimes related to wildlife.  They enforce federal wild life laws, prevent smuggling, conspiracy, money laundering, and fraud.  They also investigate the killing of endangered or protected wildlife and work with industry groups and companies to reduce hazards to wildlife.

These special agents often work undercover and in covert operations.  They don’t wear uniforms, generally remain anonymous, and rarely give interviews.  Special agents must be in excellent physical condition, pass mandatory drug tests and psychological screenings, and have a four-year degree in wildlife management, criminal justice, or other related field.  And only the best of the best are accepted.  There are currently only 250 special agents working for the Fish and Wildlife Service.

Why does the Fish and Wildlife Service need a class of covert special agents?  While illegal activities involving wildlife are not often an apparent problem to the general population, they do frequently occur.  Illegal trade in wildlife is second only to narcotics.  Special agents often go undercover to infiltrate trafficking rings and illegal guiding operations to document violations.  The black market for wildlife is estimated to be worth more than $20 billion.  These animals are often smuggled into the United States as a part of the pet trade or for collectors.  And preventing this illegal trade is extremely important, because illegal wildlife trade can lead to mass extinction of species.

When an animal is recovered from an illegal operation, the Service cannot release it back into the wild because the animal is evidence and also it is unfit to survive alone after living in captivity.  Every time a wild animal is captured for illegal trade, there is one less animal to contribute to its natural population.

The best ways for individuals to help prevent illegal wildlife trade is to stay informed.  Asking questions and getting the facts about wildlife can help prevent the success of smugglers.   Also educating others to do the same thing is important.  In addition, pushing governments to pass and enforce laws that reduce demand and impose deterrents can help.

Although not well known, the special agents of The Fish and Wildlife Service provide an important function in our environment.   The job of the special agent is to uphold the objectives of the Fish and Wildlife Service.  These objectives are: to “Assist in the development and application of an environmental stewardship ethic for our society, based on ecological principles, scientific knowledge of fish and wildlife, and a sense of moral responsibility,” to “Guide the conservation, development, and management of the Nation’s fish and wildlife resources,” and to “Administer a national program to provide the public opportunities to understand, appreciate, and wisely use fish and wildlife resources.”

The Swamp Stomp

Volume 16, Issue 25

Residents of the San Francisco Bay Area recently approved an unprecedented tax on Tuesday June 7 to fund the restoration of lost wetlands. Known as Measure AA, the tax is expected to raise as estimated $25 million a year for the next 20 years.

The Environmental Protection Agency has found that the Western U.S. has the country’s sickest wetlands. In the San Francisco Bay Area, wetlands have been paved, diked and invaded by weeds at a rate unmatched elsewhere in the U.S.   An assessment based on more than 1000 wetland surveys conducted in 2001 concluded that while nearly half of the wetlands in the continental U.S. are in good shape, only one-fifth of the wetlands in the Western U.S. are doing well.

In California, the destruction of wetlands, has been even worse than in other areas of the west. An estimated 90 per cent of California wetlands have been lost over the last two centuries. The steep cliffs of the Pacific coast contained fewer natural wetlands than are found on the Atlantic coast.

Much of California’s wetlands were concentrated on rivers and around the banks of the San Francisco Bay. These areas have been paved over and built up. Additionally, ships in the Bay introduce invasive species, which has left the area with one of the words infestations of invasive wetland weeds in the United States.

Groups such as the Golden Gate Audubon Society use volunteers to help clean up wetlands in the San Francisco area. They host monthly workdays during which volunteers can sign up to remove invasive plants and pick up trash in areas such as the Pier 94 waterfront. The Pier 94 wetland restoration began when a shoreline on a Port of San Francisco property collapsed into the water and began to return to marshland. A decade ago, heavy trash such as pieces of pavement was cleared away, creating a place for plants to take root.

Coastal wetlands such as these may be important around the nation as sea levels rise. Coastal wetlands can help ease flooding and erosion as sea levels are getting higher. By growing taller as seas rise, marshes and other wetlands are increasingly valuable as buffers from the possible effects of climate change. It is estimated that seas may rise two to six feet over the next two centuries.

Wetlands are also helpful to filter pollution from the water and to provide habitats for multiple species of plants, fish, and animals. They improve water quality by trapping sediments and retaining excess nutrients and other pollutants such as heavy metals. These purification functions are especially important when a wetland is connected to groundwater or rivers and lakes that are in turn used for human activities and as a habitat for wildlife.

There are also economic benefits associated with the preservation of wetlands.   Without wetlands communities may have to build flood control or water treatment systems to replace the functions that are naturally provided by wetlands.  Is so, these costs could be much higher than those of preserving natural wetlands.  Also, wetlands provide valuable fish habitats, that if lost could be detrimental to the recreational and commercial fishing industries.

Wetlands perform a number of significant ecological functions that are not known by most people.  Over 100 years ago, some organizations campaigned for the elimination of wetlands, as they were considered a nuisance.  Now ecologists, scientists and environmental groups recognize the environmental benefits that wetlands provide, and hence have raised the public awareness of the importance of preserving them.    This type of awareness has made a difference in cities such as San Francisco where significant tax dollars are being used to restore wetlands.    Because of this increased awareness and the subsequent efforts being done by some communities in the western U.S., it would be expected that we will see increased efforts to improve wetlands in the 21^st century.

The Swamp Stomp

Volume 16, Issue 17

A few months ago, I was observing one of the Swamp School’s wetland delineation training courses in the field.   I was interested in some of the techniques that the students were using to collect data.  I watched several of them taking measurements and then entering those values into the data form.  Those values were then used calculate the prevalence index and dominance test and to evaluate hydrology and soil indicators.     All these measurements were then used to determine if the assessed area was considered a wetland.  The Army Corp of engineers would review the area at a later time and determine if these measurements were done correctly and if the assessment was accurate.

The first student I observed was reviewing the vegetation section of the data form.  She was determining the absolute percent cover of three tree species that were recorded in the data form.  Here observations were: River Birch – 34%, Red Maple 12%, and Black Oak – 6%.  Her wetland partner had the same tree species identified but his absolute percent cover values were quite different:  River Birch – 54%, Red Maple – 33% and Black Oak – 18%.  Why were their values so different?  Who was closer to the true values of absolute percent cover?    This is course led me to wonder that if both students were assessing the same area would their wetland conclusions be different?

In statistics, the variability that I observed is called “measurement error” and is present in all wetland delineations, as well as any process where measurements are taken by individuals.   Measurement error has two components:  accuracy and precision.  Accuracy is the difference between the average measured values and the true value.  Precision is how close all the measured values are to each other.   The graph below visually demonstrates the difference between accuracy and precision. Source: (http://kaffee.50webs.com/)

Going back to our example of the percent cover, let’s assume that the true values were River Birch – 43%, Red Maple – 21% and Black Oak – 15%.  If we took the average of the percent covers for each person it would be Birch – 44%, Red Maple – 22% and Black Oak – 12%. So it would seem that the accuracy of all the assessors (average values) was good.  But the precision in the measurements (variability between assessors) was not very good.   If we had asked each person to measure the same percent covers multiple times (unknowingly of course) we could have also measured the variability within the assessors.

Why does this error in measurement exist?  The answer, in general terms, is that each operator has slightly different methods for calculating percent cover.  In order to correct measurement error, the wetland delineation team would have to improve the process of how the percent covers were estimated. For instance, they could have a written procedure that explains exactly how the process should work, including pictures that demonstrate different percent covers.

There are of course other measurements taken during a wetland delineation that have potential for measurement error.   Examples include measuring the soil depth and determining the color percentage for the soil section.  Or determination if hydrology indicators are present at the site, such as surface soil cracks or moss trim lines.

Error exists in all wetland delineation processes where measurements are taken.  You will not be able to eliminate all the error but you will need to take steps to ensure that the error is minimized.   Error in your measurements could lead you to making incorrect conclusions regarding the decision about a site being a wetland.   Sometimes these errors can cost your company thousands of dollars.

There are statistical methods available such as control charts, analysis of variance, and attribute assessments to quantify the amount of measurement error that exists in your processes. These techniques can be useful in assessing measurement error in any data collection process. Understanding the concepts of measurement error, the tools to measure it, and being able to improve your measurement processes will provide you with meaningful data which you can use to make fact-based decisions.

The Swamp Stomp

Volume 16, Issue 12

As we venture through the wetlands, forests, swamps and even our backyards this spring we need to be aware of spiders. These arachnids are nearly everywhere and are pretty hard to avoid. Since you’re likely to run into one of them sooner or later, you should be aware of the potential dangers. There are a variety of spiders whose bite that will result in swelling, itching, and moderate pain. There are also a few spiders whose bite can be quite dangerous, so it’s a good idea to learn something about these arachnids.

In the U.S., the most common spiders that can cause harm are the black widow and the brown recluse. Although it is not likely that you will die from a bite from one of these spiders, you need to be aware of the danger and how to prevent exposure to them.

The brown recluse and black widow spiders both have special markings on their bodies that can help identify them. Brown recluse spiders are typically brown with a violin shaped marking pointing towards the abdomen on their heads. Another defining characteristic of this species of spider is that they have six eyes instead of the usual eight. In terms of size, these spiders can be anyway from ¼ to ¾ inches across their bodies. Black widow spiders can be easily identified by their shiny, black bodies and red hourglass shaped marking on the underside of their abdomen. However, it is important to keep in mind that this marking can range in color and the shape can sometimes be closer to a dot. Black widows are typically ½ inch in size.

Brown recluse spiders are found throughout the United States, but predominantly in the South. These spiders like to build their webs in small, dry hideaway spots, but can also be found in piles of leaves or under logs and rocks. Black widow spiders are common throughout the entire United States, but are mostly likely to be found in the southern and western states. They often live underneath things like woodpiles, debris piles, stones, and sheds. However, black widows can be found inside in places like basements and crawl spaces. So be aware of them even inside your house.

If you’re working in an area where you’re likely to encounter these spiders, it is vital to protect yourself from potentially getting bitten. To ensure safety, take the following precautions:

• Be able to identify these spiders. Proper identification can be one the most effective strategies to avoid getting bitten.
• Shake out clothing that’s been outdoors.
• Inspect clothing and tools before use.
• Wear protective clothing, like long sleeved shirts, long pants, hats, gloves, and sturdy boots while working in proximity to these spiders’ habitats.
• Reduce empty space between stacked materials and clear debris, as these can provide excellent hiding spots for spiders.

If you have been bit by a spider, check your symptoms to make sure it is not a venomous black widow or brown recluse. Some symptoms of spider bites can include itching or rash, pain around the bite area, muscle pain or cramping, red/purple bite or blisters, increased sweating, difficulty breathing, headache, and fever or chills. If you are experiencing any of these symptoms, seek medical help. Although extremely rare, you can die from a venomous spider bite!

While brown recluse and black widow spiders can pose a threat in the work place and everyday life, with proper safety techniques they can be avoided. Just be mindful of when you are in one of their habitats or near a place where these little creatures prefer to reside.