When a Species is Endangered

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Published on: Jul. 2, 1999

Last revision: Nov. 3, 2010

It is one thing to track the kinds of plants and animals living in Missouri, but quite another to collect enough information to know how every individual species is doing--to track the health of our living resources. Fortunately there are professional biologists and resource managers to assist with the task.

The process of designating endangered species is more rigorous than many people guess. It is as factual as existing data allows and is scrutinized by people who know the species well and can make an informed assessment.

How many places a species lives is a fact, and biologists try to keep as accurate a count as possible. How many of these remaining populations of animals or plants are capable of surviving into the future is professional judgement. How long threatened populations will persist is prediction. Biologists and managers are asked to predict if the remaining populations are likely to disappear in the near future. This is not science at all, but prognostication. Endangered or not, it's hard to say.

Robins and white oak trees are doing well. Clearly they are not endangered.

Greater prairie-chickens and western prairie fringed orchids are not doing well. They are endangered.

How do we know? Conservation Department biologists assess the current condition of the species, compare it to the historic condition, evaluate present threats and recommend a status.


Greater prairie-chicken numbers, for example, have never been lower in Missouri, at least not in recorded history. And the population monitoring record is good. Conservationists reported approximately 12,500 birds in the state in 1907, and hunting was stopped. Populations have fluctuated through the years, and the current population is estimated at 1,000 to 3,000 resident birds.

Prairie-chickens are declining in Missouri. Their population trend is best represented by annual counts made along 13 routes that cover 236 square miles. In the spring of 1997, we counted only 214 displaying males, suggesting that prairie-chicken numbers continue on a long-term downtrend that began in the late 1960s. If the trend set over the past 30 years continues, our resident birds will disappear from Missouri by the year 2009.

There continue to be threats to the birds that remain in Missouri. Overgrazing, late hay mowing and poorly timed burning reduce the amount of cover available for nesting and roosting. Lack of large blocks of grassland habitat also limits them. The same habitat problems that affect other grassland birds, such as quail, have caused prairie-chicken numbers to decline. Along with

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