Newspaper article The Tuscaloosa News

ECOVIEWS: Butterfly Populations Stable, despite Observations

Newspaper article The Tuscaloosa News

ECOVIEWS: Butterfly Populations Stable, despite Observations

Article excerpt

A tornado took down all the shade trees in my yard. Since that time, I have had two successful seasons of wonderful butterfly gardens frequented by as many as 20 different butterflies at a time. This year, however, I have only seen six all season. I know that some butterflies are endangered, but I never expected such a significant and precipitous decline.

Our climate has been very odd this year, with unusually cool and cloudy weather far into the spring and even summer. Many of my flowers have bloomed an entire month later than normal. Now, many of the plants I set out specifically to attract butterflies have run their course and, still, no butterflies. On two recent trips to south Alabama, I made careful notes of the few butterflies that I saw. Very few. So, it's not just my area. What insights do you have about this situation?

An environmental paradox is that on average about half of the populations of any native species decline in number each year. The reason is that the size of a local population of any organism (deer, turtles, dandelions) depends on how many individuals are born or immigrate to the area versus how many die or emigrate. Since, under natural conditions, no species (other than humans) remain in a state of overpopulation for many generations, declines in animal and plant

populations must be in proportion to their increases. Thus, constantly fluctuating population numbers are the norm, although the reasons may be undetermined. Ecologists often speculate about the whys of declines or unusual abundances of particular species, with the weather being a common explanation, but sometimes we are just guessing about causes.

Last month, I heard that fireflies were declining. Apparently some people think they are not as common in certain areas as they have been in recent years. After I was asked about the possible lightning bug decline, I began to wonder if it were true. That night, my backyard was full of them for the first time in the season. As for butterflies, I checked with an entomologist colleague to see if a butterfly

decline has been noted in the Southeast or elsewhere.

I asked Karl Espelie, University of Georgia professor of entomology, if butterflies were thought to be disappearing. …

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