One of the things about blogging is that you can put ideas out there in real time, maybe while they are in the process of being developed. So I put out the idea of a “butterfly flux,” and since that time I have been working on how it should be defined. Here is what I have come up with:
The butterfly flux for a particular habitat is the quantity of all butterflies present in that habitat, in any stage of their life cycle, and which use that habitat for growth. That quantity is constantly changing, and is expressed as a number per unit area. There is a number that correlates to the number of individuals, and a number that correlates to the diversity of species.
Woodlands, prairies, and wetlands would each have a unique flux. Similar habitats at different lattitudes would have different fluxes. But this is mostly a tool to evaluate highly modified environments. I propose the the butterfly flux of the original habitat be given an arbitrary number of “1” (actually, give a number of 1 to evaluate the diversity, and another number of 1 to evaluate the total numbers if individuals. One times one equals one).
A parking lot with no vegetation would have a value of “0”. You might see butterflies crossing the parking lot at one time or another, but they do not use the habitat for growth.
Here are the results of Pollard-walk surveys of four highly modified habitats–the suburb-like area has closely cropped lawns and trees, but the only flowers present are yard weeds (and if you watch for them, there are a lot more than you might think). The other areas are “constructed wetland” or highly modified wetland areas.
The graph is of “observations per hour”–the number of butterflies of any species measured as a function of the time spent surveying. This is not a measure of the butterfly flux, but it may approximate the trends.