11 January 2010


When I was pursuing my bachelor's degree in Ecology & Evolutionary Biology in the early-to-mid-1980s, a professor noted that (at that time) "due to human activity, a species is going extinct every hour, and an entire ecosystem is lost every day." It seems fairly certain that, given the escalation of human predation on other creatures, and of human encroachment on natural habitat, the pace of extinctions has similarly increased at a geometric rate.
This breaks my heart. My childhood in the 1950s was spent marveling at the exotic diversity of animals and plants around the world. Everything I learned in grade school, high school and college reinforced my excitement and wonder. Perhaps this, as much as anything, led me to a major in biology -- literally the study of life. What could be more fascinating?

Today, so many creatures which were numerous a mere half century ago are extinct or endangered. My blog focuses attention on predators, precisely because they are at the top of the food chain (or the center of the food web, choose your metaphor) -- their health reflects the health of the environment in which they live. Disturb one element of that interconnected community, and you disturb all elements connected to it, thence all elements connected to those, until the ripple effect is felt by all. Ultimately, human survival itself is placed at risk.

But one needn't focus just upon predators to get a sense of an ecosystem's health, and the part we play in its degradation. Witness the demise of the Dusky Seaside Sparrow (photo shown below). As described in Wikipedia, this subspecies was "found in southern Florida in the natural salt marshes of Merritt Island and along the St. John's River ... The dusky's demise began in 1940 when DDT was sprayed on the marshes for the control of mosquitoes. This pesticide entered the bird's food chain which caused the population to go from 2000 to 600 breeding pairs. When Merritt Island was flooded with the goal of reducing the mosquito population around Kennedy Space Center, the sparrows' nesting grounds were devastated, and their numbers plummeted. Later, the marshed surrounding the river were drained to facilitate highway construction, a further blow. Eventually, pollution and pesticides took such a high toll that by 1979, only six Dusky Seaside Sparrows were known to exist -- all of whom were males .... The last one died on June 17, 1987, and the species was officially declared extinct in December 1980."

So who cares, right? What's one obscure little bird, few in numbers, in the grand scheme of things? Quite a bit, as it turns out. Every species has co-evolved with its predator and prey species, and with its environment, filling a specific ecological niche. What happens to the top-dog predators may be more dramatic and easily observed, but the health of the other web members is just as important. The integrity of the whole is compromised when one member is wiped out.

Please understand -- over geologic time, species have come and gone in vast numbers. In fact, of all species that have existed, 97% are extinct. There have even been catastrophic mass extinctions caused by asteroid strikes, ice ages, sea floor changes, flood basalt events, and associated climate perturbations.

But it is precisely the current geometric increase in the rate of extinctions, at human hands, (in contrast to the flatter, natural background rate of extinction and speciation) which is alarming. We are, so far as we know, the only self-aware species on the planet, capable of changing the entire landscape, affecting climate, and .... here is the crux of it .... possessing both high intelligence and a conscience. It is incumbent upon us to regard all other creatures as having equal rights to survival, and to do whatever is needed to ensure that we have the least possible impact on our own nest. Should we fail, cockroaches shall inherit the earth.

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