Wither our Habitat? Bird Turf Battles
One of the most commonly misunderstood principals of preserving wildlife is how animals survive after their habitat has been altered or destroyed. In Sarasota, these alterations typically come from converting natural habitats into agriculture or suburban development. Many developments still share their space with remnant wildlife, and in some cases the development is named after signature wildlife found on the site. A natural assumption to make is that since some of the wildlife is still there, it has adapted to the new human landscape, and we’ll all live together, happily ever after. Regrettably, this fairy tale forecast is far from reality.
First we should clarify what happens to wildlife displaced by the destruction of their own natural habitat and relocate to other natural areas. Most wildlife habitats are already at or near capacity. When displaced wildlife moves into a new area, it overpopulates that area and displaces the resident wildlife. The net loss of wildlife is the same as if none had survived the destruction of its homeland.
For the wildlife that stays, which species will survive in human modified landscapes will ultimately be determined by the quantity and quality of resources found in the natural habitat, that are maintained in the human habitat. The more resources that are maintained or simulated, the more species will survive. This may be more easily described with some examples. Bobwhite quail and Mourning doves are both common in Sarasota’s natural landscapes, and like the miner’s canary make excellent forecasters.
Bobwhite quail live exclusively in fire-maintained prairies and open pine flatwoods habitats. Early settlers to the Sarasota area modified most of the native prairies and pinelands by chopping back and burning the palmetto so that grasses would flourish and more cattle could be raised. Wildlife that relied on the palmetto died off. The quail, however, survived as the grass proliferated under the rancher’s care. However, when this native rangeland is converted to subdivisions, the native grasses are replaced by seedless lawn-grass and the quail are lost.
The Bobwhite quail survived the cattlemen’s alterations but not the housing development’s, because it was already adapted to a grass environment, a resource maintained by the rancher. It did not inherently have the ability to survive the loss of the critical grassland resources caused by the subdivision. The quail’s survival had nothing to do with its ability to adapt to one altered environment and not the other.
Many of the quail will survive the bulldozers blade as individuals, and it may take several generations (5-10 years) to disappear as a species. South Venice scrub-jays have been hanging on for over twenty-five years because of individuals surviving the slow, lot-by-lot land clearing process. As a species, scrub-jays are doomed in developed areas without the scrub habitat resource. Longer-lived wildlife, such as gopher tortoises, could take 50 years or more before they die as a species. Bottom line is that we cannot assess the impact of wildlife lost, as the result of habitat changes, by what we see today.
Mourning doves share the same pinelands with the quail. However, unlike the quail that depend on an herbaceous grassy understory, doves can be found in many of Sarasota’s native habitats. Quail feed primarily on grass seed, where as doves are opportunistic omnivores that will take advantage of almost any food available. While quails nest almost exclusively in woven clumps of native grasses, mourning doves naturally nest anywhere. Because of the dove’s natural adaptation to a multitude of habitat conditions, they are enabled to survive the conversion of natural lands into suburbia. They survive not because they have adapted to a new environment, but because they already had behavior traits that were compatible with the new altered human environment.
If we were to expect wildlife truly to adapt to human altered environs, then we would have needed to phase in our habitat alterations over eons. Rather than Sarasota going from completely natural to seventy percent developed in 100 years, for wildlife to adapt, it might take 10,000 years.
Wildlife cannot adapt to habitat alteration that result in a loss of naturally occurring resources. It reacts. What we’re seeing are instinctive survival skills altering the individual’s natural behavior in order to survive in the strange new environment. Survival of the species depends entirely upon the species’ long established relationship with the resources afforded within an environment. If the resources are not available, mortality will exceed reproduction and ultimately the species will be lost, it’s just a matter of time.
While some of Sarasota’s native wildlife will survive in man made environments, most will not. As a community our challenge is to make responsible decisions, and base them upon educated long-term expectations, not short-term fantasies that justify bad decisions.