I'm not trying to recreate the ancient ecosystem. That is gone. I'm trying to create biodiversity.
- Douglas W. Tallamy, scientist and author of Bringing Nature Home
There is no question that humans have significantly altered the planet. Forests have been clear cut and wetlands filled to make way for subdivisions, recreation, agriculture and industry. Human activities have polluted soil, water and air. Entire species have been lost to extinction. Natural predators have been eliminated in many areas. Alien plants, animals and insects have wrought havoc as they invade the ecosystem after being intentionally or accidentally introduced.
A male Western Bluebird that was trapped inside a nestbox and killed by a House Sparrow
. Photo by Claudia Daigle.
This article does not delve into whether humans have a right to harvest earth’s bounty or to manipulate natural resources. However, I would like to explore a related issue - when human intervention disrupts the ecosystem, do we have a responsibility to help restore the natural balance as best we can?
Sometimes the choice is fairly easy from an ethical standpoint. Few people have a problem with the concept of controlling invasive weeds. It does require effort and patience, and they must decide whether to use manual approaches like hand pulling versus herbicides. They may be less motivated to manage an attractive alien species like Purple Loosestrife until they realize the damage it does to biodiversity.
When it comes to critters viewed as creepy or unhealthy, such as roaches or rats, many people are comfortable controlling their populations by eliminating food sources and employing humane euthanasia methods. The issue becomes more difficult and emotionally charged when dealing with other, more appealing creatures.
Take “Bambi” for instance. White-tailed deer are native to North America, but excessive overpopulation can affect animal and human health (e.g., deer starvation and disease, transmission of tick-borne illnesses, and injuries from vehicular collisions.) It can also cause property damage (to cars, landscaping, crops, etc.) Forest health and wildlife diversity, including wildflower, butterfly and grassland songbirds, suffer as a result of selective feeding and overbrowsing by deer. Therefore, wildlife biologists recommend maintaining deer populations at a sustainable level (about 10-30 deer/square mile), in balance with the rest of the ecosystem. Birth control has been tried, but has proven costly, labor-intensive, and not very effective. So far, regulated hunting has proved to be the most effective means of controlling local populations.
Another example is control of invasive House Sparrows. These aggressive, non-native birds can wipe out gentle cavity-nesters like bluebirds and chickadees. House Sparrows evict native birds from nest sites, peck their eggs, toss young out of the nest to die on the ground, and decapitate adults if they trap them inside a nestbox.
In order to help bluebird populations recover from the competition and other effects of human activity like loss of habitat and use of pesticides, some people like me put up nestboxes. Because they are attempting to attract bluebirds to the area, they feel compelled to do what they can to protect native birds that may want to nest in their boxes from House Sparrow attack. They can use passive methods like not feeding cracked corn and millet, and installing “sparrow spookers” on boxes. Many also trap House Sparrows (which are not protected under federal law), sometimes donating them to raptor recovery centers where they are “recycled” to feed injured native birds of prey like owls.
The difficult and controversial question is whether anyone has the right and responsibility to manage animal populations by active means. Personally, I believe that regulated, responsible control efforts targeted at undoing the negative impacts of human activities in order to restore balance to the ecosystem are justified. I also respect the beliefs of those who disagree with that opinion. I do, however, hope that they too will do their part to restore balance by whatever means they are comfortable with.