Which of the following are serious threats to wildlife?

Question

I. Conservation of wildlife habitat to space for housing agriculture.

II. Pollutants from chemical insecticides used in farms.

III. Catching of animals by families for their food.

IV. Illegal hunting and overfishing.

What is the correct answer?

a. II and IV

b. I, II, and III

c. I, II, and IV

d. I, II, III, and IV

Answer 1

Hi Anika M.,

If you've been paying attention in your science course, you should know that "all of them" is the correct answer. If humans were at the "carrying capacity" in their range, choice III would be OK. But humans are far, far above their carrying capacity with respect to most potential wildlife food. Even though some reduction of whitetail deer populations would be beneficial from humans' standpoint, that is only because humans have planted lots of potential deer food plants and eliminated deers' natural predators (wolves, mountain lions). With the predators restored, the deer populations would stabilize.

While you are reading this, increasing conversion of land to human housing is causing worldwide extinction of enormous numbers of species. An estimated 60% of insect species have been lost already in Europe, by some estimates. This is an ongoing process, and should be of utmost alarm to you. When food webs collapse, the result is not more food for humans, it is catastrophically less food. This is because food webs control insects which might otherwise explode in numbers and start eating much of human-grown food. We have one such critter loose right now in eastern North America, the spotted lanternfly. It's bad news. Also, food webs provide native species of pollinators. Honeybees are used for some crops, but they are tremendously less efficient than other species of native bees. Without native pollinators, many crops could not be commercially grown at all. Within your lifetime, this ongoing species loss, as well as climate change, will have major consequences. To reverse this process, across the world ordinary households must start providing the habitat the native species need. There are lots of plants (trees and flowers) which can help do this. I hope you will get involved in such a project at yor school.

-- Mr. d.

Answer 2

Hi Anika!

The answer is c., or I., II., and IV.

1. Converting wildlife habitat for housing/agriculture disrupts the ecosystem entirely. The animals living in said habitat before conversion will not have the traits needed to survive in a converted habitat. If you think about turning a forest into a field for agriculture, the two habitats are completely different; the animals currently living in a forest will not be able to live in an agricultural field. Forest animals have niches that allow them to survive in a forest, whether it be a food source, a specific habitat type (such as a certain tree species), or camouflage adapted to a forest environment (think moths that have wings that blend in with tree bark. They wouldn't be able to blend into a grass field!). The conversion could also cause dispersion of the animals occupying the forest into nearby habitats, or the act of conversion could harm the animals directly (getting caught by machines, etc.)
2. Pollutants from chemical insecticides used in farms can harm wildlife by contaminating their water and/or food sources. If you imagine a bunch of bug spray in your drinking water, it would make you sick, or turn away from the water entirely! While certain chemicals used in insecticides may be considered safe for human consumption, animals do not have the same tolerance that we might. Animals could consume the insecticides through a polluted water source, produce covered in the insecticide, or by consuming an insect that died from said insecticide.
3. Illegal hunting and overfishing is a threat because it can take away prey from a predator or eliminate a predator that keeps the ecosystem in balance. Food chains in ecosystems calibrate themselves and the ecosystem can support a specific number of predator/prey successfully. If predators disappear, prey populations could boom and there will not be enough resources for them to survive, or they could begin to encroach on another species' niche that would then harm their own survival. If prey disappear, predators will not have enough food to survive and could either die out or begin to encroach on other niches, too. Think about a forest (I love forests!) and our simple food chain consists of wolves, deer, and a shrub. If the deer population drops dramatically, the wolves will not have enough food among the population to sustain themselves, and they could begin to die out. The shrubs would also experience a large population boom: if the deer, which eat the shrub, are not around to eat it, it can experience overgrowth the ecosystem is not equipped to sustain. Similarly, if wolves disappear, the deer population will boom and over-exhaust the shrub, and could drive it to extinction.

III is not an answer because humans hunting for their families could be considered another apex predator. The amount of food a family hunts for eating will not disrupt the population or the ecosystem. If you think about how humans thrived for centuries without grocery stores, they were hunting enough food for their families and were not wasteful. The energy it took to hunt and prepare the animal drives humans, who expelled the energy, to consume as much as they could. A similar principle is found in other apex predators: the amount of risk and energy associated with the hunt has to be less than or equal to the amount of energy that comes from eating what was hunted.

This is a little difficult because people will differ on whether or not III is counted as a threat or not. For me at least, it's not!

I hope this helps explain some of the concepts. Feel free to ask any questions!

Ella