Leon Kolankiewicz's picture


  by  Leon Kolankiewicz
For the past two decades, my NumbersUSA colleagues and I have prepared ten studies reporting on the relationship between immigration-driven U.S. population growth and urban sprawl. In recent years, our research has shown that in general, some 70 to 90 percent of all sprawl is related to population growth.

Most of that population growth is now due directly and indirectly to immigration, and the Pew Research Center projects that 88 percent of future U.S. population growth to 2065 will be due to future immigrants and their U.S.-born descendants.

What we try to impress on people when discussing sprawl and its effects is that if we decide to continue to increase the U.S. population through immigration, and inevitably lose more open spaces, there will have to be trade-off, particularly the loss of habitat for wildlife.

Most people think that means mammals such as deer, foxes, and the iconic American bison. It does, but it also includes species that many people give little thought to. Insects

Sulphur butterflies are one of the many types of insects that have been disappearing in recent decades

Everywhere, invertebrates are threatened by climate change, competition from invasive species and habitat loss.” Insects and other invertebrates are “the little things that run the world.

-- Entomologist E.O. Wilson

A new study reported in the journal Science evaluated insect abundance over time from data compiled in 166 long-term surveys of insect communities worldwide. These surveys or population inventories were conducted at 1,676 sites around the world, but as expected, were most heavily concentrated in North America and Europe, where the majority of professional and amateur entomologists live.

Overall, the authors found an average decline in terrestrial insect abundance of nine percent per decade. Earth’s insect populations in aggregate were estimated to have shrunk by a shocking 30 percent in just three decades.

Lead author Roel van Klink of the German Centre for Integrative Biology did not discover a connection between a changing climate and insect population trends. However, he did observe that both urbanization and widespread farming practices are damaging insect populations.

Of course, both urbanization and farming are related to a growing human population: more urbanization is needed to accommodate greater human numbers and more farmland to feed them.

As Nick Haddad, a butterfly specialist at Michigan State University who was not involved with the study, told the Associated Press (AP):

Ongoing decline on land at this rate will be catastrophic for ecological systems and for humans. Insects are pollinators, natural enemies of pests, decomposers and besides that, are critical to functioning of all Earth’s ecosystems.

Indeed, a vivid illustration of Haddad’s point came to light just last year, in another research paper published in the same journal Science, the flagship publication of the American Association for the Advancement of Science (AAAS) and one of the world’s leading, peer-reviewed scientific journals.

A team of ornithologists reported that the number of birds in North America has dwindled by about 30 percent since 1970, or nearly three billion individual birds. The number of breeding birds in the United States and Canada was estimated at 10 billion in 1970. By last year it had plummeted to approximately 7.1 billion.

Many birds of course feed on insects, so major, widespread declines in the populations of their prey is bound to have a deleterious effect on bird populations too.

The AP reported that that the current study in Science actually noted an increase in freshwater insect populations – mayflies, dragonflies, mosquitoes, and the like – perhaps because of improvements in water quality in recent decades due to successful efforts to reduce water pollution. However, these aquatic insect species (which hatch in streams, ponds, and marshes) comprise just a small percentage of total insect species on Earth.

Good news: Dragonflies, in the taxonomic order Odonata, are one group of insects that may actually be increasing in numbers because of improved water quality

Bad news: Mosquito populations appear to be increasing as well, for the same reason (cleaner water bodies)

The habitat loss finding is troubling but not surprising. The Natural Resources Inventory (NRI) of the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) indicates that between 1982 and 2015, land development devoured 43 million acres of land, or 67,161 square miles. This is an area of land about the size of New England.

All developed lands in the country in 2015 comprised approximately 180,000 square miles, equal in area to New England plus New York, Pennsylvania, and New Jersey. Fully 37 percent of all habitat and farmland loss in U.S. history had taken place in just the 33 most recent years.

According to the NRCS, almost half of the land developed comes from forestland, and the rest from cropland, pastureland, and rangeland. The rate of sprawl from new development has slowed somewhat more recently, but there are no signs it will come to an end.

It’s easy for Americans not to think about the effects of sprawl. There is massive effort on many fronts to convince Americans there is no downside to continued growth. Those who point out the trade-offs and state the obvious impossibility of perpetual growth are given little voice in the media, and little heed is paid to their advice when it comes to planning, from the local level all the way up the decisions made in Washington, D.C. about immigration policy.

Unless Americans decide that plotting a different course that serves us and posterity, insect populations and the many ecosystem services they provide will continue their longtime slide.

It's not glamorous to stick up for insects, but it is necessary. As E.O. Wilson said, they are “the little things that run the world.”

LEON KOLANKIEWICZ is the Scientific Director for NumbersUSA

Updated: Wed, May 20th 2020 @ 12:20pm EDT

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