New Study Finds Pesticides Leading Cause Of Grassland Bird Declines

Monday, February 25, 2013
Horned Lark and chicks
Horned Lark and chicks
- photo by Middleton Evans

A new study led by a preeminent Canadian toxicologist identifies acutely toxic pesticides as the most likely leading cause of the widespread decline in grassland bird numbers in the United States, a finding that challenges the widely-held assumption that loss of habitat is the primary cause of those population declines.

The scientific assessment, which looked at data over a 23-year period – from 1980 to 2003 – was published on Feb. 20, in PLOS One, an online peer-reviewed scientific journal. The study was conducted by Dr. Pierre Mineau, recently retired from Environment Canada, and Mélanie Whiteside of Health Canada.

The study looked at five potential causes of grassland bird declines besides lethal pesticide risk: change in cropped pasture such as hay or alfalfa production, farming intensity or the proportion of agricultural land that is actively cropped, herbicide use, overall insecticide use, and change in permanent pasture and rangeland.

“What this study suggests is that we need to start paying a lot more attention to the use of pesticides if we want to reverse, halt or simply slow the very significant downward trend in grassland bird populations. Our study put the spotlight on acutely toxic insecticides used in our cropland starting after the Second World War and persisting to this day – albeit at a lower level. The data suggest that loss of birds in agricultural fields is more than an unfortunate consequence of pest control; it may drive bird populations to local extinction,” Dr. Mineau said.

Many grassland bird species have undergone range contractions or population declines in recent decades. In fact, analyses of North American birds indicate that these birds are declining faster than birds from other biomes.

Habitat protection has long been considered a central pillar in efforts to stem the decline of grassland bird species, such as the Vesper Sparrow, the Ring-necked Pheasant, and the Horned Lark.

“We are still concerned about loss of habitat in agriculture, range management, and urban development,” said Cynthia Palmer, manager of the Pesticides Program at American Bird Conservancy, a leading U.S. bird conservation organization. “This study by no means diminishes the importance of habitat fragmentation and degradation. But it suggests that we also need to rein in the use of lethal pesticides in agriculture, and that we need to be especially careful about any new pesticides we introduce into these ecosystems such as the neonicotinoid insecticides. It reminds us that the poisonings of birds and other wildlife chronicled a half century ago by famed biologist and author Rachel Carson are by no means a thing of the past.”

The researchers focused on the extent to which lethal pesticides, such as organophosphate and carbamate insecticides, are responsible for the decline in grassland bird populations. The study found that lethal pesticides were nearly four times more likely to be associated with population declines than the next most likely contributor, changes in cropped pasture – an important component of habitat loss associated with agricultural lands.

The publication says that “…..large quantities of products of very high toxicity to birds have been used for decades despite evidence that poisonings were frequent even when products were applied according to label directions.”

The authors argue that only a small proportion of total cropland needs to be treated with a dangerous pesticide to affect overall bird population trends. The production of alfalfa stands out for its strikingly high chemical load, constituting the third highest lethal risk of any crop based on toxic insecticide use. Pesticide drift from croplands is also affecting birds that favor the adjoining grasslands.

Using data from the U.S. Geological Service Breeding Bird Survey for the years 1980 to 2003, the study found that declines of grassland birds were much more likely in states with high use of toxic insecticides lethal to birds. The species with the greatest number of declines included the Eastern Meadowlark (declining in 33 States), the Grasshopper Sparrow (25 States), the Horned Lark (25 States), the Ring-necked Pheasant (19 States) and the Vesper Sparrow (18 States). The states with the greatest number of declining grassland species were Minnesota (12 species), Wisconsin (11 species), and Illinois, Michigan, Montana, Nebraska and New York, all with nine species.

The current study relies on pesticide data from the 1980s and early 1990s, a time when organophosphates such as diazinon and chlorpyrifos, and carbamates such as carbofuran and methomyl, were still largely in vogue. Since that time, a new class of insecticides, the neonicotinoids, have soared to the top of global pesticide markets. Unfortunately, a major toxicological assessment soon to be released by American Bird Conservancy puts to rest any notion that birds and other organisms will fare much better under the new pesticide regime.



MGHC To Hold Rain Barrel Class Saturday

The Master Gardeners of Hamilton County, in association with the University of Tennessee Extension, hold their Rain Barrel Class this Saturday from 10 a.m.-noon. MGHC classes take place at the UT Extension, Agricultural Service Center, 6183 Adamson Circle, located off Bonny Oaks Drive. The cost is $40 per person (payable to UT-TSU Extension) and includes the barrel, plus the ... (click for more)

Hamilton County Locals Win Conservation Achievement Awards

Tennessee Wildlife Federation, one of the largest and oldest nonprofits dedicated to the conservation of Tennessee’s wildlife and natural resources, hosted its 53rd Annual Conservation Achievement Awards. The ceremony was held in Nashville and presented 16 awards to recipients from all corners of the state, including Chattanooga-based Tennessee Chapter of the American Chestnut Foundation ... (click for more)

Witnesses Say Donaldson Was Calm After Killing Son-In-Law - "I'm Just Sitting Here Waiting For The Law"

Witnesses said Glen Allen Donaldson was calm after killing his son-in-law on Dec. 29, 2016, saying, "I'm just sitting here waiting for the law." Donaldson, 57, is facing a first-degree murder charge in the death of 39-year-old Adam Levi. The jury in the courtroom of Judge Don Poole was told that Donaldson left the residence on Niles Terrace where Levi was living and drove ... (click for more)

Chattanooga Man Who Served Time For Attempted Murder Now Facing Armed Robbery Charge

A Chattanooga man who earlier served time for an attempted first-degree murder is now facing an armed robbery count. Garion Devilliar Lewis Jr., 33, is charged with aggravated robbery as well as drug and gun counts. In an incident on May 9, a man who no longer lives in Chattanooga said he was leaving his mother's residence on Sholar Avenue when he saw a man he knows across ... (click for more)

Refuting Racism

In an opinion piece, 5/18/18, Rev. Josh Woodrow referred to me and my fellow School Board member, Joe Smith, as racists and white supremacists because we spoke out against busing. I have never met or spoken with Rev. Woodrow so he knows nothing about me. The reverend obviously knows nothing about Joe Smith either. Seems one of the reverend’s hobbies is “brewing beer”. Maybe, ... (click for more)

Roy Exum: ‘Don’t Invent, Discover!’

When Randy Boyd stood in front of more than 75 black ministers in Memphis on Tuesday, the ever-dynamic “doer of deeds” told the pastors an exciting story. He talked about “First Things First” of Chattanooga because the Tennessee gubernatorial candidate is totally sold on what Julie Baumgardner and her team have proven keeps families together. Boyd then met with some representatives ... (click for more)