Contrary to publicized research, the decline in grassland bird populations may be related to habitat loss and not insecticide use.
Last year two researchers linked the drop in grassland bird population to insecticide use, but after a reexamination of the data suggests the loss of grasslands is a more likely cause, a Penn State news release reported.
"Many people think of grassland loss as something that happened long ago in North America, but the amount of grassland lost since the 1980s is absolutely staggering, whereas the insecticide use greatly declined prior to the 1990s," Jason M. Hill, a postdoctoral research associate in ecosystem science and management, Penn State said in the news release.
The researchers looked at data that showed a loss of grasslands larger than the state of Indiana between the years of 1982 and 1997; this loss was linked to the expansion of agricultural practices.
The researchers that claimed the population loss in birds such as the upland sandpiper and the Henslow's sparrow was linked to insecticide excluded lands in the Conservation Reserve Program (CRP). In this program farmers are paid to remove environmentally sensitive land such as grasslands from environmental production. Excluding this data could have skewed the results.
"We reanalyzed their data in a more statistically-appropriate way, including CRP acreage, and found 1.3 to 21 times more support that habitat loss was more strongly connected to grassland bird declines than insecticide use," Hill said. "Grassland bird trends were positively associated with the acreages of CRP lands and some types of pastures."
This misinformation could divert attention and funding away from crucial land conservation programs.
"Conservation Reserve Program contracts are not being renewed," J. Franklin Egan, research ecologist, USDA-Agricultural Research Service, said in the news release. "My biggest concern is that we get distracted and lose focus on preserving the remaining grasslands."
