New study finds pesticides leading cause of grassland bird
declines
February 2013. 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 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.
Spotlight on acutely toxic insecticides used on cropland
"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 on 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," 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.
