A recent study shows that common pesticides
could seriously harm and disorient a songbird
native to North America.
Migratory bird populations across the world
are declining.
While that trend has been linked to a litany
of complex factors, one of the most concerning
is the widespread use of common pesticides,
namely, organophosphates and neonicotinoids.
Neonicotinoids, the more modern of the pair,
were originally thought to be less harmful
to the human and wildlife nervous system.
But mounting evidence suggests that may not
be the case.
One group of animals susceptible to the brain-altering
effects of the pesticides are migratory songbirds.
In a recent study, researchers looked at the
white-crowned sparrow in particular.
The white-crowned sparrow migrates as far
north as Canada during breeding season and
as far south as Central Mexico in the winter.
Like many other migratory birds, the sparrow
relies on the rich farmland in between to
rest and refuel.
And that’s where danger may lie.
The seed-eating sparrow could unwittingly
be ingesting grains contaminated by neonicotinoid
coatings or organophosphate granules posing
as food or grit.
Researchers showed that both are harmful to
the white-crowned sparrow.
Normally oriented northward during breeding
season, sparrows fed either pesticide appeared
to have lost their internal compass—attempting
to fly off-axis in orientation trials.
While sparrows fed the neonicotinoid recovered
their bearings after two weeks, those on the
organophosphate did not.
Such changes in migratory orientation are
problematic because they could alter the ability
of the songbird and others like it to successfully
reach their breeding or wintering grounds.
Ultimately, that could compromise the birds’
reproduction and survival.
The organophosphate did not appear to affect
sparrows in any other profound way.
The neonicotinoid, however, had other, more
visceral effects.
Sparrows fed the pesticide lost significant
body mass, up to a quarter of their original
mass in only 3 days.
And although not statistically significant,
some birds on the neonicotinoid were observed
to suffer from respiratory stress, lethargy,
and even death.
No control birds showed any of these effects.
The research team plans to leverage advanced
tracking technology to determine whether free-living
birds suffer a similar fate.
Their findings could provide valuable information
on how human activity is affecting the livelihood
of various migratory bird species.
