Birds that feed on insects that hatch in the lake or near streams can help track environmental clean-up efforts. Unfortunately, their abilities as ‘biomonitors’ for pollution stem from that fact that any contamination in the sediment will inevitably make its way into the bodies, their eggs, and their young. Nature News reports.
Toxic chemicals called polychlorinated biphenols were showing up in the eggs and chicks of the tree swallow (Tachycineta bicolor, pictured) near a former capacitor-manufacturing plant in Crab Orchard National Wildlife Refuge in Illinois. Significant quantities were still found seven years after remediation efforts started, which prompted further sediment removal.
Swallows represent hyper localized contamination since they forage over small distances, usually less than half a mile from their nests. And researchers can attract them to areas of interest by putting out nesting boxes on poles – providing replicable experiments.
For monitoring air quality, researchers turn to homing pigeons (Columba livia domestica). Since many of these birds are kept in lofts in cities, they breathe ambient air and are exposed to the same environmental contaminants as us. And unlike with wild birds, their life histories are well known.
In Beijing and Manilla, researchers have found black lungs and enlarged testes in pigeons -- compared with less polluted cities elsewhere in China and in the U.S., where their organs were much healthier. Also, the lungs and livers from the birds from Beijing contained up to four times more polycyclic aromatic hydrocarbons (by-products of fossil-fuel burning).
Some of these findings were presented at the annual meeting of the Society of Environmental Toxicology and Chemistry in Long Beach, California, last week.
[Via Nature News]
Image: tree swallow via Wikimedia
A birdy post for Thanksgiving.