The Plight of Birds and the Hand of Man in the Sixth Great Extinction

June 5th was World Environment Day.  A UN outreach program hosted by a different country each year, it is designed to draw attention to its environmental challenges and to offer it support.  This year the host country is India and the theme is beating plastic pollution.  But plastics are not just a blight on the landscape, they are in the seas destroying coral and the species it shelters, painfully killing whales and other creatures … including birds.  Yet, it is far from the only cause of bird distress and their sharply declining numbers.  One example comes from the Arctic, where receding ice has taken with it the nutritious cod, which favor cold waters, and has  endangered the black guillemot now forced to feed their chicks on the bony and difficult-to-digest fourhorn sculpin.

When the EU commissioned a State of Nature report, they expected bad news but not quite as dire a result.  Prepared by the European Environment Agency and sourced from EU-wide data, it found one in three bird species threatened and only a little over half secure.  It also drew a bleak picture of European habitats finding over half of those studied to be unfavorable.  Habitat loss, pesticides particularly neonicotinoids, even excessive hunting, notably in southern Europe, are all to blame.

Earlier, a comprehensive study conducted by University of Exeter (UK) professor Richard Inger and colleagues had analyzed avian biomass across 25 countries over 30 years.  Using data from Birdlife International and the Pan-European Common Bird Monitoring Scheme, they discovered a surprisingly large and troubling decline:  from 1980 to 2009 the estimated total avian population had been reduced by 421 million birds.

Meanwhile, research in the US with far-reaching consequences places blame squarely on human activity.  It examines avian consequences of noise pollution.  If certain constant noises irritate humans — think of road repair and a pneumatic drill — then birds are no exception.  Noise from oil and gas operations is stressing out birds and harming reproduction.  They exhibit signs of chronic stress, lay fewer eggs or fewer eggs hatch, and nestling growth is stunted.

So reports a study by Nathan Kleist and colleagues in the Proceedings of the National Academy of Sciences (unfortunately not available to the general public without a fee).  The authors studied three species of cavity nesting birds (the ash-throated flycatcher, the mountain bluebird and the western bluebird) breeding near oil and gas operations on Bureau of Land Management property in the San Juan Basin in New Mexico.

The researchers placed 240 nest boxes on 12 pairs of sites, close to and at varying distances from the drilling pads where loud compressors operated non-stop.  The team took blood samples of adult females and nestlings from all the nest boxes for three years.  They also examined nestling body size and feather length — less well developed in both noisy and lower noise areas, suggesting any level of irritating noise disrupts.

Baseline levels of a key stress hormone, corticosterone, showed high stress in birds nesting closest to the noise.  And nestlings in noisy areas produced significantly greater stress hormones than those in quiet areas when subjected to the test of being held for 10 minutes.

It also turned out that the western bluebird was the only species willing to nest in the sites closest to the compressors; such behavior had led to the belief it was immune to noise.  Not so, the study results revealed.

Environmental stress is increased by noise pollution and that it degrades avian reproductive success is the conclusive message of this study.  With background noise constantly increasing in the US, even protected areas are no longer immune.

If the anthropocene is our age, it is also our look in the mirror to see what the human footprint has wrought, even if unwittingly.  Global warming, extreme weather events becoming more severe, plastic pollution and stressed wildlife, record extinctions, insect declines … all portents of an impaired future warning humans repeatedly of urgency.  The sixth mass extinction is underway but it will take centuries if not thousands of years, and man can help by alleviating global warming and preservation efforts.  Related to CO2 levels, global warming has been the culprit in the previous five.  CO2 levels are already in excess of 0.04 percent perilously close to the 0.05 percent calculated to melt icecaps through temperature rise causing serious flooding of coastal areas.

Are leaders and decision-makers listening?