Since 1977, House Sparrow populations have declined by 67 percent in Great Britain. Once a very common bird, the mystery of their disappearance has apparently been solved: a lack of insects. Disappearance of habitats, pesticides, and the conversion of gardens into parkin spaces have all contributed. But it’s not just House Sparrows and not just in Great Britain that birds are in trouble.
Modified from an article in the New York Times, April 11, 2018: Birds in farming regions of France are in trouble, and that may indicate problems in similar areas across Europe. Over the past 17 years, the numbers of some bird species in French farming regions have dropped considerably. Meadow pipits have declined by 68 percent.Scientists involved in long-running regional and national bird-counting surveys in France have reported precipitous declines in agricultural regions, even among common birds well adapted to human activity — the generalists, like blackbirds, that seem to do well in most circumstances. This finding follows news of a devastating loss of insects in Germany, a decline of nearly 80 percent over the last 40 years.
Modified from the NY Times , Dec. 4, 2017: In a nature preserve in western Germany, an elderly gentleman approached a tent-like structure that was in fact a large trap for flying insects. Peering through thick eyeglasses, the 75-year-old retired chemist checked the plastic bottle attached at the top, filled with alcohol and bugs. Then, with a glance at the clear, late-autumn sky, the man, Heinz Schwan, recalled comparing a 2013 haul from a trap like this one to samples taken in the same place some 20 years earlier. The drop was huge. The insect populations sampled had declined by more than 75 percent over the last three decades.
The drop is thought to be occurring throughout Europe.
Modified from the Guardian Weekly, Oct 18, 2017: The abundance of flying insects has plunged by three-quarters over the past 25 years, according to a new study that has shocked scientists.The newly revealed scale of the losses to all insects has prompted warnings that the world is “on course for ecological Armageddon”, with profound impacts on human society. The new data were gathered in nature reserves across Germany but has implications for all landscapes dominated by agriculture, the researchers said. The cause of the huge decline is as yet unclear, although the destruction of wild areas and widespread use of pesticides are the most likely factors and climate change may play a role. The scientists were able to rule out weather and changes to landscape in the reserves as causes, but data on pesticide levels has not been collected.“The fact that the number of flying insects is decreasing at such a high rate in such a large area is an alarming discovery,” said Hans de Kroon, at University in the Netherlands and who led the new research.“Insects make up about two-thirds of all life on Earth [but] there has been some kind of horrific decline,” said Prof Dave Goulson of Sussex University, UK, and part of the team behind the new study. “We appear to be making vast tracts of land inhospitable to most forms of life, and are currently on course for ecological Armageddon. If we lose the insects then everything is going to collapse.”
The research, published in the journal Plos One, is based on the work of dozens of amateur entomologists across Germany who began using strictly standardized ways of collecting insects in 1989. Special tents called malaise traps were used to capture more than 1,500 samples of all flying insects at 63 different nature reserves.The loss of birds has been going on for a long time. And in a sense it is no surprise that birds — as well as amphibians, reptiles and mammals — face population declines around the world because of habitat loss and other problems.