In recent years casual observation has suggested that both the number and variety of birds visiting our feeders was declining. Turns out, it was not my imagination.
Two studies were eye-opening and disturbing.
The first, in 2006 in the journal BioScience, The Economic Value of Ecological Services Provided by Insects,
evaluated the vital ecological services provided by ‘wild’ insects’ by focusing on four crucial services they
provide : dung burial, pest control, pollination, and nutrition for wildlife. The answer? $57 billion in the US alone. That is about $156 million per day, or in excess of $100 000 per minute. I suspect that only the US military spends
more per hour.
The second, published in PLOS One in 2017, looks at changes in flying insect biomass in a set of 63 protected areas in Germany, based on insect-trap measurement over a 27 year period. Between 1989 and
2016, the biomass of flying insects in these areas fell by between 76 and 82 %. Remember, that’s the total biomass, not the number of species that were found.
According to the researchers, “Loss of insect diversity and
abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services ... Our results demonstrate that recently reported declines in several taxa such as butterflies, wild bees and moths, are in parallel with a severe
loss of total aerial insect biomass, suggesting that it is not only the vulnerable species, but the flying insect community as a whole, that has been decimated over the last few decades.”
We cite constantly how much of our food is
pollinated by honey bees yet forget at our peril that insects provide 80% of wild plant pollination and 60% of birds rely on insects as a food source Of course, the decline in insects is only part of what the natural world has lost. Another study found that
between 1970 and 2012, the planet lost roughly 58% of its wild vertebrate abundance. Do we have any idea what happens when birds eats insects that have ingested pesticides, or earthworms exposed to chemicals in the soil, or fish exposed to toxins
in the water, or beetles exposed to herbicides on grasslands? Ands what about eating the seeds themselves? According to Ross Conrad writing in Bee Culture in 2017, one neonic-soaked seed can kill a bird the side of a sparrow, and twelve such
seeds can kill a grouse or partridge.
Does anyone know the sub-lethal effects as we ingest, even if in minute quantities, toxic substances in the water, the air and our food?
David Goulson, et
al, in Science, 2015, point to several, interacting factors for the decline in the biomass : availability of food and nest resources, exposure to agrochemicals, incidence of disease, parasites and invasive species, and climate change. Nor do they
act singly so much as synergistically. Looking at food availability, for example, the conversion of land to human infrastructure isolates patches of flowering plants. in the US, 6000 acres of undeveloped land are lost to urban growth every day. Intensively
farmed regions of monoculture provide insufficient resources and climate change is causing similar deficits in wilderness areas.. For example, in the same publication, Science, Nicole Miller-Struttmann et al spent 40 years studying alpine meadows
that are largely protected from land use changes and recorded a floral decline of 60%.
Neonicotinoids, as systemic chemicals, pass readily into reproductive tissues and interfere with beneficial, as well as antagonist, insects. It
is clear that honey bees exhibit neonicotinoid-induced declines in foraging success and navigation but Maj Rudolf, et al, in Nature, 2015, suggest that honey bee susceptibility may actually underestimate that of other bees. When the authors
monitored feral and honey bee populations in 14 fields paired by land-use history and neonicotinoid treatment, the declines of feral bee was significantly higher in the neonicotinoid-treated oilseed rape fields than in the honey bee colonies.
The reason might be the eusocial behavior of honey bees : a colony of 40 000 bees can loose 5000 and still recover, albeit in a weakened state, whereas feral bees are primarily solitary.
In the 1960‘s, when the solutions to
conservation issues appeared to be relatively simple, such as in the cases of ozone-depletion caused by halocarbon refrigerants and
CFC’s, and eggshell-thinning caused by DDT, concerted efforts quickly rallied public and political
support to protect important natural resources. Today, not only is the world becoming a less colorful place, it’s becoming a less functional one as well. The reasons are complex and less easy to simplify in terms of mobilizing the public,
but the visual evidence is real if one cares to look, hence the importance of something so simple as bird feeders. The time to ignore these global warnings has passed. Put it this way: canaries in coal mines only reveal the presence
of coal gas if one is willing to listen to their singing, notice when it stops, and look in their cages to see if they are dead. If one just keeps blindly digging out coal, the eventual result is pretty obvious.