Wednesday 3rd of June 2020

a sparrow fart in the hand is worth two in the bush...


The dwindling number of sparrows seen in Australian backyards — and around the world — is considered by some to be one of the great natural mysteries of recent times.

Passer domesticus, known to many as the house sparrow, was introduced to Australia from Britain between 1863 and 1870.

The species usually remain in the same region year-round, but in recent times they have been few and far between.

House sparrow facts
  • Average size is 16 centimetres
  • Average weight is 27 grams
  • Introduced from Britain in 19th century
  • Breeding season is year-round but more concentrated in spring and summer
  • Clutch size is three to six eggs, with an incubation time of 14 days
Source: Birdlife Australia


Brisbane resident Catherine Leutenegger said she noticed their numbers had dropped compared to the large populations that were about when she was a child.

"My partner and I were kids in Brisbane in the 1950s, and my partner remembered the threepence bounty from the council for sparrows," she said.

"Kids would shoot them with air rifles, as the sparrows would get under the corrugations in the roofs and into the ceilings — they also brought lice."



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Picture at top: old tramp feeding sparrows in Paris c. 1960s. Picture by Gus Leonisky.

declining for decades...

Once a common sight around London, house sparrow (Passer domesticus) populations have been declining for decades; they’re down 71% since 1995. Now, researchers believe they know why: a mosquito-borne disease called avian malaria.

Scientists collected 3 years of data from 11 sparrow colonies around London where the birds breed. They counted raw numbers of birds each year, and collected blood and excrement from a number of individuals.

Seven out of the 11 colonies were losing birds, and roughly 74% of the sparrows carried avian malaria (Plasmodium relictum). That’s the highest rate of infection with this parasite seen in any wild bird population in Northern Europe, the researchers report today in Royal Society Open Science. Avian malaria may be causing declines in Western Europe, North America, and India as well, the team says.


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imidacloprid is one of the culprits...

White-crowned sparrows in Canada were given a small, sublethal dose of imidacloprid — a neonicotinoid insecticide — alongside control birds that were given none.

The dose was meant to be equivalent to how much birds would ingest by eating a few very small, insecticide-coated seeds.

Seed coating is a common practice where crop seeds are doused in an insecticide, which is then absorbed into the plant as it grows and is present in the pollen.

In all, 12 birds were given the low dose, 12 were given a higher dose, and 12 were given none.

The birds treated with both the high and low doses shed significant weight within six hours, compared with the control birds that didn't, according to research published today in the journal Science.

"If birds are exposed to a big enough dose, [it's] lethal. A small handful of seeds is enough to kill a songbird," said Christy Morrissey of the University of Saskatchewan, who led the study.

"But what we're seeing is that even an incidental dose can have a substantial effect."

The researchers found the insecticide had an "anorexic" effect, with birds on the higher dose consuming 70 per cent less food than the controls in the six hours following dosing.

The migrating birds were then fitted with lightweight transmitters and released in Ontario, Canada, where their movements were tracked by a network of research towers.

On average the untreated birds continued their migration within half a day, whereas the birds that had been given the imidacloprid delayed their departure by three days for the low dose and four days for the high.

The hypothesis is that the treated birds spent the extra days working the insecticide out of their system, and then regenerating fat stores to continue their migration.

"The amount we gave them to cause that delay was miniscule," Professor Morrissey said. 

"Essentially it was the equivalent of giving a bird one-tenth of a corn seed treated with neonicotinoids."

While there has been some evidence linking neonicotinoids to bee mortality and even colony collapse, Professor Morrissey said her research showed the impacts of pesticides might be much more widespread.

"It's not just a bee problem, or a water problem, this is a pretty compelling case that for birds these [insecticides] are having a pretty serious effect."



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Note: while this experiment shows imidacloprid as a culprit for the decline of some birds, there are MANY other insecticides and human-made poisons doing similar crap.

silent spring, summer, autumn, winter...

When Rachel Carson's book Silent Spring was published in 1962, it caused a national outcry and breathed life into the environment movement in the US.

Key points:
  • There are 2.9 billion fewer birds in North America today compared to 1970
  • Bird collapses are coinciding with insect collapses in many parts of the world
  • Shifting baseline syndrome allows us to miss the signs

The title was taken from a line in a Keats poem: "The sedge has withered from the lake, and no birds sing."

The book warned of the silence that would fall if the US kept spraying DDT, which was knocking out insects and birds at an alarming rate.

DDT was banned soon after, but the natural world is quieter today than we've ever known.

There are now 2.9 billion — about 29 per cent — fewer birds in North America than in 1970, according to research published today in the journal Science.

And that's a trend across much of the globe that is going hand-in-hand with a rapid decline in insects.

Most of the worst-affected birds are insect eaters, according to the research.

A silent spring would have consequences for all life on earth, and we need to heed the warning, said researcher Mike Parr, president of the American Bird Conservancy.

"Birds are both predator and prey — buyers and sellers — and they are numerous in all ecosystems," he said.


"This isn't a good sign. We need to pay attention."


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Insecticides, it's called, not for nothing... 


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3 Billion North American Birds Have Vanished: ‘It’s Just Staggering’

The number of birds in the United States and Canada has declined by 3 billion, or 29 percent, over the past half-century, scientists find.

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