Unnoticed Death.

(source)

This was a deadly summer for Australian fauna.

In this blog I’ve reported a number of animal mass death tolls ranging from a few tens of large mammals (wild horses and donkeys) and hundreds of birds, to hundreds of thousands of cattle and maybe millions of fish, with intermediate numbers ranging in their thousands or tens of thousands for wild camels and flying foxes and farm chickens.

The causes of death vary: some drowned (cattle in the Queensland floods), some were culled (feral horses and camels in the Northern Territory and Western Australia respectively); others died through human inept and reckless -- if not unlawful -- mismanagement (fish in New South Wales). In some cases mass death resulted from excess heat (flying foxes in QLD, Victoria and South Australia), even in spite of human attempts to save the animals (farm chickens in SA). In other cases (native birds deaths in SA) the cause of death remains unknown.

Lacking reports from Tasmania (scene of devastating and deadly bushfires), one can still say that every single mainland state (plus the NT) was affected.

As distressing as blogging about this was, my task was facilitated by the ABC’s nationwide network of regional radio stations, with their own journalists. Apart from the effort it saved me, this had another practical advantage: in all those cases there were independent witnesses, often acting in official capacities.

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There are drawbacks to that source of information. For one, death counts are approximate; for another, by themselves they tell us little how abundant or rare the species was before the death event.

As importantly, in the cases reported there were witnesses because either those animals had their own minders (say, the farmers) or died in circumstances that made their deaths difficult to ignore (it’s not every day that dead and dying spectacled flying foxes “rain” upon one’s backyard, for instance). The bottom line is that one cannot be sure there were no unreported cases of mass deaths: Australia is a big and sparsely populated place.

If a species catches little attention, it may disappear unnoticed.

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That is precisely what happened to Melomys rubicola (the little guy in the photo above), the first Australian mammal extinction due to climate change: a loss entirely foreseeable and preventable, and yet, unavoidable given the paralysis affecting society. The recovery plan, drafted in 2008, was never acted upon. By 2016 no individuals remained in the last sanctuary of that species.

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Another species heading that way, pretty much for the same disinterest, is Hemibelideus lemuroides, a kind of marsupial lemur. It is currently classified as near threatened. Having evolved in a stable environment, they developed no mechanism to cope with body heat: they don’t sweat or pant. And the Queensland cloudy forests are shrinking inexorably.

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(source)

Less cute, but probably more ecologically important, Pteropus conspicillatus is one among several species of flying foxes, all of them pollinators and seed propagators. A third of the Australian population of P. conspicillatus was lost in a hot summer afternoon last December. It was reclassified as endangered. Other species of flying foxes experienced mass death, all apparently caused by heat.

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I don’t know of any estimates of the population of the already critically endangered Maccullochella peelii but if such estimates exist, they are now useless: M. peelii is the scientific name of the Murray cod, tragically known for the three Menindee mass fish kills.

After the event, the NSW Minister for Water, Niall Blair, ordered the rescue of survivors, to establish a program to “restock” the Darling. Blair expressed his optimism:

“We know that moving 100 fish doesn't compare to the hundreds of thousands that were lost.

“But I am hopeful that these small relocation projects will allow us to breed hundreds of thousands of fingerlings that can find a home once again in the much loved Darling River.”

I am more pessimistic: they plan to release tens -- maybe hundreds -- of thousands of inbred fish in those waters. The genetic diversity lost to those mass fish kills will never be recovered. Ever. Sadly, I won’t be surprised that species went extinct: its chances of adaptation to climate change are forever diminished.

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As tragic and ominous as those losses/near-losses are, there is a species whose troubles have gone entirely unnoticed and whose extinction shall have catastrophic consequences for Australian fauna. Nobody knows how many species could be in similar situation.

Around late spring, early summer, the humble bogong moths (Agrotis infusa) used to be a frequent sight, even in Sydney. Occasionally, as in 2007, they would appear in plague proportions. I am not sure when was the last time I saw one, but it may well have been ten years ago.

The way A. infusa’s quick disappearance was discovered seems to share some elements with the way the Krefeld team discovered the decline of insect populations in their native Germany.

(source)

So, this is how this mass extinction looks like.

As a bookish kid, I grew up thinking of mass extinctions as huge events, the kind of thing one sees in a Hollywood blockbuster. Asteroids striking Earth, nuclear exchange. Certainly dramatic and impossible to miss.

There’s a kind of quiet despair in those unnoticed deaths