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Alex Slavenko

@alexsla.bsky.social

730 followers 600 following 100 posts

Zoologist & ecologist Obsessed with herps, birds, and PNG Doing ecological modelling for a living and still shocked by that

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Alex Slavenko @alexsla.bsky.social · Apr 15

New species alert!
🦎🧪

We (myself, Glenn Shea, Stephen Richards and Paul Oliver) just published a description of a fantastic new species of Prasinohaema from New Guinea. A short thread:

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Reposted by Alex Slavenko

Emily Troyer @fishfetisher.bsky.social · Sep 1

Excited to announce that the 1st paper from my postdoc is now out in @currentbiology.bsky.social ! Using a large dataset of 3D preserved fossils, we explore the diversification of jaws in early bony fishes. 1/15
www.cell.com/current-biol...

Macroevolutionary role reversals in the earliest radiation of bony fishes

Troyer et al. examine lower jaw evolution in Silurian-Devonian bony fishes and find substantial differences in patterns of morphological disparity, rates of shape evolution, and functional diversity b...

www.cell.com

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Alex Slavenko @alexsla.bsky.social · Apr 28

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Alex Slavenko @alexsla.bsky.social · Apr 17

A recent paper claims, opposed to what conservation science has known for decades, that there is no evidence that foxes and cats were a major driver of Australia's mammal extinctions. Turns out there are quite a few issues here. Strap in for a looong thread 🧪

academic.oup.com/bioscience/a...

Review of evidence that foxes and cats cause extinctions of Australia's endemic mammals

Abstract. Over half of Australia's threatened and extinct endemic mammal species have been attributed to introduced red foxes (Vulpes vulpes) and cats (Fel

academic.oup.com

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Alex Slavenko @alexsla.bsky.social · Apr 17

And to do this, they try to paint the conservation community as suffering from "bias, groupthink, and overconfidence" - all while their own very clear biases are showing in every page of this paper.

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Alex Slavenko @alexsla.bsky.social · Apr 17

Wallach & Lundgren are not dumb, nor are they bad scientists. They're disingenuous scientists. They know exactly what they're doing, which is trying to discredit the well-supported role of invasive predators in driving extinction, because they don't think we should kill invasive predators.

Compassionate Conservation | The International Wildlife Coexistence Network

The king parrot is eating my pomegranates and teaching me to accommodate thieves in my life. Arian Wallach I don’t know what he wants from me,” says Arian W ...

wildlifecoexistence.org

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Alex Slavenko @alexsla.bsky.social · Apr 17

But as we've seen, their own sweeping claims are based on some pretty dodgy tactics, very liberal interpretation of some results, and consistent downplaying of any result that is inconsistent with their own preconceived idea - that foxes and cats did not (and do not) drive Aussie mammal extinction.

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Alex Slavenko @alexsla.bsky.social · Apr 17

Wallach & Lundgren summarise: "Sweeping claims have been made about introduced predators with ambiguous, weak, and—in most cases—no evidence. This challenges the notion that a core paradigm of conservation biology is evidence based, at least in Australia."

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Alex Slavenko @alexsla.bsky.social · Apr 17

This means the species they studied had ample time to evolve to live in the presence of foxes. You know who didn't? The one that had prey naiveté, that were more vulnerable to fox predation, and went extinct long before Wooster et al. came around to run their experiments. Classic survivorship bias.

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Alex Slavenko @alexsla.bsky.social · Apr 17

Obviously, there's a bit of a problem here. The study was conducted in 2018 and 2019 - small mammals in Australia have lived in the presence of foxes for decades. 104 and 108 years, specifically, in the sites Wooster et al. studied, where invasive predators are also protected and not controlled.

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Alex Slavenko @alexsla.bsky.social · Apr 17

One specific study they mention in detail is Wooster et al. 2024, which showed that "small mammal responses to fox scent was essentially the same outside the foxes’ native range (Australia) as inside (Israel and United States)"

nsojournals.onlinelibrary.wiley.com/doi/full/10....

Prey responses to foxes are not determined by nativeness

Introduced predators are thought to be responsible for the decline and extinction of their native prey. The prey naivety hypothesis provides a mechanism for these declines, suggesting that native pre...

nsojournals.onlinelibrary.wiley.com

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Alex Slavenko @alexsla.bsky.social · Apr 17

But Wallach & Lundgren claim there is no evidence for this, citing some studies to support this, including a few they were themselves authors on. Remember that bit about overlap in authors? Funny how that's suddenly not a problem. Anyway.

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Alex Slavenko @alexsla.bsky.social · Apr 17

We've known this is a thing ever since Darwin bashed in the head of a fox with a geological hammer.

en.wikipedia.org/wiki/Darwin%...

Darwin's fox - Wikipedia

en.wikipedia.org

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Alex Slavenko @alexsla.bsky.social · Apr 17

Wallach & Lundgren also claim there is no mechanism for foxes and cats driving extinction in Australia. That's a pretty bold claim, considering we do have one - prey naiveté. Aussie mammals evolved without eutherian predators like cats and foxes present, and so are more vulnerable to predation

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Alex Slavenko @alexsla.bsky.social · Apr 17

Regardless of those examples, the point here is not whether other factors can cause failures (they can) but what *did* cause the recorded failure. If predation by foxes and cats causes the reintroduction to fail, that's pretty compelling evidence they caused the extirpation in the first place.

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Alex Slavenko @alexsla.bsky.social · Apr 17

They also cite a paper on failure of brown treecreeper reintroduction in Australia - but that paper not report which predators caused the failure. In fact, they attribute it more to aggressive behaviour by noisy miners, which would be more of a competitive interaction.

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Alex Slavenko @alexsla.bsky.social · Apr 17

They also claim that reintroduction failures are not good evidence because "reintroduction programs are foiled by native predators as well". As support, they cite two studies from South Africa - which, unlike Australia, has many native predators remaining.

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Alex Slavenko @alexsla.bsky.social · Apr 17

Wallach & Lundgren have no argument against this, other than "Although there could be other reasons why extinctions concentrated in this body mass and in that region, to our knowledge, no competing hypotheses have been put forward". What, pray tell, are these competing hypotheses?

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Alex Slavenko @alexsla.bsky.social · Apr 17

One of the key points of evidence for fox and cat-driven extinctions is that many of the extinct Aussie mammals fall within the 'critical weight range' of 35 g-5.5 kg, just the right prey size for cats and foxes.

onlinelibrary.wiley.com/doi/10.1111/...

Body mass and extinction risk in Australian marsupials: The ‘Critical Weight Range’ revisited

Australian mammals have suffered an exceptionally high rate of decline and extinction over the last two hundred years. Body mass is linked to extinction risk in Australian mammals, but the nature of ...

onlinelibrary.wiley.com

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Alex Slavenko @alexsla.bsky.social · Apr 17

Then, they go about explaining why they think foxes and cats do not drive extinctions. Remember their claim I started the thread with? That they're not aiming to prove or disprove the hypothesis? Here's where that claim falls apart.

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Alex Slavenko @alexsla.bsky.social · Apr 17

And this is for the species they themselves admitted has the best evidence! With no studies not in support! I think this begs the question, what do Wallach & Lundgren consider sufficient support? When will they admit that foxes and cats are to blame for an extinction?

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Alex Slavenko @alexsla.bsky.social · Apr 17

The online supplementary again offers even less tempered language, that makes Wallach & Lundgren's position very clear:
"Cats are among a range of ecological variables negatively correlated with rat abundance, but causality cannot be inferred due to confounding variables."

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Alex Slavenko @alexsla.bsky.social · Apr 17

Also, if overlap in authors is an issue, I'd like to point out Wallach and Lundgren are authors on many of the papers cited in this study. So....

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Alex Slavenko @alexsla.bsky.social · Apr 17

Can anyone think why there might be overlap in study sites for a species that is widely extirpated from the majority of its historical range and is now restricted to only a ew small populations? Anyone?

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Alex Slavenko @alexsla.bsky.social · Apr 17

Alas, "We do not agree that one can go further to claim that there is sufficient evidence that cats are the cause of the threatened status of rabbit rats, because the studies are not fully independent (the articles overlap in data, study sites, and authors)".

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Alex Slavenko @alexsla.bsky.social · Apr 17

See how they downplay the evidence in the 20 species with supportive population data. For brush-tailed rabbit rats, "We identified six population studies, all in support, of which five met basic qualities for testing predator–prey interactions". Sounds good right?

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Alex Slavenko @alexsla.bsky.social · Apr 17

This is a classic tactic used by anti-vaxxers - set the bar too high, then claim there is no evidence because nothing meets that bar. And if anything does, shift the bar even higher. We'll see that Wallach & Lundgren do this too.

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