[Tweeters] Hooded Merganser/Rough-skinned Newt update

[John Riegsecker]

All,

In February 2014, I photographed a female Ring-necked Duck eating a 
rough-skinned Newt at Ridgefield.

https://skygardener.zenfolio.com/p657549207/h24deca4f#h3eb0569f

I of course was curious of the outcome.  I asked Dennis Paulson about 
this, and he and Gary Shugart were very helpful in pointing me to the 
literature and getting in contact with some other folks.

Don McVay sent me an email referencing an early Tweeters post:

https://tweetersarchives.org/2003/March/12140357How%20do%20they%20do%20that%3F.html

In response to that, someone sent him an email

Begin Quote:

"The Rough-skinned Newt (Taricha granulosa) on Vancouver Island, British 
Columbia, has low levels of TTX. . . . Skin extracts from these newts 
are at leat one thousand times less toxic than those obtained from 
Rough-skinned Newts from the Willamette Valley, Oregon (Brodie and 
Brodie, 1991).  Studies suggest that they have lost most or all of the 
TTX toxicity.  It is of interest that the Common Garter Snake 
(Thamnophis sirtalis) a newt predator that is resistant to newt poison 
in mainland areas, has either lost or not evolved significant resistance 
on Vancouver Island, where newt toxicity is low."

The full reference citation:  Brodie, E.D., III, and E.D. Brodie, Jr. 
1991.  Evolutionary response of predators to dangerous prey: Reduction 
of toxicity of newts and resistance of garter snakes in island 
populations. Evolution, 45:221-224.


End Quote:

More along those lines here:

https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.0060060&type=printable

My best guess would be that you are far enough north that the newts are 
not very toxic and the Hooded Merganser is fine.

On 3/1/2024 1:16 PM, Sego Jackson wrote:

> This morning, I (again) happened to see from our bedroom window that the 

> Hooded Merganser was thrashing away at a Rough-skinned Newt. This time I 

> was determined to see if it swallowed it or not. After watching for 10 

> minutes, it drifted behind some vegetation on the near edge of the pond, 

> and out of sight. So I ran outside and positioned myself where I could 

> watch it and within 5 minutes it swallowed the newt.  So it is consuming 

> them and not just playing around.

> 

> And assuming it swallowed the first two times too, what I note is that 

> from first noticing the merganser has a newt to it having “finished the 

> job” has been about 15 minutes each time. I have no idea how long the 

> merganser had hold of the newt before I noticed in each case.

> 

> Anyone know what a merganser typically does with prey? Is the thrashing 

> the prey about and time to get it down typical for other merganser prey?

> 

> Sego Jackson

> 

> Whidbey Island

> 

> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows

> 

> 

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-- 
John Riegsecker