Frosty Rough-skinned newt

[Shawn & Paul Jacobsen]

We were walking on the paved path at Bald Hill this morning, temp about 29 degrees, when we came upon this rough-skinned newt along the  side in the grass.  He appeared frozen and immobile.  Of course, it may have been dead, but we wondered how they survive such cold temps and reanimate.  Do they have a sort of antifreeze?

Do they just stop when it gets cold, and everything shut down until it gets warmer?  

Paul

[Lisa Millbank]

I didn't know what range of temperatures newts can tolerate, but I found this on the Rough-skinned Newt page on AmphibiaWeb:

J. Torpor (Hibernation). The activity of rough-skinned newts is affected by cold temperatures in aquatic and terrestrial habitats. Movement does not occur at air or water temperatures below 5 ˚C (Pimentel, 1960). Nussbaum and Brodie (1971) reported finding torpid newts at the bottom of an Idaho pond in early spring when water temperatures ranged from - 1 ˚C to + 1 ˚C, suggesting that adults probably overwinter in the pond in a torpid state. By contrast, in the Cascade Range, most adults leave the water after spawning and move to underground retreats to hibernate during winter (Chandler, 1918). At low elevations in Oregon, the behavior is a bit different. Adults emerge from the water in October–November and wander about on land, then curl up in cavities under stumps, logs, or stones in November–December to spend the cold part of the winter, sometimes forming aggregations of > 12 animals. They emerge from their underground retreats on warm days to forage. Chandler (1918) speculates that in the northern portion of their range, rough-skinned newts leave the water to escape being frozen into small pools in their aquatic habitats.

So these sources indicate that newts either spend the coldest weather in some kind of underground shelter or at the bottom of a pond or slow-moving stream/ditch.  I'm guessing that maybe this poor newt was trying to forage or move from one spot to another when it was sunny and in the low 40s yesterday, but the sudden temperature drop immobilized it before it was able to reach water or a place to hide away.  Another possibility is that it suffered an injury (such as being stepped on) to which it succumbed, and later froze, though it doesn't have obvious injuries.

Whatever happened, it doesn't look too good for this individual, and I would be surprised if it actually survived.  We've probably all seen documentaries featuring the Wood Frog of eastern North America, which survive freezing nearly solid by protecting their cells with large amounts of urea and glucose.  I haven't been able to find information suggesting that any of our local amphibians can do this.  I've been wondering how the Pacific Chorus Frogs are handling the cold.  On Wednesday night, while it was snowing and 33F, I could still hear them calling loudly from the field on NE Conser St., a few blocks from our house!  My guess is that they can go down into vole burrows in the field, or perhaps they are capable of submerging themselves and surviving under the ice on the vernal pools.

Lisa Millbank

Lisa Millbank

--
You received this message because you are subscribed to the Google Groups "Mid-Valley Nature" group.
To unsubscribe from this group and stop receiving emails from it, send an email to mid-valley-nat...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/mid-valley-nature/IA0PR11MB73299D7C539CDF997DE00D17A2A89%40IA0PR11MB7329.namprd11.prod.outlook.com.