In the last week or so I’ve managed to accumulate quite a backlog of potential post subjects. This is largely because I’ve been out looking at things, rather than sitting indoors in front of a computer, and with spring progressing there’s the potential for a lot of interesting observations. For the same reason that I’m getting lots of good stuff, I’m also falling behind on writing about it – it’s hard to write when you’re not at the computer! I rather suspect that a number of these subjects will be tucked away for safekeeping, to be pulled out at a future date when things aren’t coming quite so fast and furious, or when I’m stuck indoors and haven’t been out to observe much. Julie Zickefoose refers to a person who sequesters posts for lean times (such as herself) as a “blog ant”, referring to the ant’s habit of building a larder in the underground (think of the Aesop’s fable of the ant and the grasshopper). I’m probably more akin to a packrat than an ant – an ant, it would suggest, is discerning. My blogging habit more closely resembles my living habits, where I store things that may come in useful, and when I decide I need something I go back and look over my cache for something that might work.
None of that has anything to do with this post, of course. I’m not writing about packrats, or ants (although I do have some ant photos tucked away). Rather, today’s post is on salamanders, who I’m pretty sure don’t participate in caching behaviour. While visiting my parents this week, my mom and I went out to a local site where she often does pond study field outings with schoolgroups for a local non-profit. It’s a relatively small, but still nice pond, set in the woods back from the road. They usually scoop up some water or sediment and poke through it to see what they can find, learning about the aquatic environments in the meantime. So, to be prepared for what they might encounter, my mom wanted to scout the site and see what was happening.
Along with a handful of different invertebrate species, there were a couple species of frogs heard, and these guys. This is a Red-spotted Newt, a subspecies of the widespread Eastern Newt. A newt is actually a type of salamander, one belonging to the family Salamandridae. The Eastern Newt is the only representative of this family in North America, although they’re fairly widespread on other continents, primarily in the northern hemisphere. There are in fact 10 different families of salamanders, but the other ones we typically think of here in North America, such as the Jefferson’s or the Spotted, are mole salamanders, family Ambystomatidae. Most other salamander families aren’t differentiated by name the way the newts are, however.
The Red-spotted Newt inhabits still or slow-moving waters such as ponds or small streams. They generally prefer moist woodlands, with sufficient debris or submerged vegetation in the water to be able to hide under. The ones we saw were all doing that, they’d cruise languidly along in the warm surface waters (the water was less than a foot deep in the very gradually-sloping pond edges, so it was pretty much all surface water) but as soon as I made an attempt to come in with the net they’d dive under the leaf litter at the bottom. They never went very far, but they disappeared completely.
They eat aquatic insects and insect larvae, small molluscs and crustaceans, and even small frogs and tadpoles. They have an amazing lifespan – females can live up to 12 years in the wild, males up to 15. I suppose this difference could be due to the greater energy demands on a female in creating and laying eggs, versus the relatively energy-“cheap” effort of creating sperm. One study notes that female survivorship from year to year is generally lower than that of males, though a reason isn’t provided.
At just 7-10cm (2.5-4 in), they’re not large creatures. They also aren’t very difficult to catch, once you know how. I started out trying to catch them by surprise by swooping in quickly before they could dart away. Although I successfully got the first one this way, the drag of the net through the water reduced its speed to the point where speed was not the answer anymore; the salamanders were all easily able to dart off before the net reached them. Then I discovered that if you came in quite slowly, they would just sit there, and you could practically scoop them up without them moving.
The species has three life stages. The first is as “larvae”, the salamander equivalent of a tadpole. Eggs are laid in the spring, and take about a month to hatch into young. These are gilled, and spend the next 2-3 months in the water hunting small aquatic prey. They hatch at less than a centimeter (less than 1/2″), but grow quickly; within a couple months they’ve reached nearly 4 centimeters (just under 2″). At this point they metamorphize into their second stage, pictured above.
The second stage is called a Red Eft, and is terrestrial. They can remain in this stage for as many as 4-7 years, depending on latitude and the richness of the local habitat. This is the most commonly seen stage of the species’ life history, likely because of the bright colouration and also their on-land habits. It is in this stage that dispersal takes place, with individuals undertaking long treks of 800m or more where they may encounter new ponds. While their olive-green back is useful for camouflage in the water, on land they have a different strategy. Newts in non-larval stages have toxic skin that is used as a deterrent to predators, but the skin of the efts is ten times more toxic than in the adults. Their bright orange colouration is a warning to creatures wanting to make a meal of them (this special warning colouration is termed “aposematic”).
Of course, I didn’t know this at the time that I was looking at them, and I happily (though gently) picked them up to get a couple of side-on photos that better showed their faces and bellies than a top-down view of them sitting in the water. Fortunately, I suffered no ill effects from the encounter. The back is more toxic than the belly, and despite this defense, newts are often preyed upon; predators get around the toxicity by targeting the newt’s underside. The newts rely on a learned avoidance by predators, where young predators that attempt to take a newt for dinner will remember the distastefulness of it and not try any others. This may result in the loss of one newt, but the protection of many others. Some predator species have an innate avoidance of aposematically-coloured creatures.
The eft I caught was found in the water. This is an unusual spot for one, as they generally stick to the land, and it could be that it was preparing to metamorphize into the third life stage, the adult (perhaps resulting in a lowered toxicity level). Only the olive adults mate, which means that sexual maturity isn’t reached until often three or four years of age, or potentially up to seven or more if the efts metamorphize late. I wonder how old some of the newts I was looking at actually were.
The adults have an amazing homing ability, like that of homing pigeons. Displace a newt from familiar territory and it can still find its way back. It orients using magnetic fields, but also uses its sense of smell (to detect water) and sight (to orient against the sun) to guide it, although in experimental tests even newts with no smell or sight could successfully find water. Displaced newts will automatically orient downhill, which is reasonable, since water usually lies in the lower areas. I wouldn’t’ve thought that newts would find themselves displaced often enough to have needed to evolve such a complicated system.
I probably saw more salamanders in that single outing than I had in my life prior to that combined. They don’t occur in the ponds on my parents’ property (or, if they do, certainly not in great numbers like they were here, and don’t hang out in the open). I will admit to never having made a special outing to look for them before, either, though. As is the case with so many things, if you actually go looking for something, you can amaze yourself with how common it actually is.