Spotted salamanders are done for 2014

No incoming salamanders after the few rain events over the last week, so looks like they are done breeding for the year. Only 141 animals came to the Windhover pond this year, the lightest migration yet. Also the shortest, maybe owing to the long winter?

Nevertheless, larvae are on the way. Here’s a spotted salamander egg mass. Notice that this thing is larger than a female! When an egg mass is laid, it swells up with water, mostly due to the formation of a thick protective jelly-like coating. You can just start to make out the external gills forming on the developing embryos.

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In other news, snapping turtles are on the move. These are only slightly more difficult to help over the fence.

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About Scott Thomas

I'm a graduate student seeking to contribute to our understanding of how ecology, evolution, and their interplay contribute to the abundance and distribution of animal populations. Since 2011, I have been a part of the Niewiarowski Lab, where I help run a long-term demographic study of an Ohio breeding population of spotted salamanders.
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4 Responses to Spotted salamanders are done for 2014

  1. John says:

    Do the historical data indicate a downward trend in population?

  2. scelop says:

    John, it’s the most common question we get, and yet the hardest to answer. Take a look at an earlier post from this blog that shows recapture data through 2010:

    https://scelop.wordpress.com/2012/03/18/breeding-recaptures-since-1999-at-windhover-pond/

    definitely trending down recently. And there are many studies that support the idea that amphibian populations are declining globally. Still, the life cycle of these guys is long enough that the trends measured over 5-10 years can be misleading in and of themselves. Maybe we can get Scott to weigh in on this and also summarize some other studies that attempt to answer your question in a general way.

  3. Scott Thomas says:

    Thanks for the good question John. Like Peter said, we have been seeing a decrease in breeding numbers. But spotted salamanders live long lives, and that may mean that changes in breeding numbers represent year-to-year changes in the decision to breed as much as actual changes in population size. A few other things may also be worth bearing in mind:
    Population booms and busts seem to be common for animals, and especially for amphibians. Here is a good depiction of this in a population of the closely related tiger salamander studied for the last 30+ years in a network of ponds in a remote part of the Rockies( so it’s probably natural and not human-driven). So, we may just be in the “bust” phase of a population cycle. The big question is what causes the booms and busts? If we knew this, then it’d be easier to identify a decline in numbers as reason or not for concern. But even with 30 years of study on the tiger salamander population, this isn’t clear, and we hope to be able to weigh in with our data.
    Also, our pond is just one of many salamander ponds in the area, a few of which are just a few hundred meters away. One thing we’ve noticed from working the region is that there can be a lot of variation between ponds in breeding effort. One pond will be carpeted in eggs, while a neighboring one only has a few. So, even in perfectly healthy populations, some ponds might occasionally dip below sustainable breeding numbers, but movement between ponds keeps things going.

    So, using the breeding numbers, it’s hard to say whether the Steiner Woods population is in decline. I think too that it’s hard to say whether 140 animals (including 50 females = in the range of 12,000 – 50,000 eggs each with a very small chance of making it to metamorphosis) is actually a low population size. Maybe it is, but given the number of animals I see in other nearby ponds, the population does not seem to be in imminent danger. On the other side of things, we’d love to see thousands of animals in the pond at once again, and these baby booms may be very important for long-term persistence, but it’s likely that populations of that size will make for a not-so-nice pond, and forest, to live in, and the harsher realities of nature are going to work to push numbers back down (through animals moving or dying).

  4. John says:

    Thanks Scott.

    Does your study include comparing and contrasting the populations of salamanders that use the nearby ponds?

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