Turns out that over 100 salamanders moved into Windhover Pond a couple Wednesdays ago when around a dozen people came to see them be released while more salamanders mosied in. That stretch of rain brought a few nights of migration to put the total over 160 for the year. Winter is not leaving without a fight, though, and overnight temperatures look to be near freezing for the next week or so. The last warm and rainy night only brought 1 salamander in, which usually means they’re pretty much done for the year, but we’ll see how things play out when spring comes back.
So far, this season continues a trend dating back to 2010 where the number of captures has hovered around the 150 mark:
Only a few individual salamanders will breed for longer than seven years, so this may be a sign that the number of new arrivals in the population has been enough to offset the number of animals leaving or dying. The new guys could have been born in Windhover or immigrated from another pond.
The numbers from recent years are well within the ranges found for other spotted salamander populations, but they’re small compared to the thousands of captures seen in many of the first 10 years of the study. Those seasons also had a lot more year-to-year variation:
It’s hard to say what caused that early population boom or the dip to the more stable numbers, but conveniently there are only a few ways to change the size of a population: births, deaths, and migration. Since we are only dealing with the breeding portion of the population, another factor is whether animals skip breeding in a given year.
These guys live a long time. I saw some salamanders last week that were old enough to vote in Tuesday’s primary. This is one thing that makes long-term studies like ours necessary and worth the delayed gratification. As the study approaches the 20 year mark, the data should now cover the lives of many individual salamanders, so we can start to dig in to investigate what’s going on underneath trends we’re seeing.