What an Odd Spring

Dry pool in Stoneham, MA, 26 March, 2012

2012 is turning out to be one of the strangest springs that a lot of us can remember.  In early March the first reports of salamander and frog migrations in Massachusetts started trickling in.  Before the end of March, Massachusetts vernal pool observers were reporting chorusing American toads, Gray Treefrogs, and Leopard frogs – three to four weeks early!  There were even Green frogs calling just to the south in Connecticut.  To boot, the water levels in many vernal pools around eastern Massachusetts seem to be extremely low – many have even been observed dry already.

The fact that spring is happening so early has generated a lot of discussion about what we're observing, and what effects there may be on the ecology of vernal pools in the northeast.  Are we observing a major shift, or an extreme swing within the range of “normal variation” this year?  Will the long-term patterns of rain and snow change enough to affect vernal pool ecology?  What will happen to the salamanders and frogs that usually breed in my pool if it's dry this year?

Vernal pool organisms are adapted to significant variation year to year.  They "expect" boom and bust years, in as much as their life cycles are adapted to tolerate quite a bit of annual variation.  For spotted salamanders and other long-lived amphibians, a very dry year is no big problem to a population; many will sit out the year, and they will just try again next year.  Populations of shorter-lived animals (wood frogs, for example) might wink out in pools that are affected in a year like this, but tend to get around the landscape pretty well, and so can easily recolonize pools after a string of bad years has wiped out a breeding population.

The really low water and early breeding that we're seeing this year is bizarre and a little disquieting to some folks that watch the early spring amphibian phenomenon.  But are we seeing the beginning of major change in the environment?  Data show that the climate is trending toward warmer conditions (not saying anything about why - that's a topic for a different blog).  The Blue Hills Observatory in Milton, Massachusetts (http://www.bluehill.org/) has data that show we're also getting wetter here in Massachusetts.  However, the curious thing about these observations is not necessarily the amount of water, but when it comes.  Though anecdotal, winter and spring seem drier than usual, and we seem to get dumped on in late spring and early summer - too late to be of much use to early spring pool breeding amphibians.  That's a pattern to start paying close attention to, because it could have real implications for vernal pools.

We won't really know for a long time if the strange spring of 2012 is just a "bust" year or if it portends real changes in the environment that will affect vernal pool ecology.  For the time-being, we're kind of left to wonder, and hope that we still get to see some salamander congressing.

Migration Update for Southern New England

   In general, the lack of rain events has made for erratic migration of wood frogs, spotted, Jefferson, and blue-spotted salamanders. In CT, greater numbers of animals have been seen or heard chorusing.  Less from observations through MA and from southern NH and ME.  The overall lack of precipitation for the winter has water levels lower than usual at most pools.

Spotted salamander with hail.  frog-shots.com

Tuesday night, March 13.  Several observers reported migrations during and after storms of hail,severe lightning/thunder and downpours moved along the MA/NH border from midnight into the morning hours.

March 14.  Abundant woodfrogs and spotted salamanders in pools in southeastern MA.  Some wood frog egg-laying but not spotted salamander eggs observed.

March 16.  Evening visits to several pools in Stoneham, Concord, and Lexington found lots of male spotted salamanders in the pool no congressing or egg masses.  Some spermatophores seen in Lexington and one spotted salamander egg mass.

March 17-18.  Wood frog chorusing everywhere.  Some large choruses and others relatively (compared to other years) week.

  From the Salamander Crossing Brigades :  "I spent just over an hour at one of our local crossings in Keene, NH last night. The roads were wet after sundown, and wood frog movement tapered off as the roads dried and the temperature dipped into the low 40s. On a "Big" Night, we can see upwards of 800 frogs in several hours at this site. Last night, we crossed 16 wood frogs and 52 peepers, and found a handful of dead frogs. Folks at a nearby crossing, which tends to be more salamander-y, crossed 3 Jefferson salamanders and a few wood frogs. A “small” night for both of those sites."

In reading many other reports from various sources, it seems animals are moving but not necessarily in the numbers of previous years.  As always, there are many nights of migration with the best being in the midst of rain.  Wood frogs are chorusing in daylight with the warm weather.

Spring migrations to begin

   Throughout the northeast, vernal pool amphibians are primed to make their annual migration to vernal pools to breed.  In doing so, they often are forced to cross roads which provides good viewing for the curious naturalist but can be mayhem for crossing amphibians.  Good family viewing times - early in the evening - are not safe crossing times - better late at night with little traffic.

Spotted salamander on the road.
(photo thanks to frog-shots.com)

    Mole salamanders and wood frogs migrate from their wintering sites in the uplands to vernal pools for breeding when the conditions are right. The ideal conditions are thawed ground, air temperature in the 40's, rain, little wind, and darkness. Early migrations are sometimes light in numbers of animals. Migrations take place on several nights if the conditions are right.

   This winter has been unusually mild.  Animals are probably ready to move with a good rain.  Some minor movement has already been reported, in some cases without rain, but large migrations have not been observed.  Migrations are usually from mid-March to late-April with the variations depending on the local climate.

   If you go out on a rainy night to observe migrations, do be careful if you are looking at road crossing sites. Drivers will have trouble seeing "salamander people" on the road. Resist the urge to stop traffic to save amphibians. Don't become a statistic. If you find a location with significant roadkill, work with local authorities for road closings in future years.

   Once mole salamanders and wood frogs reach their vernal pool, breeding activities commence. For spotted salamanders, this means the males congress and lay down spermatophores from which the females pick up sperm.Wood frogs commence a "quacking" chorus.

   These animal activities signal spring for many of us.