Conserve Wildlife Blog

Morning After Migration

March 13th, 2013


by MacKenzie Hall, Amphibian Crossing Project Coordinator


The past week has been like a wild trip through biomes and time zones.  A half-foot of wet snow buried NJ on Friday, but it didn’t stand a chance against a  sunny weekend above 50˚F and the valiant arrival of Daylight Savings Time.  Bam!  Spring.  Suddenly birds were singing, crocuses were blooming, and salamanders were stretching their hamstrings for the journey ahead.

Throughout the day on Monday (March 11) a long wall of rain crept eastward across the US.  It couldn’t possibly miss NJ, and the temperature would hold around 50˚F overnight – excellent predictors for a migration.  The question was when the rain would hit and whether a rainfall starting very early in the morning would trigger many amphibians to move.  There seem to be almost unlimited permutations for how the important factors of ground thaw, temperature, rainfall, date, and time of night can converge, and after almost 10 years with the Amphibian Crossing Project I still learn new and surprising things. 


Snapshot of a Jefferson salamander being helped across the road.

Snapshot of a Jefferson salamander being helped across the road.

A handful of us chose to wait out the rain at one of our big road-crossing sites in Byram (Sussex Co.).  At least 3 hours before the rain even started, someone noticed a salamander crossing the dry road.  We spread out to cover more ground and kept counting.  By the time the first raindrops hit we had already tallied (and ferried) 190 salamanders and 20 frogs across the asphalt threshold dividing their forest habitat from the breeding pool below.  We were all pretty surprised and excited by what we were seeing.

The rain came around 2:30 am, and in the 4 hours before dawn the road was swimming with frogs and salamanders.  We did our best to keep up with the count, and the rescue, especially as vehicle traffic picked up toward dawn.  Eight cars per hour around 3:00 am, then 10 cars per hour, then 26.  By 6:15 it was hard for the last of us – Bob Hamilton and I – to keep our feet on the pavement as the vehicle count crested 100 per hour.  We also started to lose the battle against roadkill – as many animals were getting hit as we could save.  Luckily it was just a short period, and at dawn the migration would pause.   Our totals for that night:  1,119 salamanders and frogs, 954 of which made it to their destination!

Our “scouts” all across northern & central NJ had similar reports.  A big migration had happened before dawn, and there was some roadkill as evidence.  But you can listen for a happier kind of evidence – the honking and peeping of those who made it to their pool.  The harbingers of spring are arriving.

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