2015-16 Frog Migration Began

12/7/2015, after over 3 inches of rain.

12/7/2015, after over 3 inches of rain.

December 7, 2015

Well, the little devils fooled us again.  On January 6, 2013 we discovered the migration (see History); began catching frogs in 2014 on January 7; last year they took us by surprise by beginning to migrate December 20 of 2014. Last night we got 3.06 inches of rain, the streams of the Tualatin Ridge exploding down the steep slopes, roads awash, flooding along the highway at the ridge’s foot. Where I live a culvert carrying a tiny stream under the property blew out, the road below it a sudden creek, taking a little slice of the slope down with it. I was watching the water erupt out of the hillside with Pat, my neighbor, when he mentioned he’d seen frogs on our road the night before.

That would mean the first frogs migrated December 6 this year, two weeks ahead of expectations, just as they had last year! The weather was very wet and warm, so I sent a message out to our core group -- frogs! -- and that I’d be at the usual place at dusk checking. I called Shawn with the bad news that the frogs may have taken over our nights earlier still, and she said to call if I needed help. 

  • Got down to the Harborton falls a little before 5 PM, just as it got dark. 

  • Caught a male immediately.

  • Checked along the highway, caught another male. 

  • Called Shawn. 

A car pulled in, its headlights raking the road.  It was Sue, our biologist and technical leader, on her way home from work. She was a touch surprised I had two frogs, but then said, “Well, we know they move in December.”  Then Shawn arrived, then Jeff, then Jane, who got right to installing fabric on the guardrail, excited to see if it would make frog catching easier.

Large female frog   Photo credit Panos Stratis

Large female frog

Photo credit Panos Stratis

Quite a few frogs were dead on the highway, so they’d tried to cross the moment it was dark, as I arrived just a few minutes later. (They perhaps migrate during the day up in the forest, as well as night, massing at the forest edge waiting for darkness?) Later Sue and I were chatting about the frogs when she said, “I hate doing this!” -- meaning that catching frogs was unnatural; what if the juveniles were helped from the pond to the forest, where they would stay for a couple years, and then didn’t know how to get down to the pond, because they’d not made the trip up to the forest on their own?  Unnatural and problematic perhaps, but what is the alternative?

A new storm was to arrive at 3 AM, so when I awoke at 4:30 I went down to see what was happening. The storm hadn’t arrived yet; still well above 50 degrees though. The traffic was heavier on the highway than I expected at that hour, especially semis, coming in long, noisy spurts. No respite for the frogs! Our little neighborhood road was seemingly quiet, with no little hops arching from the dark pavement. But then I caught three beautiful females, each looking quite patient sitting at the edge of the road, and each full of eggs. Walked them across to the far side of the highway. So the night’s totals -- the first of the 2015-16 winter -- came to 29 males and 8 females, with somewhere between 15 and 30 killed on the highway (impossible to tell, the bodies so smashed). 

-posted by Rob