Back in September we had a little bit of rain that fooled the local bull frog population to think their fall migration period had started. Frogs dispersed from Galloway marsh into every direction of the compass. Quite a number stalled on Harwood Drive, and some on my driveway, and became very flattened. My first observation of this migration happened late in the evening when I opened the back door and found two frogs. The two frogs were crouched side-by-side very close to the door, and I got the distinct feeling I had interrupted them in the very act of knocking! What were these frogs doing? Selling products door-to-door? Soliciting for some charity? Or maybe looking for a handout? They looked like runaway frogs, leaving home without a thing to carry. (Which ironically was the case.) Where did they think they were going? How would they make a living? What should I do with them? Well, of course, first thing I gave them a stern lecture about being out so late at night and bringing themselves close to the peril of being stepped on, being so close to the door as they were. Then I moved them to the back corner of the lawn so they could continue their journey.
It was the next day that I realized the extent of the frog migration, and the extent of the carnage. There must have been a huge number of frogs migrating to account the large number that got squished on my driveway alone! But walking my dogs the next day past Galloway Marsh I saw a huge number more were still there.
And now, at the end of September, with continued rains, I find that bullfrogs have again embarked on millions of migrations away from the mother marsh. It is obvious that what I’m seeing is the way that bullfrogs disperse and find new habitats, new marshes, or new ponds. They obviously have no way to determine where to go to find new ponds, so their survival strategy is to spread out in every direction. Sure there will be huge losses, but there will also be huge successes as some frogs will find new homes. The strategy works because frogs have spread over much of the southern east coast of Vancouver Island.
The fall frog migration is as predictable as the change in seasons, and the coming of fall rain. It is one of nature’s marvels. It astonishes me that anyone would think there is anything we could do about it. Yet there are many instances where people are trying to control or cull the bull frog population. They might target the mature adult frogs, and have some temporary influence. But like Star Trek’s Borg say “resistance is futile”.
What we can do is to put up some interpretative signs up near the marshes to inform people about the presence of frogs, and warn them about the frogs’ tendency to go door-to-door on rainy fall evenings. In some cases, like where roads run next to marshes, culverts can be installed to allow passage under the road, and little fences can be installed to direct frogs to these culverts. This has notably, and successfully been done along the highway north of Courtenay.
So if you see a frog at your door some rainy night, give it a short lecture, move it to a safer location (yes, they are safe to touch), or just shut the door.