The humble toads hang on

When I ask residents about toads in Columbia County, they respond, “What toads? I didn’t think we had toads here.” And indeed, for 30 years I wasn’t sure whether or not toads were still present. But this summer, Matt and I verified that at least one population is still thriving in a hidden alcove in the county.

A helpful landowner directed us to a population of toads that he’s been monitoring for decades. Every June they waddle down from the uplands into the Nehalem River, the males calling from the shallows and the females laying their eggs amongst the vegetation. This watchful observer called us up when breeding started, and we witnessed an event few in our corner of the Coast Range ever see.

The breeding section of the river is rather small, but it was well used. Toads were hiding amongst aquatic vegetation, within algae below the surface, and even floating in open water.

I’m quite used to finding toads in ponds and lakes in other parts of Oregon, Washington, and California, but it was a new experience to watch them utilize a river with significant flow. They comfortably float in the current with body splayed, then use powerful strokes to push back upstream.

I briefly caught one toad (legal under my ODFW scientific research permit) in order to get a clear photo of an adult on land.

Otherwise we didn’t find any toads on the riverbank – they all remained in the main body of the river. The rest of the year Western Toads are a terrestrial species, but everything changes during breeding season.

Matt and I were lucky enough to observe several toads initiating the breeding process. While some of the pairs were too far out in the river to get good pictures, I did capture this couple in amplexus.

Elsewhere we saw fertilized eggs from the previous days’ breeding. Toad egg masses are easy to identify as they lay in long strings of single-file eggs. Several sections of water next to the riverbank were loaded with these strings.

Since we took these pictures the eggs have hatched, the tadpoles have metamorphized, and the toadlets have begun migrating back to upland habitat. Let us know if you see any where you live!

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If this population is doing well, then why are toads rare in our region and struggling in western Oregon in general?

I don’t know of any sure answer. Possible explanations that have been given include the loss of wetland habitat, pesticide use, or changes in the climate. My guess is that it has to do with their vulnerable eggs. Toad eggs sit on the bottom of the water rather than floating on the top or adhered to vegetation like other local frogs, and thus are easily smothered by sediment. If dirt washes into the water and covers the eggs, they don’t hatch.

Why would smothering be such a vulnerability? Well, nearly all of the Coast Range has been logged, developed, or had roads built through it. When this happens the topsoil gets dislodged and washes into nearby water bodies. If that water is a pond, lake, or puddle, the dirt settles and smothers any existing eggs. Even loose sediment washed in from storms before the eggs were laid could be a problem, as any further disturbance in the water would kick up the sediment again and put the eggs in danger.

Is it a coincidence that the only toad population we’ve been able to find is breeding in the Nehalem River, where the flow of water is stronger, logging buffers are larger, and the toad’s breeding pools are better protected from the settling of topsoil runoff? Or that the closest major population we’re aware of is in a similar situation along the Sandy River just east of Portland? This is only a theory, but it would explain why toads seem to be surviving in rivers of significant flow but not elsewhere.

Western toads are now an Oregon Conservation Strategy Species. While this does not mean that their habitat is preserved (as is the case for an Endangered Species), you’re not allowed to catch/kill them. If you happen to find one, please don’t bother them but take a picture and let us know exactly where your toad was observed! We’d be excited to find any other existing populations in the county.

Observations of toads and any other local reptiles/amphibians can be uploaded at the following iNat project, or just leave us a message here.

https://www.inaturalist.org/projects/columbia-county-reptiles-and-amphibians