Predator v. Predator

A great blue heron pulls a large bullfrog out of the water

Bullfrogs are voracious predators and not native to the Northwest but they are also a food source for a variety of animals that have learned to eat them. This large bullfrog was I think killed by a family of otters that came through earlier, it looked like one of them had caught the frog and eaten its front legs and a bit near the back before leaving. The heron was happy to eat what the otters left, dunking the frog a couple of times in the water (birds like herons and bitterns do this at times with their prey when near water) before getting it positioned in its beak where it could swallow the frog whole.

A great blue heron holds a large bullfrog in its beak

A  great blue heron dunks a large bullfrog in the water

A great blue heron prepares to swallow a large bullfrog

Surviving and Not Surviving into the New Year

Surviving into the New Year

A shoveler swims past late in the day on New Year’s Eve of 2014, meaning she likely survived into the new year. The little bullfrog below almost made it into the new year but an egret plucked it from the shadows shortly before sunset. The bullfrogs move pretty slowly in the cold of winter and if spotted are easy pickings for the egrets and herons and bitterns that patrol these shores.

Not Surviving into the New Year

When Two Frogs Love Each Other Very Much …

Two bullfrogs mating while floating in the water

These mating bullfrogs were serenely floating in the water while around them was chaos, with males playing leapfrog and wrestling each other into submission and croaking loudly. The male here is the one on top with his characteristic yellow throat and large tympani (the eardrums, the big circles behind the eyes). The water was mostly still but there was a subtle current and they both used their webbed rear feet to control their speed and balance. They don’t have webbing on their front toes, so the female used her front legs to maintain balance while the male has his wrapped around her body.

An End to Hibernation

End of Hibernation: The Dunk

Bullfrogs hibernate during the winter so their metabolism slows significantly and they aren’t very active but they don’t bury themselves in the mud the way a turtle might. Many bullfrogs at Ridgefield found their hibernation cut short this winter by the herons and egrets and bitterns that worked the shallow channels and ponds of the refuge.

This egret in particular was just walking up and down one such channel, avoiding a great blue heron doing the same, striking at bullfrog after bullfrog, following a familiar process between catching the frog and eating it. First, the frog would be dunked quickly into the water, as shown above. Next, the egret would spin the frog rapidly, presumably causing massive internal injuries to the frog, as shown in the following two pictures. In the first picture, the egret has closed the nictitating membrane in its eyes, a transparent third eyelid that protects the eye from damage while still allowing the egret to see, as water spins off the frog and its clawed feet flail about, while in the second picture the membrane has been retracted.

End of Hibernation: Spin Cycle No. 1

End of Hibernation: Spin Cycle No. 2

Then the egret would toss the frog into the air, catching it in a different place on its body, and either repeat the process again if it caught it by a leg, or perhaps crush it in its beak if it caught it by the body. This would happen multiple times until I gather the frog had died or given up fighting, although with the egret constantly keeping the frog moving it was hard to tell exactly when or if the frog itself stopped moving.

End of Hibernation: Throw & Catch

The final step was to position the frog head first in its beak and swallow it whole. Bullfrogs are voracious predators and, as they aren’t native to the area, have had a big impact on some of the other small creatures in the ponds and sloughs. However I’ve seen the bullfrogs themselves become prey for the larger predators of the refuge, including not just egrets and herons and bitterns but otters, raccoons, and grebes.

End of Hibernation: The End

A Mouthful of Bullfrog

An American bittern prepares holds a large bullfrog in its mouth

Normally I’m pretty good at spotting bitterns at Ridgefield but I saw them on only three out of ten visits to the refuge over the Christmas break. I worried I was losing my touch until I found this bittern on Christmas Eve slowly working the channel beside Rest Lake. I suspect the real reason I haven’t seen as many this year is that the grasses in this area, normally my best spot for seeing them, have been cut lower in places, eliminating cover for both the bitterns and the animals they are hoping to catch.

The bittern snagged a large bullfrog from the water as you can see in the top picture. In the picture below the bittern has swallowed most of the frog with only the rear feet sticking out of its mouth. The bittern has protected its eyes from the frog’s claws with a nictitating membrane, a common tactic in the chaos of swallowing something that doesn’t want to be swallowed.

An American bittern swallows a large bullfrog

Water

A great egret eats an American bullfrog in the rain at Ridgefield National Wildlife Refuge

In 2001 I bought what at the time was my most expensive lens, Canon’s 100-400mm lens. Since then it’s gone with me on every hike and nearly every trip and been one of my most treasured lenses. However the image stabilization system needs repair but I haven’t sent it in as I was hesitant to spend much money on a lens that could benefit from a modern re-design.

To my great delight, Canon finally brought out a new 100-400 lens and I pre-ordered the day of the announcement. It arrived on Friday so Saturday morning I opened it up and took it to my favorite refuge to try it out. One of the nice new features is that the lens has some weatherproofing, which I got to test with my very first pictures when I encountered this egret in the pouring rain. The egret was on the passenger’s side of the car so I slid over, stuck the lens out the window into the rain, and had just got the exposure and focus set when the egret struck into the water, pulling out this small bullfrog.

I meant to frame a little looser but in my haste to even get the shot I didn’t keep the camera quite level, so I rotated and cropped in post. Still I was pleased that with the zoom I was able to pull back and show a bit of the world these animals live in. The egret with its long featherless legs is built to wade in shallow water like this, able to hunt along the water’s edge, looking for frogs and fish in the water and frogs and voles on the land.

I’ve always loved photographing in the rain, especially to show how animals still have to go out into the rain to live their lives, and I’m thankful my favorite hiking lens now can as well.