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.
Tag: American bullfrog
Are You Hoarse?
Surviving and Not 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.
When Two Frogs Love Each Other Very Much …
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
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.
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.
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.
A Mouthful of Bullfrog
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.
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.
Make a Joyful Noise
But let all who take refuge in you be glad; let them ever sing for joy.
The bullfrogs were singing in rare form at the refuge this weekend. Breeding season was in full swing and the males were croaking and wrestling and leapfrogging each other, and a few lucky ones were mating with the females. They were in a channel beside Bull Lake so I had to shoot down on them between the tall grass. Between a gentle breeze that constantly moved the grass about and my temporary bout of photographic incompetence, it took me a while to settle in and find my way.
This male was one of my favorites. I wanted to catch the ripples made by his croaking but was a bit surprised that my favorite view of the ripples is before his throat fully expands. The problem was that by the time his throat is fully extended, the ripples interfered with each other as they bounced off his rear legs, breaking up the pattern.
Beautiful creature, this one. Beautiful.
Turnabout is Fair Play
One of the stories at Ridgefield this winter has been the American bitterns which have been putting on a show at several spots around the auto tour during many of my visits. I’ve always been on the lookout for bitterns so I’m not sure why I’ve had so much success watching them hunt lately, although it may have something to do with the fact that I spent far more time at the refuge over the Christmas break than I usually do. This bittern was mostly snagging small fish as it worked the channel beside Rest Lake, but at one point it stopped and started wiggling its neck side to side and then struck into the middle of the channel, bringing up this bullfrog. Bullfrogs themselves are voracious predators and, since they aren’t native to the Northwest, have combined with habitat loss to cause problems for some of our natives. This little bittern was doing its part to turn the tables and win one for the home team.