Bullfrogs and Broad-Winged Hawks

American Bullfrog at the Homer Lake Wetland, 4/14/2021

Cue the theme music from Jaws. The American Bullfrog (Lithobates catesbeianus) is about the closest thing to a great white shark we are apt to find at the Homer Lake Wetland. I saw the first one of the season last week on April 14th. The American bullfrog is the largest frog in North America, growing up to 8" or so in length and up to a pound or more in weight, and will eat pretty much anything it can stuff into its huge mouth such as other frogs (including smaller bullfrogs), crustaceans, insects, fish and even birds, snakes, bats and small turtles! The bullfrog pictured above basically dared me to try anything as it watched me shooting underwater video nearby and then as I approached it for photos. Nerves of steel, it never flinched. I, however, was fairly confident I would not fit into its mouth.

Besides the size, how do we know this is a bullfrog?  Remember the "dorsolateral folds" -- the ridge of skin running from behind the eyes down the back to the rear of the frog on leopard frogs?  Look at the photo above. Bullfrogs don't have those. The folds they have start behind the eyes, wrap around the tympanum (external eardrum), and stop there.

Like all the other frogs we've seen in the wetland, bullfrogs will have spent the winter elsewhere, almost certainly like the leopard frogs, deep down in the nearby lake beyond the danger of freezing. The leopard frogs have come to the wetland to breed -- their eggs and young don't do well in bodies of water populated by fish. Bullfrog tadpoles, on the other hand, are not so palatable and bullfrogs lay up to 20,000 eggs, so they are able to produce succeeding generations over at the lake. Here in the wetland, however, breeding bullfrogs may well be making a mistake. Unlike the leopard frog tadpoles, which mature in a summer, bullfrog and the closely related green frog tadpoles this far north take more than a year to mature to adulthood. With the good possibility that the wetland will dry out in late summer or fall, any bullfrog eggs laid here have limited chances of becoming frogs. There have been no bullfrogs calling at the wetland yet this year, but they breed later in the season, probably in June. Frog call surveys from the past two years indicate that there have in fact been bullfrogs calling in the wetland in June, so we will see.

Meanwhile, bullfrogs who come over to the wetland from the lake will enjoy status as almost top-level predators. However, after photographing the bullfrog above as I was getting into my car, I saw the Broad-Winged Hawk (Buteo platypterus) below perched in a tree adjacent to the pond searching carefully for movement below, bending forward and leaning back, studying carefully what might be on the day's menu. The menu for these birds includes amphibians, so I'm pretty sure bullfrog would be a satisfying meal.  There is, it seems, always someone further up the food chain.*

I will be keeping my eyes open for future sightings of the broad-winged hawk. Edges of woods overlooking water is a common hunting haunt for them, so searching the edges of the woods periodically when arriving and while working the wetland will need to be part of my routine. 

Broad-Winged Hawk Overlooking the Homer Lake Wetland, 4/14/2021

For more information on bullfrogs:
For more on broad-winged hawks:

* There is often someone further up the food chain in your native habitat. Bullfrogs are native to Illinois and most of the Eastern United States; however, they have been introduced out west and in other countries where they are severely impacting native amphibian populations both through competition and by preying on the native species. PSA: Please NEVER release a pet or science experiment into the environment.

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