Before Hooded Mergansers seek out their nesting cavities in snags and stumps they engage in extensive courtship displays. Males tend to outdo females when it comes to these displays. As the accompanying photograph illustrates, courtship occurs in small groups consisting of at least one female and several males. Males engage in many more types of displays than females. The extent of female courtship consists mainly of head-bobbing and head-pumping. Male displays include crest-raising, head-throws with turn-the-back-of-the-head, head-pumping, head-shaking, upward-stretch, upward-stretch with wing-flap and ritualized (repeated) drinking.
Head-throws (see male in foreground of photo) are the most elaborate display. With crest raised, males bring their head abruptly backward touching their back. A rolling frog-like crraaa-crrrooooo call is given as the head is returned to the upright position and turned away from the intended female. This call sounds so much like a frog that the first time I observed courting Hooded Mergansers I thought it was pure coincidence that I was watching male mergansers display while Leopard Frogs were simultaneously giving their snore-like call. In actuality, the displays as well as the vocal accompaniment were being produced by the mergansers. (Note that one female Hooded Merganser appears not to be all that impressed.)
At this time of year one would expect to find Leopard Frogs lying on the bottom of a pond, partially but not completely covered with leaves or mud as they hibernate their way through winter. Because of the depth of a pond, and the fact that in winter the water temperature is around 39°F., ice isn’t an issue at the bottom of a pond, and the frogs and turtles that overwinter there don’t usually freeze.
However, sometimes ponds freeze over before amphibians or reptiles that overwinter in them arrive at their hibernacula. Apparently this is what happened to these Leopard Frogs, and they took refuge in the only open body of water they could find – a large but shallow puddle about 10’ wide by 20’ long in a dirt road. Shortly after they arrived temperatures dropped and the frogs were trapped under (and eventually will be encased in) the ice. Unlike Wood Frogs, Spring Peepers and Gray Treefrogs, Leopard Frogs are not freeze tolerant, so their demise is inevitable. (Thanks to Kelly Maginnis for photo, and Jim Andrews for his herpetological expertise.)
Pickerel Frogs emerge early in the spring from their muddy, pond bottom hibernacula, and mate in April and May in the Northeast. As part of the mating ritual, males call to attract females, with the calls resonating inside their internal vocal sacs located between their tympanum (ear drum) and foreleg (unlike Spring Peepers and American Toads, whose vocal sacs are located directly under their mouths).
These low-pitched calls resemble short “snores.” Occasionally Pickerel Frogs call from under water, but even when they are above water, their calls do not carry very far, frequently making it difficult for human ears to hear them. Their call is similar to that of the Leopard Frog’s but lacks the short grunts of a full Leopard Frog call. You can compare these two calls (and several others) by going to http://langelliott.com/calls-of-frogs-and-toads-of-the-northeast/ (Sound recording © Lang Elliott – langelliott.com)