Gray tree frog calls warning to rival frog outside of his cave

This gray tree frog has found a little cave beside a pond in a forested area of Ontario, Canada. It calls to a rival male that can be heard in the background, answering his calls. They both call back and forth, possibly arranging a meeting later in the day to sort out whose territory this is.
Gray tree frogs vary in colour. They are able to change their colour from green to gray or brown to match their surroundings. They have a striking orange or yellow patch under their forelimbs. They are beautiful frogs, often being a vivid emerald green. Their call rates are temperature determined with the average rate being 16 to 34 pulse per second. This tree frog is a male. The females do not vocalize.
Tree frogs can often be seen around windowsills and porch lights. They gather there due to the lights that attract insects, which they prey upon. They eat spiders, mites, insect larvae, and occasionally, other frogs. Gray treefrogs are often found in the open, in direct sunlight. Due to their superb camouflage, they are well disguised from predators.
Male tree frogs use their call to announce their territory, but also to attract females. The chorus of competing calls can be confusing to females. When the aggression threshold is reached, a male treefrog with change from a mating call to an aggressive call that signals conflict. Physical aggression is rare as most disagreements are settled with vocalizations.
Gray tree fogs can be found in the central and eastern United States and south eastern Canada.