I've somehow become addicted to watching the bats at dusk in Central Park at the model boat pond. I even invested in a Echo Meter Touch bat detector so I can see spectrograms of the bat's echolocation sounds. The detector is identifying (with 80% certainty) an almost even mix of Eastern Red Bats and Big Brown Bats. The Eastern Red Bats appear earlier in the evening followed by the Big Brown Bats.
Walking around the lake and out the west side of the park, I was able to detect two more Eastern Red Bats and two more Big Brown Bats tonight.