There were two males exchanging calls from the underbrush separating nearby homes from the park entrance. I tried hard to get a glimpse, but was unsuccessul; fortunately, I did succeed in avoiding a trespassing citation, as the birds are pretty much in the backyards of some homes adjoining the park. If you drive straight down the entry-road with your windows open, you can't miss hearing them!
Other highlights of the day include an orchard oriole and a pair of Wilsons phalaropes. There were scads of shorebirds.
Avalon Park never lets me down. Well worth the $4 entry fee.