The three most common “trillers” I think of are the Chipping Sparrow (which as Miriam says is the most “mechanical sounding), the Swamp Sparrow, and the Pine Warbler.
They habituate different environs as their names suggest, so what it’s like where you were, and where in the landscape the bird was (I’m not familiar with the park) could help determine which of those (if any) you heard.
Hope that helps
> On May 11, 2016, at 9:54 PM, Carol R Heffer <[log in to unmask]> wrote:
> Maybe that is it. Sounds similar though the call went on for a much longer time than any of the recorded calls I heard. But thank you. A colleague also suggested the chipping sparrow.
> Thanks again,
> Sent from my iPad
>> On May 11, 2016, at 10:35 AM, Miriam Lawrence <[log in to unmask]> wrote:
>> Carol, hard to tell from your description, but Chipping Sparrows have a
>> very steady, long, almost mechanical trill, and I find sometimes it sounds
>> a bit robotic/metallic. Could that have been it?
>> -Miriam Lawrence
>>> On Wed, May 11, 2016 at 9:12 AM, Carol R Heffer <[log in to unmask]> wrote:
>>> I was walking in Symanski Park Monday morning and heard a sound I at first
>>> thought was a small machine. I realized it was a bird trilling. It was
>>> joined by a second at a lower pitch. It went on for a long time. I tried to
>>> find it on my Merlin app, to no avail. Anyone know what it might be?
>>> Sent from my iPad
>> Miriam Lawrence
>> [log in to unmask]
>> (c) 802-238-1830