Couple more bird ID questions

Factual Questions
1

One heard, other seen. Western burbs of Chicago.

  1. Singing in my backyard, early a.m. - approx 6:30.
    High in a locust tree.
    Could not see it.

5 note song made of of 2 notes, a fifth apart, starting w/ the C above middle C
C (down to) F, C-C-C.

Imagine a 3 equal part waltz tempo measure.
The first 2 notes took the space of the first 3d of the measure, the C-C-C was the middle 3d, and the rest between phrases the 3d.
So, in equal parts: C F | C-C-C | rest

I’m pretty familiar w/ the local bird song - this was unfamiliar.
There were at least 3 birds answering each other.
Occasionally it would sing the first 2 notes (C F), followed by irregular chirps, but then it would return to the regular pattern.
Not INSISTENTLY repetitive like a (red eyed?) vireo, but definitely somewhat repetitive.

  1. Seen in local forest preserve, around 8 a.m. - didn’t have my binos or phone.
    Small grey bird, flitting between low brush and ground.
    “Very flitty” behavior - did not perch anywhere for longer than a second or 2.
    Definitely smaller than a robin.
    Main color a soft grey like a catbird, but pretty strong darker striping, from the sides of the head down the wings and sides.
    Closest I saw in books were Black and White and Blackburnian, but I’ve seen B&Ws before - this was greyer, and less boldly marked.
    And not a trace of yellow.The main identifier I saw - which I can’t see in books - was a white “rump” - almost like a yellow-rump, of like a flicker shows when flying away.
    Belly was lighter, throat almost white.

Any thoughts?

2

Maybe the second one was a nuthatch.

3

Thanks. I’m pretty good at both white and chestnut breasted’s looks/movement/song. Definitely not.

I’m just assuming I’ve spotted 2 new species! :wink:

4

I think the behavior alone would rule it out, as well as details of plumage.

Sorry, I’m not a musician, so a description of song in terms of musical notation doesn’t mean much to me. At any rate, I’m very much out of practice on North American bird songs.

As for the second one, I can’t think of any good candidates that meet the description, especially the whitish rump. A Redpoll would show a pale rump, and be streaky, but I think it would give the impression of being brown rather than gray.