Skull Guy

Young or molting male goldfinch is correct

We are planning to visit friends near Boulder next year and I am trying to focus my time for the "best" birding. We have never birded west of the Mississippi except for Houston and Hawaii, so many birds will be new. We have flexibility in the month we go, I am thinking mid May to mid June would be best for maximizing birds but am open to suggestions (migration?). We will be doing a lot of birding during the visit so can travel a distance from Boulder. Any advice is welcome!

sounds like a cuckoo - appropriately named! Both yellow-billed and black-billed could be in your area. They are tall and slender, and a distinctive ID trait is their long, barred tail. If you see the bird again, pay attention to the color of the bill. All black means black-billed. If the bottom is yellow, yellow-billed! Also look up their calls on the Cornell site, that may help you tell which species you heard/saw

Your correct, female house finch. Possibly immature

Location and date would really help but it appears to be a female house finch

Look into cormorants, species would depend on your location. I regularly see double crested cormorants flying in the way you describe

No worries, I saw your other posts so assumed where it was taken. Still a yellow billed cuckoo!

Yellow billed cuckoo - it would help to know where and when you saw this bird.

Yes to all

Try tree swallow, blue top and white bottom

Northern Cardinal for sure, either a young male or molting adult male.

Agreed - your Moderator is wrong. The bill is too short for red-breasted (or common), there is no coloration difference between the head and neck (like in red-breasted) and the overall shape of the bird makes this a hooded merganser.

Hooded merganser

Your correct, black skimmers. Awesome bird

Magnificent Frigatebird