CrossEyedDave here, filling in again. My interpretation of a theme for this puzzle would be:
Alan Olschwang is a prolific constructor, and has provided many puzzles for us to enjoy. You can find CC's 2009 interview with him on the right side of the Blog, 3rd from the bottom.
As near as i can comprehend, these birds are cooped up in the circles as follows:
18 Across. Rather often: QUITE A LOT
And, the reveal:
1. Root beer brand owned by Coca-Cola: BARQ'S. This combined with 3 down, Regan, was almost a Natick for me. But the R in Barqs was dredged up from previous Crosswords.
6. Tightly closed: SHUT.
14. Indigenous Alaskan: ALEUT. Indigenous Alaskans are diverse peoples, including Inupiaq, Yup'ik, Aleut (Unangan/Alutiiq), Athabascan, Tlingit, Haida, and Tsimshian. (And you thought they were just Eskimos...)
15. Work hard for: EARN. (I earned this puzzle review!)
16. Feminine Spanish pronoun: ELLA. (e.g., Ella es mi madre - She is my mother; Los regalos son para ella - The gifts are for her). I have no explanation for "Cinderella..."
17. Roman robes: TOGAS.
18. [Theme]
20. Jackie on the Hollywood Walk of Fame: CHAN.
21. Mardi Gras, for one: Abbr.: TUE. I cannot imagine only one person celebrating Marci Gras...
22. Selling point: ASSET.
23. [Theme]
27. Name on a former lake in Central Asia: ARAL. This word is as common as Oreo...
28. "Guys and Dolls" composer Frank: LOESSER.
32. "Been __, done that": THERE.
35. Chapel bench: PEW.
36. Med. plan option: HMO. (Health Maintenance Organization)
37. [Theme]
42. Chicken __ king: ALA.
43. Hundred Acre Wood joey: ROO.
44. Cropped up: AROSE.
48. "Othello" frenemy: IAGO.
50. [Theme]
55. Poker buy-ins: ANTES.
58. Final tally: SUM.
59. Prefix with -gram: SONO. (One of too many to mention...)
60. [Theme]
63. Hollowed out: CORED.
64. Crossword hint: CLUE.
65. Finds a purpose for: USES.
66. Blender setting for pumpkin pie filling: PUREE. And baby food.
67. "As __ on TV": SEEN.
68. "Devil Inside" band: INXS. This was another almost Natick, saved by U.S. Navy...
69. Ring-shaped island: ATOLL.
Down:
1. Baker's sheetful: BATCH.
2. "Welcome to Maui!": ALOHA.
3. Middle daughter of King Lear: REGAN. (Half an almost Natick.)
4. Difficult situation: QUANDARY. (What ever should i post here.)
5. MA, ME, MI, and MO, but not MU: STS. (And not Fe, Fi, Fo, Fum...)
6. Follow-up film: SEQUEL.
7. Rutger of "Blade Runner": HAUER.
8. Ocean State sch.: URI. University of Rhodesia Island.
9. Blasting letters: TNT.
10. __ of burden: plow-pulling animals: BEASTS.
11. Letter-shaped pipe joints: ELLS.
12. __ vera gel: ALOE.
13. "The Simpsons" creator Groening: MATT.
19. "At __, soldier!": EASE.
21. FDR energy project: TVA. Tennessee Valley Authority
24. Dirt pie cookie: OREO.
25. Escape in a hurry: FLEE.
26. Ames locale: IOWA.
29. "Go on, git!": SHOO. (Scram! Or Skidaddle...)
30. Big birds of Australia: EMUS. Not Rheas,
31. Learning by repetition: ROTE. (The answer is Oreo!)
32. Salty drop: TEAR.
33. Saintly glow: HALO.
34. Airport pickup figs.: ETAS.
35. Vietnamese soup: PHO. (Do i need to post a pic?)
38. Manhattan Project scientist Harold: UREY.
39. Multicolored horse: ROAN. I would post a pic, but I really thought they were more colorful...
40. All the __: very popular: RAGE.
41. Brings forward for display: TROTS OUT. (Hmm, see 47 down...)
46. Country between Finland and Norway: SWEDEN.
47. Merit badge holder: SASH.
48. "Well, maybe": I GUESS.
49. Sleeve: ARM. (If you are armed, would you be sleeved?)
51. English county south of Suffolk: ESSEX.
52. Masked vigilante whose name is Spanish for "fox": ZORRO. Learning moment
53. Genuflect: KNEEL. Only know this from The Wizard of Oz... (The Lions Solo song)
54. Alpine song: YODEL.
55. School basics: ABCS.
56. Aswan's river: NILE.
57. Factual: TRUE.
61. French yes: OUI.
62. Top Gun org.: USN.
63. Audit firm pro: CPA.























