[Which bird is heavier challenge?]

Eider?

[One more grebe]

Eared Grebe again. Dark cheek patches, and you can see how the bill is upturned.

[Another grebe]

Looks like a young Pied-billed.

[On the tip of my tongue...]

2 hours ago, Avery said:

https://search.macaulaylibrary.org/catalog?taxonCode=pingro&mediaType=a&q=Pine Grosbeak - Pinicola enucleator

forgot to say the call was clear toned, not buzzy at all  

sounded a lot like this! I’m gonna have it down as a Pine Grosbeak, and I’m pretty sure it’ll get flagged. Thanks all!

Have you checked Evening Grosbeak too?

[Which grebe?]

Eared Grebe. Note the dark cheeks. 

[sparrow, Toronto, today]

White-crowned Sparrow. Immature I believe.

[Bird Habitats - Deserts]

3 hours ago, Seanbirds said:

Does thorn scrub/ thorn brush/ mesquite scrub count as desert? @Melierax @Connor Cochrane @Anybody else

Sure!

[Warbler Challenge]

Virginia's Warbler

[Call]

29 minutes ago, Seanbirds said:

Pretty sure it's a Carolina Wren.

Agreed, FWIW ?

[tundra or trumpeter]

Trumpeter. The eye doesn't look distinct enough for Tundra.

[Bird call ID in Pittsburgh 10/25 (2)]

That's an American Robin.

[starling winter plumage?]

That's a Red-winged Blackbird. I believe it is a young male. 

[Dark Morph Hawks]

The right bird is a dark morph Red-tailed Hawk, not a Harlan's. In general, Harlan's tails do not have red or a faint subterminal band. In other words, there's no reason why this isn't just non-Harlan's Red-tailed Hawk (I don't remember the subspecies in AB). I'd be inclined to say the same for the left bird but it's too hard to see.

EDIT: Roughie is ruled out by the red in the tail and the lack of a substantial end of tail band (I'm pretty sure immatures have those too)

[What's this duck?]

Gadwall!

[Picholine]

Female Northern Cardinal.

[Cackling Goose?]

I agree, looks like Canada, maybe the Lesser subspecies. It's way too big compared to the Mallard behind it and the forehead is not steep enough.

[Mystery (to me) bird call in west Houston, TX]

Yep, that's a Carolina Wren. 

[Even More Bird Calls]

22 minutes ago, Connor Cochrane said:

It might just be the recording but the first one doesn’t sound right for CATO. Almost sounds more like Thick Billed Fox Sparrow, which would be very rare. It’s probably just the poor recording quality. 

Hm... my experience with California Towhees is that their calls can actually vary quite a bit. I kept getting confused by them while birding in Cali over the summer. Could be something else though, I see what you and @MichaelLong are saying about the pitch and tone.

[Confirm Black-Chinned Hummingbird?]

Agreed. Among other things, Black-chinned Hummingbirds have long wings that reach the tail tip. 

[Even More Bird Calls]

The first one is a California Towhee. I think you're correct on weird Black Phoebe on the second one.

[What are the chances these were Snow Geese?]

You should be able to see that they're white if you can tell how fast their wingbeats were. 

[Is this hawk ID-able?]

Dark morph Rough-legged or Red-tailed Hawk. There might be a roughie tail pattern in the first photo, but the other photos make the tail look red. I'm not sure which one it is though.

[Best Pictures of Birds]

This is my one sad photo of one ?

[Yellow & Black crowned Bird]

Golden-crowned Kinglet. Neato!

[Best Pictures of Birds]

Alright I have an entire folder entitled "Best Photos of the species" and it has over 400 photos.?

Black Phoebe:

Unfortunately this is my best Indigo Bunting photo:

I'm always trying to get better photos of Killdeer: