Please help confirm some ID's

[sbruenjes]

I saw these birds at Liberty State Park in Jersey City today. Any help would be greatly appreciated

Are these:

a boat tailed grackle

Forster's tern

Yellow warbler?

 

 

 

 

[Kevin]

1 and 3 look good, but I am not sure about 2.

[Connor Cochrane]

I think 2 is a Common Tern. Different wing edges and brighter red feet.  

[sbruenjes]

Let me see if I have an understanding of differentiating the two. Here is a pic that was previously identified as Forster's. It looks like this bird has more of a reddish beak than the Forsters, and it looks like the wingtips are darker than the Forster's. Are these the best ways to differentiate?

 

[Benjamin]

Your most recent picture is indeed a Forster's Tern. The difference is very slight, but the bill and feet are more orange, where the Common Tern you posted earlier is a vibrant red. Also, compare the color of the primaries to the color of the rest of the wing. In the Common Tern, notice how the primaries are darker relative to the rest of the wing, while in the Forster's it's much whiter than the rest of the wing.

Edited June 27, 2020 by Benjamin

[Tony Leukering]

On 6/27/2020 at 10:32 AM, Benjamin said:

notice how the primaries are darker relative to the rest of the wing, while in the Forster's it's much whiter than the rest of the wing.

Note that the outer primaries are contrastingly darker than the one (or two?) inner primary visible in your pic. See crop of pic, below.

Common Tern typically shows the outer five primaries contrastingly darker than the inner five primaries due to its odd molt strategy, replacing those blocks of five feathers at different times. The feathers start out pale, due to a pale bloom on them. As the bloom wears off, the underlying darkness of the actual feather shows. The inner primaries are typically molted one more time in a given year than the outer primaries, thus are typically paler. At least, I think that's most of the reason.

[sbruenjes]

Wow, that is an impressive explanation. Thank you! ?