It’s Sunday, and we have the regular Sabbathian dollop of bird photos from biologist John Avise. However, this marks an anniversary of sorts: John tells me that this is the 100th straight week in which I’ve posted his bird photos!
John’s narrative and IDs are indented; click on the photos to enlarge them.
Clothing, Grebes, and Terns
What do people’s clothes, Grebes (Podicipedidae), and Terns (Sternidae) have in common? . . . . . . . .Answer: they all come in a variety of size classes including XL, L, M, S, and Petite. Such size classes presumably allow these bird species to co-exist ecologically by partitioning the environment and exploiting somewhat different food sizes in their diets.
Today’s photos (taken in Southern California, Florida, and Texas) show several Grebes and Terns along their respective size spectra. Numbers in parentheses are adult body lengths in inches.
Western Grebe, Aechmophorus occidentalis (XL, 25″):
Red-necked Grebe, Podiceps grisegena (L, 18″):
Horned Grebe, Podiceps auritus (M, 14″):
Pied-billed Grebe, Podilymbus podiceps (S, 13″):
Least Grebe, Tachybaptus dominicus (Petite, 9.5″):
Caspian tern, Sterna caspia (XXL, 21″):
Royal Tern, Sterna maxima (XL, 20″):
Elegant Tern, Sterna elegans (L, 17″):
Sandwich Tern, Sterna sandvicensis (M, 15″):
Forster’s Tern, Sterna fosteri (S, 13″):
Least Tern, Sterna antillarum (Petite, 9″):