Fall at El Rio Preserve, Part II: Grebes and Warblers, with a little Chat on the side . . . . .

Common Yellowthroat at El Rio Preserve, September 21, 2025

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For my last post on September 27th I visited El Rio Preserve in Marana, Arizona, and focused on one food, the dragonfly, which was in plentiful supply and provided breakfast for raptors, shorebirds and songbirds alike. In this post I return to El Rio and take a focused look at the Grebe family (Podicipedidae), including a rare one for SE Arizona, the Least Grebe. 

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Least Grebe   (Caution: RARE BIRD ALERT!)

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Canon R5 Mk II RF 100-500mm & 1.4x Ext. at 700mm, 1/1600 sec., f/10, ISO 1600, +0.33EV.

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The Least Grebe, like its cousin the Pied-billed Grebe, is a small duck-like water bird that lives on fresh and brackish water ranging from the Rio Grande Valley in Southern Texas all the way into South America. See the range map to the right.

Least Grebes live year round within their range, so it is unusual to see one in Arizona, although as one might expect, eBird has sightings in Arizona, where it is considered a "causal resident", present intermittently throughout the year. This solitary Least Grebe has been sighted at El Rio Preserve repeatedly in September and October.  See the eBird range map below for the Least Grebe sightings in our area.

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In the image below our subject is fluffing up his white behind and turning it into the sun to warm up the underlying dark skin. This behavior is shared by other grebes, as well as the Greater Roadrunner (See Sweetwater Wetlands, Winter 2025).

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Canon R5 Mk II RF 100-500mm & 1.4x Ext. at 700mm, 1/1000 sec., f/10, ISO 1000, +0.33EV.

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Below, our solitary Least Grebe at El Rio Preserve is floating in a raft of multiple Pied-billed Grebes, all preening in the morning sun. Pictured side by side, these two grebes are in roughly the same focal plane, making it is easier to make comparisons.

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Canon R5 Mk II RF 100-500mm & 1.4x Ext. at 700mm, 1/2000 sec., f/10, ISO 2000, +0.33EV.

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The Least Grebe is dusky gray with a bright yellow eye and a thin and pointed bill with a light tip. In contrast, the Pied-billed is larger and browner with a thicker, stubbier bill.  Below, the two grebes are closer to each other for a better comparison, the Least Grebe on the right, the Pied-billed on the left.

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Canon R5 Mk II RF 100-500mm & 1.4x Ext. at 700mm, 1/1000 sec., f/10, ISO 1000, +0.33EV.

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Below, the two birds are even closer with the Least Grebe in the foreground, his eye partially closed.  

The two species seemed to get along, although I noticed that as they preened, they seemed to fluff up more when closer to the opposite species.

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Canon R5 Mk II RF 100-500mm & 1.4x Ext. at 700mm, 1/1000 sec., f/10, ISO 1600, +0.33EV.

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Pied-billed Grebe

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As noted above, Pied-billed Grebes are larger than the Least, and very common in SE Arizona. Above, two Pied-billed's at El Rio, and to the right the Pied-billed range map. The Pied-billed Grebe has an extensive range, living year round in most locations, but with some populations migrating to the northern U.S. and into Canada for summer breeding. 

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Below, a close up of a Pied-billed Grebe at Sweetwater Wetlands in January of 2022. Breeding adults have a vertical black stripe on the bill. This grebe is a non-breeding adult. 

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Canon R6 with RF 800mm, 1/1000 sec., f/11, ISO 8000, +0.67EV.

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Below a photo of a Pied-billed Grebe swimming on one of the ponds at Sweetwater Wetlands in February of 2020. All grebes have their feet positioned far back on their bodies, a bit like an outboard motor on a rowboat. Also, they have lobed toes, seen here just to the right of the center of the photograph. The combination of leg placement and lobed toes make them great swimmers, allowing them to dive and maneuver under water for prey. However, they are not good walkers and are rarely seen on dry land.

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Canon 7D Mk II EF 100-400mm at 400mm, 1/1000 sec., f/5.6, ISO 400, +0 EV.

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Pied-billed Grebes eat crustaceans, small fish, and whatever is available, including frogs! 

To the right we see a Pied-billed Grebe downing a frog at Sweetwater Wetlands in January of 2016. Yes, he did manage to swallow the whole frog, head first!

For more, see the post "Grebe eats frog!", or "I can't believe he ate the whole thing!"

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Clark's Grebe

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Canon 7D Mk II EF 100-400mm w/ 1.4 x ext. at 560mm, 1/640 sec., f/8, ISO 320, +0.67 EV.

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This Clark's Grebe was spotted at Patagonia Lake State Park in March of 2019. The bird was on the far side of the lake with a lot of moist air between us, creating a slightly fuzzy image in spite of good focus and low ISO. 

Clark's Grebes live year round in Mexico, with populations migrating north to the western U.S. and into Canada. They frequent lakes and coastlines. See the range map to the right. This bird may have been migrating north for breeding at the time of the photograph. 

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Clark's Grebes are black and white with long curved necks and long pointed orange bills. They are known for a dramatic courtship display, or "rushing ceremony" on their breeding grounds.

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Eared Grebe

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Canon 7D Mk II EF 100-400mm at 400mm, 1/1000 sec., f/6.3, ISO 160, +0.33 EV.

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The Eared Grebe has a thin bill and a bright red eye, seen here in non-breeding plumage. The  grebe pictured here was spotted at White Water Draw in December 2019. 
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​Eared Grebes breed in colonies in shallow wetlands in the western U.S. and Canada.  In the fall, after breeding, they head by the hundreds and thousands to salty inland waters, especially Mono Lake in California and the Great Salt Lake in Utah to stuff themselves with brine shrimp before heading farther south for the winter. This coincides with their fall molt providing the high calorie intake required for new feather growth.  
​Range map is to the right.

During this feeding phase they more than double their body weight with the digestive organs growing and the pectoral muscles shrinking to less than required for flight.  Before departure for wintering grounds the process reverses, with the digestive organs shrinking to one-fourth of peak size, and the heart and pectorals growing quickly to allow for flight. ​

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In the image above, like other grebes, our subject has his "bum to the sun" to warm up on a cold December day.

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Let's Wrap-up with Three Warblers and a Chat . . . .

In addition to the rare (or at least "casual") Least Grebe at El Rio, I spotted three warblers, plus a "used-to-be warbler," a Yellow-breasted Chat. Let's take a look . . . .

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Common Yellowthroat

Canon R5 Mk II RF100-500mm with 1/4x Ext. at 700mm, 1/1000 sec.,f/10, ISO 1250, +0.0 EV

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The male Common Yellowthroat with his bright yellow duds and black mask looks like a mysterious highwayman, but rest assured, he is only after insects and spiders from the local leaves and branches!

​The Common Yellowthroat favors the edges of marshes and wetlands, breeding throughout the northern U.S. and Canada, wintering in Mexico with year round populations in Florida and the SE U.S. 

The adult male above was spotted at El Rio on September 21st at 7:30 am, with just enough morning sun to catch a light on the eye and create a subtle shadow on the breast. 

Below, an immature male "highwayman in training,"  with a faint and patchy mask.

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Yellow Warbler, Immature Male

Canon R5 Mk II RF100-500mm with 1/4x Ext. at 700mm, 1/2000 sec.,f/10, ISO 8000, +0.67 EV

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In the spirit of full disclosure, I was not sure which species this bird was, and so as is often the case, I consulted the guru app Merlin, which gave me four choices of warbler, in descending order: Yellow, Nashville, Tennessee, or Orange-crowned. The apparent eye-ring was nudging me toward Nashville, but not being sure, I consulted the real expert, Jeff Babson! 

Jeff as always came through and told me that this looks like an immature Yellow Warbler. A Nashville would show more gray on the head, and the Tennesee and Orange-crowned would show an eye line. Young Yellow Warblers often have a more distinct eye ring than adults because the yellow is not as brilliant.  

Yellow Warblers are insectivores who winter in Central and South America and breed all the way from Mexico to Alaska, coast to coast! See the range map to the right. The birds pictured here are likely on their way south for the winter following the food!

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The photograph below was shot 30 minutes later.  This may be the same bird, with the eye ring looking smaller because of the angle, or perhaps a female.

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Yellow-rumped Warbler

Canon R5 Mk II RF100-500mm with 1/4x Ext. at 700mm, 1/2000 sec.,f/10, ISO 800, +0.0 EV

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Our third warbler for the day is the Yellow-rumped Warbler, Audubon's. They have a yellow rump ("butter butt"), a yellow patch on the throat, and yellow patches ("pits") under the wings. 

Yellow-rumped Warblers have a wide range, living from the Pacific to the Atlantic and Caribbean, breeding as far north as Alaska, and wintering into Central America. They eat a wide variety of insects during the summer, as well as fruits during the winter. Unlike most warbers, their digestive tracts are capable of digesting fruit, which allows a wider range especially further north in the winter.

For more on the Yellow-rumped Warbler see this page:  Yellow-rumped Warbler.

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And Finally, a Yellow-breasted Chat!

Canon R5 Mk II RF100-500mm with 1/4x Ext. at 700mm, 1/500 sec.,f/7.1, ISO 12800, +1.0 EV

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For years the Yellow-breasted Chat was in the warbler family, Parulidae, but in 2017 it was given its own family, Icteriidae based in part on its large size and complex and varied vocalizations. Although wide-spread, it is generally only seen in the spring when singing, and is otherwise skulking in the shadows of dense thickets and therefore tough to spot. I spotted this bird briefly, and only once, at sunrise, 6:30 am, on September 21st, and in the shade! Once the sun was up, he was gone! 

Yellow-breasted Chat's eat insects, as well as fruits and berries. 

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That's a wrap! Four grebes, three warblers, and a chat! 
​More soon . . .

Happy trails!