Agua Caliente Park, Spring 2025: Wings Over Pond 1

4/5/2025

Violet-green Swallow over Pond 1, March 22, 2025. Canon R5 Mk II, RF 100-500mm at 500mm, 1/5000 sec., f/8.0, ISO 1600, +0.33 EV.

Spring is rolling into Tucson! A great place to follow the progress is Agua Caliente Park in the Tanque Verde Valley off of Roger Road.

This is the first of two posts on spring at Agua Caliente, this one focused on two species that I recently captured in the air over Pond 1.

Neotropic Cormorant

Canon R5 Mk II, RF 100-500mm at 500mm, 1/5000 sec., f/8.0, ISO 1600, +0.67 EV.

Neotropic Cormorants are in the order Suliformes, seabirds found throughout the world's oceans. There are four families in this order: Frigatebirds (Fregatidae) that grab food from other birds, Boobies and Gannets (Sulidae) that plunge into the water for their prey, Anhinga and darters (Anhingidae) that swim and dive for fish, and Cormorants (Phalacrocoracidae) that swim and dive for fish in both freshwater and marine environments.

In North America there are six cormorant species, including the Neotropic, Tucson's "home team", a regular on lakes and ponds throughout the year. Neotropics live year round in Arizona, New Mexico, Texas, and south throughout Mexico, Central and South America. They were active in the air and on Pond 1 on March 22, 2025.

Above, a male or female (they look alike) circling the pond. Below, preparing for a landing.

Canon R5 Mk II, RF 100-500mm at 500mm, 1/4000 sec., f/8.0, ISO 2500, +0.67 EV.

The Neotropic Cormorant has featherless yellow skin in a distinct pattern on the lower jaw and at the corner of the mouth. Its cousin the Double-crested Cormorant is larger in size, with yellow skin extenting over the eye. More on the Double-crested Cormornant later in this post.

Below, our subject stalls just above the water, tail down, webbed feet out in front.

Canon R5 Mk II, RF 100-500mm at 500mm, 1/5000 sec., f/8.0, ISO 8000, +0.67 EV.

Below, splash down!

Cormorants have feathers especially adapted to allow the entry of water, decreasing their buoyancy and facilitating underwater swimming for feeding on fish. This lack of buoyancy is clear in the frame below as our subject works to keep his head above water.

Below, a photograph of one section of a large flotilla of Neotropic Cormorants at Reid Park on February 17, 2017. Being less buoyant, cormorants sit lower in the water with only the top of their backs evident. At times the long neck will look like a snake, swimming upright in the water!

Canon 7D Mk II, Sigma 150-600mm C series at 421 mm, 1/1000 sec., f/13, ISO 800, +0 EV.

If a cormorant's total body water gets above 6% of its body weight, it is too heavy to fly, and must climb out of the water and dry its wings. (Ref: What It's Like to be a Bird, David Allen Sibley, Knopf, N.Y. 2020)

Below, a Neotropic Cormorant drys off at Agua Caliente on July 20, 2017.

Canon 7D Mk II, Sigma 150-600mm C series at 600 mm, 1/200 sec., f/8, ISO 200, +0 EV.

As noted earlier, Neotropic Cormorants live year round in Arizona, New Mexico, southern Texas and all the way into South America. The range map at right clearly shows the extensive range to the south of the U.S. border. In the U.S., the biggest breeding populations are in Texas. One of the best spots to see them in action each spring is the Rookery at Smith Oaks Bird Sanctuary at High Island, Texas.

Below, a single Neotropic Cormorant nests among a crowd of Great Egrets at the rookery.

For more on spring migration on the Texas coast, See Birding Hotspots, Texas Coast.

Canon 7D Mk II, EF 100-400mm with 1.4x Mk III ext. at 280 mm, 1/640 sec., f/7.1, ISO 160, -0.33 EV.

The male neotropic picks the nesting spot, the male and female build it together. The nest and hatchlings are cared for by both the male and female.

Below, a male and female Neotropic Cormorant at their nest at the rookery with their fledglings.

Canon 7D Mk II, EF 100-400mm, 1.4x III ext. at 560 mm, 1/640 sec., f/8, ISO 250, +0.33 EV.

In the sequence that follows, both parents feed the young by opening up their mouths wide for the offspring to venture down their throats and feed off of fish held in their crop. For birds like the cormorant that harvest fish underwater, this is probably the most efficient way to feed their young.

Next, for completeness, let's look at the Double-crested Cormorant and 4 of his cousins . . . .

Double-crested Cormorant at Cape May, New Jersey, October 2021. Non-breeding plumage, no white tufts over the eye.

Although we see the Neotropic Cormorant commonly in the Tucson area, the most abundant and widespread cormorant in the U.S. is the Double-crested Cormorant, shown above (Cape May, New Jersey, October 2021) and below (La Jolla Cove, La Jolla, California, January 2018). In Tucson we may see the Double-crested occasionally in migration.

The Double-crested Cormorant gets its name from two distinct tufts of long white feathers, one above each eye, which appear only in breeding season, evident in the image below captured at the La Jolla Cove in January of 2018. In addition to the feather tufts in breeding season, the Double-crested Cormorant's bare yellow skin extends above and around the eye, evident in both photographs.

Canon 7D Mk II, EF 100-400mm at 400mm, 1/2000 sec., f/5.6, ISO 800, +0.67 EV.

All totaled there are 30 species of cormorant world-wide, with 6 species living in North America: The Neo-tropic Cormorant that we see in Arizona, the Double-crested Cormorant, shown above, as well as four coastal species, Great Cormorant, Brandt's Cormorant, Pelagic Cormorant, and Red-faced Cormorant.

The Great Cormorant lives along the Atlantic coast, the Red-faced on the Alaska coast, with the Pelagic living along the Pacific Coast up into Alaska and west to coastal Asia. Brandt's cormorant lives on the west coast from Baja, Mexico up to the Alaska Coast.

Below, an image of a Brandt's Cormorant sitting on his/her nest at La Jolla Cove in January of 2018. The bird is in breeding plumage with a vivid cobalt-blue throat patch and eyes with wispy feathers on the head. Brandt's Cormorants nest and forage in the California Current and can dive deeper than 200 feet in pursuit of fish and shellfish.

Violet-green Swallow

Canon R5 Mk II, RF 100-500mm at 500mm, 1/5000 sec., f/8.0, ISO 1250, +0.33 EV.

The second species in the "Spring Agua Caliente Air Show" was the Violet-green Swallow. The morning of March 22nd there were multiple swallows feeding on insects over Pond 1. They were likely migrating north.

Photographing any bird in flight is a challenge, but even more-so for swallows who fly continuously and fast, darting and dodging to catch flying insects in rapid succession. I was fortunate to get these images of the birds hustling over Pond 1.

All swallows have long, narrow wings with a shorted boney arm structure and very long flight feathers to facilitate prolonged flight and rapid changes in direction. For more on wing and feather structure see David Allen Sibley's What it is like to be a bird.

Violet-green Swallows winter in southern Mexico and Central America, breeding in the U.S. west of the Rocky Mountains all the way north into Alaska.

Violet-green Swallows nest in open woodlands, favoring areas with dead trees with woodpecker holes or natural cavities. Violet-green Swallows may nest as high as 11,500 feet, so it is not surprising that a pair was nesting near the Meadow Trail on the top of Mt. Lemmon, (~9000 feet altitude) in early May, 2020. The meadow was perfect for them, with lots of open air for foraging to the south toward Tucson, and lots of nesting holes in dead trees on the Oracle side.

Below, likely a female, perched on a snag not far from her nest.

Canon 7D Mk II, EF 100-400mm with 1.4 Mk III Ext. at 560 mm, 1/1000 sec., f/8, ISO 400, EV +0.67.

In this sequence she may be calling to her mate. In these images we can see the long pointed wings that when folded are longer than the tail.

Above the violet rump is evident, with white on the sides. Note that in the images of the swallows captured at Agua Caliente in March, the rump appears red, perhaps because of the angle of the light.

Colors in bird feathers are created by pigments, either carotenoids (red to yellow) or melanins (black to gray to brown to buff), combined with structural colors generated by the reflection of light off of specialized microscopic features of the feather. There is no blue pigment in bird feathers, rather blue is a structural color. Since violet is a combination of red and blue, it is possible that the rump color is a combination of pigments (carotenoids for red) along with structural color (for blue). If the angle of light is right (or wrong) red (pigment) may dominate over blue (structural) creating a red rump. (Ref: Sibley, What it is like to be a bird.)