April 27, 2021 – A rookery is a great place to observe birds interacting, since they are restricted by the needs of their nests to a small area. On this day I visited two of them. One was cacophonous and the other calm, but both were busy places!
The first rookery was new to me. It occupies three islands in the retention ponds of the Delores Fenwick Nature Center, in Pearland Texas. Rain runoff enters the western pond, settles, then flows into the eastern pond, before draining into Mary’s Creek. The satellite photo shown here is probably several years old, as the raw bank grading shown is now covered by lush grass and spring wild flowers, and the rookery islands – those three brownish/gray islands – are now lush and green with tall trees and thick screening shrubs. The gravel path is just under 1.5 miles, but if you want to see the birds, you’ll venture down onto the mowed peninsulas for a close view. Fishing is allowed all around the ponds, so be careful of the fishing gear. Snakes also live in the ponds, so watch where you are walking; I saw a nice long one in the water next to the bank.
Snowy Egrets are displaying, looking for mates. This one’s signature bright yellow feet are almost hidden in the dewberry canes and dried weed straw. The plumes high on his back are probably the most elegant of all North America’s heron and egret species; that delicate curl, and the fan-like spread make a beautiful display. This bird is in breeding plumage, showing fully developed (not worn) plumes and bright pink lores (the skin around his eyes). In this image, he is not at his full extension, bill pointing to the sky. I chose a pose that shows the crest on the back and top of his head, as well as his more obvious back and chest plumes.
The lush grass dotted with spring wildflowers was a perfect backdrop for this Cattle Egret, strutting his stuff. The crest and plumes at chest and back are light orange, and when fully grown out, the back plumes extend just beyond his tail when in flight. In non-breeding plumage, only a buffy smudge at crown and chest remain. The gray stripes along the sides of his wing in this photo are mud swipes from foraging activities among sticks and canes.
Birds were flying back and forth between the islands and the stand of ungroomed trees along the south edge of the nature center. Different species of birds in a rookery tend to build their nests on a staggered schedule. During this visit, the vast majority of the stick-bringing was by the Cattle Egrets; most of the Great Egret and Cormorant nests were already complete, while the Ibis and Snowies were just now pairing up and picking nest locations. Note the bright lores and bill coloring on this bird, compared with the strutting bird above; this bird is in full breeding plumage.
The invasive Chinese Tallow Tree is a great source of twigs and branches. Its weak wood and short fast life mean that there are trees and woodpiles everywhere with plentiful sticks; the branches can often be identified by the presence of a few lingering rock-hard seeds, or “berries”. For my readers with a taste for trivia, here is an interesting article on the possibility of using the clean-burning oil from Chinese Tallow berries as a diesel biofuel and/or methanol, and another about attempts at making soap, and using the leaves and berries for goat fodder. (Don’t look at me like that, my brain has a mind of its own.)
In this series (3 of approx. 30 shots), our intrepid Cattle Egret stretched out to grab the end of a likely stick, then pulled back against it, struggling to break it. I’m impressed by the leverage he was able to apply through body position alone. But the damp wood wouldn’t snap, and after releasing it to spring back to its original position, he flew up to another branch and tried again.
The White Ibis have claimed a section of short shrubs as their domain. Birds in breeding plumage, showing scarlet faces and legs, fiercely defended their selected nest sites. Birds dive-bombed and charged, honking and flailing at each other to defend their small perimeter. In this image, I’ve zoomed in on three birds competing; two are sparring, while the third beats his wings to drive away the interlopers (and to keep his balance on the thin swaying branches).
The left-most bill-grabbing bird gave up and flew off, while the wing-flapping bird turned to make his boundary abundantly clear to the winning contestant. It appears that, so long as they maintain the minimum distance, it’s all just pointing and honking, but there is lots of literature documenting the violent fights that can occur between the combative White Ibis.
You can see that the underbrush is filled with jostling wide-eyed bodies; my guess is that the White Ibis females perch on the lower branches, keeping a watchful eye on the contests above. It was never peaceful… in the 20 minutes I watched them, intruders kept dive-bombing, attempting to occupy the “empty” space between the two defenders, being repulsed each time. And this scenario was repeated across the tops of the bushes all over the little island.
There were more birds in the rookery… but they were farther away, or nestled deeper in the brush, than my 500mm could handle. So, it was time to head over to my old haunt, Resoft County Park, just a quick 8 miles south, in Alvin Texas.
Bird photographer reports were true! A pair of Great Blue Herons is nesting on the nearest edge of the closest island, with no obstructing sticks. The open almost-eye-level nest provides an opportunity to watch the baby birds, and the Chinese Tallow leaves provide a nice background.
It’s impossible to know whether we have the mom or the dad in the above photo, because the parents look the same and alternate duties for protecting the young birds and hunting for food. The blue lores developed during the mating season fade after mating, so this adult’s eyes are almost back to normal. I don’t think we are seeing sibling aggression here; the largest baby appeared to be “milking” his sibling’s bill for food, mimicking the motion used to get food from the parents (although, as they get older and stronger, bill-grabbing and even stabbing can occur as the competition for food gets more aggressive).
[f/16? Seriously? What was I thinking? Well, I wanted all the tails, wings and bills to be in focus, but I clearly over-did it. The photo would have been improved by use of a shallower depth-of-field, to blur the noisy background. A lower f-stop would have permitted a lower ISO providing better color depth.]
I watched for quite a while as the young moved around in the nest, and sometimes lay down so low they were just dark fluffs barely visible above the brim of the nest. I liked this image of the parent and young mirroring grooming behavior.
[The above two shots of the GBH taken at two quite different exposure settings provide a great demonstration of the effect that a lower ISO has on the quality of the photo. Notice how rich and creamy the adult heron’s head, neck and wing are in this second photo, and how translucent the foreground leaves look. This is the result of the greater color depth afforded by the lower ISO.]
Great Egrets are also nesting. These young appear to be a week or so younger than the Great Blue Heron’s chicks, because they still have significant naked parts of neck and body, and their disproportionately large bills threaten to topple them over.
Another lower nest has sticks in front, but as the babies grow, they will take positions out on the edges, so we can see them. I was interested in the way the Great Heron back plumes tent down over the nest. It was starting to sprinkle as I was wrapping up, and I wondered whether they provide any weather protection. They seem too filmy to protect the young from our Gulf Coast downpours or to keep the young hidden from any preying birds, or even to protect very young hatchlings from the sun… but I suppose even a tiny bit of cover is better than nothing.
This parent has stepped off the nest, and onto a nearby branch, leaving the three young in their own little cave. I was interested to see that only a few of the Great Blue Heron and Great Egret nests contained three young; most contain 2. The normal clutch is 2 to 6 eggs for both species, and food supply strongly affects the number of young.
As you can see from that last shot, the sky was getting more threatening by the minute, so I packed up and headed home. I’m tickled to have a whole new destination in my list of photography locations, and look forward to exciting times ahead as the chicks develop.