Heron Rookery, Wyndham, 05-17-21

I got up at 6:00 this morning and ready by 6:30 to head out with my friend and fellow naturalist, Roxanne, to look for a heron rookery in Natomas. There are actually two in this part of town, and both are by apartment complexes. We went to the one near the River Birch Park which has a large pond and walking trail in it. 

Along with landscaping around the lake, that mixed bot native and nonnative trees and plants, there were lots of cottonwood trees around the pond which the herons seemed to prefer.

When we first got there, I found it difficult to distinguish the nests and the birds, but my eye was soon able to pick them out.

We had never been to this place before, and weren’t really sure what to look for or where to look for it, but within a few minutes we were able to pick out the heron nests among the branches and twigs of the trees. Black Crown Night Herons dominated this rookery, but on the little island in the middle of the lake there were some Snowy Egrets nesting.

There were easily 30+ nests there, not counting the Snowy Egret nests. The nest sites are chosen by the males who then try to attract a female to join them. Males start the nest building, or refurbishes an old nest, but once a female is ensconced in the nest, the male continues to bring her sticks to add to it.

Cornell says: “…During and after pair formation, the male collects sticks from the ground or breaks them from trees and presents them to the female who works them into the nest. Adults may steal sticks from other active nests or old nests. The male’s twig ceremony gradually changes to nest building and may function to strengthen the pair bond…”

We hadlots of sightings of the “sticks” ceremony, and one male doing his “acceptance/greeting”. And I love all their rok-rok, scraak-scraak calls. So cool.

“…Advertising/Stretch: the male stretches its head up and forward, and treads raising legs and feet, brings extended head and neck forward and down, feathers of the back, crown, neck, and breast are raised, plumes fully erect, and the eyes protrude from their sockets appearing more red than usual…”

The herons are believed to be monogamous. According to Cornell: “…At the time of pair formation, the legs of both sexes turn pink, back and head plumage has a glossy bluish-green sheen, lores become black, plumes may reach 250 mm in length…”  We DID see evidence of that all around the rookery site.

Black-Crowned Night Heron, Nycticorax nycticorax, sporting its pink legs

We saw several birds sitting on the nests. Both mom and dad incubate the eggs, and it’s usually dad that does day duty, so I’m assuming that we were seeing the males sitting this morning.

A bonded pair of Black-Crowned Night Herons, Nycticorax nycticorax. It’s probably the male on the nest with the female overhead.

I thought I might have seen babies, but it was just adult birds snuggled down into their nests. We found one broken egg, but no signs of chicks yet. According to Cornell: “…Eggs are smooth and non-glossy, greenish-blue in color, but they are the greenest on the first day (fade thereafter); thus, color can be used to assign laying order up to one day after clutch completion…”

Egg of a Black-Crowned Night Heron, Nycticorax nycticorax

The herons seemed to like the cottonwood trees better than the others; although we did see one nest in a pistache tree.

According to Cornell, the Night Herons return to their natal breeding sites each year, so we were no doubt seeing a generation or more of birds at this site.

It was nice to see the signage put out by the Sacramento Heron and Egret Rescue group (SHER) that let folks know about the rookery and what to do if they found a fallen or injured bird in the area.

We found several areas where there was evidence that small crayfish had been taken from the water. The claws were taken off and left lying around, and there were some spots where we saw either upchucked or defecated crayfish (reddish “splots” on the sidewalk).


Night Herons are opportunistic feeders, meaning they’ll eat just about anything they can find or that’s most readily available. Cornell says: “…Foods including leeches, earthworms, aquatic and terrestrial insects, prawns and crayfish, clams, mussels, squid, freshwater and marine fish, amphibians, lizards, snakes, turtles, small mammals, birds, eggs, carrion, plant materials, and garbage/refuse from landfills…”

CLICK HERE for the full album of photos.

We also found a few very large pellets that, unlike the owl pellets I’ve found before, were still “glutinous”, a bit wet and exceedingly stinky. We put them into a bag and I dissected them at home.

Wearing a mask and gloves, I pulled apart the two pellets. Most of the pellets were comprised of undigested fur and feathers. There were lengths of skin and some partially digested organs, bones, skulls, and even a length of tail. I found evidence of at least two birds, six rodents, and possibly a bat in the pellets. I was surprised that, considering the crayfish bit we saw on the site, there was no evidence of crayfish in the pellets we found.

Walking around the lake at the site, we could see the Snowy Egrets starting to nest in the trees there. Because of their distance from us, it was hard to get clear photos of them.  We did see some of the birds gathering sticks for their nests. In this species, the female does most of the next building, but the males do bring her sticks to use.

On the oak trees around the lake, we found several galls including old Flat-Topped Honeydew galls, leaf galls and some petiole galls on a tree that looked like a Valley Oak hybrid of some kind. One of the willow trees had some bead galls on its tiny leaves, and we also found some evidence of white wooly aphid on the pyracantha bushes.

Also at the site we saw lots of Canada Geese, some crows, starlings, a few Bushtits and other birds. But none of them interacted with the herons. (Although I have no doubt that the herons would prey on the goslings during the night.)

I was also kind of disgusted by the fact that there were several dead carp in the water, just left to rot in the sun.

The Black-Crowned Night Herons are actually most active at night, and are just out and about now because it’s breeding season. After a couple of hours, the birds were all shifting into sleep mode, so activities ceased… and we headed home.

Sleepy Black-Crowned Night Heron, Nycticorax nycticorax, on his nest

I look forward to returning soon to see how things progress. This was hike #45 of my #52HikeChallenge.

NOTE: If you plan to go to the site, park only in the designated “courtesy” parking spaces or on the street. Do not park in the numbered parking spacing, and do not disturb the residents (or the birds).

Species List:

  1. Black-Crowned Night Heron, Nycticorax nycticorax
  2. Bushtit, American Bushtit, Psaltriparus minimus
  3. Butterfly Bush, Buddleja sp.
  4. California Black Oak, Quercus kelloggii
  5. California Scrub Jay, Aphelocoma californica
  6. Canada Goose, Branta canadensis
  7. Chinese Pistache, Pistacia chinensis
  8. Coast Live Oak, Quercus agrifolia
  9. Crow, American Crow, Corvus brachyrhynchos
  10. Desert Willow, Chilopsis linearis
  11. European Starling, Sturnus vulgaris
  12. Flat-Topped Honeydew Gall Wasp, Disholcaspis eldoradensis
  13. Fremont’s Cottonwood, Populus fremontii
  14. Goldfish Carp, Carassius auratus
  15. Great-Tailed Grackle, Quiscalus mexicanus
  16. Jumping Oak Gall Wasp, Spring generation, Neuroterus saltatorius [like a hard crust with holes in it]
  17. Leaf Gall Wasp/ Unidentified per Russo, Tribe: Cynipidi [on Valley Oak]
  18. Mallard Duck, Anas platyrhynchos
  19. Mistletoe, Broadleaf Mistletoe, Phoradendron macrophyllum
  20. Narrowleaf Willow, Salix exigua
  21. Oak Apple, California Gall Wasp, Andricus quercuscalifornicus
  22. Pied-Billed Grebe, Podilymbus podiceps
  23. Plant Bug, Family: Miridae
  24. Purple-Flowered Rock-Rose, Cistus × purpureus
  25. Pyracantha, Firethorn, Pyracantha coccinea
  26. Seed Chalcidoid Wasps, Sycophila sp.
  27. Seven-Spotted Lady Beetle, Coccinella septempunctata
  28. Snowy Egret, Egretta thula
  29. Valley Oak Petiole Gall, Tribe: Cynipidi 
  30. Valley Oak, Quercus lobata
  31. Willow Bead Gall Mite, Aculus tetanothrix
  32. Woolly Apple Aphid, Eriosoma lanigerum [also found on pyracantha]