Fiction Writing and Other Oddities

Friday, July 20, 2018

Green Herons

While this post has absolutely nothing to do with my writing, it is something that means a lot to me. I've been watching the nesting efforts of Green Herons at a pond next to our house for almost two months now, and although I have no scientific credentials whatsoever and am by no means an authority or even a pretender to any kind of knowledge of any kind, I have wanted to document some of my observations.

Second Brood - One Unhatched Egg
I repeat, I know absolutely nothing. (In fact, as I grow older, I've realized that I really do know absolutely nothing about anything.) I wanted to make that clear. The following observations and my comments are just that: my own observations and conclusions.

So, enough with that.

I noticed the first clutch or brood of Green Herons, Butorides virescens, on June 17, 2018. I saw a juvenile bird that still had down on its head, hanging around the pond. By June 19, I'd seen five juveniles, crowding around an adult and begging to be fed.

Before that, I'd seen adult Green Herons hanging around the dock and pond, and had watched a male adult calling from one of the pilings of the dock.

Unfortunately, by the time I observed the five juveniles, they were already out of the nest and exploring the tangle of vines and trees around the pond.

To my surprise, on July 3, 2018, I saw a new nest in a sweet bay bush overhanging the pond. There were 3 downy juveniles in the nest. I don't know if this was the same pair of adults re-nesting or if it was a second pair of adults. I suspect it was a second pair of adults since there would have had to be too much overlap between the feeding of the first set of juveniles and the activity involved in sitting on the nest for the 2nd brood, given the dates.

The second set of juveniles have allowed me to gather photographs and record the early life-cycle and activities of Green Herons. So the following is the information I've collected between the two sets of juveniles. I did, unfortunately, miss a 7 day period with the second set of juveniles, but it was unavoidable.

Although I didn't witness the actual mating behavior, I noted that by April 20, 2018, a male adult
Male Heron - Preparing to call
Green Heron was routinely visiting the pond area. He often sat on the dock piling nearest to the pond and softly called, mostly in the morning. I also saw him moving in and out of the shrubs, trees, and vines around the pond. He must have found a mate and built a nest sometime during the next couple of weeks, because this pair managed to hatch out FIVE chicks! What is more astounding is that all five fledged and dispersed to salt marshes and other feeding grounds around the nest site.

Since I first noticed juvenile Green Herons (the first clutch of five chicks) with down on their heads exploring the area around the pond on June 17, 2018, I concluded that the first nest must have been built around May 10, give or take a few days. This date was calculated based upon an incubation period of 19-21 days, and the beginnings of exploratory behavior in chicks about 15 - 21 days old. Note that all these dates are approximate. I figured that the first batch of Green Herons hatched around June 1, 2018, give or take a few days.

Second Nest - Unhatched Egg Lower Right
The first nest was too well hidden to see, but based upon the behavior of the juveniles, I believe it was built in a cedar tree well covered with Virginia Creeper and Trumpet Vines. It had limbs overhanging the pond, and the juveniles seemed to go in and out of that area. There were five chicks that survived out of the first nest. I do not know if there were any eggs that didn't hatch.

Chicks on July 3, 2018 When First Observed
I was only able to observe the second nest, since it was the only one close enough to an opening in the vegetation to be visible. The nest (the second clutch) was built out of small twigs in a sweet bay bush which was overhanging the pond. I was able to see the nest itself through a small opening under a swag of vines. A cascade of Virginia Creeper curved over the branches above the nest, helping to conceal it. The second clutch produced three chicks, but there was one blue-green egg that remained unhatched in the nest. Two weeks after first observation of chicks, one juvenile was no longer begging from the parents when they arrived. I assume that juvenile died at some point, about a week ago (sometime between July 9 to July 18).

Chick Development
Since I was only able to observe fairly recently hatched chicks in the second clutch (the first being too well concealed to observe), I'll start with them.

July 3, 2018 - 2nd clutch
Three Chicks in Second Brood
I first noticed downy Green Heron chicks, sitting in a nest with one unhatched blue-green egg, on July 3, 2018. There were three chicks, all with orangey-pink bills and covered with down. The adults were coming and going frequently, and regurgitated small silvery fish for the chicks to consume.

Based upon the available literature, the chicks were most likely somewhere around 6-8 days old at this point, so they may have hatched sometime around June 26 or so. They were all covered with grayish-white down.

Over the next couple of days, the chicks mostly stayed in or very close to the nest, but they were already interested in exploring. One chick nibbled at a nearby twig in exploratory behavior.

July 6, 2018
Feathers Starting to Push Out Down
The three chicks/juveniles were bold enough to venture out on a limb near the nest and flutter/stretch their wings.

July 9, 2018
July 9 - Feathers Developing
The juveniles are starting to show feathers (as opposed to down). The adults come regularly with food, and I noted that several juveniles from the first brood were still occasionally coming to visit "the old homeplace." When they came, if the adults were present, the adults would perform an aggressive display. Unfortunately, the fledged juveniles just ignored the adults (typical teenagers). But this first brood didn't seem interested in the second brood--they pretty much just ignored them, too.

July 18, 2018
Juvenile from 2nd Brood - Just a little down on head (30+ days old)
The juveniles from the second brood were almost completely feathered by July 18, with just a few wisps of down on their heads. They looked like they were approximately the same age as the first juveniles (from the first brood) when I originally noticed them at our pond on June 17, 2018.

We now pick up development from my observations of the first brood, since this development is still in the future for the 2nd brood...

21 Days Old
By the time the juveniles were 21 days old, they were making short flights and leaping around the shrubbery around our pond. I noticed one juvenile dipping twigs into the pond to lure small fish into striking distance (Green Herons are one of the few tool-using birds).

1st Brood Juvenile Returning to Nest Area (Age 60+ days old)
They still had down on their heads, but it was almost gone. The only way to distinguish them from the adults was that they were browner overall and their beaks were more orangey-pink than black, although the beaks were gaining more blackish color. I noted that at least one of the juveniles had a much glossier blue-green back and a richer, dark cap, versus the browner birds with more streaked caps. According to Bent's literature, I tentatively decided this was a possible male juvenile as opposed to the browner, lighter-colored females.

32 Days Old+
By the time the juveniles were around 32 days old (by June 23, 2018 for the first clutch), they were really exploring the entire area. They flew to the dock and the yard, as well as down to the small beaches nearby. While the adults continued to visit, I didn't see them feed any of the juveniles, although the juveniles still mobbed them when they arrived.

35 Days Old+
Juvenile Preening - (Age 35+ days)
The adults seemed to be "luring" the juveniles away to other feeding areas. I noticed the adult female arrive, and when she departed a few minutes later, two of the juveniles followed her down to a nearby salt marsh.

Over the next few days, the juveniles continued to fly to nearby salt marshes to forage during the day, but they usually returned in the evening.

By the time they were around 40 days old, they were pretty well dispersed. Some of the juveniles from the first clutch still returned to the pond, however. One day, three returned and took up positions on a perch they favored while "growing up."

3 Juveniles from 1st Brood Before They Dispersed
Between the two nest efforts, seven juveniles fledged. All five birds from the first brood lived to the point where they dispersed to forage on their own. I have seen as many as 3 return to the pond at one time.

The second brood was not as successful. Out of four eggs, one did not hatch, and one chick appears to have died at around two weeks. The other two juveniles are still thriving, however they have not fully fledged yet. They still have down on their heads and are making short flights/leaps around the trees surrounding the pond. The adults are still feeding them, as well.

No comments: