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Thread: Rookery Timeline

  1. #31
    Join Date
    Dec 2006
    Dallas, TX

    Default Re: Rookery Timeline

    Kala, I don't actually have field observations one way of the other but logically speaking, if the young that are out of the nest aren't able to fly to find food of their own, then they would need to be fed if they're to survive.

    I looked at the Breeding Bird Atlas species account for Little Blues ( LITTLE BLUE HERON | The Texas Breeding Bird Atlas )and found this interesting paragraph:

    Inland breeding distribution and timing of the breeding season of the Little Blue Heron is probably determined in Texas by the availability of crayfish which compose about 73% of the diet of the chicks (Telfair 1981). The greatest abundance of adults and the growth stages of the three species of crayfish used as major food items occurs during the time of breeding and corresponds to the average period of maximum spring rains. Thus, the greatest biomass of available crayfish occurs during the period of hatching and chick growth. During years when rainfall is abundant in spring and early summer, an abundance of crayfish and other aquatic prey items are available in flood plain pools, ponds, oxbow lakes, swamps, marshes, roadside ditches, and borrow pits.

    So if the parents stop feeding the youngsters before they're ready to forage on their own, it has to be because there isn't enough food available. The parents will naturally feed themselves first, and only then bring back food for their young, if there is enough to go around.

    I suggest looking at the accounts for the other species you hypothesized that the parents don't feed after they leave the nest. I suspect it has a lot to do with the availability of whatever those species eat and how good they are at catching it. Since the Great Egrets started nesting so much earlier, they were able to take advantage of all the rains we had in May and June. Later nesters won't have been so lucky. I don't believe that it's a species-specific standard behavioral difference so much as a timing and food availability difference.

    I do know that a few years ago some folks that worked at the medical center then were so worried about the drought and unavailability of food that they bought lots of small fish and left plastic dishpans of water and fish under the trees for the youngsters.
    "My heart in hiding Stirred for a bird,
    -- the achieve of, the mastery of the thing!"
    (from "The Windhover" by Gerard Manley Hopkins)

    "My favorite weather is bird-chirping weather."
    Loire Hartwould

    "You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird . . . So let's look at the bird and see what it's doing - that's what counts. I learned very early the difference between knowing the name of something and knowing something."
    Richard P. Feynman

  2. #32

    Default Re: Rookery Timeline

    Thanks Betsy,

    You gave me something to think about but I'm looking at it a bit differently. We have had good rains, including two really great ones in July. I think there is plenty of food on the ground even now for the young ones. But if the food conditions are the same right now, for all the species, I still see feeding going on for some fledgling species and not for others. So given the same conditions for all current fledglings, why the feeding difference? (of course, one good possibility is that feeding is happening for all species and I just have not seen it, which is why I wanted to know if anyone has, this year, seen a parent feed a fledgling no where near a nest of little blue, snowy, ibis, tricolor or black-crowned night herons.)
    And for my evidence to support my theory that the current fledglings can find food for themselves, I just posted photos of a little blue fledgling trying to eat a really large kind of worm like thing that I would like to get identified. My guess is that there are lots of worms and crayfish available right now. The pools are still there, you can see them.

    edited addition: That worm thing has been identified as probably a fishing lure so never mind about that being evidence, sigh.
    Last edited by Kaptured by Kala; 07-14-2016 at 06:52 PM.
    Kaptured by Kala

  3. #33

    Default Re: Rookery Timeline

    I visited the rookery yesterday, July 21st, in the morning. I had no idea nesting went on this long. Here is the latest:

    1. I actually saw one great egret couple where one was brooding on a nest and the mate was standing guard in the nest beside it. Lots of empty nests. Still some nests with older babies in it and lots of older juveniles in the tree tops still getting fed by a parent but the numbers are really dwindling now.
    2. I saw a couple of snowy nests with older babies in them and lots of juvenile snowies both on the ground and climbing around in the branches. I did not see any young nestlings and no snowies brooding.
    3. I saw some little blue fledglings both on the ground and in branches and I saw one adult little blue perched alone.
    4. I saw one adult tricolor heron perched at the top of a tree alone and I saw one juvenile tricolor heron perched on a branch. I find the juveniles on the side where TWU is behind you. The adult was with the first parking garage behind you.
    5. I still see a few black-crowned night herons brooding on nests and I saw one nest with young nestlings. Tons of juveniles both on the ground and climbing around in the branches. The juveniles continue to rove in groups. I saw an adult and a juvenile looking for food together on the ground and I saw an adult and a juvenile flying away from the rookery together so maybe there is some teaching going on? Or maybe the adult was not related but didn't feel threatened by the juvvy enough to drive it away. I have seen birds find fish on the ground under trees when someone above lost the contents of their crop accidently. When that happens, the race is on for the prize and fun to watch and usually several species going after it.
    6. There are still more cattle egrets than any other species right now. There are still some brooding and some newly hatched chicks along with older chicks both in and out of the nests. I saw one nest that had two chicks that seemed quite older and larger than a third chick which seemed at least a week younger but was as vigorous as the two older siblings. Hopefully that is a sign that the food is plentiful?
    7. I saw a few juvenile anhinga in the tree tops. I saw about 5 nests of anhinga all in the same corner going from the memorial area to the parking garage area. Several in the same tree. I had seen these brooding last week. This week they all have babies in the nests and there are little windows in the leaves and branches where you can get a fairly good look at the babies which have their heads up panting in the heat. featherless and bizarre looking.
    8. The nest of ibis babies I've been watching is empty now. About 20 feet to the left of it, there were 4 juvenile ibis, most likely fledglings from that nest, lined up on a branch together. They still have some striping on their bills. On the back of the rookery with the first parking garage behind you, I saw about 4 ibis nests with dark nestlings in them but they are a good ways back and difficult to get good shots. One looked newly hatched and the others were older with well striped beaks. The newly hatched have pinkish beaks with dark only on the tip. There is one nest that is very close to the path but it has a lot of bramble branches between you and it so you can see but lots of interference for photos. Still, it is very entertaining to watch.

    Lots of different kinds of dragonflies on the sunny side of the rookery and this time I saw several butterflies that I thought were hackberry emperors but when I compared them to the confirmed photos I have from last year elsewhere, it is not a match so I am not sure what they are, will have to get bugguide in on that. Would be nice to add a new species.
    Kaptured by Kala

  4. #34

    Default Re: Rookery Timeline

    This week I visited the morning of July 27, a Wednesday. There are noticeably less birds and more empty nests.

    1. I saw one black-crowned night heron nest that had a parent sitting on fairly young chicks and several nests with older night heron chicks but all of those were climbing out of the nest then returning. Lots of juveniles around still.
    2. There were a few great egret nests that had big chicks in it but none with small ones. Lots of adults and juveniles on the ground and in tree tops.
    3. I did not see any snowy nests with chicks this time but lots of adults and juveniles on the ground and climbing around in the trees.
    4. Lots of empty cattle egret nests now. Lots of cattle egret nests with large babies in it and lots of juveniles running on the ground and climbing in the trees. I did not see as many adults as there have been.
    5. I did not see any adult little blue herons, and no occupied nests. I saw a few juveniles on the ground or on branches.
    6. I did not see any tricolor herons at all.
    7. I saw one ibis nest with big chicks and several ibis fledglings on tree branches. I only saw a few adults.
    8. The highlight of this trip was the area with 5 anhinga nests, all of them with babies in them. I am not sure if any of them will still be in the nest by next week but I'll go back at least one more time to check on those anhinga nests. I believe I have seen at least 8 anhinga nests this year and have not seen any dead anhingas on the ground. One of the nests this week had 3 chicks and they each seemed to be a different age with at least a week difference between the oldest and the youngest. All healthy looking. Apparently food has been plentiful for them.
    Kaptured by Kala

  5. #35

    Default Re: Rookery Timeline

    I keep thinking surely it is time to stop, and weekly, I keep finding new nests. This week I visited the rookery on Thursday morning, August 4th. For the first time, I found a red-shouldered hawk there, previously I'd only seen Coopers. It was a juvenile that had taken a black-crowned night heron nestling to the ground as prey. The young hawk panicked and jumped behind a log when I rounded the corner and the "prey" got up, climbed up the log and lived another day since the hawk finally decided to leave after casting several longing looks at its meal which was now walking away from it. eBird did not have a listing for this kind of hawk at the rookery so I posted it with photos here:

    The rest of the updates:

    1. Great egrets: still quite a few adults and juveniles around. Several nests where juveniles use it as home base but explore all around the nest tree freely, returning to the nest for feedings. Many empty nests and several trees full of empty nests and no birds.

    2. Black-crowned night herons. For the first time I did not see any brooding adults on nests but I did see a few nests with young nestlings waiting on a parent to return with food. Lots of older fledglings huddled together on branches near nests and a lot of juveniles roaming in groups all over the rookery. This species seems to have the longest nesting time as they were one of the first with babies, after the great egrets and they continue to churn them out. The one the hawk had could not fly but it could climb.

    3. Plenty of adult and juvenile snowy egrets. A couple of nests had older fledglings climbing around on the tree by the nest, returning to nest for feedings. No brooding, no young ones.

    4. I saw no tricolor herons, neither adults nor juveniles

    5. I saw no adult little blue herons. I saw a few fledglings walking around on the ground. Thank goodness for the little bit of dark on the feathers at their back end because they hang out with juvenile snowies and usually I have to look at the photos on my computer to tell them apart.

    6. I saw 7 young fledgling ibis all on a couple of branches of the same tree so they must gravitate to one another as that was at least 2 nests worth of them. I saw one adult ibis brooding on a nest so that one either had eggs or very young chicks. And I saw one adult watching over a nest with older nestlings. Most of the adult ibis have disappeared.

    7. The number of adult cattle egrets has markedly decreased. Many shrubs and low trees full of empty nests. I did not see any brooding. I did see a few nests with older chicks that were climbing around the nest, returning for meals. And I saw groups of 5 or 6 older fledglings no where near nests but any time an adult cattle egret approached them, they all mobbed it for food, sometimes it looked like it would injure the adult. The adult discharges food and gets the heck out of there quickly. I wonder if they end up feeding chicks not their own with mass mobbing like that.

    8. We seem to have a minor (for them) population explosion of anhinga. I saw four new nests of brooding adults this time to go along with the 5 active nests with various ages of chicks and the one empty nest that fledged between last week and this. Add the earlier nests I followed and I have seen at least 15 active anhinga nests this season. All with healthy looking chicks even when they are obviously several days apart in age. I have not seen any aggression with these chicks with each other and no dead bodies. I can't believe there are still new nests, had no idea they continued their nesting season so late.

    Regarding sibling aggression: Great egrets seem the worst with siblicide. I have also seen a lot of it with cattle egrets, snowy egrets and little blue herons. The anhinga, black-crowned night herons, ibis and tricolor chicks seem to get along much better. Always possible I'm just not seeing them at fighting time, wonder what others have observed?
    Kaptured by Kala

  6. #36

    Default Re: Rookery Timeline

    I visited the rookery for the last time this season today, Wednesday, August 10. Things are winding down and getting a bit more quiet. No new nests to report.
    I did have an interesting encounter with an eastern cottontail in the middle of the path which was not afraid of me. It stood still as I walked towards it, then around it, then took photos from the other side. I went a little further then looked back and it was following me. I guess it was curious. Not great survival skills. It kept following me until a worker in their riding machines came down the path and nearly ran it over. I had the worker halt while I shoed the rabbit into the interior.
    I also found a large preying mantis that stepped onto my finger when I put it under it.
    As to the birds:
    1. There are a good amount of adult great egrets and also a lot of juvenile great egrets. The juveniles are still begging for food and the parents are still feeding them. I did not see any young ones but did see a few older ones standing on nests.
    2. There are both adult and juvenile black-crowned night herons all over but I did not see any in a nest. I have never seen a parent feed a juvenile once they are out of the nest.
    3. There are both adult and juvenile snowy egrets and some older juveniles still climb in and near nests. The parents are still feeding the juveniles.
    4. I did not see any adult or juvenile tricolor herons.
    5. The only adult little blue I saw was flying overhead. There are lots of the juveniles running around.
    6. I saw a few adult ibis. I saw lots of juvenile ibis, still in groups of 4 or 5 plus I saw a couple of juveniles alone on the ground. None in nests.
    7. I only saw a few adult cattle egrets. Lots of juveniles around with some climbing in and around nests. I did see one adult feeding juveniles that were near a nest.
    8. Almost all the anhinga nests are empty. The new one at the top of the trees from last week still had a female brooding on it so must either have eggs or very young chicks, it is not in a good place for photographs. There was another nest with youngs chicks but again was not in a good place to take photographs. A third nest was empty but had 3 large fuzzy juveniles on the branch beside it. The rest of the nests are empty now but one of the "empty" nests has a dead older juvenile hanging half out of the nest. It looks normal other than being dead. Perhaps it starved to death? It was the first dead anhinga I've seen.
    Kaptured by Kala

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