Beautiful pictures. I'm quite jealous that orioles are still in your area and coming to your feeder. Mine have all moved on.

Thank you for sharing!

Claire- you have made my night! Truly gorgeous pictures and narration to go with them! I shall save this link!

Great series! I really like in pic 5 how you can see the oriole's orange back. If I ever saw that view I don't remember it. TFS
Susan

Nice series of pictures showing what's going on. I wish I could have some Orioles show up. I got a new feeder that holds sugar water and jam and so far no takers at all. Enjoyed seeing your Orioles and how the babies look, too.

You always have such great pics Claire! Thanks for sharing them!

I'm glad people like the pics and story and since there's an interest, I'll post some more.

Later the same day, I saw Dad feeding a fledgling at the feeder but I couldn't get the camera out in time before he flew away leaving the kid at the table.

The fledgling just stayed there without touching the jam and Dad flew back to check. He left without feeding it.

The fledgling still didn't get the idea and eventually flew away. Maybe next time.

Next day Mom was feeding a fledgling jam.

When a juvenile cowbird suddenly joined them, probably wondering what they were eating.

Mom oriole left, while the fledgling stayed, not looking very pleased about this.

The fledgling soon left too, and the cowbird remained. It didn't even like the jam (it did try some).

There wasn't any violence and I doubt that Mom oriole would have left if the fledgling was in danger. The orioles are tough and chase catbirds away. Maybe the cowbird was one of her brood so she didn't attack it.

Claire

That's what I was wondering Claire........if the cowbird was one of her brood. I saw a cardinal feeding a cowbird baby last year.

catherinet: I know people get testy about the nesting habits of cowbirds, but the idea has some fascinating aspects. I've wondered for a while how the isolated cowbird fledglings find the cowbird flock. Do the adults cruise around looking for young cowbirds? Do the hatchlings bond with their adoptive family but leave when it's time to breed? or are they kicked out when they can feed on their own?

This set of photos also brought up something else I hadn't thought about. The adoptive parents feed the hatchlings food that's appropriate for their species, but may not be appropriate for cowbirds. I suppose most birds feed caterpillars and insects to their young and that's probably universal food, but what happens when an oriole tries to feed a cowbird fruit? A couple of sources say cowbirds eat seeds and arthropods/insects. I'm watching some downy woodpeckers, adults and fledglings, feasting on a feeder containing peanuts and suet nuggets. Could a fledgling cowbird survive on that?

After all, the young cowbird didn't choose where its egg was laid and to be force fed fruit is an added trial.

Just wondering,
Claire

Still wondering about fledgling cowbirds - this morning I saw two adult male orioles, one fledgling oriole and two fledgling cowbirds together at the feeder. One adult male stayed apart and soon left so it may not have been associated with the family.

The oriole fledgling joined dad at the jam while the cowbirds stayed on the top.

Several oriole fledglings are now eating jam by themselves.

This one seems to be particularly brightly colored for a baby.

I don't know what happened to those two cowbirds shown above that didn't follow 'Dad' to the jam. I've never seen an oriole feeding on the ground so the challenge for the cowbirds would be to figure out that there's seed lying around on the ground without having a 'parent' show them.

There are a lot of cowbird fledglings feeding on the ground with a few grackles and red-wings and a house sparrow (sorry for the blurry pic, wet window), so maybe the assorted cowbird fledglings eventually join them.

Claire

Hi Claire - you questioned,"so maybe the assorted cowbird fledglings eventually join them."
By now you too may have found Carl Strang's June, 2009 cowbird fledgling observation on Nature Inquiries:
"Over the years I have seen cowbird fledglings being fed by yellow warblers, song sparrows, scarlet tanagers, blue-gray gnatcatchers and cardinals. Cardinals are common at Willowbrook Forest Preserve, but for several years the only time I saw cardinal fledglings was late in the season, after the cowbirds were done. All early products of cardinal nests were cowbirds. This kind of selective pressure is what has led many birds to evolve the capacity to recognize and reject cowbird eggs. Obviously such an ability remains to emerge in many others. Incidentally, once the cowbird becomes independent, it instinctively seeks out other young cowbirds and behaves as a cowbird from then on." (italics mine)
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For me, this question of current instinctual behavior falls into that 'chicken and egg' category; which came first? The parasitic behavior or the need to adapt to that behavior?

If anyone is interested, Stanford has a good article on cowbird behavior -
"http://www.stanford.edu/group/stanfordbirds/text/essays/Cowbirds.html"

As far as the fledglings being fed fruit, there must be enough protein intake to get them to the independent stage or, is their DNA that adaptable that their fledgling physiology changes based solely on caloric intake? Many questions, out of my field, but fun to ponder. The pictures are good conversation starters for sure.

Jane

Thanks, Jane, for the references. I found the sites:
Carl Strang's June 2009 entry and
Stanford group essay on Cowbirds.

I'm a little skeptical about Strang's statement on instinctual behavior - it may be true but it sounds more like a belief not based on any science. (Just a quibble on my part - if he'd said the juvenile cowbirds 'appear' to seek out other cowbirds, based on his observations, I wouldn't have been annoyed - but ascribing the behavior to 'instinct' is a jump too far).

A very interesting fact in the Stanford essay is that only about 3 percent of cowbird eggs actually result in adults! That's major mortality. The cowbird female just keeps laying eggs and eggs and eggs ...

"An average female lays about 80 eggs, 40 per year for two years. About 3 percent of those 80 eggs end up as adults -- an average of 2.4 adults per female. Clearly, such numbers more than compensate for the excessive loss of eggs and young in the nests of inappropriate hosts."

I wonder how the current situation differs from the earlier situation when the cowbirds evolved to follow the bison herds and couldn't hang around to set up a proper nest without dropping behind and struggling to find food for themselves and the young. That behavior probably was dependent on the migration patterns of the bison, but nowadays the cowbirds have the luxury of being able to stay in the same area as their young, even if they don't get involved in the raising of them.

As far as which came first, the parasitic behavior or the adaptation to it, I would think that the ability to lay so many eggs and the rapid maturation of the young would come early.

There's an interesting entry in the Birds of North America Online site (subscription only) saying that "Most fledgling losses occurred 1 or 2 d after leaving nest".

There are a lot of unknowns here, but it's an interesting topic for study. I'm glad I don't have to do the research myself, it would drive me crazy trying to pull together all of the variables.

Claire

Very interesting stuff!

I had no idea the cowbird laid so many eggs. I hope that doesn't mean the same amount of eggs of other birds are thrown out of the nests.

Over the years, (being totally inundated with plants/animals/insects from other eco-systems on other continents), I've sort of thrown up my hands and decided to let nature take its course, rather than try to change it. But I would feel alot better about this "evolution" if man weren't messing so much up.
Sorry to get a bit off-topic. I'm sure bird behavior evolves, but there are so many variables now (man-made) that its really hard to figure things out.

Surely animals are hard-wired for certain things, and it makes me think that the cowbirds fledglings would fairly quickly seek out their own kind/know what to eat/where to lay their eggs, etc.

I saw a show on PBS once about cowbirds. Lots of people seem to hate them, but they're just doing their thing. Anyhow.....it showed that the parent cowbirds spend a fair amount of time, choosing a good area/nest for their eggs......and making sure their choices would benefit their offspring's chances of survival.

I found that interesting.

I found an old thread on Cowbirds on this forum back in 2010, where bob414 posted a link to a fascinating video of a Nova show called Gangster Birds.

The study showed that female cowbirds seem to monitor their egg's presence in the parasitized nest and retaliate if the cowbird eggs are destroyed. This is a whole lot more complicated than just lay an egg and disappear.

It's as if the cowbird once had the usual array of instinctive behavior to raise young (nest-building? brooding? feeding? protecting?) but due to circumstances (follow the bison) the cowbird lost most of these instincts but kept the protective behavior.

All speculation, but definitely interesting.

Claire