Jun 19 2009

Bag o’ Birds

Baltimore oriole nest (photo by Chuck Tague)If you've never seen one I'm sure you're wondering... what the heck is this?

It's a Baltimore oriole's nest, a bag of birds.

If you look closely at the top of the nest you can see the tail and wing of the adult male.  His head and feet are inside the bag but his tail doesn't fit.

Despite the leaf cover, these bags are noticable in western Pennsylvania right now because the baby birds are making a lot of noise inside.

Baltimore orioles are nothing if not noisy.  Only eight weeks ago the males came back to Pennsylvania, singing and chattering and claiming territory.  Soon the ladies arrived and the males displayed their beautiful orange feathers and made a lot of noise to attract their attention.  The females are impressed by this - and they're noisy in return.  After they've chosen a mate, Baltimore oriole pairs stay in constant audio contact.

Shortly after pairing up, the female Baltimore oriole builds her nest at the tip of a drooping tree branch.  It takes 5-8 days of weaving plant fibers, string, grape bark, grasses and pieces of old oriole nests to make this bag.  She doesn't engage in skillful weaving but her random method works nonetheless.

When she's completed a hanging structure she lines it with feathers, soft grasses, wool, willow and dandelion fluff.  Her mate sings while she builds and she replies.  She then lays 4-6 eggs and incubates them alone for 12-14 days.  Her mate's contribution is to sing nearby.  Lots of noise.

When the eggs hatch both parents feed the babies.  After about a week the nestlings take over in the noise department and become very vocal inside the bag.  I found three oriole nests at Schenley Park last week just by following the babies' sound.  It's usually a disadvantage for baby birds to give away their location but Baltimore orioles have always been noisy and it doesn't seem to have to damaged their chance at survival.

As the nestlings get noisier their father sings less.  In 12-14 days they fledge and both parents feed them for about a week.  Then mom begins to molt and travels more widely.  Dad coaches the fledglings for a couple of weeks, then the youngsters disperse.  He stays on territory until he's finished molting and leaves our area in late summer.

It all happens very fast.  From late April to mid-July there's a lot of activity and then it's over.

Now's the time to look for a noisy bag o' birds.

(photo by Chuck Tague)

8 responses so far

8 Responses to “Bag o’ Birds”

  1. faith Cornellon 19 Jun 2009 at 9:20 pm

    I have not seen any BOs here in my part of Bridgeville but from where I lived in Conway (Beaver Co.) we had a nest in back yard high up on a huge maple tree. And they sure were noisy. The first year I couldn’t imagine where all the noise was coming from. I looked for birds attacking another bird & looked on ground thinking maybe somebody’s baby fell but then the wind starting blowing & I spotted the nest. Every year for many years they returned to the same tree. They are so beautiful. It was a pleasure for me & my family to enjoy them for many springs, then one year they didn’t come & haven’t been there for a couple of springs. Have to ask my son if he sees them as he still lives in our home.
    Thanks for the story to remind me of such beautiful & unique birds.
    Faith C.

  2. Sueon 21 Jun 2009 at 7:57 pm

    We are near Bridgeville and had a male BO at our hummingbird feeder for a few weeks. He ignored the Oriole feeder we bought him and enjoyed flapping at his reflection in our sliding door.

  3. Jayeon 17 Nov 2010 at 11:12 am

    Thanks – I just saw this and like your description. I found an oriole’s nest this weekend. I’d love to see on with birds in it!

  4. Maryon 26 Feb 2012 at 11:31 am

    I am curious as to whether the birds reuse the nest? I have found one behind our new home in Lewes, DE. It is up high in a large deciduous tree and I just couldn’t figure why a “bag” was hanging off a branch of a tree. I then remembered that orioles build these type of nests so I found your site in my search. I can’t wait to see if they do return.

  5. Kate St. Johnon 26 Feb 2012 at 11:49 am

    Baltimore orioles usually don’t reuse their old nests but they often locate a new one close to an old one. They particularly like to pull material from an old nest to make the new one. You may see other species using the material too.

  6. Tami Schmidton 13 Jul 2015 at 6:53 pm

    Thank you for your timeline on Orioles. You are one of the few places I could find which provides a nesting behavior timeline. We had a tragedy today. We did not know that Orioles fledge into the tall grasses. We are reconstructing tall-grass prairie on our little acreage in order to establish a prairie/savanna. In the following year after planting native forbs & grasses, we have to mow down it all down every time it gets about 10 – 12 inches high. This keeps the weeds from shading out the new native plantings. We were unaware that nestllng Orioles disperse from the nest (like Robins) and are in the tall grass waiting for parents to bring the yummy live worms we put out for them. We would have held off on mowing. My heart was broken when I found the dead fledgling Oriole after we mowed. We thought our biggest problem was feral cats. Had we known about this Robin-like fledgling dispersal – we never would have mowed. We are just sick about this. Can you provide a time-line for Oriole nesting activity with respect to the nestlings?

  7. Kate St. Johnon 13 Jul 2015 at 7:05 pm

    Tami, it really depends on how far north you live. The rule of thumb for tall grass mowing & hay cutting in PA — for the sake of all grassland/grass-using birds — is to wait until the end of July if you can. You may be able to find more online about grassland birds.

  8. Sue streeteron 15 May 2016 at 9:44 am

    I had a female oriole pecking at my bay window for hours at a time over the last two days. I think she was trying to get to the raffia I had around plants in the window. Is that typical behavior? I finally moved the plants out of the window and put some of the material outside near the oranges and jelly and she has stopped pecking for now. Hopefully she will find it when she comes to eat.

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