Ash-throated Flycatcher babies

Right now we have 2 nests with recently hatched Ash-throated Flycatcher chicks! They are extremely fuzzy when they’re young, check these guys out:


These chicks are about 2 days old. We’ll be banding them next week!

Yolo Audubon Nestbox Field Trip

We had a very lovely morning with the field trip crew. After showing some specimens and nestbox exhibits, we walked along the Picnic Grounds path to check out some of the nestboxes.

Some of the boxes we looked at had Tree Swallow nestlings, Western Bluebird nestlings, and Western Bluebird eggs. We were lucky to have a box ready to band this morning, so we demonstrated the procedure for banding and measuring some Tree Swallow nestlings.

We also caught some adults on the nest! Both were unbanded, so we threw a band on. We named one Yolo and the other one Audubon. Hopefully we’ll catch them again in the future!

Here are some photos of the field trip this morning:


Looking at the exhibits



Showing a banding session of a box of Tree Swallow nestlings



Looking into the Tree Swallow nest


Showing some Western Bluebird nestlings


Mama Bluebird ready to feed the kids


Captured a male Tree Swallow adult


Showing a very young Tree Swallow nestling


About to release the papa Tree Swallow!

Tree Swallow banding

We keep a constant lookout to see if the nesting adults are banded. Tree Swallows have short legs but in the picture here you can just barely see the band on the bird’s right leg.


Although some of our catching attempts failed, we did successfully catch a couple of adults Tree Swallows this morning. One of females we caught was banded as a nestling in 2010 from a nearby box. Another one we caught was banded as a nestling in 2014 at a different site about 4 miles west from this one. Super cool information! Once the field season is over, I will write a post about our recaptures.

And here are some of the Tree Swallow babies we banded this morning.

Weird nest cases

Ash-throated Flycatchers have been making their nests now. Some of them don’t care that there is already a nest in the box, and will just make their nest right on top of the other bird’s nest! Here is a case where a pair of Ash-throated Flycatchers nested ontop of a Tree Swallow nest that had eggs. Ash-throated Flycatchers use mammal fur for nesting material, and lay blotchy eggs like in this picture:


6 ATFL eggs and 1 TRES egg

Since there was already a Tree Swallow egg, it somehow got brought up from under the Ash-throated Flycatcher nest. Now this pair of flycatchers are incubating 7 eggs! Having 6 eggs of their own is already a large amount, as they tend to lay about 3-4 in a clutch. We’re actually noticing more nests with large clutch sizes, I’ll write more on that later.

Here’s a similar case of an Ash-throated Flycatcher nesting ontop of someone else’s nest. This is a photo from last year, where they nested ontop of a Western Bluebird nest that had eggs. Their eggs also got uncovered in the layers of fur and resulted in a nest of 7 eggs total. In the end, the bluebird eggs did not hatch, and the Ash-throated Flycatchers successfully raised their 4 babies.


4 ATFL eggs and 3 WEBL eggs from a nest in 2015

I was relieved that the bluebird eggs did not hatch, as that would be problematic for them since bluebirds grow much more slowly and would need more time in the nest before fledging. This mismatch of fledging age between the species would create an unhappy ending.

I suspect the Tree Swallow egg in the current Ash-throated Flycatcher nest will not hatch either. I hope that is the case, since situations like this probably don’t end well.

Another interesting thing about these weird nest cases is that both of the pictures above were taken at the same site. Not the same box, but the boxes were pretty close by. Wondering if it could be the same pair nesting ontop of other birds’ nests. Unfortunately they were unbanded adults so we won’t have a way of knowing.

Itty bitty babies

These House Wren chicks are just a few days old. This nest actually has 9 chicks! (one is not in the picture because his wing chord is being measured)


House Wren chicks


These Tree Swallows are just a couple days old, still very small, naked, and blind.


Tree Swallow chicks

It’s amazing to see how fast they grow from a little egg.