Most recent hatch & other updates

Yesterday we had one hatch, a Western Bluebird nest, at Russell Ranch. This is one of the last remaining boxes with activity along the creek. This box will be banded in a couple weeks. We have a couple bluebird nests left that may still hatch at Picnic Grounds and at the Arboretum. There are a few more boxes we are banding soon including the last Tree Swallow nestling to be banded tomorrow, and the last House Wrens within a week. The end of the season is near.


Western Bluebird nest with recently hatched chicks – 7/19/17

I was hopeful this morning when checking the Interdam site that some of the last Tree Swallow nests would’ve hatched by now, but they remain unhatched and notably cold today with parents no where in sight. Here’s one of the unhatched nest that had a whopping 8 eggs (that seems a lot for a Tree Swallow):


Tree Swallow nest with 8 eggs. Photo: Haruka Endo

I’m not surprised that a large clutch of 8 swallow eggs didn’t hatch, I feel like it would be very hard for a female swallow to successfully incubate that many eggs. But a few other nests with more normal-sized clutches also didn’t hatch. A lot of these birds were on their eggs for a month or longer (keep in mind incubation normally takes about 2 weeks), but for what ever reason their eggs didn’t make it through, and the parents left once they realized that. This is not uncommon for the 2nd half of the breeding season.

This morning at Interdam we also saw some recently fledged Tree Swallows being fed by their parents, and a group of Western Bluebirds (both young and adults) foraging in the grass. The bluebirds did not carry leg bands, perhaps they came from a natural cavity. I love seeing young bluebirds with their speckled chests – they are quite cute. Unfortunately I left my memory card at home today so I do not have any photos to share of the juvenile bluebirds. An additional treat today was hearing a Lazuli Bunting singing on the other side of the creek.

Although nestbox season is not completely over yet, I am already starting to miss these guys. What better way to start the mornings than with baby birds?


Tree Swallow nestling

-Evelien de Greef


Bat, possible cowbird egg, and more!


Yesterday morning Hanika Cook found a bat roosting in one of the nestboxes in an orchard by Winters. I believe this is the first time we’ve ever observed a bat in one of our bird nestboxes! I went to go look later in the afternoon to see for myself and try to get a picture, and there he was, a little myotis perched in the upper corner of the nestbox. The nestbox had an old fledged bluebird nest. Unfortunately I was not quick enough to get a photo before he flew out, but here’s a little sketch on the right. I’ll try to make a better sketch later.

At our site at Old Davis Rd, we have a nest that has a possible Brown-headed Cowbird egg in a Western Bluebird nest. About a month ago the cowbird egg was laid and then the bluebirds laid their clutch shortly after (the order of events seems a bit unusual to me), but anyway, after a few weeks of incubation, none of the eggs hatched. I do not believe the hatching failure is related to having a cowbird egg in there, it just happened to be dud eggs. It is not uncommon for a clutch to fail when it’s this late in the season. We have a few nests that were incubated for a month and unfortunately didn’t hatch. The bluebird eggs in the photo below look very pale and almost white but that is because they are cold and dead.


Old nest with Western Bluebird eggs and a possible Brown-headed Cowbird egg

We banded a wave of batches of birds the past couple weeks. There are still a handful of boxes left to band, and lots of boxes to check soon for fledging success. This is what we like to see for a fledged nest, lots of poop and no dead chicks:


Fledged Tree Swallow nest

There is still potential for a few new hatches, which we will see by the end of this week. Otherwise, this Tree Swallow may be part of one of the last batches of swallows. Check out his developing feathers, he’ll be able to leave his nest in just about 7-10 days!


Tree Swallow nestling

Here are a couple pictures of our summer volunteers who have shown up consistently to help check boxes and band birds in the summer heat. 🙂

I will end this post with a photo of a Lawrence’s Goldfinch, which was a nice surprise for Haruka and I to see at one of our sites this morning near Winters.


Lawrence’s Goldfinch (male)

-Eveilen de Greef

Mixed-species nest

We’ve gotten a few nests with mixed-species eggs, when an Ash-throated Flycatcher takes over another bird’s nest and lays eggs. This is the first time while I’ve been working on the project where I’ve seen both species actually hatch. Usually the previous nester’s eggs fail to hatch but in this case one of the bluebird chicks made it out. Here we have 2 Ash-throated Flycatcher chicks, and 1 Western Bluebird chick.


Flycatcher nest with 1 bluebird chick and 2 flycatcher chicks


2 ATFL on left, 1 WEBL on right

The growth rates between these two species are different – the Ash-throated Flycatchers grow more rapidly and will fledge earlier. This means it is very likely that the bluebird will be left behind because he won’t be ready at the same time.


ATFL on left, WEBL on right

Luckily we have another box at another site that has Western Bluebird chicks about the same age/stage as this guy. I will probably have the Western Bluebird parents of the other box adopt this chick.

Anyway, here are some photos from this morning of some grumpy bluebirds. I think this one is one of the most grumpy-looking ones I’ve seen lately.


Western Bluebird nestling

Grumpette is on the one on the left, see how her lips curve downward more than her brother’s on the right?


Western Bluebird nestlings

-Evelien de Greef

Ash-throated Flycatchers

This season we’ve had 12 Ash-throated Flycatcher clutches (so far). Last year had almost double the number of flycatcher nests. Not sure why numbers for this species are lower this year. Although the season is not over yet, it is unlikely that we’ll get a lot of new nests for the rest of the month (although we did just get a new clutch of bluebird eggs this week).


Ash-throated Flycatcher

Ash-throated Flycatchers are the largest bird species we get in our nestboxes. They will clap their bills when they are angry. Even the nestlings will sometimes display this behavior when they are unhappy while they are being handled.


Ash-throated Flycatcher nestling


Ash-throated Flycatcher nestling

Compare the Ash-throated Flycatcher nestling with the Tree Swallow nestling. The flycatchers have huge bills and long legs (I think it could almost fit 3 bands!), versus the swallows that have very short bills and super short legs (so short that we can only fit 1 band so we do not color band tree swallows).


Tree Swallow nestling


Tree Swallow nestling

Regardless of their proportions, both of them are pretty cute. I think they are the less-grumpy looking of the 4 main species. Here’s a grumpy House Wren on the left and a grumpy Western Bluebird on the right:

-Evelien de Greef