Preparing for the 2021 Nesting Season

2021 has begun, and we are already starting to prepare for the coming Spring. There’s no telling yet what the weather will be like between now and April, but there are already a few nest boxes that will need to be replaced along the creek due to the fires last year along with the usual wear and tear. We’ll also need to restock our bands and other supplies. If conditions are right, we expect to have even more nestlings to band this year than last!

A trail close to our nest boxes near Old Davis Road, January 2021. Photo by Hanika Cook

It will be exciting to see what this year brings for our nest boxes and birds at Putah Creek and beyond. I was birding recently in Davis and saw many bluebirds without bands near our nest boxes. They could be newcomers, or they might be locals that hatched from natural cavities. We also continue to get reports from Davis and Winters residents on banded birds that have been re-sighted, which are a great addition to our data on the birds’ movements and survival. It’s always nice to hear from these folks and exchange bird info.


Aftermath of Fires at Putah Creek

We have recently learned that the LNU Lightning Complex fires have had an extreme impact on the landscape along the stretch of Putah Creek from Lake Berryessa’s Monticello Dam to near Lake Solano. This includes Interdam, one of our long-standing nestbox sites. Sadly, that site has been extensively burned.

But this image sent to us by John Hansen shows us a ray of light: At least one nestbox was still hanging! This box has housed successful tree swallow nests in recent years, with five fledglings in 2018 and four in 2019. Recently, after the fire, several bluebirds were seen in this area, showing another glimmer of hope for the local birds.

Photo: View of a burnt landscape next to Putah Creek, with some charred trees standing and visible ash on the ground. In the top right corner of the image hangs a wooden songbird nestbox on a tree branch, apparently undamaged.
Nestbox found still hanging (top right area of image) at Interdam after the LNU lighting complex fires. Photo by John Hansen.

I have not yet explored Interdam after the fire, but I plan on looking for any other remaining nestboxes. The nestboxes themselves can fairly easily be replaced, but I hope the burn area can still support a variety of bird and wildlife species as the vegetation slowly recovers.


2020 Nesting Season Review

The nestbox season is well over, and I’ve been spending time organizing and looking at this year’s data. This year, about 974 birds fledged our nestboxes, which is 145 more than last year! 476 of this year’s birds were tree swallows, and 385 were western bluebirds. We also had 83 house wrens, 25 ash-throated flycatchers, and 5 white-breasted nuthatches that fledged from the boxes.

All but the nuthatches had greater fledging success this year than in 2019. Western bluebirds had the greatest overall increase in number of fledglings: last year there were 196, and this year we had 385! As usual, tree swallows dominated the western portion of Putah Creek while western bluebirds thrived most in the middle and eastern end. Ash-throated flycatchers and house wrens did best in the middle portion.

The Davis Nestbox Network along the Covell Greenbelt finished its second year with new boxes on poles on the north end and much overall success. 15 out of the 20 boxes had at least one egg in them, and the boxes produced 85 fledglings in total (tree swallows and bluebirds).

*Soon I’ll update with our Bird Haven highlights from further north. There were several ash-throated flycatcher nests up there this year!

Walking trail at our Picnic Grounds site in Davis

Lastly, I hope everyone is staying safe this summer. My thoughts go out to those affected by the recent fires throughout California.


July and Season Ending

As summer progresses, the birds are really finishing up their nesting season. We banded our last nestlings for the season at the end of July. The very last box banded was in the Davis Nestbox Network in north Davis – a brood of western bluebirds, the second successful nesting attempt at that box this year!

I’d like to give a huge thank you from me to the rest of our small nestbox crew and helpers this season: Estefania Maravillas, Monica Burnett, Danielle Fradet, Michelle Mah, Alison Ke, Melanie Truan, Isabella Calcatera, Doris Wu, Andy Engilis Jr, and Irene Engilis. Together we managed to keep up with banding and data collection to get a good record of the nestbox activity this season despite this year’s challenges. Thanks for all of the hard work!

Below is a sped-up video by Danielle Fradet from up at Bird Haven, banding the last box of nestlings there (ash-throated flycatchers) in mid July. (Click the image below to view the video on the MWFB Instagram page!)

Almost all the songbird nestboxes were used this year. At Russell Ranch a few weeks ago, one tree swallow pair seemed to be using a duck nestbox too!

Tree swallow looking out of a large nestbox made for ducks. Photo by Monica Burnett.

Earlier in July, Dr Kevin Keel spotted one of our banded adult tree swallows at Lake Solano. He sent along the lovely photo below. This bird was most likely banded one or two years ago in Winters.

Tree swallow adult with aluminum USGS band visible on its leg. Photo by Dr. Kevin Keel.

Now we only have a few boxes to check to see if they fledged successfully this week and the next. We’ll be switching to mostly indoor work with the data again now that the breeding season is done. It will be nice to be out of the hot weather more, but I hope to still see young songbirds around nearby.

Western bluebird nestling in hand, about to be banded. Photo by Hanika Cook.
Tree swallow nestling being held on its banding day. Photo by Hanika Cook.
Putah Creek surrounded by green vegetation at Interdam near Lake Berryessa. Photo by Hanika Cook.



There are a lot of young birds out and about lately along Putah Creek and elsewhere. Most of the nestlings have fledged by now, but they often stick around their old nestbox areas for a while. You might see them at the various parks along the creek in Davis and Winters, and they may be wearing our color bands on their legs, like this fledgling seen by Mary K. Hanson.

Western bluebird fledgling near the UC Davis Arboretum where it had hatched less than two months ago. Photo by Mary K. Hanson.
Another angle of this fledgling. The visible color bands allow us to look in our records and find where this bird came from and how old it is. Photo by Mary K. Hanson.

The color bands allow us to find the bird’s information in our records, including where and when it was banded among other details. This fledgling, like most young western bluebirds, also has many little white spots on its back and breast, as well a wide yellow gape along the sides of its bill. These are all indicators that this bird is less than a year old. Another way to tell is if the bird receives food or begs from another, though this bird has started finding its own food.

We are still waiting for some eggs to hatch in our nestboxes. Bluebirds, tree swallows, and ash-throated flycatchers are still active along Putah Creek and in the Davis Nestbox Network at various stages of nesting. The weather has been pretty nice and the birds seem generally healthier overall than last year. We’re looking forward to seeing more fledglings soon!

Ash-throated flycatcher eggs near Dry Creek in Winters. Photo by Hanika Cook


Summer banding

New eggs are being laid in many of the nestboxes as our birds start their second nests or get a late start. Meanwhile there are always at least a few birds that are old enough to be banded each week. Ash-throated flycatchers are still in the middle of their main nesting season, which is usually shorter and later than it is for our more common nestbox species (tree swallows and western bluebirds). House wrens seem to be done raising nestlings this year on Putah Creek.

It’s consistently hot here in the middle of the day lately, so our crews usually work in the mornings to beat the heat. Though it won’t be as busy as May, the banding season continues!

Ash-throated flycatcher nestling banded at Bird Haven, from the first box banded of this species up there this season. Photo by Danielle Fradet
Small tree swallow nestling in Winters opening its wings. Photo by Hanika Cook
tree swallow nestling in someone's hand
Older tree swallow nestling in Winters, just banded. Photo by Hanika Cook
Nestbox monitors Michelle Mah (left) and Estefania Maravillas (right) banding western bluebirds at Russell Ranch. Photo by Michelle Mah
Bluebird nestling with new bands in Winters. Photo by Hanika Cook


Mid-June Updates

Many new hatchlings are expected to appear along Putah Creek again soon. There are currently over 40 nests with eggs all the way from Interdam (near Lake Berryessa) to Mace Boulevard in Davis. Bluebirds, tree swallows, house wrens, and ash-throated flycatchers are all still taking care of new and old nests along the creek.

Ash-throated flycatcher chicks with a half-eaten dragonfly meal in a nestbox near Winters. Photo by Michelle Mah
Adult tree swallow with a small metal USGS band on its leg, near Mace Blvd in Davis. Photo by Monica Burnett

The Davis Nestbox Network boxes have been put to good use by western bluebirds and tree swallows. So far 75% of the nestboxes there have been occupied this year. Only a few boxes currently have eggs or chicks now after the main wave of nestlings in May.

Our Bird Haven nestboxes have been very productive again this year as well. House wrens and ash-throated flycatchers are still fairly busy up there producing eggs and chicks. 26 broods have been banded so far, and there are now about seven new clutches of eggs.

Danielle Fradet (in back) and Michelle Mah (in front) banding house wrens at Bird Haven. Photo by Michelle Mah

The weather will continue to be pretty nice this week, so hopefully the birds will stay healthy and comfortable.


Fledglings and Flycatchers

It looks like we’re just about to head into the usual lull in the banding season. The busiest part of the season is mostly over, but there is usually another smaller spike in nest activity a few weeks after that. Western bluebirds often have second or even third broods of chicks after the first ones fledge, and ash-throated flycatchers are producing their eggs and nestlings now.

Two young tree swallows looking out from a hanging nestbox, surrounded by oak leaves
Two tree swallow nestlings peeking out of their nestbox, almost ready to fledge. Photo by Monica Burnett
Fledgling tree swallow sitting on top of a hanging nestbox, with another fledgling peeking out of the box entrance
Young tree swallows – one fledgling on top of a nestbox and one soon to fledge peeking out. Photo by Monica Burnett
Ash-throated flycatcher eggs in their fur nest near Dry Creek. Photo by Hanika Cook
Western bluebird chicks about to be banded. MWFB collections manager Irene Engilis made this lovely cloth bag and many others this season. Photo by Hanika Cook


Nestlings and banding

We’re in the middle of the busiest part of the nesting season. Lots of nestlings are hatching, growing, and fledging right now, meaning we have to keep track of boxes to band and boxes to leave alone. Once chicks are big enough, we give them metal and/or color bands, and then wait a couple of weeks for them to leave the nest undisturbed. Even though there’s a lot to keep track of, this is my favorite part – seeing lots of baby birds growing up.

Bluebird nestling with new color bands
House wren nestling, ready for some jewelry

I also want to show how egg color can vary in bluebirds. We usually see bright blue eggs, but now and then the eggs are white! Earlier this month I found a nest with bluebird eggs that were almost completely white. They’ve since hatched into healthy chicks that I banded recently in Winters.

Have a nice Memorial Day weekend everyone, and stay safe!


Nesting Stages

Right now our nest boxes are showing a good range of the different stages of the nesting process. We’ve begun to see more boxes with little Western Bluebird and Tree Swallow chicks!

Tree Swallow nestlings; from their size, we think they just hatched earlier that day! We’ll leave them be while they grow nice and strong then check back in a couple weeks to band them before they fledge. Photo by Estefania Maravillas.
A Western Bluebird nest with nestlings and eggs off Old Davis Road. Photo by Michelle Mah.

The rest of the boxes vary from having just a few twigs as the parents begin building their nest, to having a couple eggs as the rest of the eggs are still being laid, to having the full clutch of warm incubating eggs. The majority are incubating now, so I’m excited for the nestlings that will be hatching soon.

A nice, hearty Tree Swallow clutch. On average they lay between 4-7 eggs. Picture by Michelle Mah.

In other exciting news, we have seen Ash-throated Flycatcher nests appearing in the boxes at Russell Ranch and in Winters, and some already have eggs.

Ash-throated Flycatcher nest in Winters. Photo by Monica Burnett.