I have long waited doing this post on the Tree Swallow.   My first year of my trail (2008) had paired nestboxes because I had seen tree swallows dive-bombing searching for insects over our pond.  I did pair the boxes 15 feet apart on 1” conduits with two predator guards on each paired setup.   Much to my disappointment, no tree swallows used any of the paired boxes on my property.  I still do not know why.   The next year, I unpaired the boxes in February and moved them elsewhere in my community as part of the Woolwine House Bluebird Trail.  The reason I was a little disappointed is this.  For me, the Tree Swallow (TRES) is just as beautiful, just as graceful, and just as much allowable to use nestboxes we made for bluebirds.  REASONS:  1.  They are a beautiful cavity-nesting native bird that also cannot excavate their own cavities.  2. Unlike our Eastern Bluebird (EABL) here in Virginia that has 2-3 broods per nesting season, the TRES has one brood per nesting season. 3.  Tree swallows are aerial foragers for food, namely insects,  as their main food source.  Bluebirds generally forage for insects perched, obtaining insects—grubs, grasshoppers, spiders, crickets, etc.–from the ground.  You’ll see them cocking their heads to the sides, pointing their heads down as they use their good eyes to find that insect and then flying down quickly to retrieve it.   I have also watched a bluebird male in a flash fly out of a poplar tree behind our house and catch a large white moth mid-air.  That is a sight to see!   The tree swallow has to work harder, swooping here and there, dive-bombing using their wings and forked tail for leverage as they catch their food mid-flight-mid-air.  They are a delight to watch.  You can imagine eating for themselves and feeding their brood how much work that is from dawn to dusk.

I have had people ask about this bird competing for a nestbox–my reaction is always enthusiastic, as it’s been my wish to be able to monitor this gorgeous bird for myself, along with other cavity nesters.  I have not had that opportunity yet to monitor a nesting pair of tree swallows.  I still wait to see it on my own trail, and I still hope it will happen, as I do see them in our area.   I am fascinated with the nest building of the TRES, as it will fly for many miles from its chosen nesting site to obtain large feathers from other birds to place on top of its nest materials of grasses, such as goose feathers or other waterfowl feathers.  You will see the TRES near agricultural fields (open habitat just like the bluebird) and many times near water sources, such as ponds if available, probably for the reason of finding waterfowl feathers there and insects being available surrounding the ponds, such as dragonflies that I see by our pond.  This bird is marked strikingly, particularly the male, with a bright white neck and belly and a greenish-violet-iridescent blue on its back and wings.  It’s a gentle, assertive bird, as I have stood next to a monitor in one of my counties at a newly-installed nestbox just 4 feet away and watched a female enter to build the nest and the male sitting on top guarding the box and looking at me as if to say, “Hey there—hope you don’t mind us using this box you installed.   First come-first serve, so thank you for providing us this perfect nesting place!”  Of course, I smiled, and the new monitor I was training appeared seemingly a little disappointed, because she also wanted bluebirds.   I immediately explained that this bird, the tree swallow, has the same issue as the bluebirds with needing nesting sites which is cavity only and having the same challenge as bluebirds in finding “available” cavities to raise a family, in natural habitat, used woodpecker holes for nests.

With many thanks to a new monitor in Floyd County who has been taking excellent photographs of bluebirds and tree swallows nesting in some of her nestboxes, I can now share this wonderful bird with you here on the Woolwine House Bluebird Trail’s website.  Many thanks, Karen, for sharing these lovely pictures of this bird which you are lucky to be able to see a nesting cycle.  Many of our cavity nesters have one brood per season, so after the TRES are completed, you may get a second or third brood
nesting cycle from our beloved bluebirds after…perhaps another native species.   It’s all part of the fun of monitoring, isn’t it?

I will be highlighting other cavity-nesting birds that use nestboxes shortly.  In my opinion as a trail monitor, trail manager, and trainer to new bluebirders, I find monitoring other bird species helps us learn more about our native birds and the joys of monitoring brings variety of experiences  and joys to being a good landlord of our nestboxes.  If you find you have both bluebirds and tree swallows where you have one or more nestboxes, they will nest peacefully side by side with each other if you pair your boxes 5-20 feet apart.  Some have actually put two nestboxes on one pole.  I have included a video of that below the photo set, which you may find interesting.   This box was installed on PVC, looks like about 4” wide, with a cap on
the PVC.  I’ve seen other setups with one pole and the boxes installed with opposite directions for the entry hole.  I have heard stories from others who have successful nesting of tree swallows and bluebirds of a bluebird parent feeding a tree swallow set of nestlings when one of the tree swallow parents disappeared (probably killed).  They WILL nest next to each other if they don’t feel threatened by the other.  However, if you have one box, there COULD be the usual territorial war over the nestbox, understandably so, since both birds need an available cavity to bring up a family.  I’ve seen this with chickadees and bluebirds on my trail this year.  If this happens, you could quickly install another box right away near the other one where the competition is taking place.   You then could have both birds nesting as friendly neighbors–all the while monitoring, enjoying them, keeping notes, and seeing behaviorial antics, some similar and some different.   I still recommend the two predator guards on a pole because of the amount of predation we get here in Virginia, both ground and avian predators.  As a monitor, I want success, so I go all out to be sure the birds can be protected.   If I put up a nestbox for the birds, the least I can do is help them succeed.  Otherwise, the time and expense of installing a nestbox seems fruitless–as I say, it’s like luring them to use your setup and then playing a practical joke on them because we make it easy for those predators to get to them.  It’s not my style of managing nestboxes.

I hope you enjoy the 5 pictures posted below—photos by Karen Hale in Floyd County, VA.   I adore the Tree Swallow—I want to have some nest in my boxes SOON.  Thanks, Karen!  I support all native birds.  Lucky we humans it’s not always bluebirds we are helping.  My next post will be about the  fascinating Brown-headed Nuthatch…a bird found in the South near pine forests.  Stay tuned!

In the meantime, underneath these photos I have linked direct viewing to a YouTube video of bluebirds and tree swallows nesting side-by-side and the Cornell Lab of Ornithology’s info page on the Tree Swallow.  There you can also hear what the TRES song sounds like–a chittering sound that requires good listening ears to ID.  I hope you enjoy.  Questions and comments welcomed and encouraged on this post!

Great photo of pinkish-white eggs. Tree swallows have white eggs, but they appear to have some pink hue here, probably because of the lighting. This is a good-size mirror for seeing a nest in its entirety and taking photographs. Of course, as monitors, when we do this--we learn to be quiet and fast so as not to stress the nesting parents too much. Good job!

Great photo of the couple resting on a nearby fenceline. The male is on the left. Like the female bluebird, the female tree swallow is a muted grayish-blue. Depending on how the sunlight hits them, the coloring can be bright hues of blues-violet-greens! They have tiny bills, like the bluebird. If you go to the Cornell "All About Birds" link at the bottom of this post, you'll see an outline of the bird in flight--forkish-pointy wings and tail.

This is one of the most exciting moments of monitoring nestboxes!

See how the soft feathers are placed on the nest. These young nestlings cannot hold their heavy heads up yet.

All 5 are doing well. They will be ready to fledge in about 20-24 days from hatching date. Both the male and female feed their young, like the bluebirds. When adults, these guys will join large flocks and migrate. They need to do this to get insects in the winter. Bluebirds eat berries in the winter, so many of our bluebirds in Southwest Virginia stay as residents.







  1. I live up in Massachusetts…I put up a nice bird house with a copper top…looks nice!….The Tree swallows arrived around Early May 2016….They went in and out many times checking it out….At one point they had a battle with a English Sparrow (A Hosp as they as referred to) the Sparrows won that one Thank goodness.. Well they had 7-8 young ones, approx. what a wonderful show to watch until June 24 th, when things went very quiet in and near (no Activity at all ) the bird house one morning…..They picked my bird house to raise their young…they are truly very beautiful birds…I wanted to share this with everyone…sorry I have no photos…Best Regards to all, joe Puleo, Sharon MA.


  2. Our tree swallows must have left yesterday, or early this morning. What beautiful birds! My husband has dubbed them the ‘Prom King and Queen” because they look like they are dressed in tuxedoes. We could see their box (blue bird box) from the house, and the Queen was frequently seen with her head out of the box. Since it was near our shed we were careful for a while, but she never seemed to mind – although the lawnmower was not her favorite. We were blessed to share this time with them – the second year in a row. There was a struggle for claiming the box with bluebirds, but the swallows won and the bluebirds occupied another box. Can’t wait until next spring! We live in Culloden, WV, in a subdivision, but our property borders a wooded hollow with a creek.


    • Tree Swallows are wonderful. Finally got my first on my trail. I love the “tuxedos” comment…they DO look like they are dressed to the hilt! Such striking birds. I probabaly will be posting the picture I took today of the TRES female incubating. Love her!


  3. Thanks for the article on the Tree Swallow as I think they are amazing & fun to watch. Last year was the first year we had a swallow in a nest box. Only one made it out and we found the rest dead in the box. This year I think the same is happening but I could be wrong. There always seems to be one little swallow “hogging” up the hole and gets all of the food. I know there are at least two in the box alive because I’ve taken pictures of them. Also, a “gang” of swallows keep coming to the box at certain times of the day. I’m wondering if they are sibblings in a way. They seem like they are trying to coax the little fellow out although he still looks a little small for me. The pictures are wonderful on here today.


    • Thanks for your remarks on the tree swallow, Sue. Regarding the dead babies and only one making it, more than likely it was due to blowfly infestation in the nest and the other babies were anemic from loss of blood and not strong enough to take in the food. The other baby may have had more strength to take in food and was able to grow muscles and feathers to be able to fledge in spite of having larvae on his body at night. This is where monitoring nestboxes helps the birds. If you want more information on this, please see my tabbed paged PROBLEMS or contact me further for more information. You can also go to the best bluebird site out there,, and look up blowfly…specifically this link will direct you to that page: . It would take too much space on this reply to this post to explain what we monitors due to combat the problem of the blowfly and how we can easily deal with it in the nestbox so the nestlings can fledge. I deal with this for all of my boxes on my trail. As an learning new bluebirder when I started my trail in 2008, I lost baby bluebirds to this situation. At the time, I had no idea what happened. This is all part of learning about managing nestboxes I also had snake predation–before predator guards were used–ants, gnats, wasps (still deal with wasps in some boxes), house wren issues, and house sparrows at one location near town where my two-hole test is now located. The blowfly problem took place in ALMOST every nestbox. I attended the North American Bluebird Society’s annual convention in Grantville, PA, in 2009 and learned more about this problem in nestboxes and all the options of dealing with it. In nature, we cannot do anything about this problem. Being a landlord to a manmade nestbox gives us the opportunity to help the birds along. I hope this information in reply to your post helps.


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