Mountain Bluebird - Rare in Minnesota

We had seen reports of a way-out-of-its-range male Mountain Bluebird at Schaar's Bluff near Hastings, Minnesota, and were fortunate to be able to get extended good views of it Monday evening after work. What a beauty!

The overcast sky, fading light and rather diffuse color of the bird when seen from the front created some photographic challenges. At one point it flew to a perch within 15 feet of where I was standing, but with a network of high-contrast tree branches in the background, I could not get my camera to focus on the bird. The photos show here were all taken from many yards away with high zoom, and then cropped.

The normal range of the mountain bluebird is primarily the western mountain and plains states and up the western part of Canada into Alaska in the summer breeding season. Winters are spent in the southern part of that range and well south into Mexico. Normally it would not be closer to us than the western edge of the Dakotas.

For comparison, here (below) is the male eastern bluebird, which is the bluebird we normally see in this part of the country.

Bluebird in Soft Focus on a Gray Day

I sometimes forget what a difference good light makes to the clarity of a photo. But the flip side of that can be the tender, even painterly, softness to shots taken on an overcast day. Here is a male bluebird perching on a marker post in the Upper Arb at Carleton College, with a stand of leafing-out trees some distance behind.

2015 Bluebird Trail

Dave and I are a month or so into our fourth year of monitoring blueboxes in the Northfield area. This year, in addition to the two trails we've been covering in previous years (one currently with 12 boxes along rural roads south of Northfield and the other with five boxes near Randolph), we've taken on (at least for this year) another existing trail in the Carleton Arboretum that has 9 pairs of boxes over about a two-mile walking trail.

This trail uses a different type of nestbox than we're used to -- the modified Gilwood rather than the Gilbertson PVC style -- so that's been a learning curve. (See a comparison of box styles.) Both are mounted on conduit poles for good predator deterrence. (Please don't mount bluebird boxes on wooden fence posts and other areas where cats, raccoons, snakes and other predators can easily access a buffet of eggs and nestlings. If you have older-style boxes mounted in that way, you'd be doing a good deed by replacing them with newer pole-mounted boxes. If you're in our area and would like help replacing older boxes, message me and I'll be glad to help make that happen.)

The Gilwood has a front-opening door which is probably less alarming to a bird that happens to be sitting on eggs during a box check than the action of detaching the PVC box from its roof as you do to check inside the Gilbertson boxes. However, Dave and I aren't very tall, and even after lowering most of the boxes we find we need to use a small mirror on a wand (available at auto supply stores) to see the contents of the nests. Photography of box contents would be difficult indeed.

As of this week we have quite a few bluebird eggs, more nests that don't have eggs yet, and also much nesting activity by tree swallows. This morning as we walked the new trail I was able to get some nice photos of both bluebirds and tree swallows -- sometimes in the same shot.

Click any of the photos to see them larger.

Bluebird Report: 2014 First Report

We got out to prep the bluebird nestboxes in early April this year, our third year as bluebird monitors of two "trails," which now comprise 19 nestboxes. Though not quite as bad as last year's slow spring, still the cold, rainy weather has slowed things down. We have a few complete bluebird nests (also two chickadee nests) and several others have been started, but only a single nest has any eggs yet -- three eggs, as of yesterday.

When we first checked the boxes, we thought we already had a new egg in one, but determined eventually that it was an unhatched egg from the second brood last year. We should have done a final clean-out at the end of the summer. Our confusion at the start of this season is a good reminder of why it's a preferred practice to clean out the boxes at the end of the season. Some people take their boxes down; others close them up so nothing can get into them over the winter. We like the idea of leaving them accessible as roosting or shelter boxes, and we've seen some signs this year that they were used for that purpose.

Today we got some great views of a male and female bluebird at our prairie trail of four nestboxes, where we have three full nests but no eggs yet.

Male Eastern Bluebird

The many tiny scratches visible on the road sign suggest that it's a popular perching spot, as it was today.

Female Eastern Bluebird

We wish these two, and all their fellow birds, good luck as they embark upon the vital task of reproduction in 2014.

(Our bluebirding adventures began in 2012. You can follow the full story here: Bluebird Trail.)

Afternoon Bluebird - and Season Update

This female bluebird stayed on the wire near her nestbox as we checked it late this afternoon. She has four nestlings about a week old in this nestbox in rural Rice County -- the second brood of bluebirds in this box this year. We were there on hatch day last week, finding three tiny nestlings and one egg not yet hatched. This is one of only three locations this year where bluebirds have started a second brood, and we have quite a few empty boxes right now. Last year quite a few of them managed two broods. It's been a tough year for bluebird survival and reproduction.

This year so far 21 bluebirds have fledged out of six nestboxes, with a potential of 12 more to come in the three second-round nests, if they all survive. Tree swallows have raised broods in several of the other boxes. We took on three new nextboxes just a couple of weeks ago, which showed evidence that one brood of bluebirds and two of tree swallows had been raised there, but we don't know how many, or whether they were definitely from this year or not. Chickadees started nests in two more of our nestboxes, but, sadly, neither of them successfully raised a brood -- in one, the eggs were abandoned before hatching, and in the other the nestlings disappeared from the nextbox before they reached fledging age. We have house wren eggs in one box right now.

In the next 10 days to two weeks, in all likelihood, the bluebird breeding season will be over for this year.

Fledging and Starting Again

We checked our larger bluebird trail Sunday evening and found that three broods of bluebirds and two broods of tree swallows had fledged. In two out of three of those bluebird boxes, new eggs had already been laid to start a second brood. It is typical for bluebirds to raise two, and sometimes even three, broods in a breeding season, and with the late start this year the birds are wasting very little time starting again. We learned last year from Carroll Johnson, one of our county Bluebird Recovery Program coordinators, that it's unlikely that new eggs will be laid after late July.

We've never seen fledging happen (though last week and once last year we checked a nestbox assuming that fledging had already occurred, only to find one bird still in the nest -- either not yet fledged or perhaps, as they sometimes do, returned to the nest). Nor have we seen any of "our" bluebird fledglings after they've left the nest, at least not while they were still identifiable as juveniles. But last night we saw a family of six -- adults and juveniles together -- that most likely was not one of "ours," and we got a great look at a couple of the young birds enjoying the insect-gathering potential at a newly mown field. Here is a young bluebird on an overhead wire, already quite accomplished at dropping down to the ground for an insect and returning to a perch. The juvenile is easily recognizable by its spotted plumage.

Bluebirds (Sialia sialis) are members of the thrush family (Turdidae), as are American robins (Turdus migratorius). (It's okay, go ahead and laugh.) You can see and learn about other members of the thrush family here.

Bluebirds and Tree Swallows

With our late spring, we had a very slow start to the season along our bluebird trails, but the nestboxes are full of life now and our first bluebirds of the season are fledging. Along with the late start, we've noticed that the average clutch size is down from last year; we've typically been seeing four bluebird eggs, whereas last year five was the typical number. Below you'll see a clutch of three tree swallow eggs that were warm to the touch, indicating that laying was complete and incubation had begun. In another nestbox, we had five tree swallow eggs and two or three weeks later when we expected to see hatchlings we suddenly had a total of nine eggs; we're guessing the first set was abandoned and another female decided to lay her four eggs in the same nest. Tree swallows typically have larger clutches than bluebirds; last year we usually saw six in a clutch. Here are a few photos from the past couple of weeks.

Four bluebird nestlings within a few days of fledging

Bluebird nestling - siblings have apparently fledged

Bluebird nestlings, just a few days out of the egg

The gaping reflex shows parents where to deposit the food!

Tree swallow eggs - a small clutch, if it's complete

Tree swallow adult is watchful from the nestbox

Tree swallow nestlings - we counted six

Bluebird Report May 22 - First Eggs!

The contrasts between last year's early spring and this year's late one continue to be stark. By this date last year we'd had several sets of bluebirds fledge already, but we just found the first eggs of the season this week while checking the nest boxes we monitor weekly. As of Tuesday evening we had two nests with one egg each and this nest with three. Once they start laying, bluebirds lay one egg a day, with a typical clutch size being four or five eggs (most of ours last year had five). 

Three eggs - a beautiful sight!

There they are!

On our rural Rice County bluebird trail, which this year has eight sites (four single nest boxes and four pairs), we now seem to have four bluebird nests, two tree swallow nests (no eggs yet), and one black-capped chickadee nest.

Tree swallow nest full of feathers

Black-capped chickadee eggs in mossy nest

The chickadee nest, above and below, is at the location where our most successful bluebirds were last year. We also have chickadees nesting in one of the nestboxes at our house in Northfield. Last year we had a couple of chickadee nests started, but no eggs. Chickadees are cavity-nesters that will use bluebird boxes. They build their nests with soft moss, and as can be seen here, they obviously supplement with other found materials. This is a very soft, fuzzy nest for these six speckled eggs. Chickadees typically lay six to eight eggs (see the sialis.org page about chickadees).

Chickadee eggs

We hope to see these eggs hatch in another 11 to 14 days and the chickadee nestlings successfully fledge in about four weeks' time.

Follow our whole bluebird trail adventures here: Bluebird Trail.

Bluebird Trail - 2013 First Report

The horrendously late spring this year, including heavy snowfalls in late April and early May, has our bluebird season off to a worryingly slow start. It seems likely that there has been significant mortality for these insect-eating birds, since the insect season is also starting slowly due to the cold.

Tree swallows on overhead lines

By this time last year, we had 20 bluebird nestlings already! This year we have just started to get out to check the boxes, and we barely have any nests that are more than a few strands of grass, let alone having eggs or nestlings.

We have only seen two bluebirds yet this season, one male and one female, seen on different days at our prairie-habitat trail, where one of the four boxes today had a substantially complete bluebird nest. Tree swallows have been much more conspicuous on or near several of our other boxes. Perhaps tree swallows, which eat flying insects in the air, may have had an easier time finding food than bluebirds, which pick insects off the ground.

We have complete or nearly complete chickadee nests in two of our boxes, while last year we had no complete chickadee nests.

We plan to move some boxes from a couple of areas that last year produced wrens but no bluebirds.

Follow our whole bluebird trail adventures here: Bluebird Trail.

Bluebird Trail: End-of-Season Recap

Peterson nestbox left open at end of season

The photo above is not one of the nestboxes we monitor. But I liked the symbolism of it for this end-of-season recap post. We saw several boxes like this one at the St. Olaf College natural lands this morning -- they've been cleaned out at the end of the bluebird breeding season and left open to discourage mice and house sparrows from using them over the winter. (See http://bbrp.org/wp-content/uploads/2012/01/Trail-Guide-Final1.pdf) The boxes we monitor are all of the Gilbertson PVC pipe style, which don't have doors that open.

Here are our final bluebird trail numbers for the year:

Trail 1, Rice County, mostly south of Northfield: 7 pairs and 4 single nestboxes

• 72 bluebird eggs were laid in 11 nestboxes
• 57 bluebird eggs hatched
• 46 bluebird chicks fledged
• Tree swallows used 5 nestboxes and fledged 32 chicks
• Chickadees started to use one nestbox but never laid eggs
• House wrens used 4 nestboxes and fledged 22 chicks

Trail 2, Goodhue County, prairie habitat: 1 pair and 2 single nestboxes (we took on the monitoring of these boxes in late April)

• 19 bluebird eggs were laid in four boxes
• 18 bluebirds hatched
• 18 bluebirds fledged
• Tree swallows also used two of the boxes and fledged 12 chicks

Male bluebird on top of "sparrow spooker"

We did not successfully raise any birds in the pair of nestboxes we put up this year on our own property. That was where house sparrows killed a chickadee early in the season. In mid-season, we attracted both tree swallows and bluebirds. The tree swallows seemed to be building a nest, but did not lay eggs and eventually disappeared. The bluebirds nested and hatched a clutch of four eggs in a box where we had put up a wren guard, but when they were a few days old, the nestlings vanished from the nest. This was very distressing; we were alerted that something might be wrong when we could see the male calling repeatedly and flying to and from the box, and when we checked the box later that day we found the babies were gone without a trace, but the nest was intact. Our Rice County bluebird mentors said that most likely house wrens, but possibly sparrows, could have removed the chicks. We will see if we can find a better location next year -- one farther from the house and from large trees -- to see if we have better luck. We can't in good conscience keep trying to attract bluebirds, tree swallows or chickadees to locations where there is a recurring pattern of attacks.

Bluebirds raised two broods in quite a few of our boxes this year, but we did not have any bluebirds successfully raise three broods this summer, despite the early spring. The closest we came was in our earliest nesting location. There, we had a clutch of five successfully hatched and fledged by the second week of May. A second clutch of five was hatched in the same box in early June, but all five nestlings perished within a few days of hatching; we found them dead in the box. Soon afterward a new nest was started in the other of the paired nestboxes. Four out of the five eggs hatched and they fledged in late July. Since our theory about the dead nestlings was that their mother had been killed, the final clutch on that site may have involved the same male and a new female, or even a whole new pair, but we can't be sure.

It's been a fascinating season. We've had a lot of pleasure, a lot of learning as we went, some distress and heartache, and much wonderful outdoor time every week as we monitored the boxes. We have felt honored by this precious opportunity to observe the private lives of cavity-nesting songbirds and try to keep them safe. We look forward to next year!

Bluebird Trail, Week 13 - Fledging Tree Swallows

Much of the action in the bluebird boxes lately has been from tree swallows. A couple of broods of house wrens have also fledged.

Sadly, about two weeks ago we lost the first brood of our second-round bluebird nestlings at just a few days of age. We had seen them as new hatchlings, but they were all dead in the nest when we returned the following week. We can only presume that something happened to the mother (possibly in the day of big storms that hit Northfield that week, though based on the nestlings' development we think it was probably a couple of days earlier) and the little ones perished without her. As we understand it, while the males help feed the babies, they do not enter the nest and brood them to keep them warm, which they need until their feathers come in and they can regulate their own body temperatures. So they really need their mothers for the first week or more. It was quite a shock -- our first bluebird casualties.

However, the tree swallows have given us much to observe, as the photos below reveal.

In the first photo are six tree swallow nestlings a few days from fledging. They are certainly crowded in the round Gilbertson nestbox, but all the tree swallow nestlings we've seen seem to figure out that heads pointing out is the best arrangement. We have not lost any tree swallow nestlings to overcrowding, though we understand that it can be an issue since they have larger broods than the bluebirds do.

Six tree swallow nestlings

In the next photo, tree swallow nestlings approaching fledging age were peeping out of their box, awaiting food.

Tree swallow nestlings looking out at the world

This past weekend we checked a box where we were pretty sure fledging would already have occurred, and we found two nestlings were still in the box. We must have caught them on fledge day -- or perhaps it took a day or two for all the birds to fledge. Dave checked again the next day, and they were gone.

Fledge day - two left

And here (below) is a shot showing the remarkable construction of the tree swallow nest, revealed when we cleaned out a nestbox after tree swallows (the ones peeping out in the earlier photo) had fledged. We found an unhatched egg in this nest -- in this one case, we'd never been able to get a final count of the eggs before hatching, so we were not aware until the end that one had not hatched. This was the location where I got the lovely photo of the mama incubating, surrounded by white feathers.

Tree swallow nest after fledging

Unlike bluebirds, which typically raise two or sometimes even three broods in a season, tree swallows are usually finished after one brood, though there are exceptions. (The tree swallow page on Sialis.org has more good information about tree swallow nesting and development.) So the nestboxes that are gradually being vacated by the fledging tree swallows will become available for bluebirds or other cavity nesters that are ready to lay again at this point in the summer, and the tree swallows will not compete for those nesting locations unless their first attempt has failed.

We try to clean the nestboxes out as soon as we confirm that fledging has occurred, to ensure a more sanitary and pest-free setting for the next nest (tree swallows leave pretty dirty nests by the time they're done), but it's been amazing how quickly a new tenant can move in. We recently came back to one nestbox intending to clean out a vacated tree swallow nest, only to find a complete new bluebird nest with an egg in it already, built right on top of the tree swallow nest.

Bluebird Trail, Week 8-9 - Tree Swallows & House Wrens

This week's update covers the last two weeks. We checked the Trail 1 boxes during a very light drizzle on May 20, which we found was good weather for catching birds on their nests. Dave saw three tree swallows on nests that day while I, still in the early days of recuperating after eye surgery on the 17th, rested in the car and just took notes. We weren't able to get to Trail 2 last week. This week I was feeling much stronger, and we visited both trails on the morning of May 27, which was a hot day with temperatures already well into the 80s.

Most of the nestbox activity right now is from the tree swallows, as most of our bluebirds have fledged their first broods and are working on their second nests and eggs.

Tree swallow in nestbox incubating eggs

This is my favorite photo of the week -- a female tree swallow who stayed on her nest when we checked this nestbox on Trail 2. The light was right to catch her beautiful coloring contrasting with the cloud of white feathers. We quietly and carefully put the box back.

Tree swallow eggs in nestbox

Here is another tree swallow nest with eggs, from one of the boxes on Trail 1. I can't get over how beautiful and comfortable-looking the tree swallow nests are, with all the feathers they use to line the nest. I try to imagine being a little naked nestling, and I would much rather be in a tree swallow nest than a bluebird nest, which is generally just dried grasses with no downy lining. However, I understand that bluebirds are more fastidious about removing the nestlings' fecal sacs from the nestbox, so from that perspective I guess I'd rather be a bluebird nestling.

Tree swallow atop sparrow spooker above nestbox

In the last couple of weeks we were excited to have a pair of tree swallows building a nest in one of the nestboxes at our house, where we've had a hard time getting any successful nests going. We set up the spotting scope in our living room so we could keep tabs on  the activity there. Above, a tree swallow perches atop a "sparrow spooker" that dangles orange construction ribbons over the top of the nestbox; this is thought to discourage house sparrows. The tree swallows found it to be a handy perch. Below, before we saw a house sparrow enter the box which led us to put up the sparrow spooker, the female is looking out of the nestbox while her mate watches from above. 

Tree swallows at nestbox

We have continued to be plagued with house sparrows at this location, but we have also been hearing house wrens quite a bit lately, and it was a house wren that eventually cleaned the tree swallow nest out and drove the pair away. From what we hear, this is typical wren territorial behavior -- they clean out other birds' nests and leave the box so pristine it's as if it was vacuumed out. House wrens will sometimes destroy other birds' eggs, as well. Because of this consistent difficulty with both house sparrows and house wrens, we decided to take down the two boxes at our house. Although they offer some good bluebird habitat, they are just too close to the house (encouraging house sparrows) and some large trees (encouraging wrens).  We loved watching the tree swallows from our living room, and for a couple of days we saw bluebirds at the other box as well, which was a real thrill, but the wrens cleaned that box out too. We feel it's not safe for the bluebirds, tree swallows and/or chickadees at this location, so we thought it was better to take these boxes down.

Tree swallow nestlings, approx. day 2

Above is the first set of tree swallow nestlings we've had. There are appear to be six nestlings that I am guessing are about two days old, based on our records of when the eggs were laid and this guide to tree swallow nestling development at the Tree Swallow Projects site. They are quite similar to bluebird nestlings at this age, but less hairy. The female was in the box when we approached but flew out, allowing us to quickly confirm that the nestlings had hatched. We left as quickly as we could so she could get back to the babies.

House wren eggs

House wrens, unlike the nonnative house sparrow, are federally protected native birds. Once they have an active nest -- not just twigs in a nestbox, but a nest cup and/or eggs -- it is illegal to disturb or remove the nest. Sialis.org, the excellent bluebird site, has a good page about managing house wrens. The All About Birds site has useful breeding information: they lay 3-9 eggs, incubate them for 9-16 days and nestlings fledge in 15-17 days. We now have two active house wren nests on Trail 1, both in nestboxes that had seen very little activity all spring until the last week or two, when the wrens (which typically don't arrive in this area until May) got busy.

The full trail report follows. We have, to the best of our knowledge, fledged 30 bluebirds and have 5 new eggs this week. One nest of 3 eggs (box 18) seems to have failed, but as far as we can tell we had full success of all bluebird eggs in the other nests, as we saw no unhatched eggs or dead nestlings. We have 6 tree swallow nestlings and 5 more nests with tree swallow eggs. We have 2 house wren nests with eggs.

Follow our full bluebird trail adventures here.

Trail 1:

1. After several days of tree swallow activity, a house wren cleaned out the nest and we had also seen a house sparrow enter the nestbox, so we have reluctantly taken this box down.
2. (Paired with #1) After recent chickadee activity that didn't develop into a nest, a bluebird pair was seen at this box so we removed the guard that made the hole smaller for chickadeees. A house wren cleaned out the bluebirds' nesting material. We have now taken this box down.
3. There were two house wren eggs here on May 20 and 7 house wren eggs on May 27. 
4. (Paired with #3) Tree swallow nest with 5 eggs. Female was on nest May 20 and flew from the nest May 27. Probably now 8-10 days into incubation; we should see nestlings next week.
5. 5 bluebirds fledged, probably close to a week ago (we observed an adult on top of the box on May 20 and knew they were close to fledging so we did not check the box that day). House wren twigs in box on May 27; we cleaned out the nestbox.
6. (Paired with #5) Tree swallow nest -- did not check on May 20; 6 eggs on May 27.
7. House wren nest with 7 eggs. This box had one egg on May 12 and 7 eggs on May 20. Assuming they lay an egg a day, these eggs are now about 10 days into incubation and may hatch at any time now.
8. (Paired with #7) Tree swallow nest with no eggs on May 20 and 2 eggs on May 27.
9. We cleaned this box out two weeks ago after fledging our first set of bluebirds. On May 20 there was a full new nest and on May 27 there were 5 bluebird eggs.
10. (Paired with #9) On May 20 we removed the unused duplicate bluebird nest that had been there all along. On May 27 the box remained empty.
11. Discontinued  
12. Discontinued
13. 5 bluebirds fledged, probably early last week. We did not check the box on the 20th, which was approx. day 13 since hatching. We cleaned out the empty nestbox on May 27.
14. 5 bluebirds fledged between May 12 and May 20, when we cleaned out the empty nestbox. On May 27 there was a full new nest.
15. 6 tree swallow nestlings, approximately day 2 on May 27. There were 6 eggs on May 12 and female remained on nest during check on May 20 so we could not count the eggs again. There might be a 7th, but photo (above) appears to show 6 nestlings.
16. 5 bluebirds fledged close to May 12. We cleaned out the box on May 20. On May 27 there was a full new nest.
17. This box earlier showed signs of a chickadee nest, but was emptied probably by house wren between May 5 and May 9 and still remains empty.
18. (Paired with #17) Three pale pink bluebird eggs, cool. These eggs are well past the age when they should have hatched with consistent incubation (2 eggs were noted April 25 and there have been three eggs thereafter). Parents were always previously nearby and vigilant but were not observed on May 27.
19. Tree swallow nest with approx 7 eggs.
20. (Paired with #19) Complete bluebird nest with female present.

Trail 2:

1. Nest with no eggs -- no change.
2. (I previously reversed the description of #2 and 3 contents.) Tree swallow nest; 1 or 2 eggs on May 13; not checked May 20; female remained on nest May 27 so we could not count eggs. Assuming a clutch size of 6 or 7, incubation is probably 9-10 days along and we should see nestlings next week.
3. (Paired with #2)  5 bluebird nestlings approx. day 5 on May 27 based on appearance and incubation history.
4. 5 bluebirds fledged between May 13 (day 10 or 11) and May 20. We planned to clean out the nestbox on May 27, but it appeared that new nest material has been built over the old nest so we did not disturb it. Tree swallow was present on top of the box and there was a large white feather in the nest, so this may have become a tree swallow nest.

Bluebird Trail, Week 7 - Mom on Nest, First Fledging & Tree Swallow Eggs

Mama bluebird on her nest

While we were checking Trail 2 today,  a female stayed on her eggs when we opened one of the boxes. We have had a bird fly from a box as we've opened it before, but this was the first time one has stayed. It was quite a magical moment. We weren't able to ascertain how many eggs she's sitting on -- last week there were two eggs in this nest, so if she has the typical clutch of five, she's probably been incubating them for about four days and they'll hatch in another 8 to 10 days.

Trail 2 Box 4 nestlings at about 10-11 days

The nestlings are already quite advanced in the other Trail 2 box that has bluebirds in it (see photo above). We didn't know just when they hatched, but we estimate them to be at 10 or 11 days today, as shown in the photo above. This is the first photo we have that shows a nestling with an eye open. You can see they are becoming quite well covered with feathers.

Our very first nestlings, those in Box 9, have fledged. They were due to do so this past week, and on Saturday we found the box empty and the nest flattened out to accommodate the nestlings as they grew. You can see from the dark edges of the nest in the photo below that the nest was quite wet underneath. There was a lot of rain last week, and that box's opening faces south, exposing it to the prevailing direction of many of our rainstorms. Fortunately, as far as we can tell, the nestlings' health was not compromised. We cleaned out the box after taking this photo so that it is available for another nest. From what we've read, building the nest is an integral part of the reproductive urge, so it doesn't help to leave an old nest in place -- and starting fresh is more sanitary.

Flattened nest left after bluebird nestlings fledged

Nestlings are also very close to fledging in Box 16, if they have not already done so, and the Box 14 nestlings are due to fledge in the next few days.

Tree swallow nest with eggs in Box 15

We were very excited to find six eggs in our Box 15 tree swallow nest yesterday. We love seeing these feathery nests. We several times noticed tree swallows at Box 1 on our property today, as well -- one of the pair of boxes that have remained mainly empty but suffered the early chickadee loss to a house sparrow. And there is a bit of new moss in the other box, so we're hoping a chickadee is trying again. Still, we can sometimes hear a house sparrow nearby, so that threat remains.

Last week I did an abbreviated recap of our trail results. It's helpful to me to keep more detailed notes here, however, so those appear in the list below. Our Trail 1 totals so far: 25 nestlings! 5 fledged, 10 more are close to fledging, 5 more will probably fledge toward the end of this week, five more young nestlings, and only one nest still with bluebird eggs in it -- the worrying slow clutch of three pinkish eggs. This week they felt cold. The parents are always close by, but perhaps they just don't have the hang of this incubation business. We also have a nest of six tree swallow eggs. On Trail 2 we have four or five nestlings that should fledge in the week ahead, plus an unknown number of bluebird eggs being incubated in another nest, and one tree swallow egg so far in a third nest.


Trail 1:

1. Tree swallows observed on the box; box remains empty.
2. (Paired with #1) New moss this week, so we put the chickadee sleeve back on this box to reduce the entry hole size.
3. House wren had started to put sticks into nestbox -- removed. 
4. (Paired with #3) This is now clearly a tree swallow nest with large feathers; no eggs yet.
5. Five nestlings, 11-12 days old.
6. (Paired with #5) Tree swallow nest. No eggs.
7. House wren nest with one egg.
8. (Paired with #7) Now empty; previously contained a few strands of grass for several weeks. Wrens can clear nests.
9. Our first clutch to fledge. Nestbox was empty; we cleaned it out.
10. (Paired with #9) Complete nest, no eggs  - no change.
11. Discontinued  
12. Discontinued
13. Five nestlings approx 5 days old.
14. Nestlings close to fledging; parents still vigilant on wire when a tree swallow approach the box, so we suspect fledging has not occurred yet.
15. Tree swallow nest with six eggs.
16. Nestlings may have fledged or will do so shortly - we did not open the box. We did not open this box last week either, as parents were very protective.
17. This box contained a substantial bed of moss for two weeks, but was suddenly empty last week -- a sign of possible house wren activity.
18. (Paired with #17) Three pale pink bluebird eggs, cool. These eggs are past the age when they should have hatched with consistent incubation. Parents are always nearby and vigilant (swooping down at us protectively), but we fear incubation has not been successful.
19. Tree swallow nest - no eggs.
20. (Paired with #19) Partial nest.

Trail 2:

1. Nest with several tiny dark downy feathers.
2. Bluebird stayed on nest so we could not count eggs. Last week there were two cold eggs, so assuming a total clutch of five, probably four days into incubation.
3. Tree swallow nest, one egg.
4. Five nestlings approx. day 10-11.

Bluebird Trail, Week 6 - 20 Nestlings!

This week sped by, and we did not visit any of the nestboxes after Monday. As a result, the photo I posted last Tuesday of the Box 9 nestlings on day 8 will be our last photo of them, unless we are lucky enough to get any photos after they fledge. Today (Sunday) they are at day 14 since hatching, and standard bluebird monitoring advice is not to open the box from about day 13 on unless there is a compelling need, because it is too close to their fledging date (most often 17-18 days, though it can take several days longer).

By day 13 or so they are fully feathered, and the fear is that they may be startled into fledging prematurely, which could endanger them. This risk is thought to be less with the top-opening Gilbertson boxes we are using than with front-opening or side-opening boxes, but we don't want to take any chances. But we will try to stop by later this week, and in the weeks ahead as we continue to monitor these boxes, to see if we can see any sign of them out and about with their parents. The male, in particular, will continue to tend to them for several weeks to come; mama, in the meantime, may start building her next nest almost immediately.

Box 5 nestlings at Day 4 

Our fourth clutch of eggs, at Box 5, hatched probably Tuesday or Wednesday last week, and so were about at day four when we stopped by on Saturday (above). You can see some feathers lining this bluebird nest.

Tree swallow nest - note prominent, curling feathers. No eggs yet.

We were able to get a photo of the tree swallow nest in Box 15 (above) on Saturday. Bluebirds and tree swallows both make their nests of dried grass, but tree swallows make much more liberal use of feathers in the nest, and the feathers tend to curl up to surround the eggs (though there are no eggs yet in either the box above or the one below), rather than merely lining the nest. We have seen small feathers in several of our bluebird nests, such as the one with the nestlings above, but in comparison tree swallow nests are very feathery indeed.

Tree swallow nest on Trail 2 - no eggs yet

Above is another tree swallow nest. It is from the other set of boxes we are temporarily (?) looking after. We'll call those boxes Trail 2. Currently there are four nestboxes on Trail 2 -- two are paired, and the one above is one of those. There are two new bluebird eggs in the other box of this pair, and we have five new bluebird nestlings in one of the other boxes as of Sunday. We're waiting to see what develops in the fourth box, which contains a grass nest that looks as if it could be either a bluebird or a tree swallow nest at this point.

I am somewhat concerned about tree swallows using these Gilbertson nestboxes we are monitoring, ever since reading the opinion of the author of treeswallowprojects.com that these boxes, which have just a four-inch diameter, are dangerously small for tree swallow use, since tree swallows have larger clutches than bluebirds. People who put up nestboxes specifically for tree swallows are urged on that website never to use a box with a floor area smaller than 5 x 5 inches. I suppose cavity-nesters take what they can find to some extent, both in the course of their long natural history as well as in this age of humans providing nestboxes. One would think that a bird would "know" if a nesting cavity is too cramped for success, and would avoid it, but the treeswallowprojects site says that is, sadly, not the case. I will be interested to find out from Minnesota bluebirders who like the Gilbertson boxes what their experience has been with raising healthy tree swallows in them.

Below is one of the Trail 2 tree swallows, who sat very quietly nearby while we checked the box nearby and returned to this post when we walked past again after checking the other boxes. Tree swallows (and bluebirds too -- see below) are quite capable of diving at you from the air if they think you're too close to their nest, so we were quite surprised that this one did not display any aggressive protective behavior, though it was certainly watchful.

Tree swallow on fence wire

I took this next photo last weekend. I like the near-dusk softness of the landscape surrounding this handsome male bluebird.

Male bluebird at dusk

Box totals from our regular trail: 20 nestlings! There are five nestlings each in Box 9 (about 14 days old), Box 16 (about 12 days old), Box 14 (about 10 days old), and Box 5 (about 5 days old). As far as we know, they are all healthy. We did not look inside Box 16 this weekend, because the parents did dive at us when we approached the box, so we probably will not see those nestlings again for the same reason discussed at the start of this post -- they will very soon be too close to fledging.

There are still three pink eggs in Box 18, which is the same number as there were a week ago. They felt cool to the touch yesterday. The parents are always nearby and very vigilant, but we're not sure the incubation is proceeding as it should, so that is worrying. Stay tuned...

Bluebird Nestlings at 8 Days

Here is the first group of nestlings again, eight days old as of Monday. Look how much more room they take up in the nest than they did a week ago. I was surprised how relatively unresponsive they were this time compared to earlier visits, displaying only one brief gape in the whole bunch. We thought perhaps their bellies were full and they were sleeping (and we did look closely to make sure they were actually moving) -- but then I read that right about this age, nestlings start to react differently. (Sialis.org) Instead of gaping when the box is opened, they hunker down with their eyes closed.

Eyes -- that's right, at this age their eyes may well have opened. We did not see any evidence that the eyes on this bunch had opened yet, but they may just have been keeping them closed. Their feathers are starting to come through; you can see them on the wings quite clearly.

Here's a nice page on Sialis.org that follows a brood day-by-day from hatching to fledging.

Bluebird Trail, Week 5 - Pink Eggs, Tree Swallows & More

We now have 15 nestlings and 13 more eggs among the 18 boxes we are monitoring at 11 sites. It's also clear that one of our bluebird nestboxes has become a tree swallow nest.

Papa bluebird has a caterpillar for the Box 9 babies

As I reported midweek, all five eggs did hatch at the first site, Box 9, and five more hatched a day or two later at Box 16. Now we also have five nestlings at Box 14 that hatched probably Thursday or Friday. It got pretty cold this week, but they all appear to be okay. I could hear tiny cheeping coming from the two boxes with the oldest nestlings, which was delightful. Once again, my camera's start-up chime got several nestlings to gape (below). That one at the top left doesn't look too vigorous, but it may just be the angle.

Box 16 - Nestlings Day 5 - note darkening where feathers will grow

Last week we started to suspect that Box 15 was being used by tree swallows, as we saw one making territorial swoops past the nestbox. This week it was confirmed, as I saw swallows landing on the house and, as you can see below, even emerging from it. I took the photo below from the car and then drove on to check another box rather than disturb them when they were so active at the box. When I came back they were not in sight, so I checked the box and found several prominent feathers in the nest, but no eggs yet. Bluebirds sometimes incorporate small feathers to line the grass nest, but tree swallows routinely use larger feathers and more of them.

Tree swallows at Box 15 (note one emerging)

During our mid-week check we found two eggs in one of our newest nests, Box 18, that at first led us to question whether this was indeed a bluebird nest. We had heard that a small percentage (perhaps no more than 7 percent) of bluebirds lay white eggs rather than blue. These eggs looked the right size and shape (tree swallow eggs are somewhat more pointed at one end), but they had a pinkish color, which was unexpected.

Though usually blue, bluebird eggs can be white, or even pinkish - Box 18

There was an agitated pair of adult bluebirds on a wire directly overhead, so we were fairly sure this was indeed a bluebird nest. We confirmed at the very helpful bluebird website Sialis.org that bluebird eggs can indeed be pink! I was there again today and found there are now three pink eggs, and mama bluebird (again on the wire) was most perturbed that I was looking into her nestbox, so I didn't linger to take another photo.

Here's the full report for the week.  Boxes retain the same numbering all season, so even though two boxes have been taken over by another monitor we keep them in this list so the numbers will stay correct. We were invited to take on two more boxes this week, and were also asked to temporarily monitor some in another location, the latter of which I have not added here. Calculations of incubation time are based on Sunday's early-afternoon nest check.

1. We saw a pair of house sparrows at these two boxes earlier this week, and a partial nest was built. We set the sparrow trap but have not had luck -- but the sparrows seem to have been discouraged from this nest.
2. (Paired with #1) No activity.
3. Partial nest - no change. 
4. (Paired with #3) Nest about complete, no eggs - little or no change. Tree swallow noted nearby.
5. Five warm eggs, estimated to be 11 days into incubation, with hatching anticipated in the next 1-3 days. Male noted flying from the area of the nest.
6. (Paired with #5) Partial nest - no change.
7. Partial nest - no change.
8. (Paired with #7) A few strands of grass - no change.
9. Five nestlings approx. 7 days old  - starting to look much darker and less naked. Tiny cheeping sounds from closed box. Four had hatched on our visit a week ago, and the fifth had hatched by the time we visited again midweek -- probably only a short time after the others.
10. (Paired with #9) Complete nest, no eggs  - no change.
11. Discontinued  
12. Discontinued
13. Five warm eggs - a week ago there were three cool eggs. Incubation probably five days along, with hatching anticipated in 7-9 days. Bluebird flew from box.
14. Five nestlings approx. 2-3 days old (they had not hatched as of Wednesday when we stopped by).
15. Full nest, no eggs. We now think this is a tree swallow nest. Tree swallows were observed on top of and inside the nest box (see photo above), and the nest contains several prominent feathers, which is characteristic of tree swallow nests.
16. Five nestlings approx. 4-5 days old, cheeping; both adults vigilant and agitated nearby. 
17. Chickadee nest contains substantial bed of moss, but no change for the past two weeks.
18. (Paired with #17) Three pale pink eggs, warm (?). There were two eggs on Wednesday, so since bluebirds lay one egg per day it may be presumed the clutch is complete. If incubation began Thursday, they are 3 days into 12-14-day incubation, with hatching anticipated in 9-11 days. One egg at least felt warm; I wasn't sure if they all did. Adult female watchful and agitated nearby.
19. New box this week: A few strands of grass.
20. New box this week (paired with #19) A few strands of grass.

Follow the full saga of our bluebird trail at my Bluebird Trail page.