Three species of bluebirds are found in North America, Eastern (Sialis sialis), Western (Sialis mexicana), and Mountain (Sialis currucoides).  In Canada, Eastern Bluebirds range from Nova Scotia to Saskatchewan, with a few appearing in southern Alberta.  Western Bluebirds are mostly confined to southern British Columbia, while Mountain Bluebirds are found from Yukon to eastern Manitoba, with some occasionally appearing in the Rainy River District.  Owing to declines in the number of these species, various groups throughout North America began building nesting boxes and establishing bluebird trails, and this conservation effort, undertaken by thousands of volunteers, has been one of the reasons why bluebird populations have increased over the past 60 years.

The idea of creating “bluebird trails” is generally credited with Thomas Musselman of Illinois, who originated the bluebird conservation movement in 1926. For an extensive history of bluebird conservation and an excellent discussion of bluebird trails and bluebirds in general check out the Sialis website. 

In Canada, bluebird trails were initiated in 1959  by John and Nora Lane of Brandon, Manitoba. The success of their efforts led to the establishment of a network of trails from Saskatoon to Winnipeg.  This 2000 km route was comprised of 7,000 nest boxes and typically fledged 5,000 bluebirds each year.

Maintaining and monitoring Bluebird trails requires extensive effort. Birdhouse need to be built according to a certain standard, the proper habitat needs to be identified and located, trails monitored on a regular basis during the breeding season, records maintained, and perhaps, most important of all, nest boxes cleaned and repaired at the end of the year.

Bluebirds aren’t the only birds using the boxes; Tree Swallows, Black-capped Chickadees, and House Wrens also use the boxes, as do House Sparrows, which can be quite destructive, as they will kill both adults and nestlings to take over a box. Often the only thing that can be done is to move the entire trail to a location without that pest. The nests and boxes can also be home to mice, squirrels, and all sorts of insects and arachnids.

Rainy River District Bluebird Trails

Under the leadership and guidance of Henry Miller, the Fort Frances Sportsmen’s club initiated the establishment of bluebird trails in 1991 in the Rainy River District.  In the first year 30 houses were built from waste lumber found at landfills. The boxes were placed on fence posts along side roads. Ideal habitat for bluebirds and tree swallows is an open filed with occasional brush nearby for the fledglings to find protection upon first leaving the nest.

Under supervision of the club, school children began making boxes.  Precut pieces were brought to the children who were given instructions on how to put them together.  Once built, the boxes were taken home by the pupils.  Other classes were driven out to establish the bluebird trails along side roads.  With the help of Norbert Bragg who donated his bus, as well as the teachers, 46 trails containing 467 boxes were put out in the 1990’s.  Henry monitored the boxes three times during the summer, recorded the results, and sent the data to the Eastern Bluebird Society.  As time passed, others helped monitor trails near their residences.  The Get Outdoors Club and their parents have played a huge part.  They have built birdhouses, put them out, monitored, and cleaned out most of the boxes.  Other folks throughout the district have put up their own birdhouse and should be recognized for their contribution to the increase of the bluebird population.

Over the years, boxes have fallen into disrepair.  In 2014, 242 were replaced. Some trails have been dismantled because of predation by raccoons or by aggressive house sparrows, which kill the nestlings and occasionally adults, as well. 

I’ve included the previous reports by Henry Miller that are available. Henry continues to monitor the trails for the Sportsmen’s Club.

2010:  324 bird boxes were monitored.

Bluebirds: 53 pairs nested, some having second broods. 215 nestlings fledged, 18 dead nestlings, 24 unhatched eggs.      

Tree Swallows:  131 pairs nested; 476 nestlings fledged; 27 dead nestlings; 14 unhatched eggs.                                                    

Other birds: 12 pairs of House Wrens, 2 pairs of chickadees, 1 Great Crested Flycatcher.                                                 

Others: 2 pairs of Red Squirrels; red ants in 1 box, hornet in 2 boxes. 

Very little predation of eggs or nestlings, much less than other years.  Wrens affected several nests, as they pecked holes in eggs of both Bluebirds and Tree Swallows in adjacent boxes and, as usual, covered eggs with twigs, filling several boxes.  In two areas American Kestrels perched all summer above the birdhouses.  I saw one catch a Tree Swallow.  There were probably others.                          

2014: Since the beginning of the establishment of bluebird trails in the Rainy River District, overall, the bluebird population has been increasing.  2014 was one of the best years ever with 184 Bluebirds ad 595 Tree Swallows fledged.

2015: As with all wildlife population trends are cyclic. In 2015, number were down with large numbers of birds dying (118 eggs abandoned and 71 dead chicks.  Only 66 Bluebird and 186 Tree Swallows were fledged in the 21 trails Henry monitored that year (225 boxes).

2017 Report:  Henry Miller

It was a good year for bluebirds with more pairs per trail than in any of the 26 years of the project.

There were problems early on as spring came early, resulting in birds arriving too early.  For example, from the 19^th to 23^rd of March many tree swallows and bluebirds were starting to nest.  On March 24^th, the temperature plunged below zero and it snowed with two days of blizzard-like conditions.  By the 30^th most migrating birds had perished from lack of food and/or the cold.  Grackles also killed and ate some.

It wasn’t until the last two weeks in May that nesting began.  With the decline in tree wallow populations over the last two years, bluebirds took advantage of the extra boxes available.  Twenty-one pairs built their nests.  Not all were successful.  Mortality rates are high among wildlife populations.  Weather, predation, pesticides, human interference, and diseases take their toll.  17 pairs of bluebirds were successful, fledging 76 nestling.  85 tree swallows were fledged.

Other birds nesting in the birdhouses were 10 pairs of house wrens and 2 pairs of chickadees. No young were raised where vandalism occurred (roofs taken off) and on another trail where pesticides were used.  In these two areas there were many dead adults, as well as young birds.

Only one pair of Bobolinks were observed this year.  In the past these birds nested in every field where the trails and boxes were monitored.  Last year I observed 16 male Bobolinks.   Eastern Kingbird sightings were also down.

Notes:

1. The Tree Swallow population has not recovered from its collapse in 2016. Over the years, Tree Swallows have occupied 80% of the bird boxes.  As a result, many boxes remained empty this year.
2. The vandalism which occurred this year is only the second time anyone has ever interfered with the birdhouses.
3. I checked the trails which I don’t monitor nor take data. Several pairs of bluebirds were observed.  One trail had several House Sparrow nests.

2018 Report Henry Miller

The winter of 2018 was extremely cold and lingered until the second week of April.  There was some melting the last week of March and the first two weeks in April, but the temperatures plunged well below zero each night.  The night of our nocturnal owl survey on April 11 the snow coverage was 95%.

On May 1^st, a few Tree Swallows returned.  The first bluebird I saw appeared on May 19.  Not long after there were more bluebirds than I had ever seen.  Residents in the district whose children had built and put out birdhouses through the Sportsmen’s Club’s school programs wondered why there were so many bluebirds using boxes which had never had bluebirds in them before.  It was a great year for these birds.  They thrive in hot, dry weather.

I monitored 6 trails (73 boxes).  32 other boxes were cleaned but not monitored. 18 pairs of bluebirds fledged 86 young. Four eggs in one nest did not hatch.  My “home” trial, a 2 km line with 17 boxes had 6 pairs.  The most I ever had before was 3.

Tree Swallows did not fare as well.  31 pairs nested and only 73 nestlings fledged. I don’t know the reason for this, as no pesticides were being used in the area and predators could not have taken all the adults.

2019 Report Henry Miller

Bluebirds arrived late this year.  Normally birds are here in late April or early May, but this year they waited until mid-June because of the cool, wet weather.  In spite of the late arrival, nesting success was high.  Bluebirds and Tree Swallows thrive in hot weather.  In addition, mortality caused by weather and predators was at an all time low.

Thee were two exceptions, both to second broods.  All eight nestlings which were ready to fledge died after a violent storm swept the area with heavy rain and fierce winds.  In 108 boxes, 16 pairs of bluebirds fledged 79 young.

Tree Swallows have rebounded from the 2015 disease when most of the population perished.  This year 32 pairs fledged 151 young. There were 5 House Wren nests.

2020 Report   Henry Miller

Part One: Weather certainly influences the nesting habits and survival of birds. Last year bluebirds and tree swallow didn’t show up until mid-June.  The weather had been cold and wet until then.  This year the birds arrived early and began nesting in early May, taking advantage of the warm, dry conditions.

In May I monitored the nine bluebird trails. Another trail was monitored by Jody and Sam Bonner-Vickers.  By May 28, 16 pairs of bluebirds and 51 pairs of tree swallows had laid their eggs.  Surprisingly, tree swallows are laying more than their usual five eggs.  Some nests contain six or seven.  Bob Saunders, who checks birdhouses for the Rainy River Valley Field Naturalists, has noted the greater number of eggs as well.

Survival of the number of nestlings cannot be predicted because many are affected by a number of factors.  Birds can be the meal for many predators such as hawks, skunks, weasels, snakes, and several other animals.  Pesticides when used in fields close to the boxes, are deadly: all the nestlings, and eventually the adults, die.  Sick birds hide I the grass before they die.  Cavity-nesting birds expire in the birdhouses.

Another factor affecting then is the parasitism of nestlings by blowfly larvae.  The flies lay their eggs in the nest.  When the larvae hatch, they suck blood from the nestlings.  Usually they have little effect but if the blowfly population is high, or of the nestlings are weak from cold, wet conditions, the chicks die.

When the boxes are cleaned in the fall, which look like dark brown pellets, can be found under the nests.  Small wasps (Nasomia sp.) consume some of the blowfly pupae.

Researchers in southern Ontario found that these wasps were dying off and were interested in the state of these wasps in the north.  We sent 10 nests to southern Ontario to be examined.  Several other areas with bluebird trails sent them as well. The only information available at this time is that they discovered two new species of wasps (see below).

I monitored the trails on June 18.  Most of the eggs had hatched, although in one bluebird net there were egg shells (indicating a predator) and in another nest there were five dead nestlings that had been killed by red ants.  A few nestlings have fledged but most won’t leave their nests for at least another week.

Part Two: This has been one of the best years for bluebirds.  Every trail except one had more pairs of bluebirds than I have ever had in 29 years if monitoring the birdhouses.

By July 3, all the Tree Swallows had fledged, a total of 231 young. Some bluebird nestlings had fledged but many pairs were either sitting on eggs or caring for their young in the nests, and a few were building nests.

At the time of this writing (August 6), 98 Bluebird nestlings had fledged.  There are two pairs still nesting.  The two new trails Bob Saunders monitors fledged 98 tree swallows and 30 bluebirds.

Survival in our birdhouse trails was high this year.  There was little predation except in one trail where a pair of Merlins were nesting nearby.

The wren population was low.  When they nest in a box, they fill the adjacent boxes with twigs, covering eggs or the nestlings of other birds.

No pesticides were used on any of the crops near the trails.  Some herbicides and insecticides kill most of the birds using the boxes.

Every year late-nesting bluebirds abandon the eggs.  I don’t know why.  Perhaps it’s time to prepare for migration.  No nests were abandoned this year.

One would expect this project would be a safe endeavor, and it is.  But occasionally hornets or wasps will occupy a box.  They take exception to disturbances.  At one birdhouse this year, I decided to take a picture if the nestlings.  As I opened the box, I heard a rumbling: a bull had come to investigate.  He began stamping the ground.  I hurriedly took the picture as there was only some wire between me and the bull.  I have seen bulls twist a sturdy iron gate when angry.  I dropped the screwdriver and tried to find it in the grass.  After closing the birdhouse I retreated to the safety of the car.

I had previously mentioned the red ant that killed nestlings in one box.  When I checked the box, many angry ants crawled on me.  Does their bite ever sting!

Blowflies Proticalophora siala Calliphoridae

Adults lay their eggs in the nests of many birds.  The developing maggots (larvae) feed on the blood of the young nestlings.  During times of environmental stress, such as prolonged cold periods, it is believed that the presence of these larva weaken the nestlings, and if the infestation is heavy enough, can kill the birds outright.  The larvae grow to about 1 cm in length; larval development takes about 10 to 13 days after which metamorphosis to the adult takes place during the pupal phase in a puparium (hardened skin).  Pupation occurs at the bottom of the nest, after the nestlings have fledged.  They remain in this resting stage for about 11 days, after which the adult emerges.   The adults are about 1 cm in length and closely resemble House Flies.

A significant portion of the blowfly pupae are killed by parasitic wasp, Nasonia spp.(Hymenoptera: Pteromalidae).  Nasonia adults lay its eggs on the blowfly puparia and the wasp larvae consume the developing blowfly.  There are 4 known species  of Nasonia in North America.  Nasonia giraulti used to be found in Ontario but has not been found since the mid 2000’s.  In 2018 and 2019 bird nests were collected from throughout North America, including nests collected by Henry Miller, to try to locate this missing Nasonia species.  That species was not found, but two other species which haven’t been found previously in Ontario, were collected (N. vitripennis and N. oneida).

2020 Report   Bob Saunders

This year two Bluebird trails on Norris and Burris Roads were monitored by me for the Rainy River Valley Field Naturalists.  At the end of March Henry Miller had brought over some nest boxes and we removed the boxes on Burriss, intending to repair and paint them. However, on April 26, before I had a chance to paint them, Henry noticed bluebirds bringing grass into a box on one of his routes, so we decided to put them back up immediately, just in case. Amazingly, after I had put up the fourth or fifth box, three Tree Swallows began swooping around the box I had put up just seconds earlier, and one even landed on the hole of the box (photo below).  The amazing thing was that I had not even seen any Tree Swallows up until then – they were first of the year for me and they appeared out of nowhere.

The boxes were first checked on May 31.  One box, the first I checked, had four dead adults in it.  They had been dead for some time. I imagine they had tried to keep warm in cold, wet weather and had succumbed.  As this was the first box I had ever checked in my life, I couldn’t but help think what horrors I would find in the remaining boxes.  Fortunately, those were the only deaths.

Of the 13 boxes on Norris 5 boxes were occupied by Tree Swallows with a total 28 eggs by May 31.  On June 8 four of those eggs had hatched (from a nest with 6 eggs).  By June 21 all of the Tree Swallows had hatched, and ten nestlings had fledged and left the nest.  There were also two nest boxes occupied by Eastern Bluebirds, one with 3 blue-coloured eggs and one with 4 white-coloured eggs.  (Normally, bluebird eggs are blue, but occasionally white eggs are laid). By July 1 all of the Tree Swallows nestlings had fledged, except for one nest with 6 nestlings that were within days of fledging. One nestling had died. None of the Bluebird eggs had as yet hatched. On July 15 there were 4 new Bluebird eggs in a third box, the three in one box had fledged and there were 4 nestlings in the other box. By July 30 the 4 nestlings had fledged, and the last four eggs had newly hatched. I checked again on August 14, the four nestlings were still in the nest, but fully feathered and were just a few days away form fledging. I checked again on August 30 and those last four bluebirds had successfully fledged. Final result for Norris: 5 pairs of TRSW, 27 out of 28 eggs successfully fledged (one nestling died); 3 pairs of EABB, 11 out of 11 eggs successfully fledged.

At Burriss on May 31, 12 out of 21 boxes were occupied by Tree Swallows with a total of 62 eggs and 6 nestlings, one by an Eastern Bluebird pair with 2 eggs, and one nest with two House Wren eggs.  By June 8, there were 60 eggs in the 12 TRSW nests and 12 nestlings (72 eggs laid in total); 5 eggs in the EABB nest, and the two eggs in the House Wren nest plus another 3 eggs in another House Wren nest.  However, it appeared that both House Wren nests had been abandoned, as the eggs were cold. By June 21 all of the TRSW eggs had hatched (except one) and five had fledged.  Two nest boxes that had been successfully used by Tree Swallows had been taken over by Bluebirds and 6 eggs had been laid.  The five eggs in the first box (May 31) had hatched.  On July 1 there were 14 EABB eggs in three boxes and 5 nestlings in another. There were 19 TRSW nestlings and 52 had fledged. By July 15 all 71 TRSW had fledged; one egg did not hatch. There were 14 EABB nestlings and 5 had hatched. By July 30 all EABB had fledged. Final results for Burriss: 12 pairs of TRSW, 71 out of 72 eggs successfully hatched and fledged (one egg did not hatch); 4 pairs of EABB, 19 out of 19 eggs successfully fledged; and 5 House Wren eggs did not hatch.