The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2024

Middleton Island, Gulf of Alaska: Nest Box #2, North End, 2024 (Photo: D. Costa).


The 2024 season marked the 16th year of the Tree Swallow (TRES) project on Middleton Island, a remote outpost in the Gulf of Alaska. Led by Shannon Whelan, the ISRC field station crew managed to keep a close watch on the TRES population, despite their busy schedule focused on seabird research.




Tree Swallow on Middleton Island, North End, Gulf of Alaska, 2024 (Photo: D. Costa).


In early spring, four new cedar nest boxes were installed to replace older ones that had either not survived the harsh winter or were unlikely to last another breeding season. These new and robust cedar boxes were generously provided by Audubon Alaska, which granted the ISRC the funds to purchase 10 nest boxes last year. The design, recommended by Chris Gates (treeswallows.com), was quickly built and shipped by Glenn Foote, arriving just in time for installation in the spring of 2023. Although two of these boxes were installed last year, they went unused by the swallows, making us eager to see if they would be occupied this year and add value to the project.




One of the new Cedar nest boxes (# 2, installed last year). Middleton Island - North end, Gulf of Alaska, 2024.

When the TRES arrived on the island in 2024, they found 19 available nest boxes, crafted from various materials as part of an ongoing quest to discover the best (sustainable, durable, and affordable) designs that could withstand Middleton's extreme weather.

The crew kept a vigilant eye out for the first TRES, which was sighted on May 23—a single bird soaring past the Chateau.


Results of the 2024 Season:

Nest box check results August 4-6, 2024 (S.Whelan):

During the nest box checks conducted from August 4-6, 2024, the crew observed that five of the boxes were occupied, and at least four of these led to successful fledging of young swallows. The new cedar boxes proved particularly successful: three out of the six new boxes were used by the TRES, all resulting in fledged young. Shannon also documented each nest box and its contents with photographs, showing the promising outcomes, packed together here in a slideshow:





Unfortunately, not all stories had happy endings—three large chicks were found dead in Box 20, likely victims of the island's notoriously bad weather. While it's unclear if any chicks managed to fledge from that particular nest, the abundance of droppings in other successful nests suggested that large broods were fledged this year.




Distribution of Tree Swallow nest boxes on Middleton Island and their status in 2024:

Overview of nest box history:






Despite the challenges posed by the environment, the new cedar boxes appear to be a success. If they'll last long enough, their design will likely serve as a model for future nest box installations on Middleton Island.


Acknowledgements
A heartfelt thank you to Shannon Whelan, Scott Hatch and the ISRC team, Audubon Alaska, Chris Gates, and Glenn Foote for their invaluable contributions to the project.

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2023

Box# 7, near the FAA-weathercamera (Middleton Island, Gulf of Alaska. August 10, 2023).


2023 was the 15th year of the Middleton Island Tree Swallow (TRES) project. Martha, Katelyn, David, Shannon and Scott of the ISRC provided information and photos of the 2023 breeding season. This is, I hope, a correct interpretation and presentation of their findings.





Distribution of the TRES on Middleton Island in 2023:



7 boxes contained (largely completed?) nests. However, box#5's contents (shown below) appeared a bit strange. A lot of moss is used, something I've never seen the TRES do on Middleton. I believe this could be the work of the island's often abundant Pacific Wrens Troglodytes pacificus. Perhaps these have found their way to the TRES real estate market? I'll therefore count 6 occupied nest boxes in 2023, by the TRES.



Suspected Pacific Wren construction in Box#5 (Middleton Island, August 10, 2023).


Shannon wrote: 'It was exceptionally damp/rainy/foggy in 2023, but it seems the TRES were happy with that'. Indeed, the TRES seems to have had a good summer on Middleton. 

The first TRES sighting in 2023 was on 18 May by Sam D., who was watching for them.



*Shannon came up with two new arrival dates, for 2021 and 2022, that hadn't been reported to me before:
- For 2022 TRES arrival date, Don-Jean L. was watching for them and the arrival date was 18 May.
- For 2021 TRES arrival date, Aidan C. was watching for them and the arrival date was 21 May.


More good news: in spring 2023, two new nest boxes were installed! These replace the lost #1 and 2. The new and very fancy Cedar boxes were provided by Audubon Alaska, but could unfortunately not yet be opened for inspection or photographed.






Little is known about eggs and fledging. This could only be determined for a few nest (based on information and/or photos). Breeding results for boxes 12, 14 & 20 remains unknown; these at least contained nests.



Obvious signs of fledged young in box 4 (Middleton Island, August 10, 2023).




A single egg was found in box# 18, a case of 'egg-dumping' (Middleton Island, August 10, 2023). Like this nest box, box#19 (located within the ISRC camps site) is also constructed from white PVC-planks. If the provided information is correct, 2023 is the fist year the TRES occupied and raised chicks in a nest box made from this material. Unfortunately no photos are available.

This is box#19 on August 7, 2022. "Don't be fooled, it's not real wood... It's PVC!"

         

I thank the 2023 ISRC crewmembers, who, despite their physical struggle this summer, gathered and provided information and photos of yet another interesting TRES-summer out at Middleton. And a surprise came: Audubon Alaska granted ISRC $500 USD to purchase 10 new cedar nest boxes. Chris Gates (treeswallows.com) recommended a new model of nest box and Glenn Foote rapidly built and shipped boxes in time for the ISRC-crew to get them to the island in spring 2023. I thank them all very much for their work and participation!

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2022

2022 was the 14th year of the Middleton Island Tree Swallow (TRES) project. ISRC-crew members cleaned out the nest boxes in spring. After 5 additional boxes were installed last year, replacing some of the ones that were gone, another old wooden box (Box #1) didn't survive the winter, leaving 16 nest boxes available to the TRES this year. By the end of the summer, on August 7, al boxes were inspected again, cleaned out and photographed. Somewhat disappointingly; in 2022 only one pair of TRES nested on Middleton; the lowest number in the projects' history.


7-August-2022
Swallow boxes check
Box 1: No Box
Box 2: No Box
Box 3: Good shape! Missing a nail, empty
Box 4: Good shape, missing nail, empty
Box 5: Perfect condition, full nest, poop inside nest
Box 6: Good condition, empty
Box 7: Good shape, missing nail, empty.
Box 8: Okay condition but rotting. Should be replaced in the nest 2 seasons. Empty.
Box 9: Perfect condition, empty.
Box 10: Broken, needs to be replaced.
Box 11: Perfect condition, empty.
Box 12: Good condition, slightly rotten, empty.
Box 13: Good condition, back corner rotten but box feels sturdy. Empty.
Box 14: Perfect condition, a few pieces of grass and 1 feather.
Box 15: Good condition, starting to rot a little bit in the back and bottom. Empty.
Box 16: No box. Needs new one.
Box 17: Good condition! Empty
Box 18: Perfect condition! Empty
Box 19: Good condition. Post slightly angled. Empty
Box 20: Good condition. Empty




Remarkably, the only nest built this year, was found in box # 5; a green and relatively small prefabricated box, made from recycled plastic boards and 4 wooden blocks giving some strength to the structure. These are sold in Europe and are intented for House Sparrows Passer domesticus. Only the nest box entrance was enlarged to suit the TRES. 

 











With the ongoing decay of the wooden boxes, the search for the most "durable" nest box design continues. Here the remains of the first generation wooden box # 10. 

Two of the three new "Dutch-built partially recycled" nest boxes contained a bit of bird poop, but whether this came from a TRES or a migrant of a different species remains unknown.









The other one of the two green prefabicrated recycled nest boxes installed last year (box # 14) was still in perfect condition. It also appeared to have had the swallow's (short) interest, as it contained a few pieces of grass and a feather. Not enough to count as a nesting attempt, but perhaps an indication that the TRES has a preference for this model. More swallows will be needed to proof this. Hopefully next year a few more will make it to the island again.

I thank ISRC-members Shannon, Stella, Sierra and Scott for monitoring the TRES on Middleton this year!

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2021

2021 was the 13th year of the Middleton Island Tree Swallow (TRES) project. The season started off with an inspection of the nest boxes by ISRC-members in April. Five new nest boxes were installed, replacing ones that had rotted away. Thanks to their efforts in 2021 17 boxes were available to the swallows:


Swallow boxes check, conducted by ISRC personnel on April 19, 2021:

Box 1: Good shape, slightly rotten but sturdy. Might need to replace in 2022/2023

Box 2: No more door present, wood very rotten. Needs to be replaced

Box 3: Good shape!

Box 4: Good shape!

Box 5: Old box fell off and was no reparable. Replaced by new box (green one) in exact same location/orientation.

Box 6: Old box replaced by new one (white one) in the exact same location.

Box 7: Good shape!

Box 8: Ok condition, should last through another season but would need to be replaced in 2022.

Box 9: Old box replaced by new one (white one). Exact same location as previous box.

Box 10: Broken (bottom and side panels missing). Needs to be replaced.

Box 11: Replaced with new box (white one). Box on the angled post facing down and angle adjusted using washer to avoid having the box too tilted forward. New box slightly lower than old one as per recommendation.

Box 12: Good condition, slightly rotten but sturdy. Consider changing in 2022/2023

Box 13: Good condition, back corner rotten but box feels sturdy. Nail for the door missing.

Box 14: Box completely broken and rotten. Replaced by new box (green one).

Box 15: Good condition, starting to rot a little bit.

Box 16: No box. Needs new one.

Box 17: Perfect condition!

Box 18: Perfect condition!

Box 19: Good condition. Post slightly angled

Box 20: Unknown


Unfortunately, due to a lack of time the 2021 ISRC-crew did not manage to monitor the TRES during the breeding season, nor conduct a post-breeding season nest box inspection. The following inspection round could only take place in April 2022, during the start of the following ISRC-season. Details on the 2021 TRES-breeding season were derived from what was found in the nest boxes during this inspection:




From this information it can be concluded that in 2021 five TRES-pairs nested in Middleton Island's nest box project.

Notes on the 2021 breeding season (and looking ahead)
As for potential predators, a Peregrine Falcon was recorded on several occasions in spring, in April until May 11th, but not during the period the TRES were nesting on the island (data: ebird.org). The relative large number of dead eggs and chicks found in the nests may be the result of a long period of bad weather taking place at some point in June/early July.




Several of the nest boxes currently present on the island have been out in Middleton's harsh climate for 12 or 13 years now and underwent only a serious renovation (= complete checkup + new layers of paint) in 2016. It's inevitable that they will continue to decay and more and more boxes will be lost. To take care of this problem a number of boxes installed from 2016 onwards are (partially) made from recycled plastic or PVC:



Boxes # 18, 19 and 20 are made from white PVC-planks and were installed by the end of the 2016 summer. These have thus far never been used by the swallows (except for an occasional piece of nest material).




In spring 2021, 3 boxes were installed to replace some of the most popular, but damaged ones (#'s 6, 9 and 11). These new boxes are made from wood and are similar in size to the remaining types constructed for the project, while adding a (recycled) plastic (dark colored) roof and an aluminum mounting bar. In their first year these did not get used, although a single piece of nest material was brought into box #9.




Two of the new boxes that were installed in spring 2021 (to replace #'s 5 and 14), were made entirely from recycled plastic panels. These boxes are green and have much smaller dimensions than a regular TRES nest box. They were already brought to the island in 2016, but were at that time deemed too small for the TRES to use (and too fragile to remain there in winter). These European nest boxes are designed for house sparrows, but have a slightly enlarged entrance. Surprisingly, in 2021 box 14 (the one on the photo above) was used by the TRES! It contained a nest with 3 dead chicks...

With the ongoing decay of the wooden nest boxes in the project, in 2022 the TRES will find a relatively larger number of synthetic nest sites available to them. We will hopefully soon find out whether the TRES are willing to adapt to these boxes, so the amount of maintenance can be reduced significantly.

I thank the 2021 & 2022 ISRC-crew members for their help!

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2020

Tree Swallow perched above box 7 (facing the FAA weather camera). June 18, 2020. Photo by S. England (Ebird.org).


2020 was the 12th year of the Tree Swallow (TRES) nest box project on Middleton. This year again no data could be obtained during the breeding season, but thankfully Martha Hatch (part of the ISRC crew present in September) checked, photographed and cleaned out all nest boxes still present on the island:











Notes on the 2020 breeding season:

- 16 nest boxes were available to the swallows. 4 were either gone or had become unuseable to the birds. 7 boxes currently are in such bad shape that these might not survive the coming winter. This would leave 9 boxes for the next breeding season. This is also the maximum number of occupied nest boxes (9, in 2013). Therefore, for proper continuation of the project, some replacement boxes will have to be installed.

- Instead of wood, nest boxes 18-20 were constructed from PVC planks. These have similar dimensions to the wooden ones, but are white on the inside. Thus far, these have never been used by the swallows. 

- As far as potential predators go: a Peregrine Falcon got recorded on June 22, July 21 and July 22 (Ebird.org).

 

Again, I thank Martha and Scott Hatch for their effort!