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!