Sunday, October 4, 2020

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 (

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

Sunday, April 26, 2020

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2019

2019 was the 11th year for the Tree Swallow (TRES) research project out on the remote Middleton Island. Again, this summer the TRES-population did not get monitored during the breeding season, but thankfully Scott Hatch of the Institute for Seabird Research and Conservation (ISRC) provided me with an overview of the nest boxes’ contents, as found on their annual inspection round after the breeding season:

Field map containing 2019's TRES results (ISRC). Middleton is approximately 7x2 km.

Based on this information I suspect that this year about 6 nesting pairs roamed the island, four of which laid eggs and produced one or more young.

I took the time to organize box occupancy between 2009 - 2019...:

Thursday, September 6, 2018

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2018

2018 was the 10th year for the Tree Swallow nest box project out on the remote Middleton Island (for more information check the previous annual posts). Once again Martha Hatch was kind enough to inspect all 20 boxes shortly after the breeding season:

I thank the Hatch family and ISRC collaborators for keeping an eye out for these beautiful birds during their stay on Middleton, and Tony Rinaud for the photos included.

Let’s end this post with a text about the Tree Swallow on Middleton Island, copied and pasted from the very interesting publication BIRDS OF MIDDLETON ISLAND, A UNIQUE LANDFALL FOR MIGRANTS IN THE GULF OF ALASKA by Lucas H. DeCicco and others of the Fish and Wildlife Service and University of Alaska Museum (Western Birds, Volume 48, Number 4, 2017):

Tachycineta bicolor. Tree Swallow. Casual in fall, but local breeders remain into early Aug (e.g., 30+ from 31 Jul to 5 Aug 1983; PJG, DRN). One was notably late on 9 Sep 2012 (photos ML26887741 and 26887751, LHD, CWW) and the only one recorded after early Aug. The species’ occurrence as a migrant in late Jul and early Aug was difficult to assess because of its status as a local breeder. Uncommon in spring: Earliest dates 12 May (one, 2012; KHE) and 14 May (eight, 1981; DDG). Uncommon as a breeder in summer, when first reported nesting in “cavities in an old building” by Rausch (1958:237); nesting continued into the 2010s (TvN). As of spring 2009 the species had successfully bred in a small number of artificial nest boxes (TvN). Notes: Tree Swallows breed commonly in coastal s-c Alaska, typically departing there by mid-Aug (Isleib and Kessel 1973).

Thursday, September 28, 2017

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2017

2017 was the ninth year for the Tree Swallow (TRES) research project out on the small (8x2km) and remote Middleton Island, located in the Gulf of Alaska (59°26′59″N 146°18′26″W). It’s one of the most isolated breeding populations and research sites (that’s thus far assumed to be largely predator free) for a beautiful bird that is considered a ‘model species’ in science. This year the Institute for Seabird Research and Conservation (ISRC) provided information on the TRES breeding season after a single nest box inspection (and cleanout) after the breeding season, of the 20 boxes currently present on the island. No in-depth study on their breeding biology this summer, but basic data on box occupancy and an indication for reproduction in 2017 instead. Some additional info and photos came from ISRC 2017 crew members. On 19 September Scott and Martha Hatch recorded the following nest box contents:

1. nothing
2. nothing
3. nothing
4. complete feather-lined nest with feces
5. nothing
6. complete feather-lined nest (feces?)
7. complete feather-lined nest with feces
8. complete nest with 3 dead, nearly fledged chicks
9. large straw nest base but no feather lining
10. nothing
11. complete nest with 5 dead, nearly fledged chicks
12. nothing
13. nothing
14. complete nest with 1 unhatched egg, also feces
15. nothing
16. nothing
17. nothing
18. nothing
19. nothing
20. nothing

(Complete nests with feces are expected to have resulted in fledged young)

Besides these data, I received four photos and some opportunistically noted observations of the birds around their boxes, in particular box 7 (the one facing the FAA weather camera), from which chicks fledged, which seemed to get visited by a TRES as late as July 17 (also the last recorded sighting of a TRES that I received).

Another year added... (By the way, after analyzing the data again and for accuracy I adjusted the number of occupied boxes for 2013 from 10 to 9 (not counting a few straws as an occupied box anymore)).

Distribition of occupied nest boxes in which eggs were laid in 2017.

The FAA weather camera ( was offline throughout most of the summer, due to the installation of a new camera and further maintenance, but it’s up and running agian now and box # 7 is still visible.

Discussion (& some serious speculation...)
2017 was a relatively good year as far as the number of nesting TRES pairs goes. Total reproduction remains unknown, but was likely relatively low due to chick mortality occurring shortly before fledging. During the previous years of the project chick mortality has been low and dead TRES chicks were a rare sight, at least for me. The thought that came to mind among some was that perhaps a predator had been picking off the adults this summer, cutting off food supply to their young. Has predation become an issue for the largely predator free population? ISRC crew members observed a Peregrine Falcon Falco peregrinus, the first predator that would come to mind, on the island but only in May. Additionally, I suspect that an adult TRES would not be an easy prey for a falcon, while around the same time the island would be full with other, more easy prey types (i.e. young sparrows, snipe?) (But Peregrines will lose many larger prey items to the Bald Eagles Haliaeetus leucocephalus there, perhaps the reason they're not nesting there, and this could increase predation risk for the TRES(??)). But no Peregrine was seen in June and July, when the swallows have young.

Previously, on Middleton chick mortality only had a significant influence on reproduction in 2012. The chicks involved that year were also large and close to fledging. Bad weather (cutting off the adults from their food supply) was the obvious cause that year. When looking at the historic climatic data for 2017, the end of June/first half of July appears to be a good period for TRES ( Unfortunately data from this on site weather station appears to be incomplete again and therefore unreliable). The only significant change to bad weather seemed to occur around July 14 - 18 (complete days missing here), but it's the type of weather that I would expect to kill TRES chicks. During my stays, however, TRES chicks fledged by the end of June/first half of July, so were these boxes still occupied by the time real bad weather appeared? Perhaps they were, since the last sighting of a TRES made by the 2017 crew was on July 17, of a bird exiting box # 7. On Middleton, the TRES do not appear to visit their boxes after fledging (and box 7 resulted in fledged chicks). And when looking at the historical data of this project, first eggs can be laid as late as June (June 2, in 2012), which could indicate that boxes can still contain chicks during the second half of July. So, with only little data to support this wild speculation, 2017 was also a late breeding season. It would be interesting to compare these thoughts on the TRES breeding season again with whatever happened at Long Lake (the nearest TRES study site in Southeast Alaska) this summer, but unfortunately I don't seem to be able to get in touch with the responsible there.

Update 10-25: here's what Chris Gates ( wrote me:

Hi Tim,

Thanks for Middleton update. It's always nice to hear some of these hardy birds made it to the island and nested successfully. I put some of your information about the blog and links to it on the facebook group Tree Swallows, so others here in the US can learn of your efforts.

I do have a comment regarding the possibility of predation on TRES by peregrines and other falcons. In eastern North America TRES form very large flocks after nesting, which usually stage for the summer months in and around large marshes. By late summer and autumn the flocks begin to migrate south with heavy concentrations along the Atlantic shore. Here, the swallow flocks are followed by falcons, peregrines and especially merlins, which apparently take them with relative ease. I've attached a photo of a merlin "packing a lunch." Although the swallow in the photo is an adult I expect hatch-year swallows are heavily targeted. Also, in one of my favorite books, "Curious Naturalists," Niko Tinbergen describes behaviors of hobbies hunting swallows along the North Sea coast. So I guess if peregrines or merlins happened to summer at Middleton some year they could be potential predators of both tree and bank swallows there.

Regards, and thanks again,

Chris gates

(I've seen Merlins there regularly in spring, but never in summer. I recall installing two artificial stick-nests for the species in 2006, hoping to attrack a pair...) 

A Merlin taking a TRES... (photo supplied by Chris Gates)

Update 2: Alexandra Rose informed me 2017 was the latest breeding season she's seen in 12 years of TRES monitoring at Long Lake...

A big thank you to Scott and Martha Hatch for their participation in the project, as well as to the 2017 crew members supplying some additional information and these photos of the 2017 MDO TRES breeding season!!

Monday, October 10, 2016

The Tree Swallows (Tachycineta bicolor) on Middleton Island in 2016

2016 was the eighth year of the Tree Swallow (TRES) nest box project out on the small (8x2km) and remote Middleton Island, located in the Gulf of Alaska. It provides housing to one of the most isolated TRES breeding populations of North America. I myself had the privilege to monitor them this summer, during a stay on Middleton between May 15 – July 15, covering most of the TRES breeding season.

The first TRES for 2016 was seen shortly before my arrival on May 14 (by employees of Alaska Fish & Game), at the central cluster of boxes near the Military pond. During a first round of nest box checks on May 22, it appeared that three pairs occupied three boxes, all containing nests (one unfinished and two finished)…

… and in box 6 also the first eggs for the season (a single 3-egg clutch). Back calculating (with a rate of one egg laid per day, usually laid in the AM) this would mean a first laying date of May 20. These 3 nests resulted in 3 clutches, all containing 6 eggs. Clutches in box 8 and 11 were initiated on May 25 and 29 respectively.

All of these eggs hatched the following weeks…

… allowing to have banding of 18 circa 12 day old TRES-chicks take place between June 18 – 27...

...under the watchful eyes of their parents, which during the operation found their entrance hole blocked by paper tissue. All 18 chicks fledged by the end of June/first half of July.

But things didn’t go this easy for all TRES on the island. An additional number of lonely males (probably 3 - 4) occupied single or clusters of nest boxes. These birds spent most of their days perched on top of their box in the hopes of attracting a partner for the season. The male on the photo above occupied the northern box cluster. It must have gotten quite desperate, as it was observed displaying towards Bank Swallows on a few occasions during the second half of June. The opening photo of this post shows a male that spent most of its summer on top of box 7 (facing the FAA weather camera). It never found a mate, but none the less brought a 5 cm thick layer of white gull feathers into the box (which I don't record as nest). Other places where a lonely male was seen regularly were box 13 and the southern cluster (boxes 15 - 17).

The late appearance of a second calendar year female on the island, first recorded together with a male around box 14 on June 8 (not known to be occupied before that date), must have caused excitement among the lonely males on the island. The two birds would make up Middleton’s fourth and final nesting pair for 2016. On June 9 this female copulated on the box, which on that day contained some feathers as nest material. On June 16 their nests was finished, but instead of them, a total of 4 very noisy birds (including 3 adults and 1 2cy female, photo above) got recorded, harassing each other around the box. On June 20 the nest contained 3 eggs (first laying date: June 18), but the two birds present appeared to both be adults… When on June 27 3 cold eggs and no birds get recorded in or around box 14, the breeding attempt had apparently failed.

What exactly made the pair from box 14 fail remains unknown, but when on July 8 the unoccupied box 15 (located 2 km from box 14) was opened for maintenance, the decomposing remains of an non-banded second calendar year (born in 2015) female TRES were found (thanks to Chris Gates for confirming the ID). Since this box hadn’t been opened since June 16, a time of death remains hard to determine, but the state of decomposition indicated that ‘weeks’ seems more likely than days, making it reasonable to assume that this was the young female from box 14 (last seen on June 16). Were it the lonely male TRES that harassed her to death?

Bank Swallows Riparia riparia were abundant breeders this summer. In 2005, 2006, 2009 and 2010 I counted the total number of nest holes, resulting in a varying amount per year (112, 48, 65 and 106, respectively). This summer a total of 203 holes was counted! In 1956 Robert Rausch recorded the species for a first time, with only a few pairs.
And many young Bank Swallows fledged this summer, which would often hang out together with the young TRES, making it very difficult to catch a glimpse of the young TRES in a brown mass of young swallows. I believe that among the swallows on this stick above the Military pond there´s at least a few young TRES… (or maybe all are?).

The 17 nest boxes withstood the 7 – 8 years of exposure to the Gulf’s extreme weather conditions quite well. But the scheduled maintenance of the project’s hardware took up an unexpected large amount of time. In the end all boxes got a fresh layer of paint, but two needed to be replaced, one repaired...

…and several had to be provided with a new swallow perch (a bended metal pipe at the top), also a measure to keep eagles and gulls away from the boxes. In the absence of this device, this Glaucous-winged Gull Larus glaucescens managed to put its feet on wet paint…

Three new boxes were added to the project this summer, including this one along the Dump Road, making a total of 20 nest boxes currently present on the island. As a tryout, two of these were constructed from white PVC planks, in order to see whether this material suits the TRES needs, and if it has a longer life span than wood. I thank Scott Hatch (ISRC) for providing the materials for this project!

A new map of the new situation, and the boxes used by the four breeding pairs in 2016’s. Boxes 18 – 20 were placed later in the breeding season and were therefore not available to the birds.

Now it's all set up and ready for a new season…

Friday, August 26, 2016

On my own behalf: Middleton Island, Gulf of Alaska (May 15 - July 15, 2016)

I recently spent some time on Middleton Island, a small (2x8km) and remote island in the Gulf of Alaska, in order to take care of some unfinished bussiness. It all went fairly well. This post contains an almost random selection of photos taken during my stay, as well as some words that touch the subjects of my work only slightly. More will come out eventually, but will need to be published on paper first…

59°29’N, 146°28’W is our destination…

The northern airstrip, facing south.

Sealions (mainly Northern Sea Lions Eumetopias jubatus and fewer California Sea Lions Zalophus californianus got recorded during my stay) made a comeback to the island a few years ago. Well, they try to make one, but regular human disturbance was likely the reason for them to abandon the north spit this summer and hang out on some smaller rocks offshore. This photo was taken during my single visit to the potential rookery, from larger distance than what was kept by most other island visitors… (perhaps time for some regulation here?)

The cliffs and slopes continue to erode. The past few years several landslides occurred, one of which took this large Red-berried Elder Sambucus racemosa (a well-known specimen for the older generation of seabird researchers, it was the one in use as boundry marker during counts) from the cliff at the south end and deposited it in the current lowland, where it was found flowering.

Most of Middleton’s largest Sitka Spruces Picea sitchensis appeared to be in poor condition. The oldest generation (now around 120 years old) are decaying and regeneration did not seem to occur within the past years. The monumental tree at the FAA headquarters blew over last winter, but its currently being held up by ropes.

The island’s Bald Eagle Haliaeetus leucocephalus population was booming; no fewer than seven pairs nested (six was the previous record). The platform pair raised three chicks this summer, while the NEXRAD radar on the left underwent major renovation. The first eagle pair nested on Middleton in the mid 1980's.

As usual, a few immature eagles remained on the island this summer, often harassing the kittiwakes in the former A.C.&W. station. There seems to be some movement among these birds, as some left and new ones appeared in the middle of the summer. I found one flying many miles offshore west of the island, eventually arriving to the island's north end. During the last days of June an adult bird arrived which was later seen battling with several of the breeding birds regularly, as it was trying to fight its way in the population.

If there’s one bird I can’t get enough of it’s the Tree Swallow Tachycineta bicolor… Only four pairs occupied the nest boxes this summer, fledging 18 banded chicks. Several unpaired males occupied boxes as well. There was still a lot to learn from those birds and a full report about the 2016 breeding season will appear on this blog hopefully this fall.

View from the largest tower within the former A.C.&W. station, facing south...

Facing northeast.

Middleton once held one of the largest Black-legged Kittiwake Rissa tridactyla colonies in the world. Their number dropped quite a bit during the past decades. On my last visit to the island in 2010, much of the southwest cliff was still occupied by them. This summer the few kittiwakes nesting on boulders in the lowlands exceeded the number nesting on the cliff.

A movie of this Wilson's snipe Gallinago delicata facing variable wind directions would have been a lot funnier, I guess…

My best shot of a Killer Whale Orcinus orca (or Loch Ness Monster?) while it was on a hunt for seals.

I spent a lot of time scoping out >10.000 Glaucous-winged Gulls Larus glaucescens in their breeding habitat, suspecting there had to be a different species of gull in there somewhere (besides Mew Gulls). I wasted my time and found none.

Never did I see so many white feral rabbits on Middleton. In the first decades after their introduction in 1954, white remained one of the dominant colors. Natural selection probably changed something (in particular after the appearance of Bald Eagles in the 1980’s?). Strange to see so many, while at the same time the eagle population experienced a record high. This individual was taken care off by a Glaucous-winged Gull, who’s appetite for Middleton’s rabbits appeared larger than before.

It always seems like the whole world comes together in a Black Oystercatcher Haematopus bachmani nest. Every Zen garden should have one.

Presumed Japanese tsunami debris, providing a shelter for rainy moments after counting the island's entire oystercatcher population.

Every year a new boat washes up. This is the latest addition to the Middleton fleet. Fancy...

The rusty remains of the WWII era cargo ship U.S.S. Coldbrook are still holding up… Sydney, seen here from the back, maintained a blog about her experiences on the island (and will do so again next year?). Check out the link to that somewhere on the right.

The presence of a Bald Eagle nest on the Coldbrook’s mast detered many Common Murres Uria aalge and Pelagic Cormorants Phalacrocorax pelagicus from nesting on or inside the wreck. It was obvious that most of the 1000+ Common Murres present this summer did not breed due to regular eagle disturbance.

Inside the back of the ship an old Common Raven Corvus corax nest was found (center back in the photo, now containing kittiwakes). Ravens made their first appearance on Middleton during winter 2009/10. Two were present this summer, but no nest was found.

The South Spit

A handful of Mew Gulls Larus canus nested on the spit. They’re easily distinguished from kittiwakes as they lack a soul.

After a mild winter, Pacific Wrens Troglodytes pacificus were extremely abundant. It appeared that all available habitat was occupied this summer. On good wren-years, accumulated driftwood on the South Spit is known to hold a single territory (note the singing bird on the first photo). This year two males were singing there regularly. Numerous nests were found in the driftwood this year ( inside the largest trunk on the second photo). I recall that after a cold winter, in 2006 only a few singing birds were heard. There are some unconfirmed reports of a die-off.

Part of the vegetation study I’m conducting are several exclosures, which are small fenced off squares allowing me to monitor the development of the vegetation in absence of the island’s herbivores. Previous winter several storms damaged the already rusty chicken wire, allowing some rabbits to enter. Thankfully this happened outside the growing season so no real harm was done to the project. Every summer a few uncommon plants grow within the exclosures. As in 2010, this Unalaska Paintbrush Castilleja unalaschcensis grew at the same place inside the same exclosure at the north end. The only other paintbrushes noticed in that area were the ones used by the contractors renovating the NEXRAD.

During summer the rabbits eat most of the island’s flowers. Besides growing within an exclosure, there are several other ways in which plants manage to remain present on the island. Some of them are simply too beautiful to get eaten, like these Few-flowered Shootingstars Dodecatheon pulchellum…

Wild-flag Iris setosa

Fischer's Orchid Dactylorhiza aristata

Some plants fight back: the known patches of the carnivorous Round-leaved Sundew Drosera rotundifolia, just north from the Dwarf Forest, were still there (and increasing?)

I was hoping to put a bit more effort in social hygiene during my stay this time, by taking a plunge in some of the island’s fresh water. Too bad Leeches Hirudenea sp. recently found their way to Middleton (at least I never noticed them before). They now occur in pretty much all fresh water bodies present on the island.

Lapland Longspurs Calcarius lapponicus are birds of the alpine tundra, but Middleton's north end still provides suitable breeding habitat to 8 – 9 pairs counted there this year. They were a bit more common during previous visits between 2005 - 2010, when territories were also found along the gravel roads further to the south.

This is as close as I wanted to get to the pair of Red-throated Loons Gavia stellata in the Loonpond. The first recorded nesting of this species took place here in 2005. In 2010 a second pair showed up along the east, in a pond at the end of the Dump Rd, but it did not nest. This summer no fewer than four pairs were present, at least three of which nested and these were all seen with chicks. Red-throated Loons are on Audubons’ 2016 Watchlist, so I informed them about this positive development.

Yellowlegs sp… Tringa sp. in the Military pond. I didn’t spend a lot of time looking for migratory species (the timing of my stay was well off for experiencing fall migration). However, I was informed that up north the ice melted early this spring, allowing many shorebirds and waders to move into and depart from their breeding areas relatively early this year. That may have been the reason why I still managed to get my share during the first half of July.

July 4: low tide 07:47 AM -98 cm (predicted), northeast intertidal area.

Whatever is left of one of the exposed fossil banks in the northeast, containing large numbers of marine shells. Only visible during the lower tides.

Chamisso's Cotton-grass Eriophorum chamissonis, on a late summer evening.

It was a fantastic experience being able to connect with Middleton again this summer, to be able to observe how things change in nature and understand the different timescales on which it all takes place. And find a few new things along the way... It was also very nice to meet up with some old friends I hadn´t seen in years and make some new international contacts as well. Thank you all for making my time on Middleton an escapade I shall not forget. I hope I manage to get out there again at some point in the future.