Enigma in the garage

A case of extreme individual specialization? A bird's personal choice? It looks like mama and papa Glossy Swiftlet came to an agreement and decided to build a more luxurious home. In my garage. I'm puzzled but at the same time I'm sure that the birds know what they are doing... For me, I guess, this is enough to know. Swifts are amazing creatures and it is great to keep "wonder" as we may never figure them out anyhow. I wrote this in my first Swift article a while back; Swift flight. However, in this case, it would be interesting to know; How is science going to handle this? Just imagine, we have 1 pair in a colony suddenly doing something significantly different than all the other ones. Could it be a bird's personal choice? I can find very little about this subject, it looks like this may be taboo in science! Bolnick et al (pdf, published 2003) is an example of a paper where the intro suggests birds may make individual decisions. However further down the same paper it doesn't seem to be regarded as personal choices birds may make. A strong intro is to be followed by talk about specialization of more individuals within a population. We may call this 'niche' variation, in other words part of a population has adapted to different behaviour. Bolnick's paper title; "The ecology of individuals; Incidence and implications of individual specialization" is a little misleading. Individual gets seriously stretched to groups / sub-population of birds. Additionally most of what Bolnick described is about diet, feeding or foraging methods, which are essentials for survival and usually easy to explain as birds may get driven into these behaviours, instinct yes. Who would not want to adapt and be efficient at finding food? At the bottom of this page I have included some interesting links of articles about 'smarter' than usual birds. The Crow is a classic example of course. I like the Nightjar piece stating they may have self-awareness when blending their camouflage into the environment.

Glossy Swiftlets have taken residence in my garage for a few years now. They are allowed to poe the walls, my car, whatever I may stall in there. Not a single flying insect is safe around our house. It started with 1 nest and it took a while for a second to appear. After that they got on a roll. The oldest nest has been reused for several broods with 2 + 2 + 1 + 1 young successfully fledged. The nest is still in use, I think the pair are on eggs today 7 august 2017. We now have a total of 7 nests of which 5 are active today. Three nests have young birds in it, including two youngsters in the odd fiber-build nest. Construction of nest number 8 is half completed.

Glossy Swiftlet nests

Glossys are a widespread species; Thai-Malay Peninsula, Andamans, Philippines, Borneo, Indonesia. Thirty-one subspecies have been recognized. Plumage may show some differences between populations/individuals but much of the variation appears to be clinal and not clear-cut between subspecies. Nests throughout its range are constructed using plant material and saliva cement. Commonly used are (fibrous) moss, lichen, pine needle in some areas and (grass-straw-coconut palm) fiber or a combination of those. All those are very common materials in most environments here in the tropics (except the pine). I wouldn't accept for us to think the Swifts are just instinct driven nobodies who would just go to grab the first available material. Different populations may have learned to use different nesting material even though all of the usual material would be available at most sites. I have included below some links with info from various breeding sites in SE Asia. However, any 1 population/breeding colony seems to go with 1 type of nests. If it's moss they all do moss in the colony. I have included below some of my own photos of a colony nesting in houses of lowland Borneo with all nests constructed using (straw-grass) fiber. This was in the town of Beaufort in Sabah.

Back to my garage. The first 4 nests were done using fibrous moss only. I mean of course the saliva cement is always there to keep the whole together regardless the choice of vegetable matter. Then, and that's only a few months ago, a totally different nest appeared. Only fiber (looks like grass-straw) used. Not a tiny bit of moss to be seen. Other nests (2 more completed so far, 1 building now) were being constructed using fibrous moss again. No straw to be found in those nests. I'm puzzled. I'm free to tell you; I don't know. Amazing Swifts. Science may feel challenged here as this will be a case of "more research needed". (-; Psst translated this means; 'we don't know' ;-)

I must admit I had a few thoughts of possibilities coming up in my mind. However, there are no other Swiftlet species breeding here on the island. These are all Glossy. Moreover, the pair from the odd nest do look exactly the same. This includes size, colouration, markings... anything detectable in the field or on photo I would say. They also behave and sound the same. Flight is similar, frequency of nest visits and time on nest; nothing suspicious. To compare, the birds I photographed on Borneo on the fiber-build nests are clearly from another subspecies. They have a stronger blue gloss (extra sheen) and lack the pale scaling on the rump. I would also like to note that plenty daylight reaches inside the garage. This would not be a favourable breeding site for echo-locating swifts.

Oh, perhaps, do I have a visitor Glossy Swiftlet in my colony? A fiber-nest builder? Not 1 from Borneo. Those look different as described in the paragraph just above. From another population in Philippines perhaps but not just 1 bird then. Glossy Swiftlet parents take turns on the nest. One is sitting on the eggs or small young while the other is out on the wing for insects. Same with nest building (own observations), both birds of a pair do construct. Sometimes both birds are busy together sitting on the nest for construction. I'm not having a female with 'mossy instincts' and a male with 'fiber instincts' or the other way around. Then we would see a mixed material nest. A visitor pair? Gush, that would be seriously exciting. Do they form pairs for life? We know very little about them. Hard to figure the pair theory with birds that may nest in colonies of up to 1000s. Even then, a "fiber-nest" foreigner pair that travels together to another area and will take up new residence in a strange colony? It would be amazing especially also because we are on an island. Birds would have to travel over stretches of sea. Science tells me Glossy Swiftlet is a resident bird... They have split them up in sub-species. Populations are not supposed to mix... or???

They temporarily ran out of moss? They had to use straw fiber as second choice? This is a no-brainer. Moss nests were constructed at the same time. Moreover, we live in an area with no seasons. Conditions don't change. Moss must be available at all times. Three days without rain is called a drought over here and that's valid year round. The last time we had a dry season was because of El Nino 2 years ago. The odd fiber nest has been here for a few months only. Nothing changes here. This very much is a poor Filipino village. People (but us) do not keep their gardens, everything grows like crazy on the fertile volcanic soil, the whole village is wild, dirty and unkempt. This would be a perfect place for birds and wildlife if not the locals would kill everything. (Don't worry my Swifts are safe inside the gate.) Anyhow, what I would like to mention; over here there can not possibly be a shortage of natural material for nest building, ever.

First paragraph I mentioned the Bolnick et all paper on individual specialization. I think they had a pretty strong intro stating that individual specialization is a widespread but under-appreciated phenomenon -that poses many important but unanswered questions- ... yes it reads like that in 1 line! I think the intro may have almost cost them their job as scientists :-) However, I thought the rest of the paper saves them as they go on merely to describe niche behaviour in sub-populations. Individual? No Sir, not really. Of course they never had such a great example case. I'm very lucky with my 'garage' Swiftlets. One (1) individual bird/pair in a same-(sub)species population to do something very different by purpose as compared with the rest of the population??? And this done not related to survival or something else essential...??? This must be a science no-go, unheard of. We can't explain it so does it exist?
Science must find another 'Swift' explanation. Something logical that may justify the grant money to be spend. How are we going to handle this? Free thinking is not an option. Birds to own the ability of a personal choice is not an option. Only humans, max an ape or dog may do this. Birds can choose only because it benefits the species survival etc., right???
Time to rethink? Open our minds? Taxonomic classification has humans on the top and everything else below isn't it? Maybe those Swifs are smarter than we may think. What if we could do a view from the Swifts perspective? When I started birding at 8 years old I was already a keen observer. The child I was had started wondering why humans are the only species on earth who have not learned to live without polluting/destroying their own nest! I thought those birds were pretty smart. I learned to love them. Of course by now school and society has showed me how to grow up and they trained my brain to have different thoughts. I have unwillingly joined the race to deplete earth's resources (our 'lifestyle'). After all it is my concrete-build garage to provide those amazing Glossy Swiftlets with a safe home, isn't it. Yes, I almost saved the world :-)

Mossy-nest Glossy Swiftlet
This is the oldest nest in the 'garage' colony. It typically has more saliva cement as the birds may add some
over time. The cement also looks older, that is 'yellow rather than transparent'

Glossy Swiftlet pair
One of the newer mossy-nests with the pair attending.

Fiber-nest Glossy Swiftlet
Yes bird, you did something amazing. A master fiber builder you are. Successful, with 2 healthy young growing up.

Glossy Swiftlet bolus feeding
Mama, papa, 1 of the babies and their very special DIY home, none of the other Glossy Swiftlets have one build like this.

Glossy Swiftlet nest building
Nest number 8 during construction.

Swiftlet nest with youngSwiftlet young on nest
Two of the mossy nests, on the left with an older young, on the right with a new 'baby'.

Borneo Glossy SwiftletGlossy Swiftlet Borneo fiber nest
A few nests of a Glossy Swiftlet colony under overhangs of houses in Beaufort town, lowland Borneo.
These are from another subspecies then my Glossys at home, note the dark rump and they also have a stronger blue gloss.
All nests in this colony are constructed using straw fiber just as the 1 'special' nest in my garage.

Cebu, Philippines; Fibrous moss

Fraser's Hill, Malaysia; Fibrous moss and lichen.

Sandakan, Borneo; Collecting fiber from palm trees. (Also reported from Pen. Malaysia)

Andaman Islands; Moss - lichen.

Perak, Malaysia; Grass-straw fiber.

Gomantong, Borneo; Colony with all similar nests. (crow smart)  niche feeding in gulls

My wife, my daughter and my Swifts; that's the place I call home!


Comments received;

I think your write up may give arise to contemplation which is what you are intending to accomplish.

I am not so sure there is a need to speculate as to why the birds choose different material.
These are living organisms and capable of much more then the labeling we enforce on them.

We went to Gomantong Caves on Borneo to identify almost identical Swiftlet species
just by their different nests that they were sitting on... nice twist and new insight
which makes room for appreciation of these birds beyond identification.

More comments welcome via our
or email



Stijn De Win

I don't know
You don't know?
Science doesn't know
God doesn't know
Nobody knows
eh, wait
The Swifts,
they do know!

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