Valentine's Day.......

 ......and, I'm guessing, bushtit love was in the air.  At least I'm guessing nest-building was already under way in Portland.  I'll be there in a little over one week to see for myself.  

The bushtit nest is one of the most remarkable features of bushtits and is, as all nests are, a physical and permanent (sic) manifestation of a behavior.  If you haven't seen one, take a look at my entry on March 6, 2020.  That was a lovely nest. 

The bushtit nest is a major feat of engineering with a combination of lichen and spider web serving as the stretchy scaffolding.  You wouldn't know it just by looking at them, but the combination is magic.  Spiderweb and lichen both have velcro-like properties such that they stick together and become extremely malleable.  Together they are material of choice for many other species as well:  hummingbirds, vireos, goldfinches, etc.  

Although in the 1930s, Evelyn Addicott described two modes of nest-building in bushtits, I've only seen one.  I suspect she interpreted different states of completion during what I call "Stage 3" (see below) as different building methods.  In fact, "Stage 3" is a broad category and encompasses several substages. It's also possible she was observing nests that were also being pilfered by nest-material thieves.  These can appear very holey and thin and are often abandoned.  

So what are the nest building stages?  I'll describe them here.  I'll find pictures and post them here another day.  

Stage 1 is barely visible at first.  It consists of a hint of spider web and lichen on a branch or in a fork between two branches.  You'd never notice it on your own.  The only way to locate an early Stage 1 nest is to see the birds carrying material repeatedly to the same area in a tree.  If you see that and can't make out anything in the area they are going to, you have found one!   Sometimes you can see them placing the material and even stretching it and securing it with their beaks.  But it can certainly seems almost imaginary.  As the nest progresses, though, a late Stage 1 nest becomes a thin platform of lichen and spider web that stretches between two tiny branches or, sometimes, just a blob of spider web and lichen in, say, a clump of mistletoe.  BTW, this is often a "trial and error" stage.  At this point the bushtit builders are still gauging (in whatever mysterious method they are using) the suitability of a particular nest site.  Consequently, Stage 1 nests may appear and disappear....and even reappear.  It happens.  

Stage 2 is when you finally see something resembling a nest -- although not a bushtit nest.  A Stage 2 nest is a simple cup.  The birds have completed the platform (Stage 1) and are now bringing in more material and are sitting in it and moving about to stretch it downwards so that the cup hangs.  This is were the strength and flexibility of the spiderweb/lichen combo becomes so important!  As it stretches longer and longer is gradually morphs into a...

....Stage 3 nest which is a long hanging sack without a hood.  Stage 3 nests can vary a great deal.  They can look quite flimsy if the birds stretch more than they bring in new material.  If they are experienced breeders, they will be careful to bring in enough material so that holes never appear and the sack, although thin, seems pretty substantial.  During Stage 3 the nest reaches its full length and material is added to the bowl at the bottom of the sack to strengthen it as the "true nest."  

Once the sack area of the nest is substantial, the birds begin to fashion a hood and work primarily on that and the outer parts of the nest.  This is a Stage 4 nest.  It's not finished but it finally looks like a bushtit nest with its characteristic gourd-like shape and a hood near the top with a side-facing entrance.  But it looks rough and the entrance is barely complete.  Once the nest is at a Stage 4, the adults will sleep in it;  if there are more than 2 building, they will all crowd in.  

Stage 5 I reserve for that "perfect" finished bushtit nest.  It's tightly put together with a substantial hood and a clearly defined entrance that has been lined and tightened so that only a bushtit can enter.  Sometimes, the entrance even extends a bit out from the nest like a short tunnel.  It's festooned with moss, spider egg cases, and other material from the environment to camouflage it as mush as possible. At this point, there is little building activity.  Feathers are the primary material brought in now as they fill the nest with hundreds they find in the area.  I can never figure out how they find so many!!  

The final product is truly beautiful and a masterful structure that has taken up to 3 weeks to finish.  Which is all the more annoying when it's torn to shreds by a predator!   For me and for the bushtits.  

So that's the overall process.  This can vary in some interesting ways which I'll elaborate on in future posts.  In the meantime, that's a start.