The deadly heatwave of 2021

No recap of the 2021 bushtit field season can fail to omit the effects of the unprecedented heat wave on bushtit nestlings.  And it wasn't good news.  It was, in fact, quite sad.  And informative.  Unfortunately.  

In late June, a "heat dome" settled over the Pacific Northwest for 3 interminable days.  It was record-setting and completely out of the range of normal for the area.  Completely.  Each day the temperature climbed.  By the 28th of June it was 116 degrees in the shade.  Walking to the grocery store from my house -- only a 5 block trek -- felt risky.  My daughter, her partner, and their cat joined us in my 800 sf house which we tried to cool to barely acceptable with 2 ACs.  Even so, we had to partition the house into one small space, leaving the rest of the house to bake.  We all became vampires...avoiding the day and going out only at night for "fresh" 100 degree air and short strolls around the neighborhood.  

But what of the bushtits?  How were they faring?  It was the tail end of the field season and we had only 8 active nests.  One of them was close to fledging age.  One was still incubating.  The other 6 had nestlings....some very young, some older.   One of these was a nest (WT 12) we were particularly interested in as there were two males and one female.  All three birds had built and incubated and were now feeding.  We were, understandably, anxious to get blood samples from the nestlings once they were old enough.   Were both males co-dads??  It seemed highly probable.  So that was the only nest we kept tabs on for those 3 days.  One of us would head out at dawn, watch it for 30 minutes in the 90 plus heat, and then crawl back into whatever cool cave we had devised for ourselves to wait out the day. 

By the 29th the heat had abated somewhat so we set out to check the 8 nests we had.  I won't get into the all the sad details of what we found.  I'll just summarize:  

One nest had been torn apart by predators, the contents most certainly devoured.  That's not unusual.  Another had fledged prematurely and a grisly fledgling corpse was hanging from the entrance -- sans eyes and brain -- apparently entangled in the artificial poly the parents had used to line the entrance.  Ok.  Gross, weird........and huh???

Two others were silent and when we opened them, contained dead nestlings.  The adults were no longer even in attendance.  (We did, I might add, relocate every single adult with an active nest during the heatwave and could verify none of them had perished from the heat.)  

Happily, 3 nests had survived:  one still had eggs and the other 2 were feeding kids, although we were to later discover that only some of the nestlings had survived in each.  And only one egg hatched from the nest with eggs.  So even those nests had not survived unscathed.   

By far the saddest result of the heatwave was at WT 12 -- the nest we had such fond hopes for.  When I arrived to watch it at 6am on the 29th, all 3 adults were bringing food to the nest.  That was encouraging!  But it didn't take long for me to discover the sad reality.  Yes, they were bringing food in, but they were also bringing it out.  It was clear that whoever was in there was no longer capable of eating.  But could they still be alive?  I rushed home to get some sugar water thinking that a bit of that might revive the nestlings and save their lives.  (Bad science, but sometimes I just can't help it.) But, alas, when we opened the nest we found 6 tiny dead perfect nestlings....smaller than they should have been for their age.  They must have died not long before given the behavior of their parents.  So sad.  We collected the little bodies to take samples from the livers for DNA. 

As we encounter more of these catastrophic heating events, most certainly due to human-mediated global climate change, local birds and other animals will no doubt be affected as were the Portland bushtits.  In fact, it's highly likely that other breeding birds were impacted in a similar way during the 2021 heatwave.  It was only the fact that we were already closely monitoring bushtit nests, and have been for many years, that we were able to observe the effects of the heatwave on them and compare that to previous years.  

A sad end to the season and an ominous warning for the future.              

   

2018: Male joins at nest

One of the (many) unique characteristics of bushtits is that they have "helpers at the nest."  By helpers, I mean non-breeding birds (usually adult males) acting as parents by feeding the kids and defending the nest.  Over the years I have have had very little opportunity to observe exactly how that happens.  All that changed in 2018 with two nests.  I describe below how PYLX joined Nest 11 in 2018.  It was fascinating!  [This is an excerpt from my book still in progress]

SELLWOOD NEST 11 (2018)

By the time I find Nest 11 in late April, it’s a completed gray gourd, hanging like a ripe fruit from the outer middle branches of a tall pine on the edge of the open field that defines the southern boundary of Oaks Bottom Wildlife Refuge.  

The nest isn’t that easy to find even though it certainly isn’t cryptic.  It’s hung nestled in the drooping branches of a large pine that are so common here in Portland.  What makes it obvious, once I do find it, is that some of the vegetation is dead and so it stands out against the background of sky and hill.  But it’s still not obvious if you’re just passing by.  It’s the unbanded pair --- a male and a female --- now feeding at the nest,  that finally give it away.  Nestlings need to be fed and frequently.  It was a fairly simple matter to follow the adults eventually to the nest.  

And there it is.  A nice nest to watch with the entrance facing straight towards the open field where I can sit.  On the other hand, it is a bit far and at first I resort to a telescope to tell male from female by their eye color.  By the first week in May, I suspect there may be more than just a male and female here.  At one nestwatch, I am certain there are at least 3 bushtits in the area.  If so, it would be my first documented multibird nest in the Pacific NW.  But it’s not until Ellie and I band here that the slightly more complicated truth begins to reveal itself.  

We set up the net not far from the nest.  Since it’s so high up in the tree, I’m not afraid the calls I use to attract the parents will give the nest’s location away to the dastardly crows.  After setting up and playing the tape for just a few minutes we catch in quick succession, and surprisingly, 4 birds ….3 males (LYYX:Likes), PYLX:Piles), and PPRX:PopRocks) and only one female (GXGG:Geegee).  A fifth bird flits about the net, but never gets caught.  Still…..we have 4 birds banded and I am hoping we have caught all the attendants at Nest 11 and perhaps we have even more than three.  I am delighted and greatly anticipate my next nestwatch.  

Which is a dud.  Sort of.  The next day the nestwatch reveals that the female is not banded.  She must have been that slippery cookie that teased us the day before.  And disappointingly only one male, LYYX, is feeding and coming in with the unbanded female almost every single time.  I am disappointed.  No third bird.  

That same day I find GXGG, PPRX, and PYLX foraging merrily nearby in the undergrowth at the edge of the field, but not doing anything remotely nesty.  Just hanging out.  Oh well.

But the next nestwatch I do a couple of days later is far more interesting.  GXGG and PPRX are still lounging in nearby bushes snacking on bugs and having a quiet conversation of spits, but PYLX shows up at the nest a few times on his own.  At first he seems excited about his “discovery,” hopping about and peering in the nest a few times.  LYYX shows up at one point with food for the kids and pecks at PYLX, chasing him off temporarily.  But PYLX soon returns.  This time he’s carrying a bit of lichen….nesting material.  Not really appropriate for a nest full of nestlings.  The female arrives a minute later and he wing-flutters towards her as if trying to attract her attention.  When she leaves, he slips into the nest…with the lichen….and then exits….with the lichen, seemingly puzzled (if a bird can look puzzled.)  He enters a few more times, each time coming out with the lichen still in his beak.  The last time he emerges without it and flies off.  I can’t imagine what he did with it.  Did he convince one of the nestlings it was food?  Or, more likely, did he just leave it and give up?  

So PYLX is a “visitor.”   And he’s doing what I once saw in Washington, but never in Arizona:  bringing nesting material to a nest containing nestlings and wing fluttering towards the female.  What is he up to?  He is not what I would call an “attendant” or a “helper.”  He’s just visiting.  And he’s bringing inappropriate gifts.  

I have more nests to watch than just this one, so I don’t get back to Nest 11 for another few days. 

And by then things have changed in a big way.  Both LYYX and the unbanded female are feeding the nestlings. But now PYLX has joined them.  Instead of showing up with lichen, he’s carrying food.  And instead of chasing him off, LYYX seems to have accepted this new member of the family.  In fact, had I not observed the earlier lichen-carrying attempts of PYLX and LYYX’s annoyance at his presence, I might think this was just a big happy family made up of two males and a single female from day one.  True, PYLX is feeding separately from LYYX and the female who almost always show up in tandem with food.   And he’s feeding less often than they do.  But he is feeding and that now means he’s a “helper.” 

Nest 11 immediately becomes my favorite nest and we try to watch it daily.  As the nestlings grow and their demands increase, PYLX collects more food and shows up more often.  And now he often overlaps with LYYX who sometimes politely waits just inches away for PYLX to leave before he enters the nest with his offering of caterpillars and spiders and such.  By the time this first brood fledges, PYLX is a full-fledged (sic) member of the family.  In fact, had I found this nest now, I never would have known who was dad and who was the interloper.  They are indistinguishable.  Except by their bands, of course.

And fledging day does come with its usual mad  flurry of activity in the vicinity as the kids bolt from the nest, flying strongly, if not totally in control.  All three adults and a few neighbors are there to greet them. Mad spitting ensues.  Within 20 minutes, the newly fledged kids, short tails and all, have found each other and are perched in a tight little row high up in a small tree where LYYX, PYLX, and the unbanded female continue to feed them as if they had never left the confines of their swinging bed.  

Unlike in Arizona, where the fledglings move rather quickly over the next few days away from the nest area, these five kids along with both males and the female don’t move farther than 50 meters from home.  In ten days, I know  why.   Both LYYX and the female are  taking turns hanging out in the nest, obviously incubating a new batch of eggs that must have been begun just a few days after the next was vacated.  PYLX remains devoted to the first brood who are now mobile, long-tailed and a nuisance to their caretakers, chasing them with chittering begging calls and still being fed on occasion although they are now fully capable of foraging on their own.  I never see him incubating.  

But once the new brood hatches, PYLX joins in feeding at the nest as if he never stopped.  His contributions are indistinguishable from those of LYYX and the female. There is no way I can tell he’s the “second male.”   I do wonder (I always wonder) if he has some of his own kids in that nest this time around.  Did he and the female sneak off together at some point during egg laying for a quick liaison?  I never saw it.  But I rarely see mating anyway.  It’s possible.  In fact, I think it’s likely.