Well, thank you very much.
(audience applaud)
-Thank you. -(audience laugh)
Salt Marsh Sparrows are gonna be extinct in 40 years.
That is the conclusion of this giant
extinction threshold model that we've built
using everything we know about the biology of the species,
incorporating climate change, title projection models,
and sea-level rise.
Salt marshes are gonna go underwater,
and in a couple of decades,
the reproduction for the species is going to be impossible.
Now salt marshes occupy this linear strip of habitat
between the ocean and really expensive
upland real estate and infrastructure.
As sea level rises, salt marshes can't simply
move up into the environment,
they're physically blocked from doing so.
Organisms that occur in the spruce-fir zone
at the top of our mountains
are in that same proverbial boat.
They're already at the top of the mountains,
they can't retreat any further
as climate change or competitive pressures
from other species below them pushes them up.
And as they do so, because of the shape of mountains,
the amount of habitat as they're squeezed
to the top exponentially decreases.
Not surprisingly, we have evidence from around the world
from plants to butterflies, from mount birds,
that organisms are dispersing further up-slope
and towards the poles to retreat from climate change.
Climate is warming in the mountains
at a rate of two to five, five times faster
than the average global background rate,
faster than anywhere else on the planet,
except for the poles.
At this point, we have multiple independent
modeling sets that suggest we are likely to lose
maybe 50% of our existing spruce-fir forest here
over the next 2-300 years.
Not surprisingly, our spruce-fir bird specialists
are the most vulnerable group to extinction
from climate change of any group of birds in North America.
Of our four dozen-some species,
under moderate climate-change scenarios,
those species are likely to entirely become
Canadian endemic species by the end of this century.
Those are your crossbills, and your grosbeaks,
and your white throated sparrows,
and yellow-bellied flycatchers, and spruce grouse,
they will all be relegated to Canadian endemic species
under moderate climate-change scenarios.
Here you see the breeding range
for black warblers in red and yellow.
Anywhere you see red is where these
climate projection models suggest
that that black warbler breeding range will be lost.
So...
these are available
on the Audubon Survival by Degrees website.
So we don't have a great understanding of the...
Oh, I should say it's really important
that we've begun moving forward into this century,
it's likely that even if these models are wrong,
that these populations of boreal birds
are going to be further reduced.
They're likely gonna be more fragmented
and isolated as they already are.
It's going to be extremely important,
from a management perspective,
that we're able to understand the population dynamics
of the species and what's driving them,
in addition to climate change, of course,
and food availability and abundance certainly comes to mind.
I'm sure you've heard of the insect apocalypse.
We are still debating and figuring out
what groups of invertebrates are declining or increasing,
where and when and how severe those changes are happening.
But I think it's very likely that the same forces
that are driving global declines in vertebrates,
industrial agricultural practices, climate change,
habitat loss and degradation, tropical forest loss.
Those same forces that are driving
vertebrate population declines and range reductions
are also likely influencing invertebrate populations
in the same way.
It's really important at this time, more than ever,
that we begin to understand those population
and annex of those invertebrate groups.
Our knowledge for these groups is very limited
to begin with, and in montane environments,
it's basically non-existent.
So I'm not an ecologist that cares about invertebrates
because that happens to be what birds eat
during the summer months.
I'm an ecologist that works with invertebrate populations
and bird populations.
And this is a nice opportunity
to put them together into one project.
So I'm a coordinator for a community science project
called Mountain Birdwatch, where each June
hundreds of community scientists trek out
to more than 700 sampling locations,
from the Catskills to (indistinct),
and that is a high-elevation spruce for habitat
on established hiking trails.
They do repeated point-counts for 10 species of birds
and red squirrel, which is the primary nest predator
for these species of birds; that's each June.
Last year at 42 of those sampling locations
on Mount Mansfield, Bolton Mountain,
in the dual peaks of Cherry, and Martha,
and the White Mountains,
I deployed invertebrate sampling equipment
at those 42 locations where community scientists
also went out and did repeated point-counts for those birds.
I'm gonna be focusing on just the six birds in orange there.
Those are the most common birds
at these 42 sampling locations.
And they're present at about,
each one of those species is present
at about 40%-50% of those 42 stations,
so pretty common in the data set.
Our knowledge of the diet and invertebrate associations
for these six birds is pretty poor.
Some of our best knowledge of the diet
of these six bird species comes from 100 years ago
when somebody walked out into the woods
and shot half-a-dozen in the spurs,
and cut open their stomach.
For other species like Swainson's Thrush,
our knowledge of their diet comes from
lower-elevation habitats, not in the spruce-fir zone.
And most of our knowledge about their diet
is loosely inferred from correlations of invertebrates
in their territories, not of these birds
directly eating those invertebrate groups.
But if I had to make some guesses putting it all together,
I would predict that the occupancy of these birds
is positively related to increases in the biomass
of beetles, true bugs, hymenoptera, and flies probably.
So at those 42 sampling locations last June,
I deployed some invertebrate-sampling equipment,
they were deployed for a week, 70 consecutive dates.
At each Mountain Birdwatch sampling location
20 meters off the trail,
I deployed four pitfall-sampling traps for each standard,
spaced out in a 25-square-meter area.
They're covered with these plates
to prevent them from filling up with water.
We also deploy these modified window traps,
which I think are pretty cool, because they're largely built
with recycled materials for about $5 a piece.
That's a soda bottle in the middle there.
Insects can hit the clear plastic in the middle,
fly downwards and be captured.
Other groups of insects some are likely to flee upwards
and they're captured on a separate container up there.
We tested side-by-side in the models,
with the yellow-attractant paper in the inside,
and models without.
The models without, probably because of the small
surface area of these traps to begin with,
captured very few insects.
So last June, our modified window sampling traps
had that yellow-attracting sheet inside.
All the specimens we capture in the field after one week
are brought back to the lab, identified under a microscope,
to at least order.
And then dried in a specimen oven for 30 hours,
and then dry biomass is measured
to the nearest 0.0001 grams.
We captured about 5,000 individual invertebrates last June
at these 42 Mountain Birdwatch sampling stations.
Here you see the brown, the percentage of the biomass
of each group, and in green,
the percentage of the number of specimens of each group.
Pretty congruent for most groups,
except you'll notice halfway down at the bottom,
flies constituted about 60% of the individuals
on our sampling data set.
But they're so small and weigh so little,
they only represent about 5% of the biomass
in our total sample.
And that's an inverse relationship for common land slugs.
I will just point out that, obviously,
camel crickets are not an order,
but that's the only orthopteran that we captured
in our data set.
And likewise that this community is pretty simple, really,
for 5,000 individuals and over 1,000 trapping nights.
There's a lot of very common groups of invertebrates
up there, like scale insects,
that are not represented here at all,
I entirely acknowledge that.
Also, most of the mites we capture are development mites.
There were some mites that we captured, you know,
one millimeter or so that are difficult
to put into a specific mite order.
And as common in these types of studies,
those orders of mites are lumped together for analysis,
ditto with millipedes.
So I'm interested in taking measurements
of the invertebrate community biomass,
and using that to predict the occupancy pattern
for those six species of birds.
The first thing you do is build an occupancy model
that accounts for variation,
observer ability on the detection side,
and time of day, and day of the month.
And on on the occupancy side of the model,
I model occupancy via quadratic relationship to elevation.
And as you can imagine for montane birds,
that's a really powerful predictor
of where we expect to see Bicknell,
Swainson, and White-Throated Sparrow.
And then I add various covariates,
describing the biomass of the invertebrate community
to that same model, and see if it improves
the predictability of that baseline occupancy model
that just includes elevation.
Oh, I measure, I calculate species richness,
Simpson's measurements of diversity and evenness,
using individual specimens and biomass.
And I'll just tell you that those indices
had no predicted ability to describe patterns
of occupancy of those six bird species.
So proportional representation
of that invertebrate community's not a good predictor.
Maybe you think it's total biomass, right?
Maybe you think just locations
that have lots of stuff, period.
Some of it's gonna be available for food for those birds,
and that locations with lots of biomass
might be predictive of high-occupancy rates.
And that is also not the case
for any of those six species of birds.
Okay, maybe you think that it means
taking a chunk of beetle biomass,
and a chunk of hymenoptera beetle mass,
mixed in with a little bit of true bug biomass
in some complex relationship.
If you think like that, you think more methodically,
and you probably think PCA is a great thing to do
-on a Friday night. -(audience laugh)
If we do that and we break down
the biomass invertebrate dataset into principle components
you see the first principle component on the right there
explains a lousy 18% of the variation of the dataset.
And you probably know where I'm going with this,
but principle components of the biomass
of these invertebrate communities are very poor predictors
of the occupancy pattern of those six birds.
They don't do any better
than a simple model that just includes elevation.
What have we left ourselves with,
since we've ruled out most of the things I can think of?
And the only thing that adequately predicts occupancy,
for any of these species, is the abundance or scarcity
of biomass of specific invertebrate groups.
So for Bicknell's Thrush there at the top and middle,
you see there's a positive association
of the occupancy of Bicknell's Thrush
with increasing biomass of true bugs
around that Mountain Birdwatch sampling station,
and an inverse relationship to the biomass of beetles.
Some of these results are surprising to me.
For Swainson's Thrush, that makes sense to me,
for Yellow-Bellied Flycatcher, okay.
For some of these other groups,
I'm struggling to understand those relationships.
It could be very much because we have very limited
knowledge of the diet of these species,
that we have discovered some important new associations
of their diet for these groups, that's possible.
It's also possible with just 5,000 specimens
in one year of the study that some of these
are spurious relationships.
If that was the case, I also would've expected
some of those principle components to spuriously
show up for some of those species as well.
It may tell us something more complex though,
mites is pretty surprising to me, right?
Except that velvet mites in their juvenile form
are ecto-parasites on adult insects and plants.
And in their adult form, they're direct predators
on insects and on insect eggs.
Though the mites have these incredibly
complex relationship-enforced ecosystems with fungi
and soil formation and structure and decomposition,
it could be that the presence of some of these groups
for these species isn't telling us directly
about what they're eating, so much as it's telling us
about the health of the forest ecosystem there,
or the strength of those ecological relationships.
I don't know that, honestly.
So in conclusion, again, it's the abundance
and scarcity of individual groups of invertebrates,
that's the only thing that adequately predicts
occupancy for these species.
One year is a short study, is a short timeframe.
Lots of studies have correlated invertebrates
in the environment to birds' nesting success,
and found relationships between nesting success
and beetles in one year, but not the next year.
It's possible some of these results are spurious,
it's possible these relationships change,
based on overall food availability in a given year.
In years where there's lots of food,
maybe those preferences break down
and we don't see those relationships.
It might only be when food is really scarce
that we're able to detect those relationships.
Also you know, we're limited
in our sampling approaches, absolutely.
I think I captured a single scorpionfly
of the 5,000 in invertebrates last summer,
of the panorpa species.
If scorpionflies are important for Blackpoil Warblers,
there's no way I'm gonna be able to detect that
in this data set, because they're just not captured
with enough frequency, so I freely acknowledge that.
All sampling methods have biases.
And lastly, I'd say identifying things to order.
It takes a lot of time obviously,
but it may be that that high-order of identification
prevents us from teasing out lower-order relationships.
So rogue beetles are important to White-Throated Sparrows,
but we are lumping in rogue beetles
with tumbling flower beetles, and lightning beetles,
and ground beetles, that relationship may become
obscured for that individual family of beetles
and White-Throated Sparrow, Black Warbler.
And we may be failing to detect that,
because we are mixing data together
in a way that's uninformative.
The alternative is identifying everything to family level,
except maybe for beetles, is impossible.
I mean, it's not logistically or expertise-wise possible.
And lastly, I'd say I look forward to having
multiple years of this data.
We'll be able to look at trends
in the invertebrate communities themselves,
look at how much variation we see
in our capture rates from year-to-year,
so we can start to tease out signal from noise.
And look at the trends of the birds of these locations
compared to the trends of the invertebrates.
And in subsequent summers, we'll be taking measurements
of forced health and vegetation.
So this is just the first complete year of this study.
I'd like to thank FEMC for partially funding this study,
for the entire Mountain Birdwatch family,
and for all of you being here today, thank you.
(audience applauds)
Yeah.
[Female Speaker] Did you parse out
different populations at all?
Because I'm wondering if maybe as we see
the birds' habitat selection varying for a given species
across their range, maybe there's differences
in food-selection choices that are being obscured
when you lump all of them together.
Yes, so I did include mountain identity as a component
of the principle components.
And I didn't show that, I didn't show that by-plot,
just to be simple.
But yes, that comes across very strongly in that by-plot.
If you show the classic principle components
with the arrows going every direction,
and you color-coded sample locations by mountain,
you'd see some real clustering.
And it does suggest, I'm not sure it suggests
preferences in the birds, as much as it might suggest
localness of the invertebrate community.
But that definitely comes through
in the principle components analysis.
-These T-shirts are available, -(audience laughs)
well habitats (indistinct), always great gifts,
great stocking stuffers.
Rosalind.
[Rosalind] Are you aware, I mean, would you expect
to maybe see this complexity, where the insects
may be just indicating something else
that we're not measuring directly?
Would you expect to see that in other habitats,
or have other people done research that have found that?
Yes, and it takes a lot more direct observations of those,
well actually, you can build pathway models
that make predictions, that you say, you know,
there's a bunch of invertebrates and a bunch of birds,
and there's some reproductive success and adult survival.
I don't know how these things are all connected,
you tell me.
And I've built those models,
and absolutely you can build
those types of pathway analyses.
The vast majority of bird papers
that look at relationships between invertebrate abundance,
or biomass, and some measurement of breeding success
or just adult density.
Don't make the leap.
Don't go to the actual mechanisms,
and don't try to say that...
You know, is the stuff that we capture in their territory
necessarily is the stuff they're eating?
They tend to leave it ambiguous,
'cause it's amazing how little
direct-observations we have of foraging.
You know, for Bicknell's Thrush,
we have six dead Bicknell's Thrush, basically,
that tells us about the diet of those species,
and that's the limit.
So we definitely need some very basic,
natural history studies, documenting the actual
food items that are eaten by these species.
And then we probably need to do some more
creative modeling to try to get it,
how mites are actually informing occupancy
of White-Tailed Sparrows.
Probably not, because they're being eaten a lot
for those birds.
Okay, yeah?
[Male Speaker] Are there any, like, habitat interventions
that you could do to help mountain birds,
like, up in the outlying north?
That's a great question.
Here in Vermont, Act 250 would make that challenging.
[Male Speaker] All right.
But actually on Monday, I was in a 2-hour Zoom call
with 30 people, people that studied Bicknell's Thrush,
and 15 commercial foresters from Wagner,
and all of the other big companies,
talking about how we can manage industrial
commercial forest lands in Northern New Hampshire
and Maine, to promote Bicknell's Thrush.
And it likely means promoting food
and availability of food for them,
for those bird species.
Yeah, so the answer at the moment is no, don't know,
but a lot of us are thinking about that.
A lot of these species are disturbance-prone species,
and in Maine they are most abundant, adjacent to fir waves.
I did analysis for the state of Vermont,
looking at abundance of these birds compared to ski slopes.
And most of these bird species are most abundant,
greatest density, immediately adjacent to ski slopes.
[Male Speaker] Huh.
It may be that those ski slopes artificially mimic
the natural disturbance these species would see
in fir waves or something.
I would point out that Kent McFarland and Chris Rimmer,
20 years ago, studied the birds at the edges of ski slopes
versus the interior, and couldn't find any differences
in survival of the adults, and nesting productivity,
survival of the young, clutch size.
So it appears, as far as we know,
that adults cue in on those disturbances,
but we can't actually detect any improvements
in fitness for birds that choose to nest there.
But all that's on our mind when we're working
with commercial foresters in the next 20 years here,
to think about how to manage the remaining forest
for Bicknell's Thrush and other species.
Thank you.
[Female Speaker] Great, thank you.
(audience applauds)