Good morning, Iím Connie Millar and weíre here in Lundy Canyon.
I work with the US Forest Service Pacific Southwest Research Station.
Iím a research scientist there.
We are here at a talus field, which is a long slope of rocks.
Weíve come to this place because itís a good spot to see and to talk about American
pika.
American pikaís formal name is Ochotona princeps and itís a rabbit relative, a small animal
thatís about the size of a large rat, but itís not a rat
at all, itís a rabbit.
And itís become something of an icon for climate change.
Rabbits in general are poor thermoregulators, that is, they have a hard time dissipating
heat when temperatures are high.
So thereís been a concern that their habitat might becoming too
warm for them and they would be moving up slope.
So thatís part of the focus of my research is to
investigate some of those relationships with American pika.
All rabbits are non-hibernators, so they are active during the winter and that means they
have to find forage.
Their behavior for that is to collect, starting about this time of summer, forage from what
we call the forefields.
They donít come out very far from the talus field, maybe 10 or 12 feet, as far as we are
here, to collect and they carry food back in piles and these piles are on the surface
of the talus but kind of tucked under large rocks.
Thereís a very distinct kind of rock that theyíll put the forage under.
Theyíre generalist herbivores, which means they can
use many, many different kinds of plants, even ones like
sagebrush, which is around here, which you might think the alkaloids would not be particularly
edible, but they seem to collect that.
They collect a few species that do have powers of preserving.
By the end of the season, some of the chemicals that are not edible to the pika
have dissipated, so they are able to eat them by the end of
season.
So they collect these piles of food, we call them hay piles, but itís really much more
general than that.
Then they sit by those hay piles under the snow and munch on it all winter.
If itís a longer winter, like this year, then perhaps they might not
have collected enough, so we think this longer winter
actually might have been detrimental to pika at some areas.
Obviously, here at this low elevation it would be a
benefit in a wet year, but at higher elevations, thereís still snow pack.
They werenít able to bear their young, feed their young and then the population
would decline because there just wasnít the reproductive capacity.
My other work has focused on the potential for livestock grazing.
If itís in the area of the forefield diminishes the amount of forage they have,
and theyíre forced to take plants that grow in the talus,
which are very few in number and they tend to have very low forage capacity.
They have to go higher in the talus, which is a much poorer thermal
environment.
The best thermal environment for pika just happens to be at the base, so itís best if
they can have their haypiles along the border of the talus at the
bottom.
That is also covered by snow in the winter, and if theyíre covered by snow, itís actually
warmer.
American pika has been petitioned for listing under California Endangered Species Act three
times and dismissed partly because there isnít enough
information.
Some of the historic data really donít show enough information to know whether itís declining
or still thriving.
Initially, I set out, because I work in these rocky mountain environments for other research
reasons, to characterize the current distribution of pika.
One of the reasons itís good to be here, at this location, is
that itís quite a low elevationóitís 7,700 feet and itís considered below the historic
rangeó8,000 to 8,500 feet were the low margin.
By virtue of looking at the distribution more, we can see that in fact,
they can utilize these much lower elevation slopes than had been thought.
In fact, if you can see, this is the morning sun, we are on a south facing
slope, and the rocks behind us, which are the sole habitat for
American pika, are dark, itís a metamorphic rock so they absorb heat, so itís thought
to be as warm an environment as pika can tolerate.
This is a very active site and itís one of many like this and I think by
partly saturating the areas that would be potential habitat in this part of California,
Iíve been able to show that this range is quite wide.
Weíre in the Mono Basin here, which is just east of Yosemite National Park.
The elevation range that the pika can extend goes from about this elevation,
about 7,500, to the tops of our highest peaks, which are
over 13,000 feet.
They are basically saturating every available habitat in this part of California.
We havenít had this kind of distribution status
before.
Their individual range is about 50 meters wide, so you
can see this talus field can support maybe 10 or 15 individuals and the taluses are continuous,
so this is a very densely populated area.
So the other piece weíve been interested in, after characterizing their distribution,
because there is such concern about climate, is to try to understand
whether the surface air temperature, which is whatís
reported by weather stations and what is modeled by climate projections, really is the kind
of the environment they live in and would be a good
indicator of their future viability.
Weíve been doing studies of the thermal regime, that is the
temperatures within these taluses.
They come up onto the surfaces and down in the vegetation in the
front to feed, but they mostly live inside the talus.
These particular taluses are such that thereís
a lot of open structure and they use that to hide from predators,
the weasel is their main predator, and to avoid the heat of the day.
Their nature is crepuscular, which means theyíre active in morning and night,
like other rabbits are.
They have this environment in the talus where they tend to spend their resting
time in the middle of the day.
This particular talus is one of eight sites where we have intensive monitoring by very
small sensors called iButtons.
We program them to record temperature every four hours and they last up to a year.
We come back and download the data.
We put them in transects from the bottom of the talus up the talus
at four different lines, and then we have five plots in elevation up the talus, where
we have an iButton on the surface and one meter under the surface.
We are able to see what the temperature is, summer
and winter, over the course of the year and we find that the temperatures, as you might
expect, is cooler in the talus and temperature fluctuations
are very small, so itís a very stable and cool
environment, even though surface temperatures can be well over 40 celsius, which had been
considered a lethal temperature for them.
It seems as though pika are able to adapt to warm temperatures
behaviorally.
Even if they canít dissipate heat by sweating or panting, they are able to avoid the hot
parts of the day by escaping into the talus.
There may be some environments where even the taluses
become too warm, but because of this buffering, the rise in air temperature does not seem
to be a good indicator of how their habitat will respond.
So they lag in response, may be theyíll be cool enough in
many locations for a long time, but there will probably be some areas that become too
hot, but I think the important point is that thereís a major
lag because of this rock covering that hadnít been
documented.
Itís still quite controversial.
Our work has focused mostly in this part of the Sierra, so
maybe there are differences elsewhere.
The Great Basin of Nevada, because it has such a different
geological history and the substrate rock type is so different, could well be very different,
so our results are really restricted to this area.
What we need to do is continue to monitor and see if these locations that weíre seeing
as active now continue to be occupied.
Thatís has been one of the challenges of our work, where weíve said that in
this part of the world that pika are thriving, is that we donít have historic data to show
that they were here before and are still are here, or maybe
there were other areas where they were and were not here.
Ours is just a single time slice, so that clearly what we need is longitudinal, or decade
long studies, to see whether theyíre able to persist here.
My interpretation of the fact that theyíre currently saturating
habitat over 6,000 feet of elevation range suggests they have a good stronghold, and
even if some of the environments were to become inhospitable,
thereís enormous range of habitat.
So, if I were speaking about the future of pika in this part of the
Sierra, I would say it looks very good.