KRISTIE NELSON: A lot of people really like birds.
Birdwatching is popular.
Not a lot of people are big fans of gulls.
They're annoying to a lot of people,
particularly because they're really good at observing us
and the food resources that are around humans.
But when you stop and observe and pay attention,
there's so much intricacy in gulls.
California goals, in particular, having
to breed in these inland arid lakes, winter on the Pacific
coast, learning the best way to survive.
And just that in itself is incredible.
My name is Kristie Nelson, and I work with Point Blue
Conservation Science, and I monitor the California gull
colony out here at Mono Lake.
California's gull is a bird unlike any other.
Anything that can survive this highly-caustic, salty lake
water is an amazing animal.
So Point Blue's research on the California gulls
is a really unique project, and one
that we have a 35-year data set and counting.
One of the major goals of the research
is to see what can we learn about the relationships
of the gull colony and the health of the gull population,
and how that in turn is representing conditions
within the lake.
We want gulls to be an indicator of ecosystem health.
Historically, this species of California gulls
nested entirely in inland, arid lakes,
like Great Salt Lake in Utah and the Mono Lake because
of the food resources, primarily,
and that there's predator-free nesting islands to nest on.
When the California gulls come here in the spring,
there's not a lot of food out here.
Once the lake warms up, the alkali flies,
which are lining the shoreline right now by the millions--
they're one of the primary food sources for the California
gull.
The technique the gulls mostly use
is to open their mouth as wide as they can,
and run as quickly as they can.
And it's pretty entertaining to watch.
The other major food resource that the gulls are eating out
here are these brine shrimps.
So they're just taking the shrimp that
happen to be on the surface.
Chicks are starting to hatch at the end of May,
and so then these little young gulls,
fairly soon after they fledge from the nesting islands-- they
actually migrate back to the coast.
And the California gulls can live
to be 20 or even 30 years old.
Being colonial means that there's relatively
few of these big colonies.
That makes each individual colony
really crucially-important for not just the local population,
but even the species as a whole.
So I've been working out on the Mono Lake gull colony
since 2005, where we're counting the nests
and monitoring the chick production.
The islands are just covered in gulls,
nesting in these incredibly dense colonies.
When we're out there working you've got to kind of yell
to each other because of the din of the birds.
The population size varies quite a bit.
We've seen as few as 27,000 gulls nesting, as many
as 65,000 gulls.
And even though it's a pretty simple ecosystem,
we see a lot of complex relationships and bird
populations.
We found that when the lake is highly
stratified between fresh water and salty water--
those were the conditions where the chick production
was very low.
And what happens is, when there's a really big snow-pack
and then it melts and it brings in lots of fresh water dumping
into the lake.
I mean, that's good because it raises the lake
level of Mono Lake, which is helping
to protect the nesting islands, but when a lot of fresh water
comes in contact with the salty water,
instead of mixing it sits on top.
That interrupts the nutrient cycling within the lake.
And I think the shrimp might literally
be too small to be a good food source for the amount of energy
that it takes to forage on all those little shrimp.
When this study began in 1983, the future of the gull colony
was uncertain, because at that point the city of Los Angeles
was still diverting a lot of water.
Legislation was put in place to protect Mono Lake.
That resulted in certain caps on the amount of water
that Los Angeles could safely take.
And those limits were created in 1994,
where we didn't expect climate change.
And so what we're seeing now is that California is heating up.
We're having these extreme droughts.
And so, as the volume of the lake shrinks,
these islands become connected to the mainland.
And because they're nesting on the ground,
if a coyote were to get out onto these colonies
they can just decimate the population.
But today we see other issues with salinity, not just
from the lake declining to dangerously-low levels.
Conditions are right where there's
very high levels of runoff coming into the extra salty
water where the fresh water sits on top.
Those salinity conditions depress the lake ecosystem,
depress the nutrient cycling, that
ultimately have negative effects on the gulls and other birds.
I feel somewhat optimistic about the success
in the future for the gulls, but I
think that will take support and science from us humans.
Seeing them forage out on this lake that can be so incredibly
inhospitable--
they're a part of a vibrant Mono Lake ecosystem,
and Mono Lake wouldn't be the same without them.
LUKE GROSKIN: Hey there.
This is Luke Groskin, video producer for Science Friday.
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