How vultures can help solve crimes Lauren Pharr
[This talk contains graphic images]
My parents always wanted me
to be a doctor.
But a doctor that studies
how vultures eat dead things
is probably not the type of doctor
my parents had in mind.
(Laughter)
I study vulture scavenging behavior
and how vultures affect crime scenes.
I’m here to talk to you
about how we take vultures for granted
in forensic science.
Before we do that,
I want to tell you a story.
So we’re going to take a trip,
all 1,000 of us.
It’s May 2014 and we’re standing in a park
in Nashville, Tennessee,
because we’ve been at a horse race.
As we wait for the porta potty,
we see two ladies in their Sunday best:
heels, pearls and lovely,
floppy derby hats.
At any moment, we expect them
to start talking
about their grandma’s fine china.
But they don’t.
Instead, we hear them say,
“Oh, look.
Something must be dead.”
We look up and to the left
and see vultures circling round and round.
It occurred to me at this very moment
that if these ladies at the derby
are aware of vulture’s
connection to death,
then why aren’t we talking more
about these birds at crime scenes?
People know that vultures
are connected to death.
But they don’t really understand how.
For example, here’s an email
I received from a detective in Louisiana:
“Lauren, there’s been a kidnapping.
What buzzards or vultures
do we have in Louisiana?”
Before we address the kidnapping,
I’ll first address this buzzard/vulture
question I get all the time.
Buzzards don’t live in the United States.
They are hawks that live in Europe.
The big black birds you see circling
in the sky within the US are vultures.
The two types of vultures
that live in Louisiana
are the turkey vulture and black vulture.
To fully understand the role
of vultures in forensic science,
I’ll walk you through this forensic case.
From the email,
certain things become apparent.
We can assume the detective thinks
the individual is dead.
And he wants to use the birds
to try to find the body.
Like the ladies in Nashville,
the detective thinks
that vultures circling in the sky
will lead him to the body.
It’s not that simple.
I don’t know if you’ve ever
seen a vulture up close
or spent much time with them,
but they’re huge, huge.
Six-foot wingspan.
Vultures circle in the air
because they are too big
to flap their wings and fly,
so they soar.
They soar in thermals,
which are vortexes or little tornadoes
caused by pressure differences in the air
that form throughout the day
as the sun heats up the ground.
Therefore, when you see
a circling vulture,
the bird is usually traveling
from point A to B,
rather than circling above something dead.
Actually, if you want to use a vulture
to try to find a body,
look for a vulture in a tree
or on a fence post.
Vultures are too big and slow to hunt.
So they have to scavenge.
In fact, vultures are
the only animals in the world
that depend upon death as a food source.
The turkey vulture
that you see here is super cool,
because it’s one of the few bird species
that can actually smell.
It hones in on the deceased
by sensing a chemical
that’s coming off the body during decay.
The evolutionary role of the vulture
is to rid the earth of harmful toxins
produced following death.
Once death has been detected,
the turkey vulture lands
and quickly scavenges.
Vultures usually remove the eyes first,
then tear the skin,
start pulling the tissues,
and leave you with a skeleton.
Therefore, the importance
of vultures is not in the air,
but on the ground.
Vulture scavenging is somewhat gruesome.
If you’re ever on a bad first date,
just reference this talk,
and I don’t think you’ll have to worry
about your potential suitor
giving you another call.
(Laughter)
Although gruesome,
vultures are key forensic players,
and here’s why.
Vultures will consume a dead human
just like they will consume roadkill.
But you don’t ever hear about that,
and it’s because vultures
are so good at what they do.
If vultures depend on death for survival
and if they scavenge humans,
then how can vultures be absent from
forensic textbooks and training manuals?
The answer:
the tradition has been for researchers
to exclude animal scavengers
from decomposition studies
by placing a cage
over the decaying subject matter.
Why?
Because researchers were afraid an animal
would run away with their subject matter
and they wouldn’t have
any data to report –
consequently excluding animals' results
in a lengthy skeletonization process,
and this information is currently
what detectives use during investigations.
A lot of times at a crime scene
when people see a skeletonized body,
they think, “Wow, this has been here
for a really long time undiscovered.”
Oh, no, no, no, no.
Vultures accelerate decay.
And the skeletonized body
could have been there
for as little as five days
if scavenged by vultures.
The failure to account
for vulture scavenging
can result in forensic scientists
inaccurately estimating
how long someone has been dead
and then searching through the wrong
missing person’s files.
Therefore, the goal is to get forensic
scientists to focus on vulture evidence
and to get law enforcement
to consider vulture scavenging
and a possible recent death
when skeletal remains are found.
Let’s get back to the importance
of the kidnapping case.
I responded to the detectives
and told them that vultures
like areas with water.
They like areas with white-tailed deer,
they typically arrive within
the first five days following death,
they’re going to leave
an intact spinal column and feathers.
The detectives write back and say,
“We found the body buried
in a shallow grave.
We also found the feathers you mentioned.”
But there appeared to be a problem
because the feathers were located
40 yards from where the body was found.
The feathers were next
to a bloody pine cone.
Vultures aren’t attracted to blood,
and they typically don’t wander.
They might wander 40 feet,
but they’re not going to wander 40 yards.
That would be a waste of energy
for a bird that doesn’t know
when it will get its next meal.
So my first job here was to determine
if vultures were at the scene.
Indeed, the feather by the pine cone
was consistent with the turkey vulture.
So why in the world
would a vulture wander 40 yards?
One of the reasons I love vultures
is because they tend
to operate in a manner
that can be explained
by biology and physics.
I started mentally going through
the numerous bating experiments
I had conducted at a body farm in Texas.
A body farm is a place
where you can donate your body to science.
I also went through
my experiences with trapping
and GPS tagging vultures.
And then the year-long process
of monitoring vultures
via remote GPS technology.
Next, I brought up my field notes
and had an “Aha!” moment.
I knew of two things that would
lure a vulture 40 yards from a body.
Guts and brain matter.
I presented this information
to the detectives
and learned that they suspected
the victim had been incapacitated
by blunt force trauma to the head.
The blow to the head
was thought to have occurred
in the area where the pine cone was found,
and then the victim was drug 40 yards
and buried in a shallow grave.
This suggested that brain matter
was the lure for the vulture
and illustrates how
studying vulture behavior
can help piece together
some of the evidence.
The detectives also sent me this photo.
The victim’s arm is sticking up
out of the grave.
As a forensic scientist,
you have to think about the whole picture.
The feather by the pine cone
indicated that vultures were at the scene.
This crime scene photo also depicts
characteristic vulture
scavenging behavior.
We zoom in, we see a white down feather,
which is characteristic
of the turkey vulture.
Also note that the skin
has a cut-like tear near the wrist.
The turkey vulture
smells the decay, lands.
It can get through the pine needles,
pull out the hand,
it’s going to tear the skin with its beak
and then start pulling
the soft tissues away from the bone.
Just tear and pull,
tear and pull, tear and pull.
This photo illustrates
the scavenging efficiency of vultures.
This is important because it helps
support the time line
the detectives are putting
together for the murder.
There’s not a whole lot of evidence.
You’re not likely going to see
the vultures at the crime scene.
Instead, vultures just leave
these very subtle clues.
Rather than looking for the vulture,
look for the feathers and pristine bones.
Vultures are important
because they are so good
and fast at what they do.
They’re like tornadoes.
If you blink, you will miss them.
I provided my opinion about
the vulture evidence to the detective.
And he presented
the vulture evidence in court.
The kidnapping case
was a death penalty case.
And the defendant was found guilty.
This case illustrates
how studying vulture behavior
helps innovate forensic science.
Someone who has been murdered
deserves the most thorough
investigation possible.
When we include vultures
in forensic studies,
we paint a more thorough picture
of what happened, when it happened
and who it happened to.
So, the next time you’re
at a crime scene with a dead body –
(Laughter)
look to the ground
to find the clues vultures have left.
And if anyone ever
brings up vultures on a date,
you’ll know they’re a keeper.
Thank you.
(Applause)