Lab explores the extraordinary lives of tiny birds
by Charles Ker Staff writer
A cartoon taped to Lee Gass’ laboratory door carries the caption, “Hummingbirds
on vacation.”
The drawing depicts five birds flying over a house equipped with a feeder.
The appending dialogue reads: “Dad, dad… There’s a feeder!… Can we stop?”
Cartoonist Gary Larson, famous for taking commonly held views about animals
and putting them in human context, is half right. In the case of hummingbirds,
people don’t know much beyond the fact that they’re small, fast and have their
own feeders. As for vacations, biologists know that West Coast hummingbirds
migrate to Mexico each winter but do not, as Larson suggests, fly in groups.
Gass says they are distinctly anti-social.
Two years ago the associate professor and his zoology students gained notoriety
after a member of Parliament labeled their research a waste of taxpayer money.
The MP took exception to a $32,220 grant for a study on the behavioural energetics
of hummingbirds.
When a reporter asked Gass to explain the relevance of his 30 years of research
into hummingbird behaviour, he put Larson’s visual world into words.
“Whatever mechanisms animals use to detect patterns in the environment and
respond to them is likely to be very, very general because it is likely to be
very, very old,” he explained. “So these processes we’re beginning to see in
animals might be processes that we humans also use.”
But comparisons with Larson art end there as efforts in the hummingbird laboratory
are geared toward serious science.
The lab is located in an old, wooden building dwarfed on either side by the
Centre for Integrated Computer Systems Research (CICSR) and the Advanced Materials
and Process Engineering Laboratory (AMPEL). The location is appropriate because
work done in the lab relates to that of its neighbours.
Computer experts at CICSR are trying to determine what their artificially
intelligent robots need in terms of information processing and perception to
perform certain tasks. Similarly, Gass and colleagues seek to understand what
principles of memory and sight apply when hummingbirds are faced with new situations.
Hummingbirds are clearly engineering marvels. They routinely accelerate and
decelerate at 2 Gs — three times the force that throws a car into a skid. Herein
lies the human fascination with these phenomenal fliers — they’re extreme.
Gass’ preoccupation with hummingbirds began in the late 1960s while he was
studying at the University of Oregon. While resting during a mountain hike,
he noticed two Rufous hummingbirds squabbling.
“They both recognized a territorial boundary and both of them defended and
violated it,” he says. “Often they’d go up against a wall that obviously they
could see but I couldn’t.”
Those same birds would be the focus of Gass’ PhD thesis on feeding territoriality
and the basis for work currently carried out by students in the UBC lab.
Gass said the mountain meadows offered an ideal setting for his initial experiments
into how hummingbirds determined how much space to defend.
In short mountain summers, meadows transform from snow to a mass of flowers
and back to no flowers within eight weeks. During this time frame, hummingbirds
arrive, set up their territories, gain fat for migration and move on.
What Gass observed was that as flowers blossomed and died, territory size
was constantly renegotiated as the birds’ fuel supply grew and dwindled.
He also noted the tremendous amount of fuel and energy required to run the
average three-and-a-half gram hummingbird. Wings beating 40-80 times per second
provide power for continuous acceleration and braking. No wonder energy conservation
was uppermost in their tiny minds.
Gass would later discover, in a collaboration with UBC colleague Peter Hochachka,
that when the hot-blooded birds first arise in the morning they burn stores
of fat and within 10 minutes switch over to burning sugar for the remainder
of the day. Deprive a hummingbird of food for 90 minutes and it can lose up
to 15 per cent of its body weight.
In the meadows, Gass saw that there was little margin for error; the birds
used up almost exactly what the flowers in their territory produced.
“To break even energetically they had to be smart,” he says. “They had to
spend a lot of energy but they couldn’t afford to waste any.”
To understand how they distributed time and energy in foraging, Gass and a
graduate student boosted nectar in patches of flowers at nightfall and watched
the birds discover the feeding bonanza the next day. Amazingly, the birds immediately
returned to the same enhanced patch on consecutive days.
Says Gass: “That experiment told us that when they go to bed at night, they
do so with knowledge about the distribution of energy in a territory and they
awake with that knowledge. Our understanding at the time was that little organisms
with little brains weren’t supposed to be able to do that.”
Gass has subsequently learned that hummingbird memory extends well beyond
the meadow. He has been capturing and releasing hummingbirds for observation
at UBC since 1980. Even after a year in captivity, birds released on Vancouver
Island were later spotted back on the island after their Mexico migration.
The attributes that make hummingbirds great subjects for observation in the
wild hold true in captivity. Hummingbirds have three primary states — sitting,
hovering and flying — which makes it easier to estimate the energy costs needed
for them to survive.
Perhaps their most important attribute, however, is their capacity to learn
and be trained.
Lara Chatters has spent the last six years completing bachelor’s and master’s
degrees measuring velocity and acceleration of hummingbirds. She says acceleration
studies have been carried out on lions, cheetahs and locusts, but never on birds.
Over the course of her research, Chatters taught a number of hummingbirds
to fly through a Plexiglas tunnel with a perch at one end and a feeder at the
other. Pieces of tape were spaced 10 centimetres apart along the transparent
tunnel and a mirror placed at a 45-degree angle underneath her home-made apparatus.
A video camera recorded the exact position of the bird every 30th of a second
during its flight.
Chatters’ results were startling. In a five-metre tunnel, birds accelerated
to cruising speed and immediately decelerated. However, in a tunnel twice as
long, they accelerated, cruised a bit and then decelerated. This was a key finding
considering that hummingbirds in the wild usually travel less than a metre from
flower to flower. Gass had previously assumed that any flight less than one
metre was done at cruising speed.
“Lara’s discovery meant we couldn’t sweep acceleration under the table,” says
Gass.
Chatters also discovered that female hummingbirds, with their longer, broader
wings, accelerate considerably faster than males — the opposite of what was
previously assumed.
For her master’s degree, Chatters again used complicated mathematics — as
well as a modified tunnel with one end raised to simulate a load — to come
up with a theory of just how much energy hummingbirds expended during acceleration.
Chatters isn’t the only one shaking up the hummingbird literature.
In two concurrent studies, master’s student Janet Moore was able to dispel
previously held beliefs that the wing and body structure of males makes them
more manoeuvrable than females. Moore’s evidence is in meticulously documented
film footage of birds negotiating barriers in a four-metre-long tunnel and performing
low-velocity turns between two feeders spaced a half-metre apart in a V formation.
By transposing the film onto a computer, Moore was able to measure changes in
the angle of a bird’s body and wings frame by frame and demonstrate that, in
fact, females turned faster.
Gass says findings by Moore and Chatters are sure to cause a splash when published
later this year.
Back in the lab, Christianne Wilhelmson is the only graduate student currently
conducting research. Her computer is hooked up to a series of cubicles which
resemble miniature squash courts; at one end is the ever-present perch and at
the other, a panel of six feeder holes above which are tiny lights which the
birds use as a cue for food.
The drill appears simple but the technological ingenuity behind the scenes
is not.
Wilhelmson’s computer program simultaneously monitors and controls six feeder
lights, a video camera and six pumps providing an exact amount of food to the
appropriate feeder hole. The program also processes all information about the
hummingbird actions from the time it leaves the perch, arrives at a particular
feeder and returns to the perch.
By altering the spacing between feeders and lights, Wilhelmson hopes to learn
more about how birds use visual cues to find profitable feeding sites.
Gass ushers a visitor past the squash courts towards a separate holding area.
Humming starts immediately as the two intruders enter the enclosure. Moments
later, all is quiet as 14 Rufous hummingbirds return to their perches.
Males, Gass says, are distinguished by their trademark red throats as well
as the combined whistle and hum from wings whirling in figure eights. Females
just hum.
Scientists still don’t know how long the birds live and know next to nothing
about their breeding biology in British Columbia. Gass admits there’s a lot
left to learn.
“They surprise me by doing things and I can’t imagine how they do them.”
Gass’ career and those of his students are sure to remain full of surprises.
