Humming to extremes

Lab explores the extraordinary lives of tiny birds

by Charles Ker
Staff writer

Picture 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.