GPS tells the incredible story of a seagull that traveled 80 miles in a garbage truck

A female Western gull pulled off an unusual commute in 2018 and handed biologists a head scratcher. She rode a long-haul garbage transfer truck about 80 miles (130 kilometers) from San Francisco to a Central Valley compost site, then repeated the same trip two days later.

Her tiny GPS tag traced freeway lines at car speed, not wing beats across open water. The episode reads playful at first, yet it opens a serious window into how adaptable seabirds can be in cities that are shaped by waste, weather, and shifting prey.

GPS tracks a seagull moving too fast

The work was led by Megan A. Cimino, a biologist at the University of California, Santa Cruz (UCSC).

The team documented the behavior in a peer reviewed study that marks the first GPS observation of a Western gull using a long haul garbage transfer truck for transit.

“It was surprising and comical, so much so that we wanted to look closely into this one individual’s behavior to understand how this happened,” said Cimino.

The two truck-assisted trips were about 14 to 18 hours longer and 59 to 80 miles (95 to 130 kilometers) farther from the colony than the bird’s other trips during that week.

The gull was originally tagged on the Farallon Islands west of San Francisco, where researchers monitor breeding birds during incubation.

The light tracking device rides near the tail, records locations, and lets scientists reconstruct trips in time and space.

One detail in the record stood out right away. The tag showed freeway speeds that far exceed routine flapping flight in this species of gull.

The gull and the garbage truck

The map painted a tidy route that urban commuters would recognize. She left a Recology transfer station near Candlestick Point, crossed the Bay Bridge, moved along Interstate 880, and continued on Highway 580 to a compost center near Modesto.

“I have not seen that behavior in any other species that I’ve studied,” said Scott Shaffer, a biologist at San Jose State University (SJSU) who helped lead the tracking.

The bird spent the night near the compost site and flew back to the islands the next day.

Two days later, she tried a different crossing and reached the same destination. The pattern made the team look twice at whether this was a fluke or a tactic.

Trip timing, distance from the colony, and the long return flight all lined up with a foraging run that traded effort for predictable calories. The tracker provided a clean timeline rather than a guess based on sightings.

How does a gull hitch a ride

Researchers think the first trip was accidental. These trucks often have mesh covers to keep material from spilling, and a bird feeding on scraps could end up under the cover as the driver prepares to leave.

The second ride is harder to explain. The data say what happened, not why it happened.

Gulls are quick at learning patterns that lead to food. A quiet loading yard, routine schedules, and a river of edible waste can add up to a repeatable choice.

The tactic carries risks, however. Moving traffic, heavy equipment, and contaminated scraps are a rough bargain compared with a clean fish near the surface.

Why a gull turns to land foraging

Western gulls switch between coastal waters and urban landscapes, and the balance changes with ocean conditions.

In years when upwelling is compressed and prey near the surface is scarce, gulls spend more time on land, as shown in a study that tracked foraging shifts between 2013 and 2019.

That work also noted how gull behavior overlaps with whales that push prey toward the surface during feeding bouts. When prey is less available at sea, birds turn inland and trips on land run longer and farther.

Urban foraging taps a steady stream of wasted calories. Stadium leftovers, dumpsters behind restaurants, and transfer stations make dependable stops.

These are anthropogenic food sources, meaning they arise from human activity and infrastructure. Birds adjust when natural prey waxes and wanes.

What it says about cities and climate

The truck rides are rare, but they fit a larger theme. Wildlife uses human built networks in unexpected ways when those networks lead to food.

The episode is a reminder that waste management footprints reach far beyond pickup routes. They also shape behavior in opportunistic species that watch and learn.

Climate variability can magnify these choices by pushing prey around. When winds reshape upwelling and surface feeding ebbs, birds that cannot dive must improvise.

Other animals use human transport in different ways. Land birds crossing the Mediterranean have been recorded resting on vessels during harsh weather, according to a paper in Ibis that assessed ship-borne stopovers.

What scientists are watching next

One bird does not make a trend, but it can point to one. The team’s long term tagging on the Farallones helps reveal whether this tactic spreads as conditions change.

Small biologgers now carry longer-lasting batteries and store precise fixes. That lets field crews compare land trips and sea trips across years, storms, and marine heat waves.

If rides like this become more common, gulls could end up as inadvertent couriers of pathogens or plastics. Managers might revisit how transfer stations and compost sites handle the edible waste that attracts birds.

For now, the record sits as a sharp, slightly comic case that still matters. It shows how a common seabird reads a human system and, for a day, lets the trucks do the work.

The study is published in Waterbirds.

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