A black bear was spotted roaming the Riverton neighborhood in Portland on Wednesday evening and Thursday morning, prompting police to remind residents to stay away if they spot one and remove food sources such as bird feeders.

While the presence of a black bear in Portland is unusual, it does happen occasionally, particularly during spring, when bears have emerged from their winter dens and are searching for food.

“Spring is the time of year when bears are going to be more likely to take the risk of going into human populated areas looking for food. It doesn’t matter if you’re in Maine or Florida, this is the time of year when bears are more out and about and coming into contact with people,” said Jennifer Vashon, the state black bear biologist with the Department of Inland Fisheries and Wildlife.

A resident off Stuart Street reported seeing a bear in a neighbor’s yard between 3 and 4 a.m. Thursday, according to police. Portland police said there were also recent reports of a bear in the area of Castine Avenue.

Both of those streets are off outer Forest Avenue and abut a large wooded areas alongside the Maine Turnpike and the Riverside Industrial Parkway. Police notified game wardens about the bear so wardens could respond if needed, but there had been no additional sightings Thursday afternoon or evening, said Lt. Robert Martin of the Portland Police Department.

Brielle Sebold, who lives on Aldworth Street near Riverton Elementary School, said she spotted a black bear prowling through her backyard Wednesday evening. She said the bear left to visit a few of her neighbors’ houses, where it began eating from bird feeders.

The bear returned to her yard around 7:30 p.m., when she started to videotape its movements. At one point the bear started to approach the door to her pantry. After sniffing the air around the pantry door, the bear turned around and fled into a wooded area.

“I was a bit concerned because the door it was coming towards was to our pantry, so I knew it could smell food and I wasn’t sure how hard it would try to come in,” Sebold said in an email. “We made sure the door was double locked, though, so I don’t think there was that much danger of it pushing through.”

Sebold said she sometimes leaves the door open, but she won’t do that again after having such a close encounter with the creature.

Portland police reminded residents that bears will be attracted to a free meal even in a residential area. Game wardens and state biologists suggest removing food sources such as barbecue grills, bird feeders and trash cans.

“If you spot a bear you should stay away from it,” police wrote on Facebook. “Bears are very fast and agile. If cornered or with cubs they can be dangerous.”

It is rare, but not unheard of, for a bear to be spotted in Portland. In 2011, game wardens shot and killed an agitated 120-pound black bear in East Deering that they said had been acting unnaturally and aggressively.

In the past week, bears have also been reported in residential neighborhoods in Gorham and Berwick, where a bear ripped up a chicken coop. An adult black bear killed eight goats and destroyed three beehives recently at homes in Chesterville, Jay, New Sharon, Wilton and Vienna.

Vashon, the bear biologist, said bears are most active between April 1 and Nov. 1. They have recently come out of their dens, where they lived on their fat reserves for winter, but there is not yet a lot of natural food on the ground. As they look for food, bears are lured by food scents and may be attracted to bird feeders, garbage and grills.

Vashon said the department has already taken 100 complaints statewide about bears in May. Typically, 100 to 200 complaints come in during the month, but the number can rise to 300 in June.

The reports vary from people saying they spotted a bear to destroyed bird feeders to attacks on livestock. Vashon said people should make a complaint if a bear doesn’t run off when they make loud noises or seems to tolerate the presence of people.

“That’s the point we might be concerned,” she said.

Vashon said there are steps people can take to lessen the chance they will attract a bear to their property, including taking down bird feeders, storing trash inside and washing the food scent out of coolers stored outside. People should also be careful to avoid bears by not walking dogs at night and keeping their garage doors closed.

“The best thing to do if you see a bear in your backyard is make a lot of noise from a safe distance,” she said, noting that people should never run from a bear.

Maine’s black bear population is around 36,000, according to the Maine Department of Inland Fisheries and Wildlife.

Staff Writer Dennis Hoey contributed to this report.