(NYTIMES) - It's an unusual search that has captivated animal lovers around Norfolk in the US state of Virginia, for days: Bloodhounds, infrared cameras and even drones have been used - all to try to find Sunny, a female red panda.

Sunny disappeared from her habitat at the Virginia Zoo sometime after 5pm local time on Monday (Jan 23) but before Tuesday morning. Extensive searches by workers and volunteers inside the zoo and in surrounding neighbourhoods had produced no credible sightings by late Friday.

Sunny, who measures 86cm long - half of which is her tail - is 19 months old. That makes her a young adult capable of reproducing. It might have been her habitat mate, a red panda named Thomas, who caused her to leave, Greg Bockheim, the executive director of the zoo, said in an interview on Friday.

In preparation for the one day a year that red pandas mate, Thomas may have been pursuing her too closely, and she either left or lost her footing during his aggressive pursuit.

Although red pandas are not diggers or jumpers, they are agile climbers. The open exhibit is surrounded by tall oak trees that she could have easily reached.

Red pandas are known for being adorable.

"They really look like a plush toy," Bockheim said. They are also in trouble. The International Union for the Conservation of Nature, which assesses the status of wild populations of animals, estimated that about 10,000 live in the wild, in two subspecies, all on mountain slopes in a narrow band running from western China to Nepal. Deforestation and disease threaten them now, and climate change looms.

Sunny's disappearance has spawned her own Twitter account, with one tweet noting: "After watching 'Madagascar,' I just needed to get out of @VirginiaZoo to see what's going on outside my enclosure."

Zoo officials have established a hotline, which Bockheim personally answers, and distributed fliers to mail carriers because they are well acquainted with the city and might more readily spot the escaped animal.

While there have been no verifiable sightings of Sunny so far, there have been plenty of purported sightings that turned out to be raccoons, he said. It is mating season for raccoons, and they are active and chattering, drawing the attention of residents who were convinced it was Sunny.

Officials used a drone on Friday and will again on Saturday. The handlers of bloodhounds who have canvassed the 53-acre zoo believe Sunny might still be on the grounds. Workers have set traps with grapes and bamboo.

The zoo has provided a detailed account of the efforts to find Sunny in a blog that has been updated daily. The community has responded enthusiastically, and officials have encouraged residents to check garages, sheds and under porches.

Sunny is not the first red panda to break out. Rusty, a red panda who was less than a year old, escaped from the National Zoo in Washington in 2013 and was captured less than 24 hours later. Bockheim said a red panda that escaped a Chinese zoo was free for 202 days before it was captured.

As for the outlook for Sunny to survive, Bockheim said the conditions were in her favour: It's cold, the area around the zoo is rich in bamboo and there has been abundant rain, making water readily available.

Bockheim, who has been executive director for 10 years, said the search for Sunny has been "an experience." "I never thought we would have bloodhounds tracking through the zoo," he said.