It’s an unusual search that has captivated animal lovers around Norfolk, Va., 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 5 p.m. Monday but before Tuesday morning. Extensive searches by workers and volunteers inside the zoo and in surrounding neighborhoods had produced no credible sightings by late Friday.

Sunny, who measures 34 inches 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. Though 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 have reached.