Estrella's Strange Behavior

Last week, the daily log was filled with comments on Estrella, the boa constrictor’s unusual behavior. She was described as ‘hissing’ ‘aggressive’, and ‘did not want to move’ when her cage was being cleaned. Although she is always the most active, opinionated and responsive of our snakes, Estrella is normally tractable and fun to work with. So her behavior was alarming.



As always, we need to rule out health problems whenever an animal’s behavior changes. If she has no other way to communicate, a snake who does not feel well may react to handling by biting. For this reason, we treat all behavior issues as possible health problems.

Dr. Maas of Avian and Exotic Animal Hospital in Bothell gave Estrella a head-to-tail exam and commented that if there were no complaint, he would have said she was in excellent health. But to be safe, we did some ultrasound and blood work. The results may explain Estrella’s behavior.


She is starting to ovulate.

Boas are seasonal breeders. A drop in nighttime temperatures triggers the females to begin preparing eggs for fertilization, and the males to get ready to mate. Although we did not intentionally change the temperature of their cages, the cold weather has caused the buildings to be cooler. The snake enclosures have a fairly wide temperature range within them, and the cooler areas probably fell below the point that would induce breeding behavior.

Ovulating can bring about marked changes in snake behavior. They often lose interest in food (though Estrella has not) and may be either withdrawn or cranky. But ovulation is not a medical condition. We were instructed to continue handling Estrella so long as she cooperated, which she has been from the minute she went to the vet. Perhaps Estrella just needed someone to understand her!