First heats tend to come around the age of 250-275, any that have not experienced one by 300 tend to be considered late bloomers and/or are retested in case of being misinformed. Heat happens only twice a year and lasts for 3 to five days. On the night before and sometimes even the day before a heat starts, the siren will feel a need to be closer to their partner as well as the start to the slight fever. If they do not have a partner, then the need for that is not strong, though it does not affect the arousal or sexual desire they feel during heat. Heat is something that can be taken care of either on their own or with a partner. However, a partner is something that doctors recommend due to it helping with the heat not lasting for longer than the siren's body can handle. If drugged, a siren who is able to go into heat experiences certain things like they would if they were in heat depending on what they are drugged with. It has been suspected in males, more so than females, that they can be more possessive of a partner who they have strong feelings for or even love. Another thing that male sirens experience, whether in heat or not, is the ability to produce a kind of self lubrication. However, that lubrication is produced more when they are in heat. Though heats could happen for any gender, it is documented that any male born sirens that have this are able to become pregnant during heat, but unable to impregnant someone. For a male siren, delivery is usually done via a c-section. There is a 50/50 chance of pregnancy happening and typically lasts for 38–40 weeks. Symptoms of heat include high spike in libido, cramps and/or sweating, loss of appetite. As well as flushed cheeks due to the slight fever.