Which of the following is NOT a permanent mark used in the mark and recapture technique?

In the context of the mark and recapture technique, which is used to estimate animal populations, permanent marks are those that remain with the animal for an extended period and are easily identifiable over time. Collars, tattoos, and tags all serve as permanent marks because they are designed to withstand the wear and tear of the animal's life and can be identified by researchers during subsequent observations.

Collars are often used for larger animals and can be adapted for tracking and identification without harming the animal. Tattoos can be applied to the skin and can last for many years, allowing researchers to identify specific individuals. Tags, when securely attached, can be very durable and are used widely across various species.

On the other hand, paint is typically temporary and can wear off easily due to environmental conditions such as rain, sunlight, and abrasion. Therefore, it does not meet the criteria of a permanent mark, as it may not be reliable for long-term studies and identification of individual animals over time. The lack of permanence in paint makes it unsuitable for serious population assessments where accurate and lasting identification is crucial.