They are not MY studies. They are studies by specialists in the reptile community that have dedicated parts of their career to studying reptile behavior.
A biologist or herpetologist most likely does not have a specialty in the field of reptile behavior. The can study a number of things, but there are only a few dedicated herpetologists that have extensively studied how captivity affects the behavior of certain species of reptiles.
My mentor, for example, held a masters in Herpetology and a Doctorate in Biology. His specialty was natural adaptations - feeding, mating, territory size - in locality animals of the west and southwest. He also dabbled in central and south american colubrids. He spent literally no time studying the effects of captivity on captive snakes.
Do you understand this distinction?