if my chameleon gets a lot of natural sunlight will he need vitamin d supplement? because i plan to have his cage close to a window.
Regular glass blocks over 98% of UVB rays (which is why you don't get sunburned sitting by the window) so sitting your chameleon by the window does not provide any UVB rays unless it is open and there is no glass between the sunlight and your chameleon. The heat from the sun through a window can actually be a danger to your chameleon. A UVB bulb is necessary if unfiltered sunlight cannot be provided for at least 5-8 hours every day.