I had two rescue cats for several years and adopted a third in July, a three year old boy. I know he's had access to the outdoors in his previous life but not how much he went out; except he was picked up straying after his family got a dog then rehomed. I kept him indoors for the first six weeks or so to settle, then granted him freedom back in early September. He seems interested in the outside world but only for brief visits, and I'd like him to be more comfortable in going out and about to reduce strife in the house from him being bored. Any suggestions of how to increase his confidence in going outside?
Further context - we have a microchip cat flap. I've seen him use it to go out a couple of times but 99% of the time he doesn't go out on his own (I have a camera so can see what he's up to when I'm not there). If I'm home and open the back door he sometimes sits for a while on the doormat, looking out, then walks away. Other times he darts outside and eats some grass then sniffs around in the small back garden/immediate neighbour gardens for five or ten minutes then comes back inside. He may dart in and out a few times but then walks away and isn't interested in venturing further afield.
My other two boy cats (all three neutered) go out and roam across several streets and stay out for hours at a time, often all day, so this seems a bit unusual for a young healthy male cat. He seems to get antsy especially in the early hours of the morning, because he's been asleep all day! In the evening he's prone to starting fights with the other two when they come in to have dinner or sit with me, and it would be better for all concerned if he burned some energy off outside.
We have lots of other cats in the neighbourhood, I did wonder if he's intimidated but he's actively chased them out of the garden before with puffed up tail. He is quite a bolshy cat with my other two and will go up to them and try to start wrestling matches, and he's friendly with visitors/cat sitters, so I don't think he's especially shy and retiring. I realise six weeks of being allowed out is still early days in the scheme of things so maybe it'll improve but any suggestions?