The animal welfare charity was contacted by concerned members of the public who spotted the birds at three separate locations between Saturday and Monday.
Inspector Jenni Surgeon collected two brown hens from the back garden of a property on Ferry Road on Saturday afternoon, before rescuing a third brown hen from nearby Fraser Crescent in Trinity on Sunday.
A fourth hen was discovered in Leith at around 10.30am on Monday.
All four hens, which are adults, are now being cared for at the charity’s Edinburgh and Lothians Animal Rescue and Rehoming Centre in Balerno, where they are settling in well.
Animal rescue officer Emma Phillips was called to pick up the fourth hen from Dalmeny Street in Leith after it was spotted outside a block of flats by a resident.
The 24-year-old said: “I collected a black hen which was rather skinny, suggesting it could have been straying for a while.
“It’s unclear whether it has come from the same place as the other three birds. The hen would have had to travel quite far to end up in Leith from Ferry Road or Trinity, so it’s a bit of a mystery.”
Ms Phillips added: “There’s no way of telling if the hens have escaped or if they’ve been dumped. They were all quite skinny, so that’s an indication they’ve either not been looked after well or they have been straying for a while.”
Senior animal care assistant at the Balerno centre, Lora Booth, 31, said it was unusual for hens to be rescued, with only a handful coming in so far this year.
She said: “Quite often we get cockerels in these circumstances but not really hens, although we’ve had the odd one here or there over the year.
“The hens are absolutely fine and they’re all quite happy. They have a slightly thin body condition but they are eating well and seem healthy enough.
“I don’t know how long they would have survived on their own if they had been dumped, it could be that a fox would have got them.
“It could well be that they have wandered off from somewhere in that area, or it could be that somebody has just dumped them because they no longer wanted them.”
Staff at the centre plan to name the hens once they get to know their personalities.
They will remain at the centre for a week and if nobody comes forward to claim them, they will be rehomed.