When I lived in Oregon there were know spots where true wildlife gathered. They were marked clearly as “Wildlife Viewing Areas”. Some had deers, others elk or moose. All hd one thing in common, food. Someone took the time each day to seed these wildlife areas with fresh hay from their barns or whatever food the animals at that area liked to eat. You had to get up in the wee hours of the morning to be out there when the farmer or caretaker delivered that food to the animals. Still, you could only get within a couple of hundred yards of the dropping point so you’d better bring your longest lens.
At the Southwick Zoo you’ve got 200 acres of wooded area with a decent population of Sika deer living there year round. They not only get fed by the zoo staff but by all the visitors to the zoo. They walk right up to you and eat out of your hand. Busloads of school children and their chaperones visit these deer every day. It’s easy to walk into the huge fenced off area of the forest and feed these deer or photograph them. Understand that the deer come for the food you have, not for pats on their head. Either way if I stand there, camera in hand, I can get extreme closeups of these deer that are 3 feet of less from me. I actually must back up a few feet sometimes as the minimum focusing distance of my 55-200mm zoom is 6 feet.
I look forward to future visits to this area of the zoo when lighting conditions are just right. I don’t need to buy feed for them as there are always kids with the corn they eat waiting to reach out a hand.