My son is 4 years old and needless to say he is the perfect age for anything to do with animals. I decided to take him to Wildlife Safari (https://wildlifesafari.net/) down in Winston about an hour an and a half from Eugene. Here they have a drive thru park where you can see animals such as; rhinos, bears, elephants, giraffes, and many more! We went during the afternoon on a sunny day and all the animals were out and viewable. He was thrilled to see so many animals he had never seen before. There was even a portion of the park where you could buy buckets of food and feed reindeer, and emu.
However, Our favorite part of the trip was the visitors center that had a petting zoo and other animal sanctuaries. When we got hungry we went to the restaurant that overlooked a koi pond with ducks, and even had an island of lemurs that kept us entertained the whole time. There was also a train ride and even a camel ride for the warmer months. My son has been clamoring to go back ever since we left. We had a great day at Wildlife Safari and I think you will too!