Biomes for breeding are correct the temperature can be different due to height or different sides of the same island. You the breeder has a couple of ways to achieve success. You can stay in the mating biome and raise the babies which could require A lot of iceboxes and fires or grills. Also, you need to know you cannot breed them on a boat in the correct biome it will say "not desirable biome for mating". You have to be on land in the correct biome. I will take animals on a boat put them on land breed them then ship them back to temperate this is easier with giraffes elephants and rhinos cause the gestation is 6 hours or thereabouts. I know some people who set up bases in the correct biomes and breed and raise them there although this is more hands-on until the animal gets 10%. I breed in the correct biome ship them back to temperate and use a raised floor with campfires underneath. This I found is easiest for me doing it solo one fire is give or take 1-1.5 C degree change. I just set the fires to load them with at least 1k wood and this will last for 8 hours which is what rhinos elephants giraffes razortooth tourtugars require to get to 10%. I know some people use torches. I found in tropical and desert the temp swing from day to night is so great its hands-on till you get to 10%. You can do veggies eaters with berries though they spoil fast. A good rule for the survival of your babies which is overkill but works is one trough per baby. Meat eaters Razortooth lions tigers etc should have cooked meat this last about 13 hours with one trough per baby full. Once they get past the first day they eat a lot less. One trough per baby first night is a good formula for success. Egg incubation I only do in temperate with grills and you have to find the mix right now in my egg incubator I have 13 grills arranged in a special pattern which I use for razor tooth and tortugar eggs it a set and forget configuration that incubates the 4-hour eggs. Once you can load the baby with 6 slots of 100% food they will live till they eat off the trough some animals only need 5 slots but each type of animal is different. Also, the time that the food expires is different a lot of breeders grow potatoes cause these are the best for veggie eaters.
PS. You guys are lucky that we that have been doing it from day one showed the devs, in the beginning, the temperature affected the animal for the whole time period so the only way we did it, in the beginning, was by smoking crack rocks.