Yes they do have the same niche
They are of the same genus, not species
I'm not sure what niche you are asking about. The horse and donkey are genetically cousins. When you crossbreed these two cousins you get a mule. You never have to worry about breeding a mule though, they are born sterile. (unable to reproduce)
No, an elk is a deer, or a cousin to deer like White-tail, Mule-deer, Keystone, Black-tailed, etc. Antelope are distant cousins to the deer family.
Not usually. Deer is both singular (one) and plural (many). As is moose.Deers can be used as a plural form of the word deer. If there are several types of deers in the same area than you can use the plural, deers. For example, If there is a field full of mule deer then you use deer, but if there are a mix of mule deer and white tail deer, you would use deers.
Deer are part of the Cervidae family. The Cervidae family includes white-tailed deer, mule deer, black-tailed deer, elk, moose, red deer, reindeer, fallow deer, and roe deer.
some do. You can find a similar placental mammal for every marsupial animal. Example: Kangaroos fill the same niche as North American deer. etc.
They are about the same size as a Mule Deer which are smaller then a horse and bigger then a sheep.
It depends on the individual man and the size, sex, species and age of the deer. In a lot of cases though, if you're comparing an average ~200 lb man to a deer like that of a mule deer buck, they would both be about the same size.
no they do not have the same niche but same habitat, so what?
There about the same
no two species can share the same niche
No, they are different species. Moose are larger and have shovel like antlers. Deer tend to be smaller and have multipronged branching antlers Actually moose share the same Family as deer, being Cervidae, and consequently are considered to be the largest member of the deer family in the world, despite the difference in species name from other true deer like White-tail and Mule deer. So yes, moose can be considered a "large deer," though not literally so, because they are not "true deer."