* Species: Different deer species have different social structures. For example, white-tailed deer are usually found in smaller groups, while elk (a type of deer) can have herds of hundreds.
* Habitat: A herd's size can be influenced by the availability of food and water.
* Season: During mating season, herds can grow larger as males compete for females.
* Location: Deer populations can fluctuate based on geographic location and environmental factors.
Generally, you can expect to see herds of anywhere from a few deer to several dozen in a single group.
It's more accurate to refer to a group of deer as a "herd" rather than focusing on a specific number.