Depending on the nectar and pollen sources in a given area, the maximum number of hives that can be placed in one apiary can vary. If too many hives are placed into an apiary, the hives compete with each other for scarce resources. This can lead to lower honey and pollen yields, higher transmission of disease and robbing . The maximum size of a permanent apiary or bee yard may depend on the type of bee as well. Some honey bee species or races fly farther than others. A circle around an apiary with a three-mile (5 km) foraging radius covers 28 square miles (73 km 2 ). A good rule of thumb is to have no more than 25–35 hives in a permanent apiary, although migrating beekeepers may temporarily place one hundred hives into a location with a good nectar flow.