Why do overlapping niches lead to competition?

Which plains area lies in both the united states and canada? altiplano central canadian shield coastal plains great plains

Which of these resources is used worldwide to make construction products, pottery, and porcelain

An ecologist studied the same species of deer during the summer and the winter. she noticed that during the summer, when there was plenty of food, the deer were energetic and playful. however, during winter when food was scarce, the deer moved more slowly and did not run unless they needed to escape a predator. which scientific fact is best supported by her observations?