Also, since exponential population growths rarely occur in nature, they occur most often in a laboratory setting due to a lack of competitors and other forces that normally decrease populations. However, after day 60 the population steadily decreases below the carrying capacity and then stabilizes at a growth rate of zero on day 140. This change in growth rate was most likely cause by a limitation of resources that began after 60 days, thus causing the population to decrease and then stabilize at a new carrying capacity.
(c) While the song sparrow population (graph c) is a logistical population growth as well, the amount of sparrows vary greatly compared to the other graphs, primarily due to the fact that this population is in its natural habitat over the span of 25 years. While the populations in the laboratory setting had one carrying capacity, the sparrow population has several, all at different population amounts. This is due to the fact that, in nature, the carrying capacity changes in response to environmental changes. Also, this population experienced a few population crashes, an abrupt decline from a high to low population density. This is commonly caused by an exhaustion