Bird migrations began with the recession of the glaciers during the ice age. You will notice a great increase in insects in the spring time and early summer.The birds moved North to take advantage of this increase in the food supply that followed the warming in the spring and early summer. Their reproductive organs temporarily developed so they could lay eggs and raise a family. Look at the early flush of Night crawlers in the moist times of the early rains. By mid summer most of the insects have matured, mated and died. Their eggs have hatched and turned to larva and moved underground until next spring. The shortening of the days causes the reproductive functions to decrease and signals the birds that the food will soon become scarce. They move back to the area that makes it the easiest to find food and avoid freezing. which of course is the warmer climates nearer the equator. Not all birds move past the Tropics at approximately 30 degrees. Some like Chickadees may move down from Mi or Mn or Canada only as far south as Indiana. Some migrations may be quite short. For example from the mountains down to the plains. They don't generally reproduce in the warmer winter climes they migrate to. In the spring time they migrate along paths of the retreating glaciers. As the climate warms away from the tropics the birds follow the emerging insects etc to the birds selected breeding grounds.with increased insects and longer days to feed the hatching's. It is necesary to understand why they move to cooler climates in the summer to under stand why they move to eh warmer ones in the fall. As the days shorten the food supply dwindles and the babies have fledged. They move to warmer climates in winter to rest and refuel for the next years migration.
Answer:
A in explanation
Explanation: The cell cycle is a four-stage process in which the cell increases in size (gap 1, or G1, stage), copies its DNA (synthesis, or S, stage), prepares to divide (gap 2, or G2, stage), and divides (mitosis, or M, stage). The stages G1, S, and G2 make up interphase, which accounts for the span between cell divisions.
Answer: anaphase- the stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle
Example: daughter nuclei
Explanation:
The principle of competitive exclusion states that two species cannot occupy the same niche.
<h3>
What is competitive exclusion?</h3>
- Two species cannot coexist in the same ecological niche for very long without one becoming extinct or being driven out because of competition for limited resources.
- In Britain, the red squirrels have displaced the grey squirrels as an example of competitive exclusion.
- Due to diseases, competitive exclusion, and the elimination of hazelnuts, there were fewer red squirrels.
- Red squirrels were eventually displaced by gray squirrels, who quickly adjusted to their surroundings.
- Two species with identical niches cannot survive indefinitely, according to the "competitive exclusion principle" (CEP).
- According to the competitive exclusion principle, only one conclusion is feasible when two competing life forms try to inhabit the same niche: One of them will extirpate the other.
Learn more about principle of competitive exclusion here:
brainly.com/question/14395037
#SPJ1
