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:
communication is not the function of skeletal system
Ultraviolet light will increase on earth's surface. It will "raise" temperatures and decrease plant populations.
Actually UV rays do not increase temperature, that's wrong.
They cause mutations in several organisms as they modify their DNA. They also cause skin cancer in humans and also cataracts and sunburns.
But they don't increase temperature.
That's carbon dioxide accumulation.
The correct answer for the question that is being presented above is this one: "A. a video that shows a large river that has penguin populations on both sides."
Here are the following choices:
<span>A. a video that shows a large river that has penguin populations on both sides
B. a video that shows penguin species that have different mating dances
C. a video that shows a penguin that is laying eggs
D. a video that shows penguins in a tidal pool and an open ocean</span>
Pretty sure it’s B) BB and Bi since they both hav the dominant B gene and would exhibit the only phenotypic B trait
