First, some more facts about the Bald Eagle: it is important in the US due to its symbolic status, and it used to be endangered and threatened up to 2007, and without conservation efforts it  could have gone extinct. 
Therefore, the conservation efforts are continuing, just to make sure that the species is not threatened again. 
People hiking could endanger the animals: scare them, destroy their nests etc. That's why hiking is not allowed in the critical time: to allow the eagles engage in their roosting activities without obstacles
        
             
        
        
        
Answer: I believe the correct answer for this would be mutation. It has a change on DNA, but can not have ANY effect upon the phenotype.
 
        
                    
             
        
        
        
Primers are small snippets of DNA homologous to different regions in a target gene. For any targeted DNA gene at least two primers are necessary to delimitate a DNA variable segment targeted to be amplified.
        
             
        
        
        
Answer:
The Crainum fossils are the youngest fossils from 134 million years ago. The occur in the top layer of the earth's crust (rock)
Explanation:
Hope this helps :)
 
        
             
        
        
        
<span>Genetic
drift is a predictable event alongside with natural selection, mutation, and
migration. In every era of generation, organisms’ genes may be passed on to its
species, to further the usable genetic trait while the not-so-used genes are
trashed away.</span>