I'm sorry but can you be a bit more specific on these following observations?
        
                    
             
        
        
        
In this question, there are no options given to choose from. So i would answer this question based on my knowledge. The most likely cause of the observed variation is adaptation and evolution. The birds of that island adapted to the food source and then they evolved as per the requirement of the place and food source.
        
             
        
        
        
Answer:
incisors
Explanation:
incisors are mainly used for biting and cutting
 
        
             
        
        
        
Maintaining Homeostasis. The process in which organ systems work to maintain a stable internal environment is called homeostasis. ... Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas.
The normal blood glucose level (tested while fasting) for non-diabetics, should be between 3.9 and 5.5 mmol/L (70 to 100 mg/dL). ...
 Blood sugar levels for those without diabetes and who are not fasting should be below 6.9 mmol/L (125 mg/dL).
There are lots of different hormones in the human body that serve lots of different functions, but some are used to maintain homeostasis of various physiological parameters, like blood glucose levels. Blood glucose levels are regulated by two opposing hormones: insulin and glucagon.