Migration : The organisms (animals) can move away temporarily from stressful habitat to a more hospitable area and return when stressful period is over.

e.g - Humans moving from Delhi to Shimla during summer / many animals or birds undertake long distance migration to hospitable area any one e.g. 

• Spore formation : various kind of thick walled spores are formed which germinate on availability of suitable environment.

e.g -bacteria /fungi / lower plants.

• Dormancy : seeds or vegetative reproductive structures help to tide over stress by reducing their metabolic activity. 

e.g seeds or vegetative reproductive structures of higher plants

• Hibernation : It takes place during winter. 

e.g bears or any other correct relevant example.

Aestivation : It takes place during summer to avoid heat and dessication (in animals). 

e.g snails / fish or any other correct relevant example 

Diapause : under unfavourable conditions zooplanktons enter a stage of suspended metabolic activity. 

e.g zooplankton.

Detailed Answer: 

Three different ways by which organisms overcome their stressful conditions are : 

(i) Migration : Birds like bar-headed geese temporarily move from the stressful environment to the more hospitable environment and may return when the period of stress is over. This phenomenon of moving from one place to another is commonly known as migration. 

(ii) Hibernation (winter sleep) : It is period of long inactivity in which organism reduces all its metabolic activities and undergo a period of long sleep. e.g., polar bear hibernates during winter. 

(iii) Aestivation (Summer Sleep) : It is commonly seen in animals that live in hot and arid conditions. Frogs undergo aestivation.