Whales can be found traveling in all of the worlds oceans from the polar climates to the tropics.
These marine mammals make up one of 3 orders among the cetacean family.
The other 2 cetacean members include dolphins and porpoises.
In all there are around 90 known species of cetacea recorded so far.
Unlike many land animals that have four different seasons (winter, spring, summer and fall) cetaceans have two main seasons which are referred to as feeding season and mating season.
During feeding season many species of whale will embark on long migration trips swimming from the tropical climates near the equator to the northern/southern polar hemispheres where they feed on a variety of food in order to restore their energy and build their blubber supply until their next mating season comes around.
Part of the reason some whale species make these long migration trips towards the colder environments is due to the fact that large quantities of prey/food can often be found in these waters.
Depending on the whales species and the environment they live in their feeding season can vary because their seasons tend to be different depending on whether live in the northern or southern hemisphere.
In most cases feeding season occurs during the warmer spring and summer months when the rich abundance of fish, krill, squid and other marine life travel to the colder regions as the ice begins to melt and the habitat becomes more suitable to their needs.
Feeding season is especially important for species that fast during their migration trips and they live off of their fat stores for several months while traveling to their mating grounds.
The blue whale is a good example as they will almost completely halt eating during their migration which can last for up to 4 months.
Feeding season will continue until the colder months of the year when the cold air begins to chill and freeze the waters around them.
Once this happens the will begin their migration and travel back towards their mating grounds to mate and give birth to their offspring.
During the mating season male whales will compete with one another through song, acrobatics, challenging one another and using various communication signals and mating rituals to attract a female to mate with.
Females that are already pregnant will use this time to give birth to their offspring and nurse their young while females that are trying to become fertile may mate with several males in order to maximize their chances of reproducing a healthy offspring.
Mating season will continue on for several months until all of the whales have had an opportunity to interact with one another and give birth to their children.
After all of the whales finish mating the male whales are typically the first to leave the mating grounds and lead the way back towards their feeding environment while the female whales with their newborn children are the last to leave in order to insure that their children are healthy and able to make the migration trip back to their feeding grounds.
Seasons in the northern and polar hemispheres
When it comes to the changes of the seasons most whales that migrate from the north and south do not cross hemispheres near the equator or meet each other at the same time because the feeding/mating seasons in the northern and southern hemispheres do not occur at the same time, so it is unlikely that many of the various species of whales from opposite hemispheres will ever meet.
In some cases whales may also possess a layer of blubber that is so thick it limits how close the whale can come to the equator before become dehydrated and overheated, so the likelihood of them crossing the equator is extremely low.
Tracking the migration patterns of whales
In order to track of the migration habits of various whale species scientist use a variety of methods to track and identify individual whales.
Some whales have distinct markings on their tail which allow scientists to identify the whale and measure where it travels to and how long it takes them to get there.
Another popular method used is to embed a tracking device in the whales thick blubber which scientists can use to follow the whale via satellite and GPS.
In these cases the researchers state that the whales blubber is very thick and the implantation of the tracker does not cause any pain to the whale.
Through these studies scientists have learned that some species of whale travel further than previously estimated and can cover greater distances faster than they thought.
It also allowed them to realize that not all species of whale make these long migration trips and some species have no predictable migration patterns.
killer whale for instance migrate to where their source of food travels and aren’t nearly as concerned with the difference between the two seasons or traveling for mating purposes.
Killer whales that hunt fish and squid will follow these types of prey in order to maintain a steady food source while killer whales that hunt marine mammals such as seals and sea lions will follow those types of prey as the travel or migrate.
Sperm whales on the other hand are solitary wanderers that travel throughout the ocean with no particular pattern and can even travel the entire earth during its lifetime.
During mating season the adult males will meet up with the female sperm whales in their native mating grounds in order to find a mating partner and once the mating season ends the males will travel off in their own directions leaving the females to give birth and take care of their offspring.
Bowhead whales tend to maintain the same living area throughout the year regardless of the season and do not make long migration trips.
Depending on their environment and the amount of food that is available or ice that is surrounding them these marine mammals may travel to other parts of the Arctic waters, but they will stay in the Arctic throughout the entire year.
Of the whales that do migrate most species do so primarily for mating (reproductive) and feeding purposes.
Dolphins, porpoises and migration
Lastly, dolphins and porpoises are not known for making long migration trips like their whale relatives, however they may move from coastal to offshore waters during certain times of the year or from their local rivers to larger rivers.
For example the Amazon river dolphin will stay within its local rivers during the drought season.
Once the rivers begin to flood during the heavy rain season the will leave their local rivers to meet, socialize and mate with other river dolphins that are not accessible during other times of the year.
Dolphins and porpoises that inhibit coastal waters may travel offshore during colder months when the waters begin to freeze over and will move back to their coastal waters when the weather warms up.