Seasons and Change

Year 7 Science Lesson 5 – 6 Affect of Seasons on Living Things

How do Seasons Affect Whale Behaviour?

Timing of whale annual migration is related to the amount of light in the ocean, which in turn triggers hormonal cycles in the whales.

Krill is also light dependent, so in winter when there's less light, the whale's food supply is less abundant. This may trigger their northward journey.

The timing of the humpbacks northward migration is very constant, with a couple of exceptions every decade or so.

What is the Humpback Whale Migratory Season?

• Whales migrate northward from May with September being the peak month for southward migration, with the addition of whale calves accompanying their mothers on this leg of the journey.

• This is a roundtrip of approximately 12,000 kilometers, during which time they do not eat but calve and mate. Non breeding females don’t always make a full migration north each year.

Dinner Time

• Whales eat during the summer season in antarctic waters.

• Whales eat from November through until April and can consume 2000 – 2500 kilograms of plankton, krill and small fish at a sitting.

• Whales eat twice a day.• Whales in the northern

hemisphere eat a range of sea creatures, not just krill.

Seasonal Songs… the Oceanic Top 40

During the breeding season, male humpbacks sing long complexsongsThe sound is so loud, it is louder than the roar of a jet and can be heard under water for 30 or 40 kilometers.Songs change every season, with some sequences in a song remaining the sameSongs travel from region to region, appearing in different areas over a period of years

Global Warming and Seasonal Change

• As seasons are affected by global warming, it is predicted that whale breeding with also be affected.

• Whales may migrate earlier and return earlier to southern feeding grounds

• Lack of availability of krill at an earlier time may result in a lack of food for whales on their migratory return

Extreme Weather

Climate change affects the seasons. Extreme weatherhas been noted around the world due to global warming. In order tomaintain nature’s delicate seasonal balance, we need to reduce carbon emissions globally.