The Humpbacks You Can’t See: What Batemans Bay Heard at Night

Do humpback whales pass Batemans Bay when nobody is watching? Yes, and often. Researchers placed a passive acoustic recorder in the bay, in New South Wales, during the 2024 migration period. They analysed more than 100,000 minutes of recordings from May to September, and the whales were there for most of it, and heard more often at night.

Humpbacks were heard across most of the season

Humpback sounds appeared in 70% of monitored hours and on 87% of monitored days.

The first detection came on 19 May. From 22 May, whales were heard every day until the end of the study in late September. Activity peaked in August, with another rise near the end of September.

I love this reminder that migration is not a parade that only happens when we are watching.

The night shift is real

The study recorded more detections at dawn, dusk and night than in full daylight. At night, whale sounds were present in 80% of monitored hours, compared with 62% during the day.

This does not mean every whale sang all night. It means the recorder picked up whale sounds more often in low light. The difference could come from when whales call, how sound travels, or how animals use the bay.

The paper points to darkness as important context for communication. It also says one bay and one season cannot explain every whale’s behaviour.

Can sound recordings count whales?

Passive acoustic monitoring is brilliant at answering one question: were whales vocalising here? It cannot tell us, by itself, how many animals were there.

One whale can call again and again. Several whales may be close together. Quiet animals may not be detected at all. And this study does not promise that a visitor will see a whale on any particular day.

Why this stretch of coast matters

The east Australian humpback population travels between feeding grounds in Antarctic waters and warmer breeding areas in the Coral Sea. Batemans Bay sits on that route. Researchers had noticed a gap in monitoring along this part of the NSW coast.

The new study gives a local baseline. It suggests whales use the bay over a longer window than a quick seasonal snapshot would show.

That matters for understanding migration timing and for planning boats and coastal activity. If whales are present for a long time, management should consider the whole season, and the quiet hours too.

A good whale day may be invisible

Some days the whales show themselves. Some days we hear only a distant call, or nothing at all from where we stand. The animals are still moving through their own ocean.

If you visit the NSW coast, keep your expectations gentle. Follow local whale-watching rules, which can change, and give the animals room. A good encounter can be a quiet one. Wildlife encounters are unpredictable. Whale watching should always follow local regulations and experienced professional guidance.

For a slower look at this coast, explore Australia in our Ocean Atlas.

Questions people ask

Wildlife encounters are never guaranteed and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.