Thursday, January 28, 2010

The Greatest Show on Earth

The humpback whale, nicknamed Hook, breaches off of Hook Head, Co. Wexford. Image copyright of Padraig Whooley, Irish Whale and Dolphin Group (IWDG)

Sometimes we're really spoiled when it comes to enjoying nature up close and personal. In the early part of this week, newspapers and RTE television news reports were full of images of humpback whales launching themselves majestically through the air off Hook Head in Co. Wexford.

The humpback was first seen off Wexford in early January and on the 22nd, a team of researchers from the Irish Whale and Dolphin Group (IWDG), Galway-Mayo Institute of Technology (GMIT), Bord Iascaigh Mhara (BIM) and a camera crew from Crossing the Line Films chartered the MV Rebecca C to view and film the animals.

Padraig Whooley, IWDG's Sighting Co-ordinator reports that this is a new humpback to Irish waters. He's sure of this because of analysis carried out on photographs of the whale's tail. Each whale has a slightly different one - a bit like a human fingerprint, which allows scientists to track them around the world. Just as long as they can get a good look at their tail.

This new animal brings the number of humpback's officially sighted in Irish waters to eleven. Many of these are regular visitors and return every year and despite the seemingly small numbers, the IWDG believe there is a slow but steady recovery going on in the Irish humpback population.

On Saturday last, as if to celebrate this good news, the humpback put on a spectacular 45-minute show where it breached the surface of the water on eleven occasions. All of this activity was documented in high definition by Ross Bartley from Crossing the Line films and the footage will form part of a new series of "Wild Journeys" due to start on RTE television later in the Spring. I for one am really looking forward to seeing that.

The humpback whale (Megaptera novaeanfliae) is one of the baleen whales. This means it filters its food directly from the water. Rather than having teeth with which to eat, the humpbacks are equipped with a baleen filtration system. This is made up of stiff plates which grow down from the gums of the upper jaw and extend in rows down both sides of the mouth. Baleen is made out of keratin- the same protein that our hair and fingernails are made from.

It is estimated that an adult humpback will eat up to 4% of its body weight per day. To do this, the whale gulps crustaceans and schooling fish in to its mouth and uses the filtration system to separate the food from the water.

In some cases, humpbacks will use a "bubble net" to capture food. The animal dives down beneath its prey then swims in a spiral upwards blowing bubbles from its blowholes as it does so. These bubbles form a sort of tubular net in which prey are trapped and pushed to the surface where the whale eventually gobbles them up.

Humpbacks have even been known to bubble net collectively. So, while one animal is blowing bubbles, another might be diving deeper to 'herd' prey into the net while more animals may be driving prey into the net by singing at them.

This whale song or vocalisation is particularly prevalent in humpbacks who may sing for 24 hours non-stop.

Scientists seem to be in dispute as to why baleen whales, and particularly humpbacks put on such amazing aerial acrobatics shows. One theory is that it is all an effort to attract a mate. Presumably the higher the whale can jump or the bigger the splash the whale can make, the fitter the animal is and all the better to mate with. In fact, breaching seems to increase when the animals are in groups, so this does suggest some sort of social function.

There is also some evidence that slapping the water with such force serves to stun and disorientate prey. This may be true, but it would hardly explain such elaborate displays seen off the Wexford coast.

Another theory gaining ground is that the animals are trying to dislodge parasites which attach themselves to their sides.

The IWDG website records 157 sightings of humpback whales in Irish waters going back to 1984. Despite a tiny handful sighted off the north coast and elsewhere, the vast majority of sightings have been recorded in an area stretching from Dingle to Hook Head. That means that in Cork, we have a front row seat for what Padraig Whooley describes as the "greatest wildlife show on earth".


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