Its name is a byword for greed, but it seems the gannet is not such a glutton as we thought.
A study has found that, despite the seabird’s reputation for having a huge appetite, it does not steal rivals’ food.
Colonies
stick to their own fishing grounds and studiously avoid even flying
across sections of sea to which other gannets have laid claim.
Gannet colonies stick to their own fishing grounds and studiously avoid even flying across sections of sea to which other gannets have laid claim
What is more, this occurs
despite the birds doing nothing to defend the boundaries of their
feeding sites, the journal Science reports.
‘We
found that gannet colonies had neatly abutting and clearly defined
feeding areas,’ said the report’s joint lead author Dr Ewan Wakefield.
‘Gannets may be a byword for gluttony but, clearly, they don’t feed off each other’s plates.’
Researchers from 15
institutions, including Leeds and Exeter universities, attached
matchbox-sized tracking devices to nearly 200 cliff-dwelling northern
gannets from 12 colonies around the UK and Ireland.
The
data recorded by the tracking devices clearly showed that each colony
had its own fishing ground. And despite these sites sometimes touching,
the birds didn’t try to steal rivals’ food.
In
fact the distinctive birds, mainly white with black wing tips, rarely
even flew over each other’s fishing grounds despite round trips which
lasted up to four days and covered more than 600 miles.
This occurs despite the birds - which are white with black wing tips - doing nothing to defend the boundaries of their feeding sites
It is thought the northern
gannet – Europe’s largest seabird with a wingspan of almost 7ft – sticks
to its own parts of the sea because it has learned that these are
likely spots to catch mackerel and other favoured fish.
Dr
Thomas Bodey, the other joint lead author, said: ‘Gannets get their
chance when shoals of fish are forced to the surface, often by predatory
whales and dolphins.
‘But when the gannets start plunging in the water and feeding on a shoal, the fish start diving.
‘You
have to be one of the first gannets to get there and that is where the
maths comes in: if you go into an area that is being used by birds from a
closer colony there is a high chance that individuals from another
colony will be there first.’
Dr Keith Hamer, of Leeds University, said: ‘For a long time people have looked at what seabirds do on land but we knew very little about what they did at sea. That has changed with the advent of miniature data loggers which allow us to track them.’