June 14, 2013 6:52 pm

Each to his own: the gannet’s creed

Scientists found that these huge seabirds maintain foraging territories and respect these boundaries
Gannet©Tom Warlow

Gannet colonies respect each other’s fishing grounds, without territorial aggression

Scientists studying gannet colonies around the coasts of Britain and Ireland have made a surprising discovery about the feeding habits of these huge seabirds. Each colony has its own fishing territory where the birds feed undisturbed by intruders from neighbouring colonies. These divisions persist even though gannets do not engage in aggressive territorial behaviour. Birds entering from a neighbouring colony could fish unhindered – but choose not to do so.

“The accepted view is that exclusive foraging territories are associated with species such as ants, which aggressively defend the feeding areas around their colonies, but this opens the door to a completely new way of thinking about territory,” says Ewan Wakefield of Leeds University, joint leader of the study, published in the journal Science.

“We found the gannet colonies also had neatly abutting and clearly defined feeding areas,” he says. “Gannets may be a byword for gluttony but clearly they don’t eat off each other’s plates.”

Researchers from 14 institutions tracked 200 gannets flying from 12 colonies around Britain and Ireland. Instead of criss-crossing flight paths from neighbouring colonies as the birds headed out to fish, a tightly defined non-intersecting pattern emerged. The Irish colonies at Bull Rock and Little Skellig are within sight of each other, but their inhabitants always head off in opposite directions.

The explanation seems to be that each colony started fishing in the closest waters, and this preference has been reinforced by “cultural transmission” between generations.

“Finding such separation between colonies, even when visible from each other, indicates that competition for food cannot be the only explanation and suggests cultural differences between colonies may be important,” says Thomas Bodey of Exeter University. “As with humans, birds have favoured routes to travel, and if new arrivals at a colony follow experienced old hands then these patterns can quickly become fixed, even if other opportunities potentially exist.”

This raises the question of how many other species show segregated feeding patterns. The answer will be important for formulating conservation strategies.

“We understand an awful lot about what these seabirds do on land but until recently we knew shockingly little about what they do at sea,” says Stuart Bearhop, also at Exeter. “The technology is now allowing us to leave the coast with them and we are discovering more and more of these amazing and unexpected patterns.”

The gannet, with its two-metre wingspan, is the largest European seabird. Unlike many other species, its numbers have been growing in recent years.

syringe©Dreamstime

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Deciphering cancer’s signature in blood

An initiative to find blood tests for cancers while they are still at a very early stage is under way, through a partnership between the charity Cancer Research UK and Abcodia, a London biotechnology company.

The scientists will look for any “biomarkers” that cancers might produce before they have grown big enough to cause symptoms. Early detection gives a much better chance of a cure, though for most tumours no pre-symptomatic screening tests are yet available.

The project is an offshoot of the long-running UK Collaborative Trial for Ovarian Cancer Screening (UKCTOCS), which has built up a bio-bank of more than five million blood serum samples taken from 200,000 healthy middle-aged women since 2000. Twenty-seven thousand of the volunteers have developed cancer since enrolling in the trial.

The primary aim of the trial is to see whether screening can save lives through early detection of ovarian cancer but the samples could be vital for investigating biomarkers for other cancers. “Diagnostic technology has advanced enormously, so that we can detect biomarkers in very low concentrations that would not have been possible a few years ago,” says Ian Jacobs, UKCTOCS director and a founder of Abcodia.

The partnership will look for molecules that are in the serum of people incubating pre-symptomatic cancer but not present (or present in far lower concentrations) in the wider population. They might be proteins, antibodies or indicators of gene activity.

The researchers hope to find the first candidate biomarkers in 12 to 18 months, which might lead to a clinical trial in three or four years. Any biomarker must be easily measurable in clinical settings but also avoid false positives (which alarm patients and lead to unnecessary treatments) and false negatives (which give misleading reassurance).

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Farmers could put bumblebees to work

Bumblebee on strawberry flowers©Harriet Roberts

Bumblebee on strawberry flowers

Bumblebees, already used to pollinate strawberry flowers, can also apply fungicide to prevent the fruit going mouldy.

An ingenious delivery system, developed in Belgium and Finland, is being evaluated for British conditions by two food and farming consultancies, ADAS and East Malling Research.

Growers are increasingly using bumblebees in small portable hives to pollinate soft fruit, so that they do not have to rely on increasingly scarce wild insects and honeybees. Bumblebees, with their relatively large and hairy bodies, are particularly efficient at carrying pollen between flowers.

The Belgian company Biobest has adapted its bumblebee hives to include a fungicide powder dispenser through which the bees walk as they leave the hive. Small amounts of the fungicide stick to their bodies, and they carry it to the flowers that they pollinate.

The target is “grey mould”, caused by Botrytis fungus, which develops in strawberry flowers and then ruins the fruit as they ripen. In wet summers like 2012 the disease causes huge horticultural losses.

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The fungicide is a biological product – a powdered form of another fungus called Gliocladium catenulatum, which is harmless to fruit and insects. It outcompetes the grey mould on the growing flowers, while producing an enzyme that destroys Botrytis cells. The system is approved for use in Belgium and in Finland, where the biofungicide is produced, but more evidence of its safety and efficacy under British conditions will be required before it is licensed in the UK.

Preliminary indications are encouraging, says Harriet Roberts, ADAS project manager. “During the last two years of field trials, this harmless bee-delivered control system was demonstrated to be a practical alternative to [conventional] fungicide applications and regularly achieved levels of grey mould control equivalent to areas treated with fungicides, while significantly decreasing any residue left on the fruit itself.” For UK application the system will use a native British species, the buff-tailed bumblebee, Bombus terrestris.

Meanwhile, naturalists are expressing concern about the overall decline of bumblebees in the UK, where seven of the country’s 24 surviving species are believed to be in trouble because of habitat loss and changes in agricultural practices. Aberdeen University researchers want to recruit hundreds of volunteers to help them identify the UK bumblebee populations and distribution on the basis of photographs submitted by members of the public to the Bumblebee Conservation Trust (bumblebeeconservation.org).

An effort is under way in Kent to reintroduce one of the two British bumblebees that became extinct in the 20th century. Short-tailed bumblebees (Bombus subterraneus), from the surviving population in Sweden, are being released this month at the Royal Society for the Protection of Birds reserve at Dungeness.

The reintroduction started last year. “The queens we released had a very rough time with the weather last summer so it was vital that we return to Sweden and bring back more queens to bolster the colony at Dungeness,” says Nikki Gammens, project manager.

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