Megalithic shipping and trade routes

[hvered]

The author of Birds of Massachusetts, a renowned ornithologist called E.H. Forbush, noted that cormorants off Labrador embellished their nests with objects salvaged from shipwrecks. They'd retrieved penknives, pipes, hairpins and ladies' combs.

It may not be accidental that cormorant rocks are, or were, off the coasts of Devon and Cornwall and Scottish islands, if shag place-names can be relied on. Can cormorants (sea crows) be trained to collect objects offshore just as corvids on land are able and willing to do?

[Boreades]

Can cormorants (sea crows) be trained to collect objects offshore just as corvids on land are able and willing to do?

Yes.

Cormorant fishing

Sorry about the tourist voice-over.

[Mick Harper]

There is another, if lesser, possibility. These birds are feral domesticates who had their 'nests' built for them by shipboard human beings. Sailors are specially prone to adorning these kinds of things. They're sentimental like that. Nothing's too good for your shipmates.

[hvered]

Cormorants are famously controversial and, as with crows, large numbers are culled by fishermen mainly but also conservationists (illegally culled in Scotland, where salmon fisheries matter more than bird welfare). But the most widespread culling is in America so why would Labradoran cormorants make their nests conspicuous with gew-gaws? Can they not un-learn behaviour?

The situation in North America is reminiscent of the passenger pigeon story. In the 19th century there were huge numbers

...after birdwatching near Natchez, Mississippi, in December of 1820, John James Audubon reported: “We saw to day probably Millions of those . . . Cormorants, flying Southwest—they flew in Single Lines for several Hours extremely high.”

By the 20th century numbers were small enough for the species to be officially endangered until some protection was allowed (though wider measures such as the banning of DDT were more effective) and nesting sites were, inadvertently, provided by engineering projects to stabilise small islands. Artificial islands in distant lakes have recently been built to lure them away from fish stocks.

Artificial islands for cormorants rings a bell. The difference seems to be the islands were intended to be visible.

[hvered]

Passenger pigeons are the fastest long-distance fliers. The falcon is said to achieve the fastest diving speed achieving 200 mph, though the claim has never been scientifcally verified to date, but I was surprised to read that the eider duck is faster than falcons in level flight as they are quite heavy birds and anyway ducks aren't normally associated with speed. The RSPB explains this, sort of

They have the smallest wing area relative to body size, also known as the highest wing loading. Because of this high weight-to-wing area ratio, speed is vital to the eider in order to produce enough lift to keep the weight in motion. To achieve this they have very strong wing muscles. These come in handy in the eider's natural coastal environment, as it has to fly in very windy conditions.

Not so easy to hunt as cormorants but as ground-nesting birds they're vulnerable to predators when incubating eggs. Icelandic farmers accordingly patrol the area during nesting and encourage the birds to return

In spring the farmers prepare for the arrival of the eider. They clean the nesting area. To encourage the birds' return, farmers often use radios and colorful items.

Seems a bit counter-intuitive but a pattern is emerging.

[Boreades]

There are other possibilities.
e.g. that we (dumb humans) are slow-witted about recognising intelligence and adaptive/exploitative behaviour in other species.

Like parrots that can count.
Or Killer Whales that herd fish.
Or other primates that make tools.
Or seagulls that decide life is easier by "fishing" on rubbish dumps many miles inland instead of out-at-sea.
Or that we humans are not the only species that likes to gather attractive objects to decorate ourselves &/or our nests with (a.k.a. bling).

[Mick Harper]

I am sure you're right. It takes a particularly intelligent bird to festoon its nest with bright objects so predators can find it easily. Or critics, as we authors call them. This is done to great effect in Indonesian islands where 'critics' are thin on the ground but possibly requires an extra dimension of explanation where they are not.

[Boreades]

It takes a particularly intelligent bird to festoon its nest with bright objects so predators can find it easily.

Or burglars, as we humans might call them.

Despite my frequent notes to the servants and staff at Chateau Boreades (telling them not to do so), we also leave our valuables on display with the lights on, the curtains open and the doors unlocked. What could possibly go wrong?

Perhaps the desire to flaunt wha' ya got is not unique to humans. In which case, it's an inter-species trade-off -v- the risk of attracting the wrong sort to your nest?

[TisILeclerc]

Or inviting the right kind of victim to your lair.

Oh look a poor little goat in the clearing and I'm hungry. Let's go and have a look.

[hvered]

Icelanders need 60-80 nests, minimum (accounting for seasonal factors) to make collecting down worth their while, so safety in flocks perhaps?

On the Farne islands there is a famous eider dock colony that's also popular with fiercely territorial arctic terns, whether by accident or design. They make a pretty good job of protecting the nesting eiders, even against polar bears apparently.