Richard Collins: The Irish bird that 'does its own thing' — should it be Cork's official bird?
Rivers 'gabha Or Cinclus), Gaeilge, Along Rocky Streams Dippers Typically And As (cinclus Dubh' Live
Half of avian species belong to one huge ‘order’ known to science as ‘passerines’ or ‘perching’ birds. It’s an odd name... most other kinds of bird also perch. The order includes the ‘songbirds’, ‘garden birds’, and crows, all with fairly similar lifestyles. There is, however, one Irish one, the dipper, which does its own thing — its ecology is truly remarkable.
Great to see the #dippers back on this stretch of river in #Cork... This territory had been unoccupied for the last few years until we put a #nestbox up as part of our @uccBEES dipper project.
— DaríoFernándezBellon (@dferbel) April 19, 2019
🎥 under licence from @npwsBioData#Cinclus @johbees @BirdWatchIE @BioDataCentre pic.twitter.com/Jb1L66PRoD
Living along fast-flowing rivers and streams, this dumpy little tuxedo-clad waiter with a white bib bows and ‘dips’ obsequiously. Despite its striking resemblance to the ‘King of the Birds’, the dipper isn’t a cousin of the wren, as was once thought. Its nearest relatives are thrushes. Our Irish variety belongs to a subspecies unique to this island and western Scotland. If we had official county birds here, the dipper might represent Cork — it has been extensively studied at UCC.
Winner of the Oscar for the most unusual behaviour of any passerine, the dipper walks along the bottoms of fast-flowing rivers and streams, turning over stones to catch aquatic creepy-crawlies. It can descend to 6 metres and remain submerged for up to half a minute.
Birds must be light for flying. Their bones tend to be hollow for lightness and their feathers trap air for insulation. Walking under water, therefore, seems impossible for a bird. Dippers use their wings as fins when down under. Currents help push their bodies downward, just as air-flows give them ’lift’ when flying. Strong claws can anchor them to the river bottom.
Mammals which walk along river bottoms use extra weight to keep them submerged. Fat, being light, pushes a body upwards towards the surface. Bone helps it sink. The insides of bones are relatively hollow and spongy but, in some aquatic animals, they are filled-in to make the skeleton heavier. Hippos, which walk along the bottoms of African rivers, have extra solid bones. So have whales. With their blubber pushing them towards the surface, maintaining buoyancy can be challenging.
Calculating the weight of a fossilised creature from its bones can be tricky, as a recent case from South America showed. Some years ago, enormous whale bones were found in Peru. An analysis of the 13 vertebrae four ribs and part of a hip suggested that Perucetus giganticus, the ‘gigantic Peruvian whale’, may have tipped the scales at up to 340 tonnes. That would make it up to three times heavier than the blue whale, currently considered to be the largest animal ever to have lived. But that conclusion has been challenged in a paper just published.
According to researchers at the University of California Davis: "The fossil bones have extensive in-filling and growth of bones on the outside as well". "The assumptions made in scaling up the bone weight measurements" were flawed.
"These estimates would make Perucetus impossibly dense", they say. The ancient whale, they conclude, might have weighed up to 114 tonnes, well short of the blue whale’s limit of 270 tonnes. "Therefore it is likely that the published body mass range of 180 to 340 tonnes is vastly overrated".
How are the mighty fallen — 2nd Book of Samuel.