Mooney Goes Wild, Sunday August 13th 2017

On Mooney Goes Wild tonight: The Dipper

Dipper (photo: Shay Connolly / BirdWatch Ireland)

Take a stroll along one of our rivers or streams, and there's a good chance that you may not be the only one walking.  Under the water, out of sight, one of Ireland's most interesting and unusual birds may be walking with you. The Dipper is a strange creature indeed.  It's the only European songbird which forages underwater.

Clockwise from top left: John O'Halloran, Pat Smiddy, Barry O'Mahony, Niall Hatch, Manel López Béjar, Dario Fernandez-Bellon

In his new documentary, The Dipper, Derek Mooney meets with Professor John O'HalloranPat Smiddy and Barry O'Mahony - the UCC team who have been studying dippers for over three decades, along with PhD student Dario Fernandez-Bellon - to learn about the latest research into the habits and characteristics of this most intriguing of birds.  He walks along the River Owennacurra in Midleton as Pat surveys the river, and discovers how Barry builds dipper nestboxes.  He chats to BirdWatch Ireland's Development Officer Niall Hatch about the many interesting names given to the Dipper.  And he travels to the Autonomous University of Barcelona, to find out from Professor Manel López Béjar how analysing a dipper's feathers can indicate the stress level of the bird and the environment.

The poem The Dipper that we hear at the start of the programme was written by the wonderful Scottish poet Kathleen Jamie, and was read by Gorretti Slavin.  For more information about Kathleen Jamie's work, please do visit www.kathleenjamie.com.

For more information about UCC's Dipper Ecology Project, visit www.ucc.ie/en/dippers.

Left and right: Barry O'Mahony in his man shed in the town land of Coolatanaballey, near Carrigrohane, Co. Cork; middle: chicken wire to help grip the nesting material inside the nest box

Ringing dippers to find out more information about them

L-r: Professor John O'Halloran (UCC); Dario Fernandez Bellon (PhD student, UCC); Manel López Béjar (Prof of Embriology at the Veterinary School, Autonomous University of Barcelona)

Watch Professor John O'Halloran talk about his work on Dippers:

Dippers

The Dipper is a most unusual bird.  Although a passerine (a perching bird), you will always find it along a waterway.  It is the only passerine that actively enters the water, swims underwater, and walks along the bottom feeding underwater.  It can stay submerged for up to 30 seconds.  It has a number of adaptations that allow for this behaviour (for example, strong claws, waterproof feathers, an extra eyelid etc...).

Dippers are also a very good indicator as to water pollution.  They will only be found along clean waterways.  They are named after their ‘bobbing’ or ‘dipping’ movements.  Local names include Water ouzel, Wee water hen, and Water Colly.

Dippers are known in some areas as 'Water Blackbirds'.  They have, however, the same shape as Wrens.  Both birds have almost spherical bodies and little cocked-up tails.  Their short necks give them a double-chinned appearance.  Despite the resemblance, egg-white protein and DNA analysis show that Dippers are much more closely related to thrushes than they are to Wrens.  The blackbird is a member of the thrush family, so the name 'Water Blackbird' may be appropriate after all.

But why have Dippers the same shape as wrens?  The answer may lie in the size of their wings.  Wrens have short little wings which enable them to fly in thick cover.  Generating enough lift on small wings requires extra large breast muscles and the resulting fat breast makes for a spherical profile.  Like Wrens, Dippers also have short wings, but not for flying in confined spaces.  They use their wings as fins when swimming under water.  Puffins, which also use their wings when diving, have a similar shape.

The Dipper's plumage is dark brown, but at a distance it looks black.  A gleaming white bib extends down from the bird's chin.  For all the world, the Dipper looks like a fussy little waiter in a fancy restaurant.  Like the waiter, it bows and curtseys a great deal.  This habit of constant dipping gives the bird its modern name.  Dipping may be a form of camouflage; a bobbing bird is harder to see against a torrent of moving water.  The white eye-lids, which it shows when it blinks, may have a similar function.

Dippers are placed in their own unique family, the Cinclidae.  The family has only one European member but there are four dipper species elsewhere in the world.  Our Irish Dipper is special; it belongs to a race peculiar to this island.  Well almost, our Dipper is also found in the Outer Hebrides and in parts of mainland Scotland.

The bird is a specialist.  It feeds on creepy-crawlies, particularly caddis-flies, which live in the beds of fast-flowing streams.  It also takes tadpoles and small fish.  Oddly, for a bird which dives for a living, the Dipper has few special adaptations for an aquatic life.  Its feet are not webbed.  It's legs are not especially powerful, nor are they located back towards its tail as in most diving birds.  It has, however, developed a membrane which can be pulled over its nostrils when it is underwater.  Its plumage is denser than that of similar small birds and its oil gland, important for waterproofing, is especially large.

The Dipper's hunting strategy is unique.  It likes water with a gravel bottom and plenty of rocks and boulders.  It can dive in from a perch or from flight, but, in calm conditions, it walks directly into the stream.  Instead of swimming, it walks on the stream bed, turning over stones.  Perhaps it would be more accurate to say that it 'flies' along the bottom.  Being a bird, its body is lighter than the surrounding water and would tend to bob to the surface, but the dipper uses the current to push it downwards.  It must always face into the flow.  In calm water, it keeps the wings closed, but in rougher water it 'flies' under water.  The dives are short, typically three or four seconds long, but durations of up to 23 seconds have been recorded.  Birds may dive ten times in a minute.  They like shallow water but can go down to one and a half metres.

Irish Dippers are sedentary, reluctant to leave their mountain streams.  They can hunt under ice and will only leave their territories if the river freezes over completely.  The mountain environment, in winter, may appear to be unduly harsh for a small bird but the water in streams, provided that it is not frozen, is warmer than the surrounding land.

Dippers tend to be solitary in winter but some remain paired.  In very hard weather, the territorial system breaks down; birds face more pressing problems than defending their patch.  Rival males have been recorded, amicably using the same hole in the ice.

Both partners build the nest, which is often in a hole or on a ledge under a bridge.  The female does all the incubating and provides most of the food for the young.  Some Dippers produce two broods in a season.  Unlike most small birds, the same nest is used for both broods and may be repaired each year.  Dippers take about 18 days to build their nest, much longer than most birds of their size.  This encourages infestation by parasites but reusing the old nest saves time and effort.

Hedgerows: It is an offence to 'cut, grub, burn or otherwise destroy hedgerows on uncultivated land during the nesting season from 1 March to 31 August, subject to certain exceptions'. For more information, click here.

UPDATE: February 29th 2016 - Press Release From BirdWatch Ireland:

Putting the record straight: Dates for burning and hedge-cutting have NOT changed

BirdWatch Ireland, Ireland’s largest conservation charity, is very concerned about misinformation that is currently circulating regarding the dates within which the burning of vegetation and cutting of hedges is permitted.  It would like to remind landowners that all burning and cutting must cease on 29th February this year and that burning and cutting remains prohibited from 1st March to 31st August.

Despite attempts by the Minister for Arts, Heritage and the Gaeltacht, Heather Humphreys T.D., to change the laws regulating these dates by introducing the Heritage Bill 2016 earlier this year, it is important to note that the proposed date changes were ultimately NOT made.  This is because the bill failed to pass through both houses of the Oireachtas before the recent dissolution of the Dáil in advance of the general election.

The laws in place governing the dates for hedge-cutting and upland burning therefore remain unchanged. The period within which cutting and burning is prohibited are set down in Section 40 of the Wildlife Act 1976 (as amended in 2000), which states that:

(a) It shall be an offence for a person to cut, grub, burn or otherwise destroy, during the period beginning on the 1st day of March and ending on the 31st day of August in any year, any vegetation growing on any land not then cultivated.
(b) It shall be an offence for a person to cut, grub, burn or otherwise destroy any vegetation growing in any hedge or ditch during the period mentioned in paragraph (a) of this subsection (above).

The existing law provides exemptions for road safety and other circumstances and should be read carefully to ensure compliance.

Section 40 of the Wildlife Act exists to protect nesting birds. Many of our upland bird species are in decline and are in danger of extinction in Ireland; amongst them is the Curlew, which has declined by 80%. Many birds which nest in hedgerows into August are also in serious decline, including the endangered Yellowhammer. The changes to the cutting and burning dates which had been proposed in the now-defunct Heritage Bill 2016 would have caused serious impacts to these birds. A petition launched by BirdWatch Ireland in conjunction with several other national conservation organisations to stop these changes attracted more than 16,200 signatures and rising.

BirdWatch Ireland would also like to advise members of the public that if they see hedges being cut or fires in the uplands on or after 1st March, such activity could be illegal.  In such cases, we would encourage people to contact the National Parks and Wildlife Service (www.npws.ie) to report such activity.

BirdWatch Ireland warmly welcomes the demise of the Heritage Bill 2016 and sincerely hopes that any future administration will consider the importance of Ireland’s natural heritage and will not attempt to reintroduce such a flawed and damaging piece of legislation.

To contact your local wildlife ranger, click here for contact details. To read the Wildlife (Amendment) Act 2000, click here.

IMPORTANT NOTICE

Please DO NOT send any live, dead or skeletal remains of any creature whatsoever to Mooney Goes Wild.

If you find an injured animal or bird, please contact the National Parks & Wildlife Service on 1890 20 20 21, or BirdWatch Ireland, on 01 281-9878, or visit www.irishwildlifematters.ie

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Presenter: Derek Mooney

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