Oxford-Duden:
skirl - durchdringendes /od./ gellendes Pfeifen

Pons-Collins:
the skirl of the bagpipes - das Pfeifen der Dudelsäcke

NOAD:
skirl - n. a shrill sound, esp. that of bagpipes.
• v. [intrans.] (of bagpipes) make such a sound.


• As church bells pealed and bagpipes skirled, veterans of Tobruk, the Battle of Britain, Guadalcanal ...
• the Anchorage Scottish Pipe Band, with six sets of bagpipes, two drums and eight kilts, is skirling away at "Bonnie Lassie."
• The bagpipes skirled mournfully as a helicopter color guard flew overhead.

• The carline skirled till ye could hear her at the Hangin’ Shaw, and she focht like ten; there was mony a guidwife bure the mark of her neist day (Robert Louis Stevenson)
• But the wenches skirled, "He's no be here ! His eldritch look gars us swarf
wi' fear

• Dark winds of the mountain,
White winds of the sea,
Are skirling the pibroch
Of Seumas an Righ.
(Edward J. O'Brien, "The Last Piper")
• I spent evenings with them in their tents, thawing pemmican hoosh over a seal-blubber scove as the wind skirled outside.
• Letty told me at after, she heard her baby crying for her, above the gurgling of the rising waters, as plain as ever she heard anything; but the sea-birds were skirling, and the pig shrieking; I never caught it; it was miles away, at any rate.
(Elizabeth Gaskell, "The Sexton's Hero")
• Police whistles were skirling around the house of Huang Chow.
• As we approached Dream, kelp gulls wheeled and skirled above our zodiac. Elephant seals lay hauled out, basking in the sun.
• My own emotions, of course, are skirling under the surface of the poem.

I support adding 'skirl.' The verb sense, which is IMO more common, should also be added.

And the bagpipe explanation probably belongs, if anywhere, in italics on the German side, not on the English side. However, it's not used solely for bagpipes, but also more broadly in the sense of 'screech' for anything that makes a shrill noise.

In some of the web examples, I had the feeling the writer was probably thinking of 'swirl' instead; with wind and birds it can be hard to tell which was meant. But lo and behold, a second verb sense 'To fly with a sweeping or whirling motion' shows up in the OED, so even if it was originally a confusion of the two words, it seems fairly well established. It's up to the native speakers to come up with a translation of that one, though.

Langenscheidt, Der Große Muret-Sanders:
skirl Scot. od. dial.
I v/i
1. schrill klingen, pfeifen (bes. Dudelsack)
2. kreischen, schreien
II v/t
3. (Dudelsack) pfeifen
III s
4. Pfeifen n (des Dudelsacks)
5. Kreischen n, Schreien n

Concise Scots Dictionary"
skirl v
1 vi scream, cry out with fear, pain or grief
2 vti utter with a high-pitched discordant sound, cry or sing shrilly, raise a clamour
3 vi shriek with exitement or laughter
4 of birds scream, screech
5 of the wind blow with a shrill noise
6 creak, make a crackling, screeching, or whistling sound
7 (1) of bagpipes etc make a shrill sound
(2) vti of a (chf bagpipe-)player make a shrill sound (on the bagpipes)
8 vi, sound of something very hot, esp in frying sizzle, crackle, sputter
skirl n
1 a scream or shriek of pain, anguish, fear etc
2 a shriek of laughter etc
3 the loud cry, wail, or whistle of a bird
4 piping the shrill sound of the bagpipes; a wrong note accidentally playes
5 (1) the high-pitched sound of a strong wind; the wind itself, gusty weather
(2) a flurry (of snow or hail)
6 a screeching, whirring or whistling noise made by something mechanical

Supported.

"Skirl is a term used by pipers to describe an unintended shrill sound made by the chanter (or rarely the drone pipes), and is usually produced when the pipe is overblown or misfingered by the piper. Some non-pipers use the term incorrectly to describe all of the sounds produced by a bagpipe."

Pipers and knowledgable lovers of bagpipe music would never refer to the music of the pipes as skirling ("screeching"). In fact, as the excerpt from Wikipedia shows, pipers use the term to refer to a nasty squeak produced by poor technique.

Of course, a dictionary must reflect actual usage, and the error is so widespread as to be virtually ineradicable. Nonetheless, in the name of bagpipe lovers everywhere, I should like to suggest that the Leo entry note that the popular usage is, strictly speaking, erroneous.

Cassell's German Dictionary:
skirl, s. das (Dudelsack)pfeifen

Additional supporting reference.

skirl, v.1 Sc. and north. dial. Also 5 scrille, skrille, 6, 8 skirle, 6 skyrl, 8 skerl.
[prob. of Scand. origin: the early form skrille corresponds to a Norw. dial. skrylla, with variants skrella and skrolla in the same sense.]

1. intr. To scream, shriek, cry out shrilly.
[...]
1818 Scott Br. Lamm. xi, Stay where ye are, and skirl as loud as ye can.
1889 Barrie Window in Thrums xi. 100 The women-folk fair skirled wi’ fear.

b. Of the bagpipe (or its music): To produce the shrill sounds by which it is characterized; to sound shrilly.
[...]

c. Of other inanimate things.
1827 Scott Chron. Canongate iv, On the painted board that is skirling and groaning at the door.
1891 Barrie Little Minister iii, Blasts from the north..skirled through the manse.
1894 Crockett Raiders 388 It was comfortable too at meal-times to hear the bacon skirling in the pan.

2. To play the bagpipe.
1828 Moir Mansie Wauch ii, Three fiddlers..and a piper..all skirling, scraping and bumming away throughither.
1879 C. Keene Let. in Life x. (1892) 296 [He] had a sort of piper skirling away in his garden.

3. trans. To sing, utter, play, etc., in loud and shrill tones.
[...]

b. To cause (the bagpipe) to sound shrilly.
1885 G. Fraser Poems 219 Pate Clauchan o’ this toon, Wha skirled his pipes.


zu Bed. 1 im OED2:

krei|schen <sw. u. st.V.; kreischte/(veraltet, noch landsch.:) krisch, hat gekreischt/(veraltet, noch landsch.:) gekrischen> [mhd. krischen, lautm.]: 1. schrill, misstönend schreien: vor Vergnügen k.; sie würden k. vor Entsetzen, gellend, gellend k., immer nur k. (Bastian, Brut6); Wütend wollte er ihn abschütteln, doch da fing er an zu k.: Ein Spion! Ein russischer Spion! (Kühn, Zeit 240); die Möwen, Pfauen kreischen.
© 2000 Dudenverlag

zu Bed. 1c im OED2:
2. helle, misstönende, schrille Geräusche machen: die Säge kreischt; Die eisernen Angeln des Fensterladens kreischten mit Pfauenstimmen (Ransmayr, Welt 82); Als das neue Jahr anbrach, kreischte der Sturm in den Wanten (Hamburger Abendblatt 24.8. 85,7); Der Wagen fährt in den Gerichtshof ein. Bremsen kreischen (Ziegler, Labyrinth 305).

© 2000 Dudenverlag

to skirl (chiefly) [Scot] -- kreischen {gellend schreien od. schrille Geräusche machen}
to skirl (chiefly) [Scot.] -- pfeifen {Dudelsack}
to skirl (chiefly) [Scot.] -- Dudelsack spielen
to skirl (chiefly) [Scot.] -- schrill tönen [-> OED Bed. 3]
to skirl (chiefly) [Scot.] -- schrille Töne erzeugen {auf dem Dudelsack}

skirl (chiefly) [Scot.] -- das Gekreisch {also Gekreische}
skirl (chiefly) [Scot.] -- das Pfeifen {Dudelsack}
skirl (chiefly) [Scot.] -- (schrilles Pfeifen eines Dudelsacks wenn falsch gespielt)

Alle einverstanden?