He uses them in the 6th symphony, most strikingly (sic) in the first movement, where they feature (along with celeste!!!) in a pastoral vision that suddenly interrupts the trampling jackboots—in my post, on Bernstein’s performance from 12.05, or on Barbirolli’s recording from 8.24. This brief refuge is itself brashly crushed (Bernstein 15.01).
In a later revision to the score Mahler added this typically generous instruction:
Die Herdenglocken müssen sehr diskret behandelt werden—in realistischer Nachahmung von bald vereinigt, bald vereinzelt aus der Ferne herüberklingenden (höheren und tieferen) Glöckchen eine weidenden Herde—Es wird jedoch ausdrücklich bemerkt, dass diese technische Bemerkung keine programmatische Ausdeutung zulässt.
—which, in the spirit of David Pesetsky, I’m tempted to translate as “inaudible”, only it’s a useful insight into his vision—notably Mahler’s final comment “this technical remark does not allow for a programmatic interpretation”.
Cowbells also appear in the slow movement and finale of the 6th. But Thomas Peattie (“Mahler’s Alpine journey”, Acta musicologica 83.1, 2011) unpacks their complex associations, refining the literal programmatic interpretations of critics, and noting that such apparently bucolic scenes are both fractured and fleeting: Utopia as an illusion.
Mahler used cowbells again in the 7th symphony: as this review tells us,
Tennstedt, in rehearsals for his last performances, was intent on showing his percussionists that cows would shake their heads violently and exhorted the player to shake the bell in just such a way (so good was his impersonation of a cow shaking its head, or at least so good was the orchestra’s reaction to it, Tennstedt did it again).
Cowbells also feature in Richard Strauss’s Alpine symphony. And they made a natural choice for Messiaen—part of his huge battery of tuned and untuned percussion, along with xylophone, marimba, woodblocks, and so on (not to mention piano and ondes martenot). Cowbells feature in a group of three wonderful works from the early 1960s: Sept haïkaï (with inspirations from gagaku and Noh!), Couleurs de la cité céleste, and Et exspecto resurrectionem mortuorum.
Swiss health authorities advise public against watching oom-pah bands
With the north Chinese ritual shengguan ensemble never far from my thoughts, I’m reminded of the yunluo frame of ten pitched gongs that adds a numinous halo to the wind instruments (e.g. playlist #8, in sidebar, commentary here). No longer part of the ensemble in north Shanxi, it should be!