Why is it der Whistler?

Whistler ends in -er, and most nouns ending in -er are masculine: in a German dictionary, 86% of them take der.

All nouns ending in -er
Sense 1
der

Meaning

[1] mostly in the plural, physics: electromagnetic wave that are sent out of flashes in the troposphere and run through the space along the magnetic field lines of the earth

[1] meist im Plural, Physik: elektromagnetische Welle, die von Blitzen in der Troposphäre ausgesendet werden und entlang der magnetischen Feldlinien der Erde den Raum durchlaufen

Examples

[1]

[1]

Declension

1 Singular Plural
Nominativ der Whistler die Whistler
Genitiv des Whistlers der Whistler
Dativ dem Whistler den Whistlern
Akkusativ den Whistler die Whistler

Pronunciation

Dictionary entries include material from Wiktionary. Wiktionary