Where does “черноклювый” come from?

черноклювый (Russian) comes from Russian чёрный, from Proto-Slavic čьrnъ, from Proto-Balto-Slavic kiršnas, from Proto-Indo-European kr̥snós, from Proto-Indo-European kers- — black, dirty; run; to run.

черноклювый (Russian): black-billed, black-beaked

Definitions

  1. black-billed, black-beaked

Ancestry of “черноклювый”, step by step

черноклювый traces back through two separate lines of ancestry.

via Russian чёрный

StepLanguageWordMeaning
1Russianчёрныйblack; rough, coarse; back
2Proto-Slavicčьrnъblack
3Proto-Balto-Slavickiršnasblack
4Proto-Indo-Europeankr̥snósblack; dark, dusky
5Proto-Indo-Europeankers-black, dirty; run; to run

via Russian клюв

StepLanguageWordMeaning
1Russianклювbeak, bill
2Proto-Slavic*kľuvъbeak
Every word from Proto-Indo-European kers- →Every word from Proto-Indo-European kr̥snós →Every word from Proto-Balto-Slavic kiršnas →