Hummingbirds Eating Ashes JAMES R. DES LAURIERS Department of Biology, Chaffey College, Alta Loma, California, 91737, USA

I report five observations of nesting female hummingbirds evidently eating the powdery, white component of wood ash. The observed species included Broad-tailed, Blue-throated, Costa's and Anna's Hummingbirds. Each bird was attending a nest. Males were never observed engaged in this behavior. Wood ash contains surprising amounts of Calcium in the form of CaO which comprises between 50-75% of the total ash. Lacking medullary bone, hummingbirds eating ashes may be replenishing Calcium lost to egg production.

https://www.researchgate.net/publication/262376945_Hummingbirds_Eating_Ashes

Hummingbirds may need to replace electrolytes and minerals lost during daily diuresis and seasonal reproduction. Minerals such as calcium may not be obtained in sufficient quantities from a nectar-rich diet alone. We report observations of female Rufous Hummingbirds (Selasporus rufus) ingesting soil in western Oregon and review other known observations of hummingbirds ingesting mineral-rich compounds. We suggest these behaviors are the result of diet deficiencies of specific minerals, particularly calcium for nesting females.

https://www.jstor.org/stable/4514314