A male Broad-billed sports a layer of orange pollen on his red and black bill.

One of the most-asked questions this time of year is “What kind of hummingbird has a yellow throat?” The answer is “The kind that likes ocotillo nectar.” The ocotillo’s long stamens deposit its bright yellow pollen on the throat of longer-billed hummingbirds such as this Black-chinned female and on the breasts of shorter-billed Costa’s and Anna’s.

It’s rare that we can age spring migrants by their plumage, but this second-year male Broad-tailed is an exception. The pale, worn feathers on his chin are remnants of his juvenile plumage, soon to be replaced with his hot pink adult finery.

For many years we’ve been documenting the acquisition of white feathers by adult hummingbirds. This female Black-chinned was completely normal-looking when we banded her as an adult in July 2014, but she surprised us this year by returning with a generous sprinkling of white feathers over most of her body. This phenomenon has recently been given the name “progressive graying” to reflect its similarity to the age-related graying of human hair.

This male Black-chinned has been through some hard times. His bill is heavily scarred, most likely from a recent bout of avian pox. The pox virus, which can be contracted from feeders that have been visited by infected birds, usually attacks the bill, feet, and/or eyelids. Hummingbirds’ bills are packed with sensitive nerve endings, so pox lesions on the bill are probably very painful. Though this bird’s bill appeared well on its way to healing, he was alarmingly underweight and his plumage was disheveled from inadequate preening. The best way to prevent transmission of avian pox is to clean feeders thoroughly and often, especially if they’re being used by birds showing signs of the disease.