BLACK-CHINNED HUMMINGBIRD -- Archilochus alexandri
Immature (Hatch Year; HY) Males

A Photographic Comparision of Variation in Key Identifying Features in BCHU

PHOTOS (all © 2004 Stacy Jon Peterson; taken with Nikon Coolpix 4500, macro setting; contrast enhanced / sharpened, etc., on MS Picture It! Photo version 7.0)

Male and female HY Black-chinneds can be difficult to tell apart for a variety of reasons. This photographic guide will show the variation in HY males of this species so that banders and astute observers can make more accurate determinations of the age and sex of Archilochus hummingbirds in the field.

Feature	Band C11738 Mtn Home, Elmore County, ID, 9/17/04	Band C11742 Mtn Home AFB, Elmore County, ID, 9/19/04	Band C117xx Mtn Home AFB, Elmore County, ID, 9/xx/04
Dorsal View
Comments	Figure 1. This is the typical coloration of immature Black-chinneds in Idaho whenever they're present. Note the extensive scaling / tan edges to the feathers on the crown and nap, giving the bird a dirty look, especially at a distance.	Figure 2.	Figure 3.
Throat and Face
Comments	Figure 4. The throat on this bird is on the "clean" side of typical for HY-M BCHU.	Figure 5.	Figure 6.
Outer Retrices
Comments	Figure 7. This is a typical set of outer retrices for immature male Black-chinneds. Note the greatly reduced white on r3 and the "nippled" r5. If all immature males were this way, things would be really easy, but sometimes the amount of white on r3 approaches that of a female, and r5 may not be as distinctly pointed.	Figure 8.	Figure 9.
Inner Primaries and p6 (Open Wing)
Comments	Figure 10. The most distinctive feature for identifying BCHU (compared to RTHU) is the way the outer vane "bulges" near the tip of p10 -- AND how the width of p10 and p9 are virtually the same and both are fairly club-shaped. The width and pointed appearance of p6 in this particular bird is consistent with immature male BCHU, although the differences between males and females in this species are much less pronounced than in RTHU. The shape of p6 is actually better determined when viewing the folded wing. However, I generally consider this feature to be secondary in determining sex, behind outer retrices...	Figure 11.	Figure 12.
Folded Wing	Similar photos not available
Comments

HELPFUL LITERATURE

Baltosser, F.A. 1983. Plumage characteristics of juvenile Black-chinned Hummingbirds. Condor 85:102-103.

If you have information that supports or refutes the information posted above, I'm very interested in hearing what you have to say. Please write your thoughts to: SJPeterson@aol.com

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