American Kestrel Subspecies and Ids
NOT FULLY WRITTEN YET: REST TO BE PUBLISHED SOON
The American Kestrel is a highly polytypic, and sometimes polymorphic, species of falcon present throughout the New World. The latest taxonomy suggests 17 different subspecies (Clements 2023), though some are probably synonyms. Due to a recent series of inquiries and rebukes, I am responding to these questions via this post, rather than give a lengthy explanation on each observation. Hopefully, I can perhaps clear the air on the taxonomy of this amazing little falcon, and help you be able to confidently identify them to subspecies.
Northern American Kestrel (ssp. sparverius)
-- Range: Throughout Alaska, Canada and the lower 48 States (except southeast), including northwestern Mexico. Will winter throughout Central America, as far as Panama. Occurs regularly in the Greater Antillean as well.
-- Id marks: The most variable of all subspecies, it is hard to quantify what precises falls under the "Northern" umbrella. Perhaps the most unique feature is the red crown spot. This feature is exclusive to the Northern, though not all individuals exhibit this red crown spot. In essence, the presence of a red crown spot absolutely confirms this subspecies, but the lack thereof does not mean it's another subspecies. Here's some photos, also note the variation in markings on the upper and underparts.
Male:
https://macaulaylibrary.org/asset/301274451 (no red crown spot)
https://macaulaylibrary.org/asset/91509331
https://macaulaylibrary.org/asset/240785371
https://macaulaylibrary.org/asset/88453991
Female:
https://macaulaylibrary.org/asset/293136591
https://macaulaylibrary.org/asset/394463281 (heavily reduced crown spot)
https://macaulaylibrary.org/asset/79729131
https://macaulaylibrary.org/asset/240663961
Tropical American Kestrel (ssp. tropicalis)
-- Range: Baja California to N
-- Taxonomic Issues: Looking at photos, I believe that peninsularis (Baja California) and nicaraguensis (Honduras and Nicaragua) likely represent synonyms of this race. They share may common traits and they don't seem to fall under the 75% rule (Amadon 1949) for diagnosable subspecies.
-- Id Marks: Compared to the very similar Northern Kestrel, this subspecies differs consistently in have much more cleanly white underparts in males (vs. tawny or buffy in US birds), limited barring to the upperparts, and always lacking the red crown spot. However, in wintertime, it may become very difficult to distinguish breeding Tropical Kestrels from blue-helmeted Northern Kestrels. Female diagnosis follows a similar scheme.
Male:
https://macaulaylibrary.org/asset/613017369
https://macaulaylibrary.org/asset/168054921
https://macaulaylibrary.org/asset/362724761
https://macaulaylibrary.org/asset/388156421
Female:
https://macaulaylibrary.org/asset/85881751
https://macaulaylibrary.org/asset/187926001
https://macaulaylibrary.org/asset/191960121
https://macaulaylibrary.org/asset/124604831
Southeastern American Kestrel (ssp. paulus)
-- Range: Breeds in certain pockets from South Carolina to central Florida, though some recapture banding records come from southern Florida and the Bahamas.
-- Id Marks: Very difficult to discern from Northern Kestrel, especially in winter when both subspecies overlap ranges completely. Males are generally described as being blue-headed (no red crown spot), reduced or absent underpart spotting, and limited barring on the upperparts. However, there's plenty of individuals that push the boundaries of these id traits, and it's likely due to some intergradation with Northern Kestrels in the Gulf states. Females are often credited with having thinner streaking below, not having quite the globous streaking of northern females. Mustaches are also thinner, making the face appear more whitish.
Males:
https://macaulaylibrary.org/asset/313816471
https://macaulaylibrary.org/asset/611948514
https://macaulaylibrary.org/asset/150739531
https://macaulaylibrary.org/asset/304948521
Females:
https://macaulaylibrary.org/asset/210593681
https://macaulaylibrary.org/asset/479744491
https://macaulaylibrary.org/asset/616272753
https://macaulaylibrary.org/asset/579451421
East Caribbean Kestrel
