posted October 9th, 2009; last edited November 18th, 2010 –– David Sibley

Savannah Sparrow Passerculus sandvicensis

Subspecies

Corrections and updates to the Guide:

In WA all birds are in between reddish and grayish types shown in the Sibley Guide; coastal breeders dark-striped but not as extreme as beldingi, interior birds close to grayish type; some large Aleutian breeders winter on coast. (fide D. Paulson).

Identification of Belding’s Savannah Sparrow

“…in many ways intermediate between northern [typical] and “Large-billed” Savannah Sparrows. …alongside the migratory northern subspecies the Belding’s Savannah Sparrows in southern California seem quite distinctive.”

Subspecies illustrated in the Sibley Guides

Typical P. s. savanna group

Ipswich P. s. princeps

Belding’s P. s. beldingi

Aleutian P. s. sandwichensis group

Large-billed Sparrow P. s. rostratus group

The five subspecies groups listed above are illustrated in the Sibley Guide, representing a widespread continental or “typical” form and four other recognizable populations with restricted ranges. Variation in this species is considerable with about 25 named subspecies across North America.

Most variation is clinal, however, and only a few subspecies and subspecies groups are really distinguishable. In general subspecies in the east and in humid Pacific coastal areas are more rufous, while those in the drier interior are gray, but there is considerable variation and I found it difficult to separate broad eastern and western groups among the continental birds.

Of the groups recognized here the most distinctive in plumage, structure, voice and DNA is the Large-billed group, which has been proposed for species status. In the past Ipswich has been considered a separate species, a treatment supported by its isolation during the breeding season and clearly different size and plumage, but this subspecies apparently interbreeds freely with mainland birds when they come in contact.

References:

Rising 2010. The Many Savannah Sparrows. Birding 42(6): 44-55.
www.aba.org/birding/v42n6p44.pdf

2 comments to Savannah Sparrow

  • Chris

    Hey David,

    I have a question concerning the ID of Savannah Sparrows in flight. There seems to be no good references to identifying sparrows in flight and your field guide to North American birds is the only book that mentions anything specific about their flight pattern. What exactly do you mean when you say “flight bounding, buoyant unlike other grass sparrows. Maybe it is just me but the words bounding and buoyant contradict eachother and leave me wondering. The reason I ask is because I am currently working on a project in Saskatchewan nest searching for various grassland birds and the 2 species that are of the most difficulty identifying when flushing from the nest are Baird’s and Savannah Sparrow. Most of the time Savannah’s will stick around and Baird’s will just take off, but this is not always the case. I would really appreciate it if you could give me some ID tips on how to distinguish these two birds in flight reliably.

    Thanks a lot
    Chris

    • Hi Chris, This is a really tricky ID problem. What I meant by “flight bounding, buoyant” is that the other grassland sparrows generally seem to fly low and straight with steady rapid wingbeats, like bumblebees, while Savannahs often fly higher with more swooping (bounding) and seem more comfortable in the air, with streamlined body and relatively pointed wings. Another thing I’ve noticed is that Savannahs often sit up in view on a weed or fence, while others like Baird’s and Grasshopper usually dive back into the grass. This is all subtle and obviously there are lots of exceptions – Savannahs can look stocky and clumsy and sometimes fly low and straight and dive into the grass (and they probably do this more often when flushed from a nest), and Baird’s can look pretty long-winged and sleek and may fly higher and land in view. Most of my experience trying to distinguish them is in Arizona in winter, where I was reduced to trying to get a good look at the head pattern of the flying bird through binoculars. The bright white belly and undertail coverts of Savannah often show well as they take off, and other species are less white there (but maybe that’s just because Savannahs tend to fly higher and show the belly more). I would suggest watching for differences in overall patterns of dark and light, maybe Baird’s has a paler head overall? or some contrast between nape, back, rump, or tail that differs from Savannah? Some careful study might lead to discoveries. Good luck with it!

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