Vesper & Savannah ID Issues

Vesp= er and Savannah Differentiation Issues

I am having difficulty with the ID of a sparrow as described below. I think the = answer may be found in the strength or weakness of field marks. To review the images, go to: http://thebusinessb= irder.com/vespersparrow.pdf

I'll pose my questions first and you can read on if interested:

1) Is= the bird a Vesper or a Savannah? If a Savanna= h, is it an Ipswich?

2) I = assumed the rusty patch of a Vesper is created or enhanced by feather wear which may explain why it is difficult to see. I could not find reference to this and my assumption is based solely= on a small amount of anecdotal evidence.

3) I = mention several field marks, useful in differentiating these two species. Which would be strong and which wo= uld be weak, given the time of year and location in Eastern= NC?

Comments would be appreciated!

VESPER v. = SAVANNAH FINDINGS=

I asked for ID help (on the carolinabirds listserve= r) concerning a sparrow I photographed at Alligator River NWR in mid-February. After taking the pictures, I wrote the bird off as a Savannah. In looking at the images days late= r, I thought the bird was a Vesper Sparrow.

The replies I received from the Carolinas plus some= from Northern Florida were divided with many pro-Vesper = and many pro-Savannah and with experts in both camps.

In my original post, I called my bird a Vesper main= ly because of the distinctive white eye-ring, the long tail, and buffy color underneath. The malar stripe = and throat looked right and there is a hint of white on the edges of the outer = tail feathers.

Since April I have observed 100+ Vespers from TX to= ND (mid-April to mid-July) and photographed almost a third of them. Same for Savannahs except the numb= ers are much lower.

I observed Vespers at length as I herded them up ro= ads and along fences...noting the major field marks...but I could never see the three major field marks at the same time.&= nbsp;

I saved and reviewed all of the e-mail responses to= my original post. The five points below, based on my review and new-found experience, should address the comments made in the e-mail reponses I received:

1) Distinct white eye-ring/eye stripe – while Savannahs may have eye-rings, I could not find one with an eye-ring as large and distinct as my bird. Also= , I found reference to the fact that, within a species, eye-rings are generally consistent in appearance. Tho= ugh it is anecdotal evidence, most of the Vespers I photographed have eye-rings comparable to my bird and none of the Savannahs do.

I have, however, seen one Sav= annah photo with an eye-ring that is close to being comparable - the picture in Kaufman’s of an Ipswich. I have se= en an Ipswich in winter on the beach at Oregon Inlet on the OBX, about 20 miles as the sparrow flies from Alligator River NWR (60% of distance is over the wat= ers of Croatan Sound). Two of the original responses mentioned Ipswich as a possibility for my bird because of its paleness. Could that be?

Most S= avannah photos I have seen, including my Savannahs, show a post-ocular eye-stripe.<= span style=3D'mso-spacerun:yes'> How reliable is this field mark? Enough to say my bird in question = is not a Savannah?

2) Crown and neck stripes - there are multiple white stripes on the crown and not a distinct median crown stripe characteristic = of a Savannah. While Savannahs may also show mult= iple white stripes, the median stripe seems more distinct. See Note 1 on image.

3) White outer tail feathers - very hard to see unt= il the bird flies, then easy to see from behind, especially as the bird spreads its tail in landing. However, on a perched Vesper, you can sometimes see a slim outline of the white outer tail feathers.&= nbsp; See image Note 2. I th= ink this image shows edges of white outer tail feathers.

See also Note 3 on the image. The outer tail feathers may show a= white edge; however, I cannot be sure since the bird is being observed from underneath and at an angle. T= he tail in this flight image seems long.

4) Rusty lesser coverts - most guides state this fi= eld mark is rarely visible and it is not visible on my bird.

I observed 30+ Vespers during a mid-April trip to K= S, OK, NE, and CO. On some the rusty= patch was visible, others had a rose-colored patch, and on many no patch was evident.

I am fairly sure the rusty lesser coverts are creat= ed or at least enhanced with the feather wear that creates the Vesper "breed= ing plumage".

Vespers have only one complete molt a year, after t= hey have acquired definitive plumage, and no partial molts. In summer they have a darker, worn= look which may account for the rose patch becoming a more distinct rusty patch.<= span style=3D'mso-spacerun:yes'> I have pictures of a Vesper taken = in mid-July in North Dakota that shows the rusty patch.

5) Size and length of tail – my Vesper looks = larger and longer that the other sparrow in the in-flight picture. See Note 4 on page two of the docu= ment. I am not sure the species of the other sparrow (Savannah?) but I am sure the Vesper is = larger and the in-flight image seems to show a long tail.

Additional observations:

I received of pictures of skins from the Florida museum collection, showing dorsal and ventral views of 5 sparrows...a Vesper with 2 Savannahs on each side. I tri= ed to develop a ratio for both species of overall length to the distance from cen= ter of its eye to tip of its bill. I gave up on this for a number of reasons given live versus skin, angle of attack, and gender size differences.

I cannot find a field mark that convinces me that t= his bird is a Savannah= . The closest mark to that is the ap= pearance of a light supercilium; however, I have seen this light supercilium on other Vespers plus my bird did not have yellow supraloral. The yellow, however, seems t= o be a weak field mark for Savannahs in NC in winter.

DISCUSSION= EXPERT 1

Thanks to John Ennis for posting these photos and the carefully thought-out questions. The bird in question looks like an "Ipswich" Savannah Sparrow in = the plumage stage that we'd expect in February, i.e., still relatively fresh plumage. The other bird with = it in the photos is a typical eastern Savannah, = so these images show just how strikingly distinct the I= pswich can look. It's larger and pal= er, and some elements of its markings are different, such as the more obvious eye-ring and the very conspicuous white submoustachial= stripe.

I can see why many observers would have considered = Vesper Sparrow here, but Vesper would show more uniform narrow dark streaking on t= he crown and invading the supercilium, and it would be darker in the area immediately below the eye, setting off the white eye-ring more distinctly on its lower half. It would also= have narrower dark streaking on the nape, a longer and wider tail, and a different patter= n of streaks on the flanks. The pa= le median crown-stripe on Vesper would never be as obvious as on the bird in t= he photos.

The rusty lesser coverts that John discusses here a= re of uneven value in identifying Vesper Sparrow: good if you can see them, but meaningless if you can't, because they're often completely covered by body plumage (scapulars or breast feathers or both). As John suggests, these lesser cov= erts may be more obvious on birds in worn plumage, because they're more likely t= o be visible as the scaps and breast feather edges b= ecome reduced by wear.

It's typical for Savannah Sparrows, at least of most subspecies, to have pale areas in the outer tail feathers, as seen very wel= l in one of these photos. These ar= eas still don't contrast as much as the white outer rectri= ces of Vesper Sparrows.

These images are well worth studying for what they = show of an underappreciated field I.D. problem.= The Ipswich Sparrow was lumped with the Savannah more than a generation ago, and hasn't received much attention since, but it can be a strikingly different = and confusing bird in the field.

DISCUSSION= EXPERT 2

I agree with Expert 1 that this bird is perfectly f= ine for an Ipswich Savannah Sparrow, for reasons he pointed out quite clearly. = We see fairly good numbers of Ipswich Sparrows along the NJ coastline in winte= r, with a group of 15 Ipswich spending this past winter at Stone Harbor Point, near Cape May.

I cannot argue with the similarity of the bird in question here to the photo in Kenn Kaufman’s field guide. However, Ip= swich often show a decent amount of variation with res= pect to plumage, so I wanted to comment on a few points here.

This bird is about mid-range in paleness for an Ips= wich, with some birds extremely pale (see the next issue of Birding for a photo o= f a very pale Ipswich photographed in Januar= y, 2006). Birding is covering Ipsw= ich Sparrow in an issue of confusing sub-species.

Most Ipswich Sparrows that I see from December to M= arch are in very fresh plumage, with neatly arranged scapulars and coverts. One outstanding feature separating Ipswich from Eastern Savannah is the generous amount of gray edging and internal portions of scapulars and upper/median wing coverts, with a few rusty subterminal borders to some of these feathers mixed i= n. I have photos of multiple Ipswich, and all= show this subtle mixture of mostly grayish edged scapulars with a few rusty subterminal borders mixed in. Many of these show neat= ly arranged dark centered, rusty-edged lesser wing coverts, so this is not a helpful, distinctive ID feature. They are also noticeably paler on the face= and crown, with much less of dark contrasting feathers on the crown and face.

As Expert 1 pointed out, Ips= wich are larger bodied with typically rounded heads and pronounced eye-rings, and have a tendency to stand upright a good deal of the time, probably a byprod= uct of their chest-heavy weight distribution. They are right at home in open sp= aces with very little cover, such as rocky jetties and open sandy beaches, with small amounts of vegetation. Some have pronounced yellow lores in February, with striking white moustachial st= ripes, while others, such as the bird in the upcoming Birding issue, show no yello= w in the lores. Others have a buffy wash to the lower cheeks and moustacials, so don't always look for contrasting white moustacials to seal the ID of Ipswich.

A combination of overall larger, heavier bodied str= ucture and paler plumage features, bold eye ring and often almost vertical upright posture, similar to Sprague's Pipit, all seem to contribute to a solid ID of Ipswich Sparrow each winter in NJ. I have never seen these birds at an inla= nd location, so this is a noteworthy report. I would be interested to see if others have definitely seen this former species inland.