Sunday, November 22, 2009

Nelson's Gull

Nelson's Gull was originally described as a new species by H.W. Henshaw in The Auk Vol. 001 No.03 in July of 1884.  the original article can be accessed at  http://elibrary.unm.edu/sora/Auk/v001n03/p0250-p0252.pdf .


It was named after Mr E. W. Nelson an Alaskan ornithologist who had collected the first specimen of this distinct taxa. Henshaw compared its similarity to Glaucous Gull as Kumlien's is to Iceland Gull. He also noted its resemblance to Herring Gull. Although initially described as a distinct species currently it is well accepted that Nelson's Gull is a hybrid of Glaucous and Herring Gull.



Juvenile Nelson's Gull in flight

It would be safe to say that traditionally Nelson's Gull is the most common hybrid gull on the Great Lakes and eastern seaboard. Lesser Black-backed X Herring Gulls and Great Black-backed X Herring Gulls are becoming increasingly common and may rival Nelson's at some locations. Nelson's Gull is of course also seen in the west being described from Alaska and recorded along the west coast into Southern California. In many areas of the west it is vastly outnumbered by the "Olympic Gull" the hybrid result of Western and Glaucous-winged Gull "interaction". In the Anchorage area it can be hard to find any pure large gulls the majority being Glaucous-winged X Herring hybrids. Fortunately in the east hybrids are still an oddity and vastly outnumbered by pure birds.



Adult Herring X Glaucous-winged Gull





Adult Herring X Glaucous-winged Gull

The two Herring X Glaucous-winged Gull hybrids above were photographed at the Palmer Landfill north of Anchorage. The first bird looks like a stalky Herring Gull. The white eye and orange orbital ring is typical for Herring Gull. The primaries are an odd greyish-black. The second bird has a dark eye and pinkish orbital ring typical of Glaucous-winged Gull and the same odd greyish-black primary coloration.

On the shores of eastern Lake Superior Nelson's Gull is still a relatively rare find. The first record that I am aware of was a juvenile photographed at the Sault Ste. Marie landfill in November of 2005. It stuck around for two months and was a regular feature at the landfill. I  imaginatively nicknamed him "Nelson".



"Nelson" the Nelson's Gull

Since the  initial sighting I have seen about one Nelson's Gull per season. A noted exception to this being this year with a minimium of three birds being present. All the birds except one have been juvenile birds. I have never seen a third year bird or an adult locally. My initial impressions were that juvenile Nelson's Gulls looked distinctly like a Glaucous Gull with some dark pigment on the primaries as was the case in "Nelson".






"Juvenile" Nelson's Gull - St. John's

The "Nelson's Gull" pictured above photographed at the St. John's Landfill looks to be identical in size and structure to the pure Glaucous Gulls. The only difference in plumage that I can discern is the dark pigmentation of the primaries. A second winter bird I photographed subsequently in the Soo further suggested to me that the Nelson's Gull was dominated by Glaucous genes.











Second winter Nelson's Gull showing faint pigmentation and "ghost' primary pattern on both wings

In the first picture above I think one can discern some structural differences from the average Glaucous Gull especially in the head shape. The bill however is entirely Glaucous Gull. Unlike the above pictured juvenile bird I think this bird does have some subtle plumage differences from Glaucous gull other than the faint primary pattern.






Second- winter Glaucous Gulls

The second winter Glaucous Gull usually has some dark smudging scattered about and a white ground color but little or no fine barring. The coverts are largely unmarked with just a bit of dark smudging. The second winter Nelson's Gull shows dark smudging along the neck but has some fine vermiculations on the scapulars and wing coverts and tertials which I believe would be out of range for Glaucous Gull. In this view I also note some gonydeal expansion of the bill that also suggests Herring Gull influence.                                                                                                                          




Second Winter Nelson's Gull

This year I have seen three juvenile Nelson's Gulls. One was very similar to the previously noted birds - basically a Glaucous Gull with darker primaries. The other two however were much further towards the  Herring Gull end of the spectrum than any I had viewed previously.











Juvenile Nelson's Gull

The above bird although certainly very Glaucous Gull - like shows a lot of Herring Gull influence in the plumage especially in the juvenal scapulars and tertials. The primaries show relatively heavy dark pigmentation somewhat reminiscent of Thayer's Gull. The next bird is even further down the Herring Gull line to a point where I was intially unsure if in fact it was just a pale Herring Gull.







Juvenile Nelson's Gull (probable)

The structure of this bird screams Glaucous Gull (well maybe only shouts). The bill, head shape and general feel of the bird is Glaucous. In the closed wing view it has a lot of fine vermiculations on the scapulars, coverts and tertials belying Glaucous Gull influence. The primaries are perhaps just a shade paler than the Herring Gull but in the open -winged view I think there is definitely  decreased pigmentation of the flight feathers and the primary coverts which would have to be at the extreme end of the range for Herring Gull. I believe but am not 100% certain that the following picture represents the same individual. The eye is clearly white in this better light which is atypical in first year birds for both Herring and Glaucous Gull. It is certainly acting goofy which is very characteristic of Glaucous Gull but can certainly be an attribute of any of the larger gull species.



Juvenile Nelson"s Gull (probable)

Unfortunately this was the only close-up picture I managed before it flew the coop. After reviewing the Nelson's Gull pictures on-line and in the literature I have concluded that there is a very wide variation especially in the plumage of this hybrid. The overwhelming majority of these hybrids have Glaucous Gull type structure and bill.

Correction: Thanks to Kevin McLaughlin for pointing out that the above bird is not a juvenile but a 2nd year bird. Here are his helpful comments:


This is concerning the Nelson's Gull from the November 22 posting. This is the bird immediately above the Glaucous hybrid with the California Gull in San Diego. The bird is looking skyward out of its left eye. You label it as a juvenile and this is where I have a concern. There are several things which point towards a second basic bird. A few roadblocks are there as you allude to. This is the only good photo and as a result, only one side of the standing bird is shown. We have no assessment of the open wings, tail and so on. The bill pattern is good for a second basic Glaucous, Nelson's or Herring Gull. I have never seen Nelson's or Glaucous in juvenile or first basic which had a pink area at the tip of the lower mandible like this bird. They always show a bill with a complete black tip, the remainder being pink or bubblegum pink. The upperparts look too variegated, too messy, for a juvenile hybrid combo. The finely white spotted pattern on the greater coverts is absolutely bang on for a second basic Herring and by extrapolating this to a suspected hybrid, can fit that as well. The edge spotting gets larger on the inner greaters at the margin and this is normal for second basic. As you know, some juvenile-first basic Herrings and Thayer's, for example, can be finely marked on the greater coverts also but I do not believe that they will ever show the larger notches on the inner greaters as shown on a second basic. I intend on checking into this point however. To carry on, the tertials show several fine white spots on the outer margin and I consider this as being most likely, age diagnostic for second basic. (mind you, you can see this on third basics as well, so I mean to say diagnostic vis-a-vis first basic).The last point is the most obvious one and that is the colour of the eye. This bird shows a clear straw coloured eye, just right for a great many second basic large gulls, and absolutely wrong for a juvenile or first basic. I won't say that this aberrant eye colour could never happen in a first year bird, but can say that I have never seen it happen in the field or in photographs.





While in San Diego several years ago I photographed a hybrid gull that I initially felt was likely a Glaucous-winged X Glaucous hybrid (based on likelihood I suspect). On reviewing the pictures I don't think given the bicolor bill and the heavy wear and bleaching that you can be certain it's not a Nelson's.


Worn First Winter Glaucous Gull hybrid  Second Winter California Gull



Worn First Winter Glaucous Gull hybrid

I have yet to stumble across either a third winter or an adult Nelson's Gull locally. I have seen at least a couple adult Nelson's Gulls along the Niagara river but they were to distant for good photos. Brandon Holden has some great pictures of Nelson's Gull as well as other interesting hybrids on his web page of unusual Ontario Birds      http://www.peregrineprints.com/ind__UOB.htm     .

I will report later in the week on The First Annual Sault Area Gull Roundup that I coordinated (its not to difficult coordinating one participant especially if its yourself) last Monday.

Comments are always welcomed.
Kirk


2 comments:

  1. Kirk, I like the detail and the photographs in your Nelson's Gull discussion. I'm not a gull person per se, but I do enjoy finding gulls that are "different" and seeing new gulls. I have never seen a Ross's Gull either. When that happens, it will be quite an event. Last weekend I went on the Detroit Audubon sponsored Ontario Niagara River trip where I saw my first Nelson's Gull. Curiously, Alan Wormington (trip co-leader) said the bird in question had a dark eye. I could not see that detail. Later, however, this bird was posted as a Nelson's Gull.

    I've linked your blog to my blog where I write about seeing the Nelson's Gull. Check it out if you like:
    http://intothewoodsandelsewhere.blogspot.com

    Thanks for the great discussion and photos.

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  2. I recently stumbled across what I think may be an adult Nelson's in Barrie, ON, but I am in no way an expert. I have included links to a couple of pictures if you can in any way enlighten me on what I am looking at.
    https://flic.kr/p/qiZwij
    https://flic.kr/p/puHy2f

    It was suggested to me that Nelson's was a possibility, but I thought it was just a light-colored Herring Gull. Any input would be great.
    Thanks, Rick
    rjbaked@gmail.com

    ReplyDelete