Saturday, October 2, 2010

Lesser Black-backed Gull - A to Z - Part 1

During my formative birding years in the 70s the Lesser Black-backed Gull was a major rarity. When I drifted away from active birding in the late 70s to pursue a career in carousing I had still yet to add this species to my lifelist. After a career change in the late 80s I ended up back in southern Ontario and I eventually met up with an adult Lesser Black-backed Gull in 1992 by which time it was a regular visitor to the Great Lakes region. When I returned to fanatical birding in 2005 I visited Virginia Beach for a pelagic and was shocked to find Lesser Black-backed Gulls to be abundant along the beach easily outnumbering Great Black-backed and Herring Gulls.

Second cycle Lesser Black-backed Gull at Virginia Beach Sept, 2005 - recorded with primitive digiscoping technology

Locally Lesser Black-backed Gull remains a minor rarity with an average of one bird a year (prior to 2010-11).  Of the yearly Lariid visitors to the area it is the rarest. I have now had the opportunity to study this species not only locally but on numerous locations along the Atlantic and Gulf coasts as well as the Caribbean. I recently had a great opportunity to study a large number of Lesser Black-backs at Daytona Shores in Florida.


Adult Lesser Black-backed Gull at Daytona Shores, Florida March, 2009 - recorded with modern DSLR technology

I would like to digress briefly to highly recommend Daytona Shores for larophiles especially for photographers. Short of the landfill at St. John's, Newfounfland (which is a lot colder and a tad less aesthetic) this is the best site I have ever visited for close up study of 1000s of gulls. The gulls stop here for a couple hours in the afternoon on there way from Volusia Landfill to there nocturnal roost which I assume is a ways offshore. The birds are completely oblivious to the many people on the beach and binoculars are rarely necessary. The light is great in the late part of the day.

Daytona Shores - The Promised Land
Worn first winter California Gull (affectionately known as "Beaky" for obvious reasons)
Daytona Shore, FL

Taxonomy
Larus fuscus the Lesser Black-backed Gull is typically divided into three subspecies. L.f. intermedius and graellsii being very similar other than mantle shade and L.f. fuscus being quite distinct.  The nominate subsp. L.f. fuscus commonly known as the Baltic Gull has not been officially recorded in North America. However if you look back in my blog you will see a very good candidate for L.f.fuscus was found in St. John's, NFLD in January of 2007.

Adult Great Black-backed Gull and putatative adult Baltic Gull
St. John's NFLD - Jan/2007

Putative Baltic Gull, St. John's NFLD - Jan/2007

The Baltic Gull is quite  distinct from the rest of the Lasrus fuscus clan. It breeds primarily along the Baltic Sea in Finland and its breeding range does not overlap with the other subsp. It is a long distance migrant wintering primarily in east Africa. The Baltic Gull is a three year (attains adult plumage in its third year) gull quite unlike L.f.graellsii/intermedius and most (Yellow-footed Gull being another exception) of the large white-headed gulls. It is amply distinctive in plumage and I would refer you to my previous post from Nov/2009 for more pictures and information on this taxon.

One other point of significance the Baltic Gull (unlike the other subsp. of Lesser Black-backed Gull) has not been expanding its range in fact its range has been shrinking and numbers decreasing. 

Larus fuscus graellesi and intermedius may not be distinct subspecies. Olsen and Larsson state "graellesi and intermedius may represent only one clinal taxon graellesi the situation in N and W Europe paralleled by the (albeit much more complex) Herring Gull races argentatus and argentus". L.f. graellesi has typically referred to the palest backed birds that inhabit the British Isle well L.f. intermedius are darker backed primarily breeding in the Netherlands,Denmark to Norway.

Paler backed adult Lesser Black-backed Gull suggestive of L. f. graellesi


Darker backed adult Lesser Black-backed Gull more typical of L.f. intermedius

In reality it seems of little value and in many cases impossible to separate these two forms and a growing consensus seems to be that this is in reality one subspecies with a cline from light to dark-backed birds. One further caveat -shades of grey are notoriously light dependent. Bright direct light can make even the lightest mantled gulls look like a Slaty-back.


Third winter Lesser Black-backed Gull


The same bird less than a minute later in different light

The above pictures illustrate how lighting significantly affects the perception of mantle color. The picture also nicely demonstrates how posture can play similar tricks with head shape.

Plumage

I would like to move along to discuss and illustrate the age development of Lesser Black-backed Gull through its four year plumage transition from juvenile to adult.

Juvenile Lesser Black-backed Gulls have a sharp, crisp and distinctive plumage. Although other species may have a very similar juvenile plumage (Yellow-legged, Kelp) differences in molt timing and structure along with range can usually differentiate the aforementioned species. In North America the species of confusion would invariably be the Herring Gull.


Typical juvenile Lesser Black-backed Gull

Under most circumstances with careful study I don't think differentiating juvenile Lesser Black-backed and Herring Gulls is a significant challenge. The upper parts feathers are a dark blackish with neat white edging. The coverts are dark blackish as are the tertials. Olsen and Larsson note that the neat white edges of the tertials do not reach the greater coverts and on checking many pictures this seems to be consistent. This gives the juvenile Lesser Black-backed Gull a very contrasting, black and white look. Some sources suggest the juvenile of this species has a darker "eye-mask" than Herring Gull. Juvenile Herring Gulls do seem to have a more uniformly brown head with the Lesser Black-backed having more white to the anterior face giving it a more masked look.



Typical juvenile Herring Gull

The above picture illustrates the browner, less contasting look of the juvenile Herring Gull. The significant differences in the tertial edging and the patterning of the coverts is readily apparent. 

In flight the dark blackish primaries, secondaries and coverts without a inner primary window clearly seperates the Lesser Black-backed  from the Herring Gull.


Juvenile Lesser Black-backed Gull showing uniformly dark primaries, secondaries and greater coverts


First winter Herring Gull showing classic "inner primary window"

In flight the very white ground colour of the rump with fewer markings than the Herring is also very helpful in the field.

Juvenile Lesser Black-backed Gull

First winter Herring Gull

I have included a few more juvenile Lesser Black-backed Gull pics with the birds seeming fairly uniform.


Juvenile Lesser Black-backed Gull


Juvenile Lesser Black-backed Gull

There does seem to be some some variation in the juvenile plumage. I came across this bird last week.

Juvenile Lesser Black-backed Gull

No doubt a Lesser Black-backed but a lot wider and scalloped white edging in the scapulars and tertials and a lot more white on the coverts giving it a much more checkered look. I had a similar bird which is more worn looking on the lower coast of Texas last December.


Worn juvenile Lesser Black-backed Gull

So clearly this species has significant variation in juvenile plumage which is hardly surprising given its variability in general and the complex variation noted in its close relative the Herring Gull. 

Juvenile Herring Gull variation with similarities to juvenile Lesser Black-backed Gull
The above juv. Herring Gull although somewhat superficially similar to a Lesser Black-backed has a fairly uniform brown face and underparts and a different structure being stocky and having a shorter primary extension. The jizz is very much that of a Herring Gull not a Lesser Black-backed. With experience the recognition of these features is  fairly instantaneous and happens at  a subconscious level.
So on occasion a juvenile bird might provide a bit of a challenge but this seems much more of an issue with first winter birds.
The Lesser Black-backed Gull often retains its juvenile plumage well into the winter. Howell and Dunn tell us that this species will molt there scapular and upper wing coverts from midwinter on producing the first alternate plumage or as we often say a "first winter" bird. Bleaching of head often results in a white headed look.


First winter Lesser Black-backed Gull- Feb, Daytona Shores

The above bird has replaced his scapulars but the coverts and tertials are very worn. Interestingly to my eye it looks like P10 my have recently been replaced. Note the white ground cover to the head and underparts.



First winter Herring Gull    First winter Lesser Black-backed Gull
February/ Freeport, Texas

The above picture illustrates some of the key differences between first winter Herring and Lesser Black-backeds. Note the whiter ground colour of the head especially the mostly unmarked anterior face around the bill. The underparts are also white with dark flecking and smudging. The Herring Gull has a uniformly brown face and underparts. This Lesser Black-backed defies defies many of the usual structural features of this species - I will look at this bird closer when I review structure.




First winter Lesser Black-backed (I think)
February/KittyHawk, North Carolina

I photographed thie above bird at Kittyhawk in a parking lot. The small flock of gulls present included  a dozen Lesser Black-backed Gulls with some Ring-billeds, Laughing and a Black-headed Gull. There were no Herring Gulls present. I was quite convinced this was a first winter Lesser Black-backed Gull at the time.

I have repeated looked at this birds pictures and every time I see my first reaction is its a first winter Herring. The face looks quite uniformly brownish, the structure seems Herring Gull like. Then  look at the open wing shot and think hmmm-the flight feathers and greater coverts are Lesser Black-backed like but is there a bit of an inner primary window? The rump seems more in keeping with a Lesser Black-backed.

The clincher for me is the darker grey mantle feathers especially near the back of the mantle. I don't think you would ever see this on a Herring Gull. I come away each time thinking yes its a Lesser Black-backed but not with 100% confidence. I think this bird illustrates that with wear and some sun the coverts and tertials become much browner and less distinct and the new mantle feathers are not as distinctively blackish as the juvenile. Although some first winter birds are distinct others may be a bit of a challenge.

I will finish part one with my only picture of a first summer ( more accurately second cycle) bird taken in early September in Virginia Beach. A near identical bird in Howell &  Dunn from August in the Netherlands is described as a "second-cycle Lesser Black-backed Gull completing PB2 molt."

 My understanding is that PA1 (post alternate 1) molt  occurs after juvenile plumage and may be slow and gradual over the fall and early winter and starts with the mantle and scapular feathers and may progress to head, chest and flanks. PB2 (Post basic 2) which marks the beginning of the second cycle begins in the spring usually involving the coverts. PA1 & PB2 may overlap and it all gets very confusing-at least to me.

Steve Howell has just authored an excellent book entitled "Molt in North American Birds" as part of the Peterson Reference Guides series. It is very well illustrated and I am sure it will be the authoritative reference on this topic for years to come

Second-cycle Lesser Black-backed Gull- September/Virginia Beach

The combination of heavy bleaching and replacement of the coverts along with heavy wear gives this bird an entirely different look from the first winter birds.

In Part 2 I will continue to work through the second cycle to adult birds with a section on structure illustrating a few oddballs that demonstrate the extremes of variability. Part 3 will focus on the amazing expansion of this species over the last 40 years. This will include a interesting bit on this rather famous individual.

Celebrity Lesser Black-backed-identity revealed in Part 3

Be back with Part 2 soon.

Kirk Zufelt
zufelt_k@shaw.ca




2 comments:

  1. Great post! Just thought I'd add something about the occurrence of LBBGs in my area (Chicago). It seems that it is somewhere in between your gulls in the Yoop and the LBBG hotspots you mentioned in the post. At "the" IL gull place, I normally get 4-5 a day during prime season. Recently (a bit before of the time I normally think of as prime LBBG season), I got 5-6 individuals in one day (including an interesting looking 3rd cycle bird and a great textbook 1st cycle). I was also lakewatching one day and a nice 1st cycle happened to land on the beach in front of me. I personally love this species, and it is always nice to see them.

    Ethan G

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    1. My name is John Heidecker, I'm asking permission if I can copy the jpegs on the lesser black-back in order to use them for a slide show in my club on local gulls for my camera club. I live in NY..

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