31 December 2018

December 2018 Quiz


Age: The dark carpal bar across the upperwing coverts, and apparent full tail band point to a 1st cycle gull.

Identification: The overall wingtip pattern and carpal bar point to a small tern-like gull (so-called sternine gull). There are only two species in North America that show a complete black trailing edge from the body out to the outermost primary: Black-headed Gull and Bonaparte's Gull. Seeing the bill would've been helpful as the two typically show different bill patterns. But there's something much more obvious that we can use here. Black-headed has considerably more black on the under-primaries, as seen here. The light gray/white pattern on the under primaries on our December Quiz bird are spot on for a 1st cycle Bonaparte's Gull.

Cuyahoga County, Ohio. November. 

28 December 2018

Field Museum Musings - Kodak Gray Scales and Such

A few notes from a visit to Chicago's Field Museum last week.

I'm currently working on a project that requires quite a bit of data collection from both live birds and museum specimens. One component to this data is measuring gray tones. Now a standard for measuring gray colors on the upperparts of gulls, the Kodak Gray Scale has steps 1-19, with 1 essentially being white and 19 black. My objective with measuring these gray tones is to compare them to current values given in the literature. In particular, I would like to verify (or contradict) what has been recorded by previous workers. 

The two specimens below are Western Gulls. The left bird is the paler, northern, race: L.o. occidentalis. The right specimen is the darker, southern, race: L.o. wymani. One challenge is to come up with an "average" for what is seen on the upper mantle (lighter) versus the mid to lower scapulars (usually darker). The other challenge is determining whether there are two noticeable generations of feathers. Newer feathers will generally appear darker (in adults) and older feathers should have suffered from some fading, and hence paler.

For the specimen on the left, I averaged it to be a KGS value of 8.5
For the specimen on the right, I averaged it to be a KGS value of 10





Another long-term project of mine is evaluating Iceland Gull specimens collected from the presumed ranges of the various subspecies during the breeding season. Just for fun, here's a spread of dark-end thayeri, to pale kumlieni. At some point, I'll find some time to post on my progress in this endeavor.



And like most of my visits to any gull collection, I usually find myself distracted by all the toys. Pictured below is a 1st cycle male Great Black-backed Gull (New Brunswick, November) and a 1st cycle male Little Gull (India, September).



A special thanks to Ben Marks for allowing access to the gulls here, again! The staff from the bird division at the Field Museum is an incredible resource.

27 December 2018

Kenosha & Racine Wisconsin - Glaucous x Herrings

A collection of Iceland Gulls from last weekend, with a putative Glaucous x Herring at the end. 
Kenosha & Racine Counties. Wisconsin. 23 December 2018.

1st Cycle Thayer's Gull. 1 of 3.

2 of 3.

3 of 3.

2nd Cycle Thayer's Gull. 

2nd Cycle K-T Iceland Gull.

2nd Cycle Thayer's Gull. 

3rd Cycle type Thayer's Gull.

3rd Cycle type Thayer's Gull.

Adult Thayer's Gull. 

Adult Thayer's Gull.

Adult Thayer's Gull.

Adult Thayer's Gull.

Adult Thayer's Gull (left of center with Herring Gulls). 

1st Cycle Kumlien's Gull. 1 of 4. 

2 of 4.

3 of 4.

4 of 4. 

3rd Cycle type. Kumlien's Gull. 1 of 3. 

2 of 3.

3 of 3. 

Adult Kumlien's Gull. 

Adult K-T Iceland Gull. 

2nd Cycle, Putative, Glaucous x Herring (right of center). 1 of 6.

2 of 6. 

3 of 6.

4 of 6.

5 of 6.

6 of 6.

...perhaps you noticed my favoring photos of birds facing to the left. Cheers!

26 December 2018

Academy of Natural Sciences at Drexel University

A few notable specimens from an impromptu visit to the Academy of Natural Sciences at Drexel University, last week.  The museum is the oldest in the New World, boasting the 8th largest ornithology collection in the world, and 5th largest associated with a university. One of the highlights of my visit was looking over the Kumlien's-Thayer's specimens. Here's an adult type from Ellesmere Island, collected on 19 August 1934 (sex unknown). Skins from Ellesmere Island - presumably from the core of thayeri's range - have been difficult for me to find in the collections I've visited in the last few years.

p8-p10 retained (4th basic?), p7 dropped, p6 growing, p5 almost fully grown. 

The molt here is rather typical for a large gull in mid-August in the northern hemisphere. For what it's worth, the thayeri I see here on Lake Michigan in late October to early November are still molting/growing p9-p10 upon arrival, exhibiting molt migration.
The pigment on p8-p10 on this individual is somewhat extensive and pale. I'm writing this off as a adult type showing some seasonal fading/bleaching. Perhaps some of it is a collections artifact? Further, the p5-p6 subterminal bands were just a hint paler than I was expecting for a Thayer's taken from Ellesmere.

Next up is a presumed nominate fuscus, Lesser Black-backed Gull, from northern Egypt. Most interesting is the size of the p10 mirror (~48mm). This measurement seems to exceed ranges given in the literature. I'd appreciate some comments on this bird.

Lesser Black-backed Gull. 

Same LBBG (left) with Peruvian Kelp Gull (right). 

A special thanks to Jason Weckstein for showing me some of the gulls here!

25 December 2018

Bucks County Pennsylvania CBC

For the last 5 years or so I've had the "Bucks County" CBC on my "to-do" list, intrigued by the thousands of Herrings seen at the Tullytown Landfill. On Saturday, 15 December 2018, I joined George Armistead and Jason Weckstein for a jaw-dropping day at the dump, estimating some 35,000 Herring Gulls for the day.


Tally: 4 Glaucous, 8 Iceland, 25 Lessers, 450 Greats, 600 Ring-billeds, ~35,000 Herring Gulls.

1st Cycle Glaucous with Adult Great Black-backed.

Putative, adult, Lesser Black-backed x Herring Gull. 1 of 6 seen on this day.

Adult Lesser (center) flanked by twin Herring Gulls. 

1st Cycle Great Black-backed Gull, with Adult Herring Gulls.


Yes, in my zone...gull patrol is not for everyone.

01 December 2018

Land of the Rising Sun - Upcoming Japan Tour

Friends, I'm super excited to be leading a winter tour to Japan in December 2019 into January 2020. This remarkable island has to be the most alluring land mass in all of Asia. A wide range of ecosystems and climatic zones make for amazing bird diversity, and the spectacles of large bird congregations, at such close range, will make this a memorable and unforgettable experience!

I'm currently enlisting people to join me on this trip - please reach out if you or someone you know have any interest. Read for yourself what breathtaking birds we'll spend time watching, as we travel to the Land of the Rising Sun!

Click on URL:

https://www.rockjumperbirding.com/tourinfo/japan-winter-eagles-cranes-gulls-galore-with-amar-ayyash-2019





Monthly Notables November 2018

Sightings

  • California Gull (adult). Cameron Parish County, Louisiana. 01 November 2018.
  • Lesser Black-backed Gull (3rd cycle type). Curry County, Oregon. 02 November 2018.
    • 1st County Record. Retained p9-p10.
  • California Gull (1st cycle). Jacksonville, Florida. 07 November 2018.
  • Laughing Gull (1st cycle). Lake County, Indiana. 07 November 2018.
  • Little Gull (adult). Capital District, British Columbia. 07 November 2018.
  • Lesser Black-backed Gull (2nd cycle). Santa Clara County, California. 10 November 2018.
  • Great Black-backed Gull (adult). Pueblo County, Colorado. 10 November 2018.
    • Believed to be the same individual returning for the 25th year!
  • Lesser Black-backed Gull (3rd cycle). San Francisco County, California. 12 November 2018.
    • 1st Farallon Island record. Missing left foot. Likely the same individual seen in San Mateo County in April 2018 (then a 2nd cycle). 
  • California Gull (adult). LaPorte County, Indiana. 12 November 2018.
  • Slaty-backed Gull (adult). Benton County, Washington. 16 November 2018.
  • Glaucous-winged Gull (1st cycle). Larimer County, Colorado. 16 November 2018.
  • Mew Gull (adult). Oklahoma County, Oklahoma. 17 November 2018.
  • Sabine's Gull (2nd cycle). Sarasota County, Florida. 18 November 2018.
  • Lesser Black-backed Gull (2nd cycle). San Francisco County, California. 19 November 2018.
  • Black-legged Kittiwake (1st cycle). Wilson County, Tennessee. 21 November 2018.
  • Black-headed Gull (adult). Georgetown County, South Carolina. 22 November 2018.
  • Common Gull (adult). Essex County, Massachusetts. 24 November 2018.
    • Returning for the third consecutive winter, this individual has a silver band on the right leg, originating from Iceland. No p8 mirror and a broken p5 band. 
  • Slaty-backed Gull (adult). Nipissing County, Ontario. 24 November 2018.
  • Sabine's Gull (1st cycle). Sarasota County, Florida. 24 November 2018.
  • Black-legged Kittiwake (1st cycle). Perry & Faulkner County, Arkansas. 25 November 2018.
  • European Herring Gull (1st cycle). St. John's County, Newfoundland. 25 November 2018.
  • Glaucolus Gull (1st cycle). Madison County, Mississippi. 26 November 2018.
  • Lesser Black-backed Gull (adult). San Diego County, California. 28 November 2018.
    • Retained p8-p10.
  • Black-legged Kittiwake (1st cycle). Clark County, Nevada. 29 November 2018.


Miscellaneous Notes

  1. An estimated 170 Lesser Black-backed Gulls were reported at the Findlay Reservoir in Hancock County, Ohio on 11 November 2018. This count would certainly be a new high record for the Great Lakes region. Observer Jeff Loughman. 
  2. On 15 November 2018, the Seaside City Council in central California approved a permit to have a floating Heermann's Gull nesting island put in place at Roberts Lake. 
  3. Six California Gulls were observed at a water treatment plant in Culberson County, Texas on 24 November 2018. To my knowledge this is a single site high count. Observers Martin Reid, Sheridan Coffey, Willie Sekula.

November 2018 Quiz


Age: We can be sure this individual is not sporting definitive adult plumage. The heavily marked tail, ink spots on the upper side of the secondaries (right wing), black-marked primary coverts, and smoky brown pigment on the under wing coverts along the leading edge (left wing), all make this a relatively straight forward bird to age. It has adult like gray secondaries and primaries, with broad white tips, ruling out a 2nd cycle. This individual would best be aged as a 3rd cycle type if we can agree it's a large, four-year gull.

Identification: The gray upperparts don't appear dark enough for any black-backed species. Which gray-backed gull has pale eyes and a medium size bill? The black subterminal tip to the bill superficially resembles Ring-billed Gull, but our bird has more of a menacing look with a barrel chested-body and broader wings. Of course if we were observing this bird in real life, we'd immediately get a sense for size and structure, but we don't have that information in a single snapshot. However, if it were a Ring-billed, it would be a 2nd cycle as this is a 3 year gull. The tail band is too wide for Ring-billed with black coming up more than half the length of several rectrices. Here's a typical tail band on a 2nd cycle Ring-billed Gull. It helps to zoom in on what look like pink feet (Ring-billed is yellow-footed).

Our November Quiz bird is a 3rd cycle Herring Gull, a species we should be comfortably familiar with anywhere in North America. Ottawa County, Michigan. December.

11 November 2018

1st Cycle Kelp Gulls - Part 2 Molt

I recently returned from Peru where I spent some much needed time watching and photographing Kelp Gulls. I spent most of my time working several beaches and coastal lagoons around Lima (-12S, 77W). The subspecies of Kelp found in Lima is nominate L.d. domincanus - incidentally, this population is the northernmost stronghold for the species in South America. The Kelp Gulls can be rather accomondating in relatively large numbers here, often seen with Belcher's and Gray-hooded Gull, along with Franklin's Gulls and the occasional Gray and Andean Gull.


As noted in Part 1 of this two-part series, there is a dearth of information on Kelps in the north of South America. Perhaps not surprising, there is little data on molt timings or molt strategies for populations in Peru. Howell & Dunn (2007) give molt descriptions for southern South America, while Olsen & Larsson (2004) simply assert that northern birds molt "later" than southern conspecifics.



With this being the austral spring, I was expecting to find the majority of 1st cycles with juvenile flight feathers intact, or at the most, a few advanced individuals commencing inner primary molt. Instead, I discovered a radically different flight feather molt sequence - one that, to my knowledge, has not been documented for this species.

Below, I present a series of images illustrating a molt sequence not previously described in Larus dominicanus. A rough estimate of the percentage of individuals with similar molt patterns (n=375) is provided where necessary.

A: Hatch Year (HY) Kelp Gull with all renewed, 2nd generation, rectrices and secondaries. All juvenile primaries retained. Flight feather molt apparently suspended at s1/p1. Approximately 35% of this age cohort showed a similar molt sequence. Chorrillos, Peru. 03 November 2018.

B: Renewed tail feathers and more than half of secondaries already 2nd generation. Secondary molt in motion. All juvenile primaries. Approximately 15% of birds showed a similar sequence with some scaling back to a less advanced pattern to the outer secondaries (see next example). Miraflores, Peru. 01 November 2018.

C: Similar to individual above, but note the outermost secondaries now take on more of a regressive, 1st generation apperance. This was noted in roughly 5% of individuals. Miraflores, Peru. 01 November 2018.

D: This individual has roughly half of its secondaries renewed, but with no apparent active molt or molt gaps. Tail feathers 2nd generation. Seen in about 25% of individuals. Chorrillos, Peru. 02 November 2018.


E: Similar to the bird above, tail feathers 2nd generation (except for r5 on right). Tertials renewed as are a few adjacent, inner secondaries. All juvenile primaries. Chorrillos, Peru. 03 November 2018.


F: Again, tertials renewed as are a few inner secondaries. Ony two 2nd generation rectrices. Juvenile primaries and outer wing coverts. Miraflores, Peru. 01 November 2018.

The sequence of tail feathers and secondaries being renewed before any primaries have been dropped is unlike the regimen followed by large gulls in the northern hemisphere, where flight feather molt is typically initiated via a prebasic molt, usually beginning at p1, p2 and so forth. With this being the austral spring season - a time of transition from prealternate to prebasic molts, and a time when the two molts commonly overlap - important questions to consider are:

1) Are the 2nd generation secondaries and rectrices a result of an extensive 1st prealternate molt? 

2) Are they the first flight feathers to be replaced in the 2nd prebasic molt, preceding molt of primaries? 

3) With the highly variable mixture of retarded upperwing coverts and scapulars, versus those that are rather advanced and adult-like, is it possible some hatch year Kelp Gulls have a preformative molt soon after hatching, followed by an extensive prealternate molt late in the austral winter/early spring? 

4) The advanced, adult-like, aspect to the renewed secondaries is puzzling. Is it possible these individuals become adult-like via 3 molt cycles?

Perhaps the explanation isn't an easy or straightforward one. In those individuals undergoing active molt in the remiges, roughly 1/4 showed some primary molt. This is where matters become much more interesting and perplexing.

G: The outermost secondary is retained juvenile, with p1-p2 dropped. Rectrices 2nd generation. Found in approximately 10% of individuals. With such an advanced aspect to the scapulars, tail and secondaries, is it possible this is a 2nd cycle with 1st generation primaries never molted in the first prebasic molt? Chorrillos, Peru. 03 November 2018.

H: More similar to the molt sequence of a large gull from the northern hemisphere, this individual has renewed p1-p2, but has also replaced tertials and 2-5 adjacent secondaries. This molt pattern was the exception rather than the rule and only observed in a handful of birds (less than 1%). Miraflores, Peru. 01 November 2018.


I: Another bird "seemingly" coming close to the flight feather molt pattern of a northern gull, although the assumption here is that molt began with the innermost secondaries and worked its way out, distally. In reality, this sequence isn't very similar to a northern gull's flight feather molt pattern. All tail feathers 2nd generation. Note the contrast between s1 and p1, suggesting some time lapse. Found in less than 5% of all individuals. Chorrillos, Peru. 02 November 2018.


J: All 2nd generation secondaries and rectrices. Outer primaries renewed (p5 dropped, p6-p10 2nd generation on right wing; p8-p10 2nd generation on left wing). This sequence appears to be eccentric! Found in roughly 5% of all individuals. Chorrillos, Peru. 02 November 2018. 

K: Similar to "J" above, but only primary molting is p9 with all others juvenile. Chorrillos, Peru. 03 November 2018. 


L: A most unusual case. P1-P3 juvenile, new p4 tip emerging past primary coverts, p5 dropped, p6-p8 renewed 2nd generation. P9-P10 retained juvenile (symmetric). Secondaries renewed. Chorrillos, Peru. 02 November 2018.
L2: Same individual above. Note the innermost primaries have been dropped on the right wing. 

L3: Same individual above. The tail feathers are 2nd generation, corresponding with the same molt which produced the 2nd generation secondaries. 


The percentages given above are crude estimates based on my daily field notes and review of several thousand photographs. The values are percentages of birds in active molt, and don't account for the subgroup showing entirely juvenile remiges. These numbers are only meant to give an impression of how common (or uncommon) each molt pattern is in November for this particular population. 

Of importance from Howell & Dunn (2007) is mention of tertials and upperwing coverts sometimes being replaced in a variable and protracted 1st prealternate molt. Consider this individual:


Limited prealternate molt has produced mostly new 2nd generation scapulars, several proximal wing coverts and a few tertials (bold white edges). But also notice the replaced p9 on the left wing. Chorrillos, Peru. 02 November 2018.


Needless to say, larger samples and more study is necessary in order to get a more accurate assessment of which molt is producing which feathers. But if the 1st prealternate molt is said to include tertials, then naturally, the few inner secondaries replaced on birds such as D-F must only be an extension of this. Further, some advanced birds apparently go on and continue to replace all secondaries (such as A). The big wrench in this new data is where the primary molt fits in. Birds such as I-L need careful analysis. 

These molt sequences may vary from year to year depending on breeding success, food resources and competition. As this is a single point in time from the calender year, there's no telling if those with more extensive primary molt are individuals that have migrated from southern populations, or, are largely resident birds which are afforded a speedy and extensive molt due to the rich food source of the Humboldt Current. A question to ponder is if such birds - as adults - are confined to a 12 month breeding cycle. A population's breeding cycle is an integral component to understanding how that group regulates feather molt. My visit, being at the onset of the breeding season (November 1st), is a time when many adults are building, protecting and sitting on nests. From Yorio et al (2016), we can infer that young fledge from January through February in Peru. Thus, the youngest free-flying Kelp Gulls on display during my visit were approximately 8-10 months of age. 

A large number of individuals - from those with some degree of renewed secondaries - resembled the bird above. This is a striking appearance that would attract attention in a flock of gulls in North America or Europe. Chorrillos, Peru. 01 November 2018.

Same individual above. We can be sure these young Kelp Gulls replace flight feathers beginning closest to the body and outward. Most interesting is the aspect of these new secondaries, appearing 3rd generation in nature. The uppertail coverts and central tail feathers are likely juvenile (?).


Final Thoughts

Do other populations of Kelp Gull share similar molt sequences in southern South America (or anywhere else)? If not, then what taxonomic implications might this present?

Finally, if an individual such as the bird above was to stray to North America in the boreal winter season, the flight feather molt pattern should be useful in establishing a good Kelp Gull candidate. Certainly any young black-backed gull found with such a pattern out of season would send off red flags to the discerning eye. With the paucity of records of 1st and 2nd cycle Kelps in North America, perhaps this note will give observers one more incentive to investigate feather molt of their local gull flocks.



References
Howell, S.N.G., and J. Dunn. 2007. A Reference Guide to Gulls of the Americas. Peterson reference Guide Series. Boston. Houghton Mifflin. 

Olsen, K.M., and H. Larsson. 2003. Gulls of Europe, Asia and North America. London: Christopher Helm.

Pyle, P. 2008. Identification Guide to North American Birds, Part 2. Slate Creek Press, Bolinas, CA.

Yorio, P. 2016. Distribution and Trends in Kelp Gull (Larus dominicanus) Coastal Breeding Populations in South America. Waterbirds 39: 114-135.