20 July 2016

Manitowoc: Putative Great Lakes Gull & Summering Franklin's


Wes Serafin and I ventured up to the Wisconsin lakefront on Friday to look for summer gulls. Our most interesting bird for the day was this putative 4th cycle type Great Lakes Gull (Great Black-backed x Herring).

Manitowoc, Wisconsin. 15 July 2016.

The darker Herring type on the left is our presumed hybrid/backcross.
There's at least one other theory beside the hybrid possibility: A sub-adult Herring that has darker upperparts than a definitive adult.
  • 3rd/4th cycle types (and even presumed young adults?) do at times show darker gray upperparts to some extent, although I've never seen one that was this obviously dark (see open wing photos). Martin Reid made an astute comment suggesting frayed and worn feathers also appear darker, and this is likely due to a collection of shadows that are combined for a darker effect.



A 4th cycle "type" wingtip pattern not out of range for Herring.


Size and structure wasn't too helpful as the bird was also within range for Herring, although a bit bulgy (think Great Cormorant bulgy...). But then again, the presumed Great Lakes Gulls I've seen have ranged in size from Herring to typical Great Black-backed...

I think it may be best to leave this individual unidentified.


Summering Franklin's Gulls

It's unusual to have more than 1-2 Franklin's on Lake Michigan in the summer months, and so the 7-8 birds that have been in the Manitowoc impoundment since late May are quite special. All appear to be 1st summer individuals (~ 1 year olds), undergoing their 2nd presbasic molts.

This individual nicely shows an "average" molt pattern seen on this contingent of FRGUs.

FRGU #1
P1-P5 fully grown, P6 half grown. P7 dropped. P8-P10 retained (1st alternate).
The thinking behind 1-year olds like this is that they migrated to South America last fall, molted their juvenile (1st basic) flight feathers via a complete prealternate molt (PA1). Some time during (or slightly before) their northbound migration the 2nd prebasic molt commenced, and viola, a 3rd generation of primaries (P1-P6) and secondaries are grown. It's also possible that PB2 begins once the breeding grounds (or summering grounds) are reached. This is what makes Franklin's Gull a standout gull - two complete molts in roughly 12 months!

But then there are Franklin's - for reasons we don't know, and probably will never know - that don't molt any flight feathers in PA1 on the winter grounds, or may have incomplete/suspended PA1 molts when we see them in their 1st summer.

Here's an example (Illinois. 04 July 2010):

3 retained juvenile primaries. P1-P7 new via 1st prealternate molt. Whether this prealternate molt is incomplete, suspended or ongoing isn't clear. Only two new outer secondaries (S1-S2) and retained outer rectrices. 
It's suspected these absent/incomplete PA molts are tied to the amount of food (or lack thereof) on the winter grounds, but I digress. Back to the Manitowoc birds...this one decided it wanted to renew p8-p9 before growing p6, or dropping p7 altogether! 

FRGU #2
P1-P5 new (B2). P6 dropped. P7 old (A1). P8-P9 new (B2). P10 old (A1).
I've labeled what I presume is happening here:

Note it may be P6 that's retained 1st alternate and P7 dropped. Nonetheless, it's interesting to see P8-P9 have been renewed "out of order".

My favorite Franklin's of the group, this individual showing 3 generations of primaries.

FRGU #3
P1-P5 new (2nd basic). P6 dropped. P7-P9 1st alternate. P10 juvenile (=1st basic)! 
P-molt in this age group of Franklin's Gulls in the summer months is somewhat variable. It's too bad we don't have more detailed profiles of known-age, banded, birds from the colonies they're born in. This would be a great project for anyone interested in molt and gulls!!

01 July 2016

Monthly Notables June 2016

  • Little Gull (1st summer). Cayuga County, New York. 01 June 2016.
  • Western Gull (adult type). Costilla County, Colorado. 04 June 2016.
  • Lesser Black-backed Gull (1st summer). Portage, Manitoba. 07 June 2016.
  • Iceland Gull (1st summer). York County, Maine. 07 June 2016.
  • Glaucous Gull (1st summer). Pinelaas County, Florida. 10 June 2016.
  • Thayer's Gull (1st summer). Clallam County, Washington. 11 June 2016.
  • Franklin's Gull (1st summer type). Barnstable County, Massachusetts. 12 June 2016.
  • Western Gull (2nd summer type). Washington County, Colorado. 17 June 2016.
  • California Gull (2nd summer type). Kenai Peninsula County, Alaska. 17 June 2016.
  • Lesser Black-backed Gull (1st summer). Washington County, Colorado. 17 June 2016.
  • Franklin's Gull (2nd summer type). Barnstable County, Massachusetts. 23 June 2016.
  • Franklin's Gull (1st summer type). Leon County, Florida. 30 June 2016.

June 2016 Quiz


Age

Both of our gulls appear to have mostly new upperparts, although notice some feathers have been dropped and others are actively growing (namely, lesser/greater coverts and lower tertials on the left bird). The tertial patterns appear to be 2nd generation on both individuals, but the outermost primaries that are visible have an old "brownish" aspect. These primaries are juvenile feathers (=1st basic). Therefore we can comfortably assume both birds are molting from 1st to 2nd cycle and are roughly a year old (2nd calendar year).

Identification

The disparity in size among these two individuals will most definitely be a deciding factor in assigning labels. The gull on the left has a genuinely hefty bill and legs with remarkable girth. The head is proportionally large and the body is reminiscent of a duck. All of these structural features, along with the ghost-white head and solid dark upperparts point directly to Great Black-backed Gull. The bird on the right looks like a mini version of the Great Black-backed but with a slimmer bill and more attenuated look to the rear - a classic Lesser Black-backed type. The heavy "grease" stain (or neck boa) on the lower hind-neck of the Lesser Black-backed is often present in this age group.

This photo was taken in Barnstable County, Massachusetts in mid-July. 


28 June 2016

Sheboygan Gulls - Late June

For a small Midwestern town that sits on the western shore of Lake Michigan, Sheboygan, Wisconsin can hold relatively nice numbers of larids in the summer months (primarily May-July). I recorded 7 species there on Friday, missing an 8th species (Franklin's Gull) seen by others.

  1. Little Gull (5-6)
  2. Bonparte's Gull (700+)
  3. Laughing Gull (2)
  4. Ring-billed Gull (200+). Breeder.
  5. Herring Gull (125+). Breeder.
  6. Lesser Black-backed Gull (23+)
  7. Great Black-backed Gull (2)

So what would attract these birds to Lake Michigan in late June? Sheboygan sits well south of the breeding grounds of species like Bonaparte's, Little Gull, and presumably Lesser Black-backed Gull. And aren't Great Black-backs and Laughing Gulls coastal species?


Eat & Molt - Simple

The majority of the unexpected gulls here are sub-adults that are in the midst of a complete molt (prebasic molt) and have no pressing reason to situate themselves among a colony of conspecifics. So long as a reliable food source is available - and a reliable food source there is - the gulls summer here under low-pressure conditions, and complete their molts.

LBBG. Sheboygan, WI. 24 June 2016.


This bird has begun its 2nd prebasic molt. Three inner primaries have been renewed, with the fourth primary about half grown.The greater upperwing coverts have been dropped exposing the white bases to the secondaries. A mostly complete set of new median wing coverts is visible too.










On a "good" year like this, the food source is no other than alewives. The young fish are stagnant near shore where they're either close to dying or already have perished. The gulls don't bother with the dead fish. Instead, they go for the "fresh" ones that are almost dead. This makes for easy pickins'.






A 1st summer Bonaparte's with a nice-sized alewife. In front sits a similar-age Little Gull.

Any bird coming this close to shore, allowing this sort of approach, must have something good it wants to eat.


This Lesser Black-backed Gull made the whole process look easy...

Greater Lessers than All the Land of Great Lakes

Speaking of Lesser Black-backeds, I know of no other site on the Great Lakes where one can easily find 20+ individuals loafing around on one beach in the breeding season. In one scan I counted 23 birds (all 1st and 2nd summer), but I'm sure I saw over 30 on this day (photographs show unique 3rd summer types that weren't counted with the 23 scan).

Yes, Lessers! How many? My count is 15.
Young Lesser Black-backs can be a bit tricky to nail, especially since many of the 1st summer Herrings can show solid, dark upperparts on their 2nd generation feathers.

How many Lessers in this image? I can't confidently make out a single one.
Many 1st/2nd summer Lessers retain more black on the bill, like this one of the left (although NOT always). Also note the longer wing projection and attenuated look to the rear. The other two are Herrings (notice the right bird has lighter gray scapulars that have recently grown in).
From left to right: Herring, Herring, Lesser, Lesser, Herring, Herring, Lesser. The stuctural clues on the LBBGs is primaries that project farther pass the tail, smaller heads and straighter bills (but not necessarily shorter).

Little Gull numbers here aren't too shabby either. Sheboygan and Manitowoc, Wisconsin are among the top 5 sites on the Great Lakes to see this species in summer.

Two Little Gulls with similar-aged Bonaparte's in the background.

Little Gull with new greater coverts grown in. Two Bonaparte's in the back.
Soon the alewives will be virtually non-existent on the lakefront...by late July/early August most of these birds will have moved on.

07 June 2016

Turning Point Herring Colony



Myself & Tim working on PINK 86.
Photo by Bruce Buckingham.
Last Friday, Cleveland wildlife rehabber Tim Jasinski and I joined Bruce Buckingham, a research technichian with USDA Wildlife Services, for a morning of Herring Gull chick banding at the Turning Point colony in Sandusky, Ohio.




The colony, which holds about 900 pairs, sits slightly off shore on Lake Erie. Bruce has been banding birds here, and Herrings in particular, since the early 1980s. Very exciting is his recent use of "pink" field readable bands on some of his HERGs. Color bands are proven - for obvious reasons - to yield greater resights.








Keep your eyes peeled for these pink bands.








The colony's breeding progression was all over the place in terms of egg-laying, incubating and feeding young. More than half of the adults appeared to already have chicks running around, many with 3 chicks. But still, there were a number of late nesters still on eggs.





Turning Point Colony. Multi-tier colony with egrets and cormorants nesting above in the trees and Herring Gulls on the ground beneath the canopy.

Adult Herring with federal band.
Photo by Tim Jasinski.



Tim was very keen on finding previously banded adults. It takes some finesse and a fair deal of patience to record an entire band sequence. Fortunately, the birds aren't very inclined to take off or abandon the site.








Adult with what is likely Chick A (still incubating). Photo by Tim Jasinski
Parent with, presumably, its 3 chicks. Leftmost chick is likely Chick C. Photo by Tim Jasinski.
 Photo by Tim Jasinski.
Ouch! Watch the eye...Photo by Tim Jasinski.

The next few photos demonstrate varying fledgling stages:

Likely a day or two old. 
Maybe 5-6 days old.
One of the more advanced chicks we spotted. This bird
is showing many "true" juvenile scapulars and wing coverts (1st basic).

Same individual above. Rectrices still haven't
unfurled from their sheaths.
Bruce wins the "best t-shirt" contest.

Tim in the zone with Pink 86 (er, 98...)
The colony here is one of the neatest I've had the pleasure of visiting. I found the terrain really enchanting. The gulls are perfectly fine living in the "basement" with their neighbors "upstairs" (cormorants and egrets) occasionally dropping fish parts, and even entire fish from above. That wasn't the only thing they were dropping from above...

So much to observe. So much to learn. So little time. Yours truly waiting on a banded adult to come a bit closer. Photo by Tim Jasinski.

A big thanks to Bruce for his invite and generosity. His dedication to understanding these birds and his curiosity is contagious and admirable!

04 June 2016

What's That On Your Bill?

June is here and many adult gulls are busy tending to their newly hatched young. These semi-precocial fuzzballs can be unrelenting when ordering up a morsel.

Adult Ring-billed having just delivered "fresh" bolus to its three chicks. 
East Chicago, Indiana. June.


Juvenile Great Black-backed Gull patiently waiting next to its mother. A vibrant red gonys spot decorates the adult's bill tip.

Appledore Island. Maine. July.
The gonydeal spot is thought to have evolved as a prodding stimulus to help chicks focus their solicitation when begging for food (Tinbergen 1950). In effect, chicks nudge or peck their parents which usually results in food being regurgitated from the crop, or proventriculus. Bill pecking may also serve as a cue for adults to vary their diet accordingly (note that some females peck at the male's bill, although near the bill-base and gape instead of the tip). Interestingly, the tip of the bill is suspected of being more sensitive than any other part of the bill (Ferns & Smith 2009).

Gonys spots are only found on some of the so-called large white-headed gulls (for example, Herring Gull, Glaucous Gull and the like). Recent gull phylogonies show this group of gulls is youngest. The medium and small-sized gulls don't show gonys spots (for example, Ring-billed, Mew Gull and all of the hooded gulls).

Do you recognize any of these handsome adults? How many
show a gonys spot? © Amar Ayyash

Hatch year gulls never show a gonys spot.© Amar Ayyash


Not All Gonys Spots Are Created Equal

There's no apparent size differences in adult gonys' spots based on sex or age, intraspecifically. There is, however, an appreciable difference in size from species to species.

Lesser Black-backed Gulls, such as this adult type, often have red creeping onto the upper mandible. This species can show an obscenely large gonys spot. New Buffalo, Michigan. October.
For having such a wide gonydeal expansion, Western Gulls average small gonys spots.
Half Moon Bay, California. September.

American Mew Gull (L.c.brachyrhynchus) with a smidgen
of a false gonys spot. Seattle, Washington. January.

Mew Gulls (particularly Asian Kamchatka Gulls) often show pseudo gonys spots. These are nothing more than an insignificant smudge of the "right" mixture of colors (perhaps just a result of yellow, black and gray expressing themselves simultaneously?).





Adult Thayer's Gull. Ocean Shores, Washington. December.







In nonbreeding condition, Thayer's Gulls often show an orange-red gonys spot. The accompanying "saddle spot" on the upper mandible is a bill pattern that has many a time assisted me in picking out this species.



 Adult California Gull. Seattle, Washington. January.




A classic California Gull in non-breeding condition showing its famous red/black bill pattern. The black coloration vanishes in the breeding season when hormones are raging.

Herring Gull (2nd summer). Cape Cod. Massachusetts. July.



An individual that's far from ready to breed, this advanced 2nd summer Herring Gull (molting into 3rd basic) is beginning to show a red gonys spot.







Many chicks discontinue bill-pecking at around 10 days old. Appledore Island. Maine. July.

Spotless

I'm sure you're asking yourself the best question one can ask at this point, "Why do some gull taxa have gonys spots, and others not?". Don't the chicks of other species need to prod their parents to encourage feeding? Yes, but perhaps they achieve this in a similar way.

Franklin's Gull (near-adult type) and Ring-billed Gull (adult). Two examples of gull species that never show red gonydeal spots. Chicago, Illinois. March.

A number of species that lack a gonys spot still show some type of marking or bi-coloration near the bill tip. The young of Sabine's Gulls reportedly peck at the divide between black and yellow on their parent's bills (BNA 2015) and Ring-billed Gull chicks readily aim for the obvious black subterminal band on adults (pers obs.) These contrasting patterns are all believed to serve a similar purpose to that of the red gonys spot.



Adult Ivory Gull with a standard grayish bill and bright yellow tip. Such bill patterns have multi-purposes. In addition to stimulating begging chicks, the patterns lure aquatic prey and also serve as fitness indicators in selection.

Quincy, Illinois. January. 





Note the bright red tip on this adult type Franklin's Gull. Most fascinating, chicks of this species (between the ages of 4 hours and 4.5 days old) responded much more readily to red colored cardboard bills (attached to gull head models) than they did to other colors (Collias and Collias 1957). 

Chicago, Illinois. March.




The pattern is reversed on this adult Heermann's Gull - a black tip that contrasts sharply with an all red bill.

San Francisco, California. January.

To Feed Or Not To Feed

Still, there are curious questions regarding bill patterns in gulls. What about species with entirely uniform colored bills - kittiwakes for instance? Adults in the genus Rissa have all-yellow bills with not the slightest trace of any bi-coloration. These steep cliff nesters are sufficiently different than most other gulls. I've always found it interesting that hatch year kittiwakes don't have cryptic brown juvenile feathers.  Further, 1st cycle Red-legged Kittiwakes are the only juvenile gulls we know of that are without any hint of a tail band. Oddly, young kittiwakes don't commonly run off and abandon the nest when threatened, as do the chicks of larger gull species (Cullen 1957). Kittiwakes are known to have smaller clutches (~98% of Red-legged Kittiwakes produce a single egg clutch. Black-legged Kittiwakes average 2 egg clutches) and they typically feed their chicks throat-to-mouth, similar to true seabirds.

Herring Gulls, like other large gull species, average 3 eggs per clutch. East Chicago, Indiana. June.


Herring Gull chick no more than 3-4 days old. 
Sandusky, Ohio. June.

Ferns & Smith have presented convincing evidence that the larger gulls have proportionally small eggs, resulting in relatively small chicks at the time of hatching. Therefore, the young have inherited a great need to grow and develop quickly in the few precious days after hatching. Beside hatching with cryptic-colored plumes, the red gonys spot is an additional vehicle that large gulls have evolved in order to bolster these ambitious fledglings.









References
Tinbergen, N. & Perdeck, A.C. 1950. On the Stimulus Situation releasing and the begging response in newly hatched Herring Gull chick. Behaviour 3: 1-39.

Birds of North America (http:www.bna.birds.cornell.edu/bna) 29 May 2016.

Howell, SNG & Dunn, J. 2007. Peterson Reference Guide to the Gulls of the Americas.

Coulson, J. 2011. The Kittiwake.

Ferns, P.N. & Ross-Smith, V.H. 2009. Function of Coloured Bill Tips, Stripes, and Spots in Breeding Gulls. Marine Ornithology 37:85-92.